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Abstract:
Keywords: Muscular strength, weightlessness, astronaut performance, torque
Abstract: Strength, the capability to produce an external force, is one of the most important determining characteristics of human performance. Knowledge of strength capabilities of a group of individuals can be applied to designing equipment and workplaces, planning procedures and tasks, and training individuals. In the space program, with the high risk and cost associated with spaceflight, information pertaining to human performance is important to ensure mission success and safety. Knowledge of individuals' strength capabilities in weightlessness is of interest to NASA, including workplace design, tool development, and mission planning. The weightless environment of space places the human body in a completely different context. Astronauts perform a variety of manual tasks while in orbit. Their ability to perform these tasks is partly determined by their strength capability as demanded by that particular task. An important step in task planning, development, and evaluation is to determine the ability of the humans performing it. This can be accomplished by using quantitative techniques to develop a database of human strength capabilities in weightlessness. If strength characteristics are known, equipment and tools can be built to optimize the operators' performance. There is a spectrum of ways of looking at strength, from basic research to applied engineering. This study examined strength in performing a simple task, specifically, using a tool to apply a torque to a fixture.
Keywords: students, Texas Fly High Program; KC-135 aircraft; weightlessness; vehicle, recovery; Space Station; interactive control; control equipment
Abstract: This report was created by students from Longview High School, Longview, Texas. Longview High School was selected from a group of Texas high schools to participate in the 1999 Texas Fly High Program. This program gives Texas high school students a chance to work with NASA engineers to design and fly a real-world experiment aboard the KC-135 during zero-g parabolas. Jeffrey Fox’s role was to provide a concept for the experiment and to mentor the students in its design and testing. The students were responsible for executing all phases of the project. The X-38 Project Office at the Lyndon B. Johnson Space Center Johnson Space is designing a crew return vehicle (CRV) to be docked at the International Space Station for crew rescue in an emergency. Vehicle controls will be almost completely automated, but a few functions will be manually controlled. Four crew input control devices were selected for evaluation by Longview High School students as part of the 1999 Texas Fly High program. These were (1) Logitech Trackman Marble (optical trackball), (2) Smart Cat Touchpad, (3) Microsoft SideWinder 3D-Pro Joystick, and (4) Microsoft SideWinder Gamepad. In two flight tests in the KC-135 aircraft and a series of ground tests, the devices were evaluated for ability to maneuver an on-screen cursor, level of accuracy, ease of handling blind operations, and level of user comfort in microgravity. The tests results led to recommendation of further tests with the Joystick and the Trackman by astronauts and actual space station residents.
Keywords: orbital debris; space debris; aerogel; orbital debris collector; microscopes; spectroscopy
Abstract: The Mir Environmental Effects Package (MEEP) was deployed on the Mir station and retrieved after 18 months in space. The payload included the orbital debris collector (ODC), designed and built at the Johnson Space Center to capture and return analyzable residues of the manmade and natural particulate environment in low-Earth orbit for a detailed assessment of its compositional makeup and potential origins. The ODC exposed 2 identical trays, with highly porous, low-density Si02 aerogel as the basic collector medium, pointed in opposite directions. The aerogel was expected to gently decelerate and capture hypervelocity particles, as opposed to other media that resulted in melting or vaporization of many impactors. Even cursory examination of the returned ODC collectors revealed a surprising variety of impact features. The compositional analyses using scanning electron microscope-energy-dispersive X-ray spectroscopy concentrated on a survey-type inventory of diverse particle types and associated impact features. Detections, in the form of carrot-shaped tracks and shallow pits, included metallic Al, stainless steel, soldering compounds, human waste, and paint flakes. Many pits contained no detectable impactor residue (it was assumed to have vaporized), but most of the tracks contained analyzable residue. The study showed that aerogel would be useful for future low-velocity impact analysis.
Keywords: decompression sickness, decompression models, survival models, meta-analysis, rapid decompression, aircraft operations
Abstract: Estimating the risk of decompression sickness (DCS) in aircraft operations remains a challenge, making the reduction of this risk through the development of operationally acceptable denitrogenation schedules difficult. In addition, the medical recommendations which are promulgated are often not supported by rigorous evaluation of the available data, but are instead arrived at by negotiation with the aircraft operations community, are adapted from other similar aircraft operations, or are based upon the opinion of the local medical community. We present a systematic approach for defining DCS risk in aircraft operations by analyzing the data available for a specific aircraft, flight profile, and aviator population. Once the risk of DCS in a particular aircraft operation is known, appropriate steps can be taken to reduce this risk to a level acceptable to the applicable aviation community. Using this technique will allow any aviation medical community to arrive at the best estimate of DCS risk for its specific mission and aviator population and will allow systematic reevaluation of the decision regarding DCS risk reduction when additional data are available.
Keywords: solar arrays, plumes, momentum transfer, rarefied gas dynamics
Abstract: Measurements of momentum transfer coefficients were made for gas-surface interactions between the Space Shuttle reaction control jet plume gases and the solar panel array materials to be used on the International Space Station. Actual conditions were simulated using a supersonic nozzle source to produce beams of the gases with approximately the same average velocities as the gases have in the Shuttle plumes. Samples of the actual solar panel materials were mounted on a torsion balance that was used to measure the force exerted on the surfaces by the molecular beams. Measurements were made with H2, N2, CO, and CO2 incident upon the solar array material, Kapton, SiO2-coated Kapton, and Z93-coated Al. The measurements showed that molecules scatter from the surfaces more specularly as the angle of incidence increases and that the scattering behavior has a strong behavior has a strong dependence upon both the incident gas and velocity. These results show that for some technical surfaces the simple assumption of diffuse scattering with complete thermal accommodation is entirely is entirely inadequate. It is clear that additional measurements are required to produce models that more accurately describe the gas-surface interactions encountered in rarefied flow regimes.
Keywords: man environment interactions; environment pollution; space pollution; earth orbital environments; orbital debris; pollution; space debris
Abstract: Before 1990, knowledge of the orbital debris environment could be broken down into 2 size regimes. For low Earth orbiting objects larger than 10-20 cm in diameter, the U.S. Space Command maintains a catalog which includes debris as well as satellites and rocket bodies. The diameter limit is the result of the wavelengths and sensitivities of the radars used. To better characterized the orbital debris environment, NASA began using the DOD-funded Haystack radar; in return, NASA paid for the construction of the Haystack auxiliary radar. The Haystack Orbital Debris Data Review Panel was established in 1996 to consider the adequacy of the data on orbital debris gathered over the past several years with the Haystack radar, and the accuracy of the methods used to estimate the flux vs. size relationship for this debris. This paper discusses specific issues addressed by the Panel, interpretation of these issues, the current status of the measurement and analysis program NASA is conducting, the statistical aspects in use of the Haystack radar data, the Panel's conclusions on these issues, and recommendations.
Keywords: motion, motion perception, perception, control, adaptive control
Abstract: The purpose of this report is to identify the essential characteristics of goal-directed whole-body motion. The report is organized into three major sections. Section 2 reviews general themes from ecological psychology and control-systems engineering that are relevant to the perception and control of whole-body motion. These themes provide an organizational framework for analyzing the complex and interrelated phenomena that are the defining characteristics of whole-body motion. Section 3 applies the organizational framework from the first section to the problem of perception and control of aircraft motion. This is a familiar problem in control-systems engineering and ecological psychology. Section 4 examines an essential but generally neglected aspect of vehicular control: coordination of postural control and vehicular control. To facilitate presentation of this new idea, postural control and its coordination with vehicular control are analyzed in terms of conceptual categories that are familiar in the analysis of vehicular control.
Keywords: seats; levers; spacecraft equipment; spacecraft cabins; spacecraft structures; backrests; resistance; pulling
Abstract: In 1999, a Shuttle crewmember was unable to operate the backrest lever for the lightweight seat in microgravity. It's essential that crewmembers can adjust this backrest lever, which is tilted forward during launch and then moved backward upon reaching orbit. This adjustment's needed to cushion the crew during an inadvertent crash landing situation. JSC's Anthropometric and Biomechanics Facility evaluated the seat controls and provided recommendations on whether the seat lever positions and operations should be modified.The original Shuttle seats were replaced with new lightweight seats whose controls were moved. They designed a 12-person experiment to investigate the amount of pull force exerted by suited subjects, when controls were placed in the front and back of the lightweight seat. Subjects performed the pull test. The results showed that, in general, the subjects were able to pull on the lever at the back position with only about half the amount of force they exerted on the front lever. Also, the subjects wearing pressurized suits were unable to reach the lever when located at the back, and the pull forces diminished about 50% when they wore the pressurized suits. We recommended that levers not be located in the back and that we need further investigation to see whether the front lever could be ajusted to increase the leverage for crewmembers wearing the pressurized suit.
Keywords: data processing; design analysis; factor analysis; postflight analysis; databases; data correlation; data recording; human factors engineering; anomalies; flight optimization; flight safety; adaptive control; systems analysis; data base management system;
Abstract: The space operations incident reporting tool (SOIRT) is an instrument used to record information about an anomaly occurring during flight which may have been due to insufficient and/or inappropriate application of human factors knowledge. Space Shuttle crewmembers participated in a usability test of the tool after missions STS-70 and STS-73. Since NASA currently has no system for continuous collection of this type of information, we developed the SOIRT to report issues such as reach envelope constraints, control operation difficulties, and vision impairments. However, if the SOIRT were to become a formal NASA process, information from crewmembers could be collected in a database and made available to individuals responsible for improving in-flight safety and productivity. Potential benefits include documentation to justify the redesign or development or new equipment or systems, provide the mission planners with a method for identifying past incidents, justify the development of timelines and mission scenarios, and require the creation of more appropriate work and rest cycles.
Keywords: space station; health; space crews; rescue operations; medical equipment; medical sciences; medicine; medical personnel; medical services
Abstract: In developing a permanently crewed space station, the importance of medical care has been continually reaffirmed; and the health maintenance facility (HMF) is an integral component. It has diagnostic, therapeutic, monitoring, and information management capability. It is designed to allow supportive care for non-life-threatening illnesses, moderate to severe, possibly life-threatening illnesses; and severe, incapacitating, life-threatening illnesses. Since the HMF will not have a general surgical capability, the need for emergency escape and recovery methods has been studied. Medical risk assessments have determined that it is impossible to accurately predict the incidence of cremember illness or injury. A best estimate is 1:3 per work-year, with 1 percent of those needing an ACRV. For an eight-person crew, this means that one ACRV will be used every 4 to 12 years. The ACRV would serve atleast three basic objectives as a crew return if the Shuttle is unavailable; an escape vehicle from a major time-critical space station emergency; and a full or partial crew return vehicle for a medical emergency. The focus of this paper is the third objective for the ACRV.
Keywords: fuel, solid fuel, diffusion flame, extinction, gas-phase radiation, kinetics, surface radiation
Abstract: This is the first attempt to analyze both radiation and detailed kinetics on the burning and extinction of a solid fuel in a stagnation-point diffusion flame. We present a detailed and comparatively accurate computation model of a solid fuel flame along with a quantitative study of the kinetics mechanism, radiation interactions, and the extinction limits of the flame. A detailed kinetics model for the burning of solid trioxane (a trimer of formaldehyde) is coupled with a narrowband radiation model with carbon dioxide, carbon monoxide, and water vapor as the gas-phase participating media. The solution of the solid trioxane diffusion flame over the flammable regime is presented in some detail, as this is the first solution of a heterogeneous trioxane flame. We then compare the adiabatic solution to solutions that include the surface radiation only and gas-phase and surface radiation using a black surface model. The analysis includes discussion of detailed flame chemistry over the flammable regime and, in particular, at the low stretch extinction limit. We emphasize the low stretch regime of the radiatively participating flame, since this is the region representative of microgravity flames. When only surface radiation is included, two extinction limits exist, and the burning rate and maximum flame temperatures are lower, as expected. With the inclusion of surface and gas-phase radiation, results show that, while flame temperatures are lower, the burning rate of the trioxane diffusion flame may actually increase at low stretch rate due to radiative feedback from the flame to the surface.
Keywords: Expert Systems, Programming Languages, Computer Techniques
Abstract: Expert systems are computer programs which emulate human expertise in well defined problem domains. The potential payoff from expert systems is high: valuable expertise can be captured and preserved, repetitive and/or mundane tasks requiring human expertise can be automated, and uniformity can be applied in decision making processes. The C Language Integrated Production System (CLIPS) is an expert system building tool, developed at the Johnson Space Center, which provides a complete environment for the development and delivery of rule and/or object based expert systems. CLIPS was specifically designed to provide a low cost option for developing and deploying expert system applications across a wide range of hardware platforms. The development of CLIPS has helped to improve the ability to deliver expert system technology throughout the public and private sectors for a wide range of applications and diverse computing environments. The Third Conference on CLIPS provided a forum for CLIPS users to present and discuss papers relating to CLIPS applications, uses, and extensions.
Keywords: Apollo, Apollo Lunar Experiment Module, reduced gravity, manned lunar surface vehicles, lunar dust, lunar roving vehicles, astronauts, tools
Abstract: This catalog reviews Apollo mission reports, preliminary science reports, technical crew debriefings, lunar surface operations plans, and various relevant lunar experiment documents, collecting engineering- and operation-specific information by experiment. It is organized by discrete experimental and equipment items emplaced or operated on the lunar surface or at zero gravity during the Apollo missions. It also attempts to summarize some of the general problems encountered on the surface and provides guidelines for the design of future lunar surface experiments with an eye toward operations. Many of the problems dealt with on the lunar surface originated from just a few novel conditions that manifested themselves in various nasty ways. Low gravity caused cables to stick up and get caught on feet, and also made it easy for instruments to tip over. Dust was a problem and caused abrasion, visibility, and thermal control difficulties. Operating in a pressure suit limited a person's activity, especially in the hands. I hope to capture with this document some of the lessons learned from the Apollo era to make the jobs of future astronauts, principle investigators, engineers, and operators of lunar experiments more productive.
Keywords: eye movements; image processing; algorithms; eyes; pupils; pupil size; least squares method; centroids;
Abstract: This paper describes a video eye-tracking algorithm which searches for the best fit of the pupil modeled as a circular disk. The algorithm is robust to common image artifacts such as the droopy eyelids and light reflections while maintaining the measurement resolution available by the centroid algorithm. The presented algorithm is used to derive the pupil size and center coordinates, and can be combined with iris-tracking techniques to measure ocular torsion. A comparison search method of pupil candidates using pixel coordinate reference lookup tables optimizes the processing requirements for a least square fit of the circular disk model. This paper includes quantitative analyses and simulation results for the resolution and the robustness of the algorithm. The algorithm presented in this paper provides a platform for a noninvasive, multidimensional eye measurement system which can be used for clinical and research applications requiring the precise recording of eye movements in three-dimensional space.
Keywords: mass; extravehicular activity; postural control; human-environment interactions; nested control systems
Abstract: This report describes the theoretical and operational foundations for our analysis of skill in extravehicular mass handling. A review of our research on postural control, human-environment interactions, and exploratory behavior in skill acquisition is used to motivate our analysis. This scientific material is presented within the context of operationally valid issues concerning extravehicular mass handling. We describe the development of meaningful empirical measures that are relevant to a special class of nested control systems: manual interactions between an individual and the substantial environment. These measures are incorporated into a unique empirical protocol implemented on NASA's principal mass handling simulator, the precision air-bearing floor, in order to evaluate skill in extravehicular mass handling. We discuss the components of such skill with reference to the relationship between postural configuration and controllability of an orbital replacement unit, the relationship between orbital replacement unit control and postural stability, the relationship between antecedent and consequent postural movements. Finally, we describe our expectations regarding the operational relevance of the empirical results as it pertains to extravehicular activity tools, training, monitoring, and planning.
Keywords: mass; extravehicular activity; postural control; human-environment interactions; nested control systems
Abstract: In this report we describe the details of our empirical protocol for investigating skill in extravehicular mass handling using NASA's principal mass handling simulator, the precision air-bearing floor. Contents of this report include a description of the necessary modifications to the mass handling simulator; choice of task; and the description of an operationally relevant protocol. Our independent variables are presented in the context of the specific operational issues they were designed to simulate. The explanation of our dependent variables focuses on the specific data processing procedures used to transform data from common laboratory instruments into measures that are relevant to a special class of nested control systems (discussed in Volume I): manual interactions between an individual and the substantial environment. The data reduction is explained in the context of the theoretical foundation described in Volume I. Finally, as a preface to the presentation of the empirical data in Volume III of this report series, a set of detailed hypotheses is presented.
Keywords: pressure reduction; decompression sickness; hypobaric atmospheres; altitude chamber; tissue ratio; extravehicular activity
Abstract: It is important to understand the risk of serious hypobaric decompression sickness (DCS) to develop procedures and treatment responses to mitigate the risk. Since it is not ethical to conduct prospective tests about serious DCS with humans, the necessary information was gathered from 73 published reports. We hypothesize that a 4-hr 100% oxygen (O2) prebreathe results in a very low risk of serious DCS, and test this through analysis. We evaluated 258 tests containing information from 79,366 exposures in altitude chambers. Serious DCS was documented in 918 men during the tests. A risk function analysis with maximum likelihood optimization was performed to identify significant explanatory variables, and to create a predictive model for the probability of serious DCS. Useful variables were Tissue Ratio, the planned time spent at altitude, and whether or not repetitive exercise was performed at altitude. A prebreathe and decompression profile Shuttle astronauts use for extravehicular activity (EVA) includes a 4-hr prebreathe with 100% O2, an ascent to P2 = 4.3 lb per sq. in. absolute, and a Talt = 6 hr. Given 100 Shuttle EVAs to date and no report of serious DCS, the true risk is less than 0.03 with 95% confidence. It is problematic to estimate the risk of serious DCS since it appears infrequently, even if the estimate is based on thousands of altitude chamber exposures. The true risk to astronauts may lie between the extremes of the confidence intervals since the contribution of other factors, particularly exercise, to the risk of serious DCS during EVA is unknown. A simple model that only accounts for four important variables in retrospective data is still helpful to increase our understanding about the risk of serious DCS.
Keywords: Vlasov-Maxwell Equation; equations; Vlasov Equations; Maxwell Equations; electron distribution; Jacobi Equation; hypergeometric functions
Abstract: A spectral method algorithm is developed for the numerical solution of the full six-dimensional Vlasov-Maxwell system of equations. Here, the focus is on the electron distribution function, with positive ions providing a constant background. The algorithm consists of a Jacobi polynomial-spherical harmonic formulation in velocity space and a trigonometric formulation in position space. A transform procedure is used to evaluate nonlinear terms. The algorithm is suitable for performing moderate resolution simulations on currently available supercomputers for both scientific and engineering applications.
Keywords: histories; documentation; records; simulator; simulation; thermal-vacuum; vacuum; rotation; temperature; mobility; lunar; environment; laboratory
Abstract: Few undertakings in the history of humanity can compare to the great technological achievement known as Project Apollo. Among those who witnessed Armstrong’s flickering television image were thousands of people who had directly contributed to this historic moment. Amongst those in this vast anonymous cadre were the personnel of the Space Environment Simulation Laboratory (SESL) at the Manned Spacecraft Center (MSC) in Houston, Texas. SESL houses two large thermal-vacuum chambers with solar simulation capabilities. At a time when NASA engineers had a limited understanding of the effects of extremes of space on hardware and crews, SESL was designed to literally create the conditions of space on Earth. With interior dimensions of 90 feet in height and a 55-foot diameter, Chamber A dwarfed the Apollo command/service module (CSM) it was constructed to test. The chamber’s vacuum pumping capacity of 1 x 10-6 torr can simulate an altitude greater than 130 miles above the Earth. A lunar plane capable of rotating a 150,000-pound test vehicle 180 deg replicates the revolution of a craft in space. To reproduce the temperature extremes of space, interior chamber walls cool to -280°F as two banks of carbon arc modules simulate the unfiltered solar light/heat of the Sun.With capabilities similar to that of Chamber A, early Chamber B tests included the Gemini modular maneuvering unit, Apollo EVA mobility unit and the lunar module. Since Gemini astronaut Charles Bassett first ventured into the chamber in 1966, Chamber B has assisted astronauts in testing hardware and preparing them for work in the harsh extremes of space.
Keywords: radiation, galactic cosmic rays, fluence, radiation absorption, radiation shielding, radiation transport
Abstract: space radiation transport models for shielding applications. The NASA space radiation transport model now predicts dose and dose equivalent in Earth and Mars orbit to an accuracy of +20%. However, larger error may occur in particle fluence predictions and there is interest in further assessments and improvements in NASA’s space radiation transport model. In this paper we consider the effects of the isotopic composition of the primary galactic cosmic rays (GCR) and the isotopic dependence of nuclear fragmentation cross-sections on the solution to transport models used for shielding studies. Satellite measurements are used to describe the isotopic composition of the GCR. Using NASA’s quantum multiple-scattering theory of nuclear fragmentation (QMSFRG) and high-charge and energy (HZETRN) transport code, we study the effect of the isotopic dependence of the primary GCR composition and secondary nuclei on shielding calculations. The QMSFRG is shown to accurately describe the iso-spin dependence of nuclear fragmentation. The principle finding of this study is that large errors (+100%) will occur in the mass-fluence spectra when comparing transport models that use a complete isotopic-grid (~170 ions) to ones that use a reduced isotopic-grid, for example the 59 ion-grid used in the HZETRN code in the past, however less significant errors (<20%) occur in the elemental-fluence spectra. Because a complete isotopic-grid is readily handled on small computer workstations and is needed for several applications studying GCR propagation and scattering, it is recommended that they be used for future GCR studies.
Keywords: decompression sickness, extravehicular activity, Hypobaric Decompression Sickness Databank, Cox proportional hazards model, censoring, frailty model, model validation
Abstract: In this paper we fit Cox proportional hazards models to a subset of data from the Hypobaric Decompression Sickness Databank. The data bank contains records on the time to decompression sickness (DCS) and venous gas emboli (VGE) for over 130,000 person-exposures to high altitude in chamber tests. The subset we use contains 1,321 records, with 87% censoring, and has the most recent experimental tests on DCS made available from Johnson Space Center. We build on previous analyses of this data set by considering more expanded models and more detailed model assessments specific to the Cox model. Our model, which is stratified on the quartiles of the final ambient pressure at altitude, includes the final ambient pressure at altitude as a nonlinear continuous predictor, the computed tissue partial pressure of nitrogen at altitude, and whether exercise was done at altitude. We conduct various assessments of our model, many of which are recently developed in the statistical literature, and conclude where the model needs improvement. We consider the addition of frailties to the stratified Cox model, but found that no significant gain was attained above a model that does not include frailties. Finally, we validate some of the models that we fit.
Keywords: glovebox, foot restraint, microgravity, posture, restraint, interfaces
Abstract: Various gloveboxes (GBXs) have been used aboard the Shuttle and ISS. Though the overall technical specifications are similar, each GBX's crew interface is unique. JSC conducted a series of ergonomic evaluations of the various glovebox designs to identify human factors requirements for new designs to provide operator commonality across different designs. We conducted 2 0g evaluations aboard the Shuttle to evaluate the material sciences GBX and the General Purpose Workstation (GPWS), and a KC-135 evaluation to compare combinations of arm hole interfaces and foot restraints (flexible arm holes were better than rigid ports for repetitive fine manipulation tasks). Posture analysis revealed that the smallest and tallest subjects assumed similar postures at all four configurations, suggesting that problematic postures are not necessarily a function of the operator’s height but a function of the task characteristics. There was concern that the subjects were using the restrictive nature of the GBX’s cuffs as an upper-body restraint to achieve such high forces, which might lead to neck/shoulder discomfort. EMG data revealed more consistent muscle performance at the GBX; the variability in the EMG profiles observed at the GPWS was attributed to the subjects’ attempts to provide more stabilization for themselves in the loose, flexible gauntlets. Tests revealed that the GBX should be designed for a 95 percentile American male to accommodate a neutral working posture. In addition, the foot restraint with knee support appeared beneficial for GBX operations. Crew comments were to provide 2 foot restraint mechanical modes, loose and lock-down, to accommodate a wide range of tasks without egressing the restraint system. Thus far, we have developed preliminary design guidelines for GBXs and foot restraints.
Keywords: symmetry, transformations, regions, models, robotics, translational motion
Abstract: This paper discusses the problem of automatically generating stable grasp regions for a robotic end effector on a target object, given a model of the end effector and the object. In order to generate grasping regions, an initial valid grasp transformation from the end effector to the object is obtained based on form closure requirements, and appropriate rotational and translational symmetries are associated with that transformation in order to construct a valid, continuous grasping region. The main result of this algorithm is a list of specific, valid grasp transformations of the end effector to the target object, and the appropriate combinations of translational and rotational symmetries associated with each specific transformation in order to produce a continuous grasp region.
Keywords: Hubble Space Telescope, orbital replacement units, extravehicular activity, spacewalks, International Space Station, zero-g environment, PABF, COSTAR, motion analysis
Abstract: The STS-61 mission was for servicing the Hubble Space Telescope (HST), which had been providing valuable information; but modifications were necessary to correct the degraded performance of several components. In addition to servicing orbital replacement units (ORUs), STS-61 crew members replaced the HST solar arrays and performed other maintenance. Without a correction to the optical flaw, usefulness of the HST in the visible light spectrum would have been less than optimal. Also, although NASA had considerable experience in on-orbit extravehicular activities (EVAs), it had never performed such a quantity of complex EVAs as was scheduled for this mission (5 days of EVA and high demands on the crew members and the ground team); it was to be an indication of NASA preparedness to build and maintain a space station. Quality training, therefore, had to be provided so that there were no significant surprises during the tasks of this mission. The purpose of this study was to validate the training techniques for STS-61 crew members in a simulated zero-g environment and to simulate and monitor the reaction of test subjects who were maneuvering the ORU. It was hoped that this study would provide information concerning whether the crew, while moving ORUs, could react to, and counteract comfortably, those forces imparted by the simple motions of mass and inertia. Four subjects participated in our study; tests were conducted on the PABF; mockups were built to simulate the mass characteristics of the COSTAR . Video cameras obtained video data for motion analysis. The main objective of this study was to determine the forces and moments applied and encountered by test subjects during the RMS run start/stop condition.
Keywords: space debris, space pollution
Abstract:
Keywords: carbon nanotubes, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffractometry, thermogravimetric analysis
Abstract: This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser over process. Most of the procedures are tested using laser-grown, single-wall nanotube material. The material is characterized at each step of the purification procedures by using different techniques including a scanning electron microscope, energy-dispersive X-ray spectroscopy, a transmission electron microscopy, Raman, X-ray diffractometry, a thermogravimetric analysis, nuclear magnetic resonance, and high-performance liquid chromatography. The identified impurities are amorphous and grphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of single-wall nanotubes by increasing crystallinity and reducing intercalation.
Keywords:
Abstract: The White Sands Test Facility (WSTF) government-contractor team began the International Organization for Standardization (ISO) 9001 implementation on October 3, 1994. The team of approximately 550 personnel then received a well-earned certification from the Det Norske Veritas (DNV) organization on October 20, 1995, approximately a year later. This was the first certification of both a National Aeronautics and Space Administration (NASA) installation and joint government-contractor partnership. The NASA Associate Administrator for Safety and Mission Assurance, Frederick Gregory, congratulated the NASA and site support contractor team for earning certification and indicated that WSTF was a benchmark for NASA. In recognition of this unique achievement, Vice President Al Gore’s National Performance Review recognized WSTF for exceptional progress in reinventing government. National Performance Review Project Director Bob Stone presented the prestigious Hammer Award on March 4, 1996. The ISO audit team had only five minor findings in contrast to the 20 to 30 that are usually associated with certification audits. Additionally, the quality system was put in place in a surprisingly short time, considering the magnitude of changes made to the documentation system. Overall, certification of ISO 9001 emphasized WSTF’s commitment to preeminence and demonstrated that the facility is well positioned to perform quality testing for domestic and international government and commercial entities. This document is designed to encourage others to apply the ISO family of standards to their organizations and assist them in their efforts by providing the WSTF certification approach and lessons learned. ISO 9000 background information and WSTF post-certification survey data are included in the attachments. Other helpful references are included in the appendixes.
Keywords: space shuttle missions; Mir Space Station; astronaut performance; astronauts;
Abstract: This report consists of inputs from each of the Phase 1 Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.
Keywords: motion, motion perception, perception, control, adaptive control
Abstract: This report reviews the operational demands made of a Shuttle pilot or commander within the context of a proven empirical methodology for describing human sensorimotor performance and whole-body coordination in mechanically and perceptually complex environments. The conclusions of this review pertain to a) methods for improving our understanding of the psychophysics and biomechanics of visual/manual control and whole-body coordination in space vehicle cockpits. b) the application of scientific knowledge about human perception and performance in dynamic inertial conditions to the development of technology, procedures, and training for personnel in space vehicle cockpits. c) recommendations for mitigation of safety and reliability concerns about human performance in space vehicle cockpits. d) in-flight evaluation of flight crew performance during nominal and off-nominal launch and reentry scenarios.
Keywords: Moon, Human Exploration, Lunar Science, Technology Demonstrations, Human Health and Performance, Candidate Sites, Timelines
Abstract: The goals and objectives of future lunar exploration are defined in terms of science, preparation for long-duration stays on the Moon, preparation for human exploration of Mars, exploring the possibility of economic uses of the Moon, and maintaining the health and performance of humans and machines on the Moon. These objectives can be met by carrying out a set of functional activities on the Moon such as scientific field investigations; sample collection and analysis; deployment of surface scientific instruments such as seismometers and telescopes; teleoperation of exploration and technology demonstration systems; intravehicular activity, maintenance and repair; and other activities. These are combined into a set of surface exploration mission options. Short-stay missions (e.g., 4 people for 4 days) that principally address scientific and technology verification are defined for three different types of sites, and long-stay missions (e.g., 4 people for 30 days), which can build up infrastructure for longer duration stays, are defined for two sites, including a south polar site. Representative timelines for crew surface activities are presented.This document is considered to be a snapshot that will be revised as the nature of human lunar missions become better understood.
Keywords: charged coupled devices; debris; space debris; telescopes; Earth orbital environments; geosynchronous orbits; Schmidt cameras; Schmidt telescope
Abstract: NASA has been using the charged coupled device (CCD) debris telescope (CDT)—a transportable 32-cm Schmidt telescope located near Cloudcroft, New Mexico—to help characterize the debris environment in geosynchronous Earth orbit (GEO). The CDT is equipped with a SITe 512 x 512 CCD camera whose 24 m2 (12.5 arc sec) pixels produce a 1.7 x 1.7-deg field of view. The CDT system can therefore detect 17th-magnitude objects in a 20-sec integration corresponding to an ~0.6-m diameter, 0.20 albedo object at 36,000 km. The telescope pointing and CCD operation are computer controlled to collect data automatically for an entire night. The CDT has collected more than 1500 hrs of data since November 1997. This report describes the collection and analysis of 58 nights (~420 hrs) of data acquired in 1998.
Keywords: plasma control; magnetohydrodynamics; plasma turbulence; plasmas (physics); Fourier transformation; Liouville theorem; pseudoscalars; ergodic process
Abstract: Plasmas, such as those found in the space environment or in plasma confinement devices, are often modeled as electrically conducting fluids. When fluids and plasmas are energetically stirred, regions of highly nonlinear, chaotic behavior known as turbulence arise. Understanding the fundamental nature of turbulence is a long-standing theoretical challenge. The present work describes a statistical theory concerning a certain class of nonlinear, finite dimensional, dynamical models of turbulence. These models arise when the partial differential equations describing incompressible, ideal (i.e., non-dissipative) homogeneous fluid and magnetofluid (i.e., plasma) turbulence are Fourier transformed into a very large set of ordinary differential equations. These equations define a divergenceless flow in a high-dimensional phase space, which allows for the existence of a Liouville theorem, guaranteeing a distribution function based on constants of the motion (integral invariants). The novelty of these particular dynamical systems is that there are integral invariants other than the energy, and that some of these invariants behave like pseudoscalars under two of the discrete symmetry transformations of physics, parity and charge conjugation. In this work the "rugged invariants" of ideal homogeneous turbulence are shown to be the only significant scalar and pseudoscalar invariants. The discovery that pseudoscalar invariants cause symmetries of the original equations to be dynamically broken and induce a nonergodic structure on the associated phase space is the primary result presented here. Applicability of this result to dissipative turbulence is also discussed.
Keywords: metamorphism (geology); beds (geology); geology; geomorphology; geophysics;
Abstract: We collected ~ 400 rock chips in continuous vertical profile at Meteor Crater, Arizona, representing - from bottom to top - the Coconino, Toroweap, Kaibab, and Moenkopi Formations to support ongoing compositional analyses of the impact melts and their stratigraphic source depth(s) and other studies at Meteor Crater that depend on the composition of the target rocks. These rock chips were subsequently pooled into 23 samples for compositional analysis by XRF methods, each sample reflecting a specific stratigraphic “subsection” ~ 5-10 m thick. We determined the modal abundance of quartz, dolomite, and calcite for the entire Kaibab Formation at vertical resolutions of 1-2 meters. The Coconino Formation composes the lower half of the crater cavity. It is an exceptionally pure sandstone. The Toroweap is only 2 m thick and compositionally similar to Coconino; therefore, it is not a good compositional marker horizon. The Kaibab Formation is ~ 80 m thick. XRD studies show that the Kaibab Formation is dominated by dolomite and quartz, albeit in highly variable proportions; calcite is a minor phase at best. The Kaibab at Meteor Crater is therefore a sandy dolomite rather than a limestone, consistent with pronounced facies changes in the Permian of SE Arizona over short vertical and horizontal distances. The Moenkopi forms the 12 m thick cap rock and has the highest Al2O3 and FeO concentrations of all target rocks. With several examples, we illustrate how this systematic compositional and modal characterization of the target ideologies may contribute to an understanding of Meteor Crater, such as the depth of its melt zone, and to impact cratering in general, such as the liberation of CO2 from shocked carbonates.
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: Issued as a companion to Johnson Space Center's Research and Technology Annual Report, which reports JSC accomplishments under NASA Research and Technology Operating Plan (RTOP) funding, this report describes 47 additional projects that are funded through sources other than the RTOP. Emerging technologies in four major disciplines are summarized: space systems technology, medical and life sciences, mission operations, and computer systems. Although these projects focus on support of human spacecraft design, development, and safety, most have wide civil and commercial applications in areas such as advanced materials, superconductors, advanced semiconductors, digital imaging, high density data storage, high performance computers, optoelectronics, artificial intelligence, robotics and automation, sensors, biotechnology, medical devices and diagnosis, and human factors engineering.
Keywords: biostimulation; photbiology; laser therapy; nanotechnology; nanobacteria; biomineralization; biofilm; biological systems; molecular; biology
Abstract: The International NASA/DARPA Photobiology Conference held at the Johnson Space Center in Houston/TX demonstrated where low level laser therapy (LLLT), respectively low intensity light activated biostimulation (LILAB) and nanotechnological applications employing photobiomodulation techniques will presumably go in the next ten years. The conference was a continuation of the 1st International Conference on Nearfield Optical Analysis organized by Andrei Sommer (ENSOMA Lab, University of Ulm, Germany) in November 2000 at Castle Reisensburg, Germany, which started with a group of ten scientists from eight different countries. The 2nd conference was co-sponsored by DARPA, NASA-JSC and the Medical College of Wisconsin. The 2nd conference hosted 40 international experts from universities, research institutes, agencies and industry. Materials published here are expected to become milestones forming a novel platform in biomedical photobiology. The multidisciplinary group of researchers focused on LLLT/LILAB-applications under extreme conditions expected to have beneficial effects particularly in space, on submarines, and under severe battlefield conditions. The group also focused on novel technologies with possibilities allowing investigating the interaction of light with biological systems, molecular mechanisms of wound healing, bone regeneration, nerve regeneration, pain modulation, as well as biomineralization and biofilm formation processes induced by nanobacteria. The proceedings of the 2nd NOA, together with the proceedings of the previous meeting held in Germany (Journal of Clinical Laser Medicine & Surgery, 2001, 19, 109-112) demonstrated the synergistic interplay and complementary output of a coherent approach to interrelated scientific questions of excessive clinical relevance, offering results beyond any previous expectation. The 3rd NOA is scheduled for 2002, in Brazil.
Keywords: human factors engineering; spacecraft design; human performance; human tolerances; human behavior; aerospace engineering; long-duration spaceflight; human safety
Abstract: These guidelines and capabilities identify points of intersection between human spaceflight crews and mission considerations such as architecture, vehicle design, technologies, operations, and science requirements. In these pages we provide clear, top-level guidelines for human-related exploration studies and technology research that will address common questions and requirements. The human element is likely the most complex and difficult element of mission design because it significantly influences every aspect of mission planning - from basic parameters, such as duration, to more complex trade-offs including mass, volume, power, risk, and cost. Beyond a cause-and-effect statement, human-driven requirements are highly variable because of destination, operational environment, mission objectives, and more. Often a precise quantification of parameters for a human mission is difficult without further study or arriving at a precise definition of a specific mission architecture. Each mission design requires several iterations as the effects of the crew on the system architecture (and vice versa) coalesce. We thus see this document as a tool that mission designers can use to understand the many trade-offs inherent in planning a human spaceflight mission, with an emphasis on human safety, health, and performance.
Keywords: posture, human body, microgravity, physiological effects, gravitational physiology, human factors engineering
Abstract: Research has shown that the space environment induces physiological changes in the human body, such as fluid shifts in the upper body and chest cavity, spinal lengthening, muscular atrophy, space motion sickness, cardiopulmonary deconditioning, and bone mass loss, as well as some changes in visual perception. These require a period of adaptation and can substantially affect both crew member performance and posture. These physiological effects, when work activities are conducted, have been known to impact the body’s center of gravity, reach, flexibility, and dexterity. All these aspects of posture must be considered to safely and efficiently design space systems and hardware. NASA has documented its microgravity body posture in the Man-Systems Integration Standards (MSIS); the space community uses the MSIS posture to design workstations and tools for space application. However, the microgravity body posture should be further investigated for several reasons, including small sample size in previous studies, possible imprecision, and lack of detail. JSC undertook this study to investigate human body posture exhibited under microgravity conditions. STS-57 crew members were instructed to assume a relaxed posture that was not oriented to any work area or task. Crew members were asked to don shorts and tank tops and to be blindfolded while data were recorded. Video data were acquired once during the mission from each of the six crew members. No one crew member exhibited the typical NBP called out in the MSIS; one composite posture is not adequate. A range of postures may be more constructive for design purposes. Future evaluations should define precise posture requirements for workstation, glove box, maintenance, foot-restraint, and handhold activities.
Keywords: exercise physiology; human body; locomotion; physiological effects; treadmills; physical exercise; contingency
Abstract: The treadmill with vibration isolation system (TVIS) was developed to counteract cardiovascular, musculoskeletal, and neurovestibular deconditioning during long-duration missions to the ISS. However, recent hardware failures have necessitated the development of a short-term, temporary contingency exercise countermeasure for TVIS until nominal operations could be restored. The purpose of our evaluation was twofold: 1) to examine whether a slick-plate/contingency exercise surface (CES) could be used as a walking/running surface and could elicit a heart rate (HR) ³ 70% HR maximum and 2) to determine the optimal hardware configuration, in microgravity, to simulate running/walking in a 1-g environment. One subject participated in the slick surface evaluation and two subjects participated in the microgravity evaluation of the slick surface configuration. During the slick surface evaluation, the subject was suspended in a parachute harness and bungee cord configuration to offset the subject’s body weight. Using another bungee cord configuration, we added a vertical load back to the subject, who was then asked to run for 20 minutes on the slick surface. The microgravity evaluation simulated the ISS TVIS, and we evaluated two different slick surfaces for use as a CES. We evaluated each surface with the subject walking and running, with and without a handrail, and while wearing either socks or nylon booties over shoes. In the slick surface evaluation, the subject ran for 20 minutes and reached a maximum HR of 170 bpm. In the microgravity evaluation, the subjects chose the aluminum plate coated with Tufram as the CES, while wearing a pair of nylon booties over running shoes and using a handrail, as the optimal hardware configuration.
Keywords: orbital debris, meteoroids, hypervelocity impact, shielding, ISS, Shuttle, Orbiter, CONTOUR, impact protection, Hypervelocity Impact Technology Facility
Abstract: This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.
Keywords: decompression sickness, extravehicular activity, NASA Decompression Sickness Database, Prebreathe Reduction Protocol Database, spacesuit, venous gas emboli
Abstract: One hundred and three cases of hypobaric decompression sickness (DCS) are documented, with 6 classified as Type II DCS. The presence and grade of venous gas emboli (VGE) are part of the case descriptions. Cases were diagnosed from 731 exposures in 5 different altitude chambers from 4 different laboratories between the years 1982 and 1999. Research was funded by NASA to develop operational prebreathe (PB) procedures that would permit safe extravehicular activity from the Space Shuttle and International Space Station using an extravehicular mobility unit (spacesuit) operated at 4.3 psia. Both vehicles operate at 14.7 psia with an "air" atmosphere, so a PB procedure is required to reduce nitrogen partial pressure in the tissues to an acceptable level prior to depressurization to 4.3 psia. Thirty-two additional descriptions of symptoms that were not diagnosed as DCS together with VGE information are also included. The information for each case resides in logbooks from 32 different tests. Additional information is stored in the NASA Decompression Sickness Database and the Prebreathe Reduction Protocol Database, both maintained by the Environmental Physiology Laboratory at the Johnson Space Center. Both sources were reviewed to provide the narratives that follow.
Keywords: trauma; acute trauma; pulmonary; critical care; ISS; International Space Station
Abstract: The NASA critical path road map identifies “trauma and acute medical problems” as a clinical capability risk category. Specific risks include major trauma, organ laceration or contusion, hemoperitoneum, pulmonary failure, pneumo- and hemothorax, burn, open bone fracture, blunt head trauma, and penetrating injury. Risk mitigation includes capability for critical care monitoring. Currently, the ISS Crew Health Care System does not provide such capability. The Clinical Space Medicine Strategic Planning Forum (1997) identified developing trauma care capabilities as a top priority for space medicine. The Clinical Care Capability Development Project (CCCDP) subsequently undertook the task to address this need. In January 2000, JSC Medical Operations Branch was invited to participate in the RIMPAC 2000/Strong Angel exercise, which involved seven nations and several public health and disaster-response organizations, establishing a 300-person mock refugee camp to simulate mass dislocation due to conflict or natural disaster. A wireless network and satellite system connected the camp to the East Carolina University School of Medicine. One of Strong Angel’s objectives was to build a nomadic computing network matrix to link the 7 countries participating in this exercise through the ECU bridge. Medical Operations personnel used this exercise to evaluate critical care monitors in a real-world telemedicine setting analogous to ISS conditions and to simulate potential ISS medical scenarios. This exercise afforded a unique opportunity to work with commercial vendors and evaluate their leading-edge technology and evaluate the feasibility of treating an astronaut aboard ISS using limited medical resources. These opportunities were consistent with the CCCDP critical path toward enhancing long-term Advanced Life Support System capabilities.
Keywords: microgravity, orthostasis, exercise countermeasures, aerobic exercise, blood pressure, extravehicular activity, EVA
Abstract: The purpose of this study was to determine whether exercise performed by Space Shuttle crewmembers during short-duration spaceflights (9-16 d) affects the heart rate (HR) and blood pressure (BP) responses to standing within 2-4 hr of landing. Thirty crewmembers performed self-selected in-flight exercise and maintained exercise logs to monitor their exercise intensity and duration. A 10-min stand test, preceded by at least 6 min of quiet supine rest, was completed 10-15 d before launch (PRE) and within four hours of landing (POST). Based upon their in-flight exercise records, subjects were grouped as either high (HIex: = 3x/week, HR = 70% HRmax, = 20 min/session, n = 11), medium (MEDex: = 3x/week, HR = 70% HRmax, = 20 min/session, n = 10), or low (LOex: = 3x/week, HR and duration variable, n = 11) exercisers. HR and BP responses to standing were compared between groups (ANOVA, or analysis of variance, P < 0.05). There were no PRE differences between the groups in supine or standing HR and BP. Although POST supine HR was similar to PRE, all groups had an increased standing HR compared to PRE. The increase in HR upon standing was significantly greater after flight in the LOex group (36 ± 5 bpm) compared to HIex or MEDex groups (25 ± 1 bpm; 22 ± 2 bpm). Similarly, the decrease in pulse pressure (PP) from supine to standing was unchanged after spaceflight in the MEDex and HIex groups, but was significantly less in the LOex group (PRE: -9 ± 3; POST: -19 ± 4 mmHg). Thus, moderate to high levels of in-flight exercise attenuated HR and PP responses to standing after spaceflight compared.
Keywords: television cameras; cameras; photographic film; Hasselblad; electronic still camera; camcorder; video recorder; high-definition television; television equipment
Abstract: As part of Detailed Test Objective 700-17A, astronauts acquired Earth observation images from orbit using a high-definition television (HDTV) camcorder. Here we provide a summary of qualitative findings following completion of tests during missions STS (Space Transport System)-93 and STS-99. We compared HDTV imagery stills to images taken using payload bay video cameras, Hasselblad film camera, and electronic still camera. We also evaluated the potential for motion video observations of changes in sunglint and the use of multi-aspect viewing to image aerosols. Spatial resolution and color quality are far superior in HDTV images compared to National Television Systems Committee (NTSC) video images. Thus, HDTV provides the first viable option for video-based remote sensing observations of Earth from orbit. Although under ideal conditions, HDTV images have less spatial resolution than medium-format film cameras, such as the Hasselblad, under some conditions on orbit, the HDTV image acquired compared favorably with the Hasselblad. Of particular note was the quality of color reproduction in the HDTV images. HDTV and electronic still camera (ESC) were not compared with matched fields of view, and so spatial resolution could not be compared for the two image types. However, the color reproduction of the HDTV stills was truer than colors in the ESC images. As HDTV becomes the operational video standard for Space Shuttle and Space Station, HDTV has great potential as a source of Earth-observation data. Planning for the conversion from NTSC to HDTV video standards should include planning for Earth data archiving and distribution.
Keywords: International Space Station; Space Shuttle; Mir; cleaning; cleanliness; zero gravity; showers; human body
Abstract: Note: This document was originally published in 1997 as an International Space University Master of Space Studies student's project. While the specifics may be a little dated, the results gleaned are still relevant and valid. Johnson Space Center is now abuzz with preparations for the International Space Station. The work on various systems for the U.S. Habitation module will begin in 1998. As a prelude, the Flight Crew Support Division perceived the need to take a closer, more critical look at planning the Whole Body Cleansing function for ISS. This report is an attempt to retrieve all data available on whole body cleansing mechanisms used, past and present, by the Russians and the Americans, analyze it and create design concepts for products for zero-g cleansing on ISS. This report takes a close look at the Skylab collapsible shower, the Mir shower/sauna, the full body cleansing methods currently in use on board the Shuttle and Mir, and at the whole body shower designed and tested for Space Station Freedom. It attempts to "listen" carefully to what Mir astronauts have to say about their personal hygiene experiences during their recent stays on Mir. The findings in the report call for a change in paradigm. What is good for Earth conditions is not necessarily good for zero-g! It concludes that a shower is not a good idea for ISS. The final concept that is proposed reflects very strongly what the Mir astronauts would like to have and to use on a station like ISS. The report concludes with directions of how to take the "idea" further and realize it in the form of a product system for whole body cleansing on board ISS.
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: Johnson Space Center research and technology accomplishments during fiscal year 1993 are described and principal researchers and technologists are identified as contacts for further information. Each of the four sections gives a summary of overall progress in a major discipline, followed by detailed, illustrated descriptions of significant tasks. The four disciplines are Life Sciences, Human Support Technology, Solar System Sciences, and Space Systems Technology. The report is intended for technical and management audiences throughout NASA and the worldwide aerospace community. An index lists project titles, funding codes, and principal investigators.
Keywords: manned spaceflight; histories; manned Mars missions; Mars probes; Mars environment; strategy; mission planning; Viking Mars Program
Abstract: The history of human Mars mission planning from the early 1950s through the 1960s is examined. For centuries, Mars has been an object of fascination and, since the 1800s, science fiction authors have imagined what it would be like for humans to travel to that planet. Space enthusiasts have shared this dream and as early as the 1950s were presenting feasible proposals for human missions to Mars. Since the creation of NASA, the Agency has maintained the idea of human Mars missions as an important long-term goal. Throughout its history, NASA has conducted studies aimed at landing an astronaut on Mars. NASA's current strategic plan still includes this goal. Therefore, it is important to look at previous planning efforts to see what work has been accomplished and to discover lessons that future planners can apply to their programs.
Keywords: composite materials; pressure vessel design; pressure vessels; impact damage; materials
Abstract: This document represents efforts accomplished at the NASA Johnson Space Center White Sands Test Facility in support of the Enhanced Technology for Composite Overwrapped Pressure Vessels Program, a joint research and technology effort among the U.S. Air Force, NASA, and the Aerospace Corporation.WSTF performed testing for several facects of the program. Testing that contributed to the Task 3.0 COPV database extension objective included baseline structural strength, failure mode and safe-life, impact damage tolerance, sustained load/impact effect, and materials compatibility. WSTF was also responsible for establishing impact protection and control requirements under Task 8.0 of the program. This included developing a methodology for establishing an impact control plan.Seven test reports detail the work done at WSTF. As such, this document contributes to the database of information regarding COPV behavior that will ensure performance benefits and safety are maintained throughout vessel service life.
Keywords: decompression sickness; doses, biological effects; altitude sickness; decompression; altitude simulation; exercise physiology; extravehicular activity
Abstract: Decompression sickness (DCS) is a complex, multivariable problem. A mathematical description or model of the likelihood of DCS requires a large amount of quality research data, ideas on how to define a decompression dose using physical and physiological variables, and an appropriate analytical approach. It also requires a high-performance computer with specialized software. I have used published DCS data to develop my decompression doses, which are variants of equilibrium expressions for evolved gas plus other explanatory variables. My analytical approach is survival analysis, where the time of DCS occurrence is modeled. My conclusions can be applied to simple hypobaric decompressions - ascents lasting from 5 to 30 minutes - and, after minutes to hours, to denitrogenation (prebreathing). They are also applicable to long or short exposures, and can be used whether the sufferer of DCS is at rest or exercising at altitude. Ultimately I would like my models to be applied to astronauts to reduce the risk of DCS during spacewalks, as well as to future spaceflight crews on the Moon and Mars.
Keywords: plants (botany); plant roots; plant stress; microgravity; porous materials; porosity; microporosity
Abstract: This NASA Technical Memorandum is a compilation of presentations and discussions in the form of minutes from a workshop entitled Plant Production Systems for Microgravity: Critical Issues in Water, Air, and Solute Transport Through Unsaturated Porous Media held at NASA’s Johnson Space Center, July 24-25, 2000. This workshop arose from the growing belief within NASA’s Advanced Life Support Program that further advances and improvements in plant production systems for microgravity would benefit from additional knowledge of fundamental processes occurring in the root zone. The objective of the workshop was to bring together individuals who had expertise in various areas of fluid physics, soil physics, plant physiology, hardware development, and flight tests to identify, discuss, and prioritize critical issues of water and air flow through porous media in microgravity. Participants of the workshop included representatives from private companies involved in flight hardware development and scientists from universities and NASA Centers with expertise in plant flight tests, plant physiology, fluid physics, and soil physics.
Keywords: space missions, anomalies, memory (computers), computer storage devices, integrated
Abstract: This paper describes a Web-based system to support the temporary Anomaly Response Team formed from distributed subteams in Space Shuttle and International Space Station missions. The system was designed for easy and flexible creation of small collections of files and links associated with work on a particular anomaly. The system supports privacy and levels of formality for the subteams. First we describe the supported groups and an anomaly response scenario. Then we describe the support system prototype, the Anomaly Response Tracking and Integration System (ARTIS). Finally, we describe our evaluation approach and the results of the evaluation.
Keywords: aviator decompression sickness, skin mottling, skin bends, bubbles, skin lesion, cutaneous circulation
Abstract: There is disagreement about the pathophysiology, classification, and treatment of cutis marmorata (CM), so there is disagreement about the disposition and medical status of a person that had CM. CM is rare, associated with stressful decompressions, and may be associated with serious signs and symptoms of decompression sickness (DCS). CM presents as purple or bluish-red skin mottling, often in the pectoral region, shoulders, chest, or upper abdomen. It is unethical to induce CM in humans so all information comes from retrospective analysis of case reports, or from animal models. A literature search, seven recent case reports from the Johnson Space Center and Brooks Air Force Base Hypobaric DCS Databases, interviews with DCS treatment experts, and responses to surveys provided the factual information used to arrive at our conclusions and recommendations. The weight of evidence indicates that CM is a local, not centrally mediated or systemic response to bubbles. It is unclear whether obstruction of arterial or venous blood flow is the primary insult since the lesion is reported under either condition. Any neurological or cardiovascular involvements are coincidental, developing along the same time course. The skin could be the source of the bubbles due to its mass, the associated layer of fat, and the variable nature of skin blood flow. CM should not be categorized as Type II DCS, should be included with other skin manifestations in a category called cutaneous DCS, and hyperbaric treatment is only needed if ground level oxygen is ineffective in the case of altitude-induced CM.
Keywords: Antarctic regions, space exploration, Mars surface, planetary environments
Abstract: Four Antarctic explorers were invited to a workshop at Johnson Space Center (JSC) to provide expert assessments of NASA's current understanding of future human exploration missions beyond low Earth orbit. These explorers had been on relatively sophisticated, extensive Antarctic expeditions with sparse or nonexistent support infrastructure in the period following World War II through the end of the International Geophysical Year. Their experience was similar to that predicted for early Mars or other planetary exploration missions. For example: one Antarctic expedition lasted 2 years with only one planned resupply mission and contingency plans for no resupply missions should sea ice prevent a ship from reaching them; several traverses across Antarctica measured more than 1000 total miles, required several months to complete, and were made without maps (because they did not exist) and with only a few aerial photos of the route; and the crews of 6 to 15 were often international in composition. At JSC, the explorers were given tours of development, training, and scientific facilities, as well as documentation of operational scenarios for future planetary exploration. This report records their observations about these facilities and plans in answers to a series of questions provided to them before the workshop.
Keywords: flight control; spacecraft control; reentry vehicles; dynamics; equations of motion; nonlinear equations; control systems design
Abstract: This report addresses issues in developing a flight control design for vehicles operating across a broad flight regime and with highly nonlinear physical descriptions of motion. Specifically it addresses the need for reentry vehicles that could operate through reentry from space to controlled touchdown on Earth. The latter part of controlled descent is achieved by parachute or paraglider or by an automatic or a human-controlled landing similar to that of the Orbiter. Since this report addresses the specific needs of human-carrying (not necessarily piloted) reentry vehicles, it deals with highly nonlinear equations of motion, and their generated control systems must be robust across a very wide range of physics. Thus, this report deals almost exclusively with some form of dynamic inversion (DI). Two vital aspects of control theory noninteracting control laws and the transformation of nonlinear systems into equivalent linear systems are embodied in DI. Though there is no doubt that the mathematical tools and underlying theory are widely available, there are open issues as to the practicality of using DI as the only or primary design approach for reentry vehicles. This report provides a set of guidelines that can be used to determine the practical usefulness of the technique.
Keywords: Time-varying electromagnetic field, rotating wall vessel, three-dimensional culture, neural tissue regeneration
Abstract: The present investigation details the development of model systems for growing two and three-dimensional human neural progenitor cells within a culture medium facilitated by a time-varying electromagnetic field (TVEMF). The cells and culture medium are contained within a two or three-dimensional culture vessel, and the electromagnetic field is emitted from an electrode or coil. These studies further provide methods to promote neural tissue regeneration by means of culturing the neural cells in either configuration. Grown in two-dimensions, neuronal cells extended longitudinally forming tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time-varying electrical current was conducted. In the three-dimensional aspect exposure to TVEMF resulted in the development of three-dimensional aggregates, which emulated organized neural tissues. In both experimental configurations, the proliferation rate of the TVEMF cells was 2.5 to 4.0 times the rate of the non-waveform cells. Each of the experimental embodiments resulted in similar molecular genetic changes regarding the growth potential of the tissues as measured by gene chip analyses, which measured more than 10,000 human genes simultaneously
Keywords: venous gas emobli; bubbles; decompression sickness; bends; extravehicular activity; goodness of fit; accuracy, predictive; random effects; distribution, lognormal
Abstract: Venous gas emboli (VGE) (gas bubbles in venous blood) are associated with an increased risk of decompression sickness (DCS) in hypobaric environments. A high grade of VGE can be a precursor to serious DCS. In this paper, we model time to Grade IV VGE considering a subset of individuals assumed to be immune from experiencing VGE. Our data contain monitoring test results from subjects undergoing up to 13 denitrogenation test procedures prior to exposure to a hypobaric environment. The onset time of Grade IV VGE is recorded as contained within certain time intervals. We fit a parametric (lognormal) mixture survival model to the interval- and right-censored data to account for the possibility of a subset of cured individuals who are immune to the event. Our model contains random subject effects to account for correlations between repeated measurements on a single individual. Model assessments and cross-validation indicate that this limited failure population mixture model is an improvement over a model that does not account for the potential of a fraction of cured individuals. We also evaluated some alternative mixture models. Predictions from the best fitted mixture model indicate that the actual process is reasonably approximated by a limited failure population model.
Keywords: Research and Development, Technology Transfer, Discretionary Fund, NASA Programs, Space Technology Experiments
Abstract: As an independent research medium, the Johnson Space Center Director's Discretionary Fund often initiates investigations of significant value to NASA with eventual application to commercial uses. The projects provide technical support to the NASA mission and development opportunities for the science and engineering staff. Thirty-six projects were supported from the $1,779,000 in FY93 funds. Some notable projects that made outstanding progress and produced significant results: multilayer microspheres of medication were processed in microgravity; virtual environment techniques were used for visualization of repair tasks and training in the successful repair of the Hubble Space Telescope; a prototype axial flow pump for heart ventricle assist was demonstrated in a calf implant; the electronic still camera rapidly transmitted high resolution images from the Space Shuttle; water was obtained from a lunar soil sample and from lunar soil simulant, confirming a patented oxygen extraction process; a regenerative water recovery system was demonstrated; patent disclosures were made on a dried blood sampling method.
Keywords: Radiation Hazards, Planetary Environments, Cancer, Space Exploration, Risk
Abstract: In this paper we discuss expected lifetime excess cancer risks for astronauts returning from exploration class missions. For the first time we make a quantitative assessment of uncertainties in cancer risk projections for space radiation exposures. Late effects from the high charge and energy (HZE) ions present in the galactic cosmic rays including cancer and the poorly undersood risks to the central nervous system constitute the major risks. Methods used to project risk in low Earth orbit are seen as hightly uncertain for projecting risks on exploration missions because of the limted radiobiology data available for estimating HZE ion risks. Cancer risk projections are described as a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. Monte-Carlo sampling from subjective error distributions represents the lack of knowledge in each factor to quantify risk projection overall uncertainty. Cancer risk analysis is applied to several exploration mission scenarios. At solar minimum, the number of days in space where career risk of less than the limiting 3% excess cancer mortality can be asssured at a 95% confidence level is found to be only of the order of 100 days.
Keywords: computer programming; computer modeling; orbital debris; space debris; population modeling; low Earth orbit; collision risk; risk assessment
Abstract: The NASA Orbital Debris Program Office at Johnson Space Center has developed a new computer-based orbital debris engineering model, ORDEM2000, which describes the orbital debris environment in the low Earth orbit region between 200 and 2000 km altitude. The model is appropriate for those engineering solutions requiring knowledge and estimates of the orbital debris environment (debris spatial density, flux, etc.). ORDEM2000 can also be used as a benchmark for ground-based debris measurements and observations. We incorporated a large set of observational data, covering the object size range from 10 mm to 10 m, into the ORDEM2000 debris database, utilizing a maximum likelihood estimator to convert observations into debris population probability distribution functions. These functions then form the basis of debris populations. We developed a finite element model to process the debris populations to form the debris environment. A more capable input and output structure and a user-friendly graphical user interface are also implemented in the model. ORDEM2000 has been subjected to a significant verification and validation effort.This document describes ORDEM2000, which supersedes the previous model, ORDEM96. The availability of new sensor and in situ data, as well as new analytical techniques, has enabled the construction of this new model. Section 1 describes the general requirements and scope of an engineering model. Data analyses and the theoretical formulation of the model are described in Sections 2 and 3. Section 4 describes the verification and validation effort and the sensitivity and uncertainty analyses. Finally, Section 5 describes the graphical user interface, software installation, and test cases for the user.
Keywords: ultrasound; video data; video equipment; video tape recorders; echocardiography; sonography; Doppler; field rate; MPEG; resolution; radiology; analog; digital
Abstract: Most medical equipment on the International Space Station (ISS) is manifested as part of the U.S. or the Russian medical hardware systems. However, certain medical hardware is also available as part of the Human Research Facility. The HRF and the JSC Medical Operations Branch established a Memorandum of Agreement for joint use of certain medical hardware, including the HRF ultrasound system, the only diagnostic imaging device currently manifested to fly on ISS. The outcome of a medical contingency may be changed drastically, or an unnecessary evacuation may be prevented, if clinical decisions are supported by timely and objective diagnostic information. In many higher-probability medical scenarios, diagnostic ultrasound is a first-choice modality or provides significant diagnostic information. Accordingly, the Clinical Care Capability Development Project is evaluating the HRF ultrasound system for its utility in relevant clinical situations on board ISS. For effective management of these ultrasound-supported ISS medical scenarios, the resulting data should be available for viewing and interpretation on the ground, and bidirectional voice communication should be readily available to allow ground experts (sonographers, physicians) to provide guidance to the Crew Medical Officer. It may also be vitally important to have the capability of real-time guidance via video uplink to the CMO-operator during an exam to facilitate the diagnosis in a timely fashion. In this document, we strove to verify that the HRF ultrasound video output is compatible with the ISS video system, identify ISS video system field rates and resolutions that are acceptable for varying clinical scenarios, and evaluate the HRF ultrasound video with a commercial, off-the-shelf video converter, and compare it with the ISS video system.
Keywords: hydrogen, combustion, flammability, detonation, fire, slush, hazards, hydrogen embrittlement, hazards analysis
Abstract: The physical and combustion properties of hydrogen give rise to hazards that one must consider when designing and operating a hydrogen system. One of the major concerns is fire or detonation because of hydrogen’s wide flammability range, low ignition energy, and flame speed. Other concerns include contact and interaction with materials, such as the hydrogen embrittlement of materials and the formation of hydrogen hydrides. The low temperature of liquid and slush hydrogen bring other concerns related to material compatibility and pressure control; this is especially important when dissimilar, adjoining materials are involved. The potential hazards arising from these properties and design features necessitate a proper hydrogen hazards analysis before introducing a material, component, or system into hydrogen service. The objective of this guide is to describe the NASA Johnson Space Center White Sands Test Facility hydrogen hazards analysis method one should perform before hydrogen is used in components and/or systems. The method is consistent with standard practices for analyzing hazards. It is recommended that this analysis be made before implementing a hydrogen component qualification procedure. A hydrogen hazards analysis is a useful tool for hydrogen-system designers, system and safety engineers, and facility managers. A hydrogen hazards analysis can identify problem areas before hydrogen is introduced into a system, preventing damage to hardware, delay or loss of mission or objective, and possible injury or loss of life. This guide is based on information from the NASA Safety Standard for Hydrogen and Hydrogen Systems (NSS 1740.16) and experience derived from the development of a similar protocol for oxygen system hazards analysis. It was previously published as TP-WSTF-937
Keywords: fluid dynamics analysis; static culture system; computational fluid dynamics; fluid mechanics
Abstract: This report is a documentation of a fluid dynamic analysis of the proposed Automated Static Culture System cell module mixing protocol. The report consists of a review of some basic fluid dynamics principles appropriate for the mixing of a patch of high oxygen content media into the surrounding media which is initially depleted of oxygen, followed by a computational fluid dynamics study of this process for the proposed protocol over a range of the governing parameters. The time histories of oxygen concentration distributions and mechanical shear levels generated are used to characterize the mixing process for different parameter values.
Keywords: radiation, shielding, space suit, electrons, space radiation, anisotropy, radiation damage, radiation protection, albedo, EMU, low Earth orbit
Abstract: This publication describes recent investigations that evaluate radiation shielding characteristics of NASA’s and the Russian Space Agency’s space suits. The Introduction describes the suits and presents goals of several experiments performed with them. The first chapter provides background information about the dynamic radiation environment experienced at ISS and summarizes radiation health and protection requirements for activities in low Earth orbit. Supporting studies report the development and application of a computer model of the EMU space suit and the difficulty of shielding EVA crewmembers from high-energy reentrant electrons, a previously unevaluated component of the space radiation environment. Chapters 2 through 6 describe experiments that evaluate the space suits' radiation shielding characteristics. Chapter 7 describes a study of the potential radiological health impact on EVA crewmembers of two virtually unexamined environmental sources of high-energy electrons - reentrant trapped electrons and atmospheric albedo or “splash” electrons. The radiological consequences of those sources have not been evaluated previously and, under closer scrutiny. A detailed computational model of the shielding distribution provided by components of the NASA astronauts’ EMU is being developed for exposure evaluation studies. The model is introduced in Chapters 8 and 9 and used in Chapter 10 to investigate how trapped particle anisotropy impacts female organ doses during EVA. Chapter 11 presents a review of issues related to estimating skin cancer risk from space radiation. The final chapter contains conclusions about the protective qualities of the suit brought to light from these studies, as well as recommendations for future operational radiation protection investigations and practices. The recent programmatic focus on radiation protection for EVA exposures is only one component of the NASA Space Radiation Health Project Office’s proactive management of radiation protection for human activities in space. Ionizing radiation exposures to long-term ISS crewmembers are increased by a factor of ~10 or more above typical Space Shuttle experiences, and it is quite possible that some individuals will receive doses that will restrict their time allowed on EVA or on orbit. Anticipation of these events prompted programmatic reviews and development of improved technologies and new procedures for the radiation mission support team, including near-real-time space weather monitoring, information analysis, integration, and reporting to flight surgeons and mission controllers. New research and dosimetry technologies and skills acquired by the NASA Space Radiation Health Project Office and its supporting research programs include improved spacecraft environmental and personnel dosimetry, improved ground-based physics and radiation transport models, leading-edge radiobiology studies of the deleterious effects of space-like ionizing radiation fields, and broadening and deepening investigations of risk analysis.
Keywords: sustainability, resources, environment, climate change, energy, waste, energy sources, solar energy, ozone, deforestation, EPA, food chain, photovoltaics, landfills
Abstract: Key environmental issues are affecting our lives more and more every day. Resources are threatened in various ways and we produce increasing amounts of waste. Spaceship Earth must address similar challenges to life support systems on extended-duration spacecraft, but on a much different scale. Issues such as declining biodiversity, ozone depletion, and climate change show us that the Earth’s natural reserves are not infinite either. Our choice of energy sources is expected to be one of the most important decisions that global society will make over the next half century. While the concept is not new, there is a renewed realization that our business practices and our lifestyles must be sustainable in order to last. Simply put, sustainability is development that meets the needs of present generations without compromising the ability of future generations to meet their own needs.NASA scientists and many others are contributing to the growing knowledge of our Earth and its ecosystems. Satellites measure sea level rise, and changes in vegetation and air pollutants that travel between countries and continents. The U.S. federal government seeks to be a leader in environmental sustainability efforts through various Executive Orders and policies that save energy, reduce waste, and encourage less reliance on oil as an energy source. NASA, as an agency that is by nature focused on the future, has much to contribute to these efforts. Pollution prevention, affirmative procurement and sustainable design are all programs that are under way at NASA. But more can be done. By sharing ideas and learning from other organizations as well as from the talented workforce we are a part of, JSC can improve its sustainability performance and spread the benefits to our community.
Keywords: mechanisms, deployment, tribology, actuators, optical, Rover,
Abstract: The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production and use of aerospace mechanisms. A major focus is reporting problems and solutions associated with the development and flight certification of new mechanisms. Organized by the Mechanisms Education Association, NASA and Lockheed Martin Space Systems Company (LMSSC) share the responsibility for hosting the AMS. Now in its 37th symposium, the AMS continues to be well attended, attracting participants from both the U.S. and abroad. The 37th AMS, hosted by the Johnson Space Center (JSC) in Galveston, Texas, was held May 19, 20 and 21, 2004. During these three days, 34 papers were presented. Topics included deployment mechanisms, tribology, actuators, pointing and optical mechanisms, Space Station and Mars Rover mechanisms, release mechanisms, and test equipment. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components.
Keywords: metric, budget, equivalent system mass,
Abstract: This document provides the official calculation of the Advanced Life Support (ALS) Research and Technology Development Metric (the Metric) for Fiscal Year 2003. As such, the values herein are primarily based on Systems Integration, Modeling, and Analysis (SIMA) Element approved software tools or reviewed and approved reference documents.The Metric is one of several measures employed by the National Aeronautics and Space Administration (NASA) to assess the Agency’s progress as mandated by the United States Congress and the Office of Management and Budget. Because any measure must have a reference point, whether explicitly defined or implied, the Metric is a comparison between a selected ALS Project life support system and an equivalently detailed life support system using technology from the Environmental Control and Life Support System (ECLSS) for the International Space Station (ISS). More specifically, the Metric is the ratio defined by the equivalent system mass (ESM) of a life support system for a specific mission using the ISS ECLSS technologies divided by the ESM for an equivalent life support system using the “best” ALS technologies.As defined, the Metric should increase in value as the ALS technologies become lighter, less power intensive, and require less volume. For Fiscal Year 2003, the Advanced Life Support Research and Technology Development Metric value is 1.47 for an Orbiting Research Facility and 1.36 for an Independent Exploration Mission.
Keywords: contamination; lunar rocks; lunar programs; manned space flight; Apollo 11; lunar receiving laboratory; test facilities; laboratory equipment; decontamination
Abstract: As early as 1959, the Working Group on Lunar Exploration within NASA advocated that "one of the prime objectives of the first lunar landing mission should be the collection of samples for return to Earth, where they could be subjected to detailed study and analysis." Within NASA, neither this group nor any other scientists working with the Agency were concerned about back contamination issues. Outside of NASA, back contamination concerns had been raised as early as 1960. Although NASA did not seem to pay any attention to the concerns at that time, the scientific community continued to be interested in the topic. In 1962 and again in 1963, as the Apollo Program loomed large, further discussions were held. These early discussions of back contamination did not make their way into NASA's administration, however, and when Manned Spacecraft Center personnel began to articulate early concepts for the Lunar Receiving Laboratory (LRL), the back contamination issue was not considered. Once this concern became a major focus, however, the LRL's development became increasingly complex. This is the history of that development.
Keywords: lunar orbiter, lunar satellites, lunar spacecraft, lunar topography, lunar geology, geological surveys, geology, geodesy, geochemistry, lunar gravitational effects, mineralogy
Abstract: The Lunar Scout Program was one of a series of attempts by NASA to develop and fly an orbiting mission to the Moon to collect geochemical, geological, and gravity data. Predecessors included the Lunar Observer, the Lunar Geochemical Orbiter, and the Lunar Polar Orbiter - missions studied under the auspices of the Office of Space Science. The Lunar Scout Program, however, was an initiative of the Office of Exploration. It was begun in late 1991 and was transferred to the Office of Space Science after the Office of Exploration was disbanded in 1993. Most of the work was done by a small group of civil servants at the Johnson Space Center; other groups also responsible for mission planning included personnel from the Charles Stark Draper Laboratories, the Lawrence Livermore National Laboratory, Boeing, and Martin Marietta. The Lunar Scout Program failed to achieve New Start funding in FY93 and FY94 as a result of budget downturns, the de-emphasis of the Space Exploration Initiative, and the fact that lunar science did not rate as high a priority as other planned planetary missions, and was cancelled. The work done on the Lunar Scout Program and other lunar orbiter studies, however, represents assets that will be useful in developing new approaches to lunar orbit science.
Keywords: extravehicular activity, EVA, space suit
Abstract: This report documents the results of a study carried out as part of NASA’s Revolutionary Aerospace Systems Concepts Program examining the future technology needs of extravehicular activities (EVAs). The intent of this study is to produce a comprehensive report that identifies various design concepts for human-related advanced EVA systems necessary to achieve the goals of supporting future space exploration and development customers in free space and on planetary surfaces for space missions in the post-2020 timeframe. The design concepts studied and evaluated are not limited to anthropomorphic space suits, but include a wide range of human-enhancing EVA technologies as well as consideration of coordination and integration with advanced robotics. The goal of the study effort is to establish a baseline technology "road map" that identifies and describes an investment and technical development strategy, including recommendations that will lead to future enhanced synergistic human/robot EVA operations. The eventual use of this study effort is to focus evolving performance capabilities of various EVA system elements toward the goal of providing high-performance human operational capabilities for a multitude of future space applications and destinations.The data collected for this study indicate a rich and diverse history of systems that have been developed to perform a variety of EVA tasks, indicating what is possible. However, the data gathered for this study also indicate a paucity of new concepts and technologies for advanced EVA missions - at least any that researchers are willing to discuss in this type of forum.
Keywords: exercise, thermal, heat production, resistive exercise, resting metabolism, aerobic exercise, interval, exercise protocol, exercise countermeasures
Abstract: This investigation’s purpose was to determine the amount of heat produced when performing aerobic and resistance exercises planned as part of the exercise countermeasures prescription for the ISS. These data will be used to determine thermal control requirements of the Node 1 and other modules where exercise hardware might reside. To determine heat production during resistive exercise, 6 subjects using the iRED performed 5 resistance exercises which form the core exercises of the current ISS resistive exercise countermeasures. Each exerciser performed a warm-up set at 50% effort, then 3 sets of increasing resistance. We measured oxygen consumption and work during each exercise. Heat loss was calculated as the difference between the gross energy expenditure (minus resting metabolism) and the work performed. To determine heat production during aerobic exercise, 14 subjects performed an interval, cycle exercise protocol and 7 subjects performed a continuous, treadmill protocol. Each 30-min. exercise is similar to exercises planned for ISS. Oxygen consumption monitored continuously during the exercises was used to calculate the gross energy expenditure. For cycle exercise, work performed was calculated based on the ergometer’s resistance setting and pedaling frequency. For treadmill, total work was estimated by assuming 25%work efficiency and subtracting the calculated heat production and resting metabolic rate from the gross energy expenditure. This heat production needs to be considered when determining the location of exercise hardware on ISS and designing environmental control systems. These values reflect only the human subject’s produced heat; heat produced by the exercise hardware also will contribute to the heat load.
Keywords: man in the loop test; interim resistance exercise device; International Space Station; exercise; resistance exercise
Abstract: The Interim Resistance Exercise Device (iRED), developed for the International Space Station (ISS), was evaluated using human subjects for a “Man-In-The-Loop Test” (MILT). Thirty-two human subjects exercised using the iRED in a test that was conducted over a 63-working-day period. The subjects performed the same exercises that will be used on board ISS, and the iRED operating constraints that are to be used on ISS were followed. In addition, eight of the subjects were astronauts who volunteered to be in the evaluation in order to become familiar with the iRED and provide a critique of the device. The MILT was scheduled to last for 57,000 exercise repetitions on the iRED. This number of repetitions was agreed to as a number typical of that expected during a 3-person, 17-week ISS Increment. One of the canisters of the iRED failed at the 49,683-repetition mark (87.1% of targeted goal). The remaining canister was operated using the plan for operations if one canister fails during flight (contingency operations). This canister remained functional past the 57,000-repetition mark. This report details the results of the iRED MILT, and lists specific recommendations regarding both operation of the iRED and future resistance exercise device development.
Keywords: interim resistance exercise device; International Space Station; exercise; resistance exercise, ground reaction force, unloading
Abstract: Musculoskeletal unloading in microgravity has been shown to induce losses in bone mineral density, muscle cross-sectional area, and muscle strength. Currently, an Interim Resistive Exercise Device (iRED) is being flown on board the ISS to help counteract these losses. Free weight training has shown successful positive musculoskeletal adaptations. In biomechanical research, ground reaction forces (GRF) trajectories are used to define differences between exercise devices. The purpose of this evaluation is to quantify the differences in GRF between the iRED and free weight exercise performed on a Smith machine during a squat. Due to the differences in resistance properties, inertial loading and load application to the body between the two devices, we hypothesize that subjects using iRED will produce GRF that are significantly different from the Smith machine. There will be differences in bar/harness range of motion and the time when peak GRF occurred in the ROMbar. Three male subjects performed three sets of ten squats on the iRED and on the Smith Machine on two separate days at a 2-second cadence. Statistically significant differences were found between the two devices in all measured GRF variables. Average Fz and Fx during the Smith machine squat were significantly higher than iRED. Average Fy (16.82 ± 6.23; p < .043) was significantly lower during the Smith machine squat. The mean descent/ascent ratio of the magnitude of the resultant force vector of all three axes for the Smith machine and iRED was 0.95 and 0.72, respectively. Also, the point at which maximum Fz occurred in the range of motion (Dzpeak) was at different locations with the two devices.
Keywords: injury; extravehicular activity; EVA; International Space Station; NBL; Neutral Buoyancy Lab; inverted body position; training; shoulder injury; musculoskeletal
Abstract: The number and complexity of extravehicular activities required for the completion and maintenance of the International Space Station is unprecedented. It is not surprising that training to perform these space walks presents a risk of overuse musculoskeletal injuries. The goal of this tiger team, created in December 2002, was to identify the different factors contributing to the risk of EVA training-related shoulder injury in the Neutral Buoyancy Lab at the Sonny Carter Training Facility and to make recommendations that would either significantly reduce or eliminate those risks. Since 1999, concerns have been expressed about the risk of shoulder injury associated with EVA training at the NBL, particularly in inverted body positions (McMonigal, 1999). A survey was developed and administered to 42 astronauts and astronaut candidates; the results suggest a causal relationship between EVA training at the NBL and the observed injuries. Also, during the tiger team review, it became evident that training in the extravehicular mobility unit may also result in other types of injuries, including fingernail delamination, elbow pain, knee pain, foot pain, and nerve compression leading to transient loss of sensation in certain areas of the upper or lower extremity. A multi-directorate team to detect, evaluate and respond to the medical issues associated with EVA training should be implemented immediately and given the appropriate resources and authority to reduce the risk of injury to crew during training to a level as low as reasonably achievable.
Keywords: sun; solar cycles; sunspots; solar radiation; solar maximum; radiation absorption; radiation dosage; radiation effects; radiation
Abstract: Since the current solar cycle 23 has progressed near the end of the cycle and accurate solar minimum and maximum occurrences have been defined, a statistical model based on the odd-even behavior of historical sunspot cycles was reexamined. Separate calculations of activity levels were made for the rising and declining phases in solar cycle 23, which resulted in improved projection of sunspots in the remainder of cycle 23. Because a fundamental understanding of the transition from cycle to cycle has not been developed, at this time it is assumed for project purposes that solar cycle 24 will continue at the same activity level in the declining phase of cycle 23. Projection errors in solar cycle 24 can be corrected as the cycle progresses and observations become available because this model is shown to be self-correcting.
Keywords: life support system; life support system, environments; environmental control; systems integration
Abstract: The Metric is one of several measures employed by the NASA to assess the Agency’s progress as mandated by the United States Congress and the Office of Management and Budget. Because any measure must have a reference point, whether explicitly defined or implied, the Metric is a comparison between a selected ALS Project life support system and an equivalently detailed life support system using technology from the Environmental Control and Life Support System (ECLSS) for the International Space Station (ISS). This document provides the official calculation of the Advanced Life Support (ALS) Research and Technology Development Metric (the Metric) for Fiscal Year 2004. The values are primarily based on Systems Integration, Modeling, and Analysis (SIMA) Element approved software tools or reviewed and approved reference documents. For Fiscal Year 2004, the Advanced Life Support Research and Technology Development Metric value is 2.03 for an Orbiting Research Facility and 1.62 for an Independent Exploration Mission.
Keywords: systems analysis; analogs; life support systems; human factors engineering;
Abstract: The Advanced Life Support (ALS) Baseline Values and Assumptions Document (BVAD) provides analysts and modelers as well as other ALS researchers with a common set of initial values and assumptions called a baseline. This baseline provides a common point of origin from which all systems integration, modeling, and analysis element studies will depart. The BVAD identifies quantities that define life support systems from an analysis and modeling perspective; provides a nominal or baseline value plus a range of possible or observed values for each physical quantity identified; and documents each entry with a description of the use, value selection rationale, and appropriate references of that quantity. Specifically, the BVAD allows the life support analysis community to carefully review and evaluate input study assumptions. Each study can benefit from the "best" available input values and assumptions by drawing on information collected by a group of researchers rather than an individual researcher. The BVAD process identifies quantities that are not well-defined by current information, allows researchers from multiple disciplines to effectively and quickly compare results from multiple studies, and allows these researchers to conduct a follow-on study to any previous work because assumptions from each study are clearly available and carefully recorded.
Keywords: decompression sickness, ergometer, exercise physiology,
Abstract: Exercise PB can reduce the risk of decompression sickness on ascent to 4.3 psia when performed at the proper intensity and duration. Data are from seven tests. PB times ranged from 90 to 150 min. High intensity, short duration dual-cycle ergometry was done during the PB. This was done alone, or combined with intermittent low intensity exercise or periods of rest for the remaining PB. Non-ambulating men and women performed light exercise from a semi-recumbent position at 4.3 psia for four hrs. The Research Model with age tested the probability that DCS increases with advancing age. The NASA Model with gender hypothesized that the probability of DCS increases if gender is female. Accounting for exercise and rest during PB with a variable half-time compartment for computed tissue N2 pressure advances our probability modeling of hypobaric DCS. Both models show that a small increase in exercise intensity during PB reduces the risk of DCS, and a larger increase in exercise intensity dramatically reduces risk. These models support the hypothesis that aerobic fitness is an important consideration for the risk of hypobaric DCS when exercise is performed during the PB.
Keywords: ISS, Space Station, ARIS, microgravity, umbilicals, planar elastica
Abstract: The International Space Station relies on the active rack isolation system (ARIS) as the central component of an integrated, station-wide strategy to isolate microgravity space-science experiments. ARIS uses electromechanical actuators to isolate an international standard payload rack from disturbances due to the motion of the Space Station. Disturbances to microgravity experiments on ARIS-isolated racks are transmitted primarily via the ARIS power and vacuum umbilicals. Experimental tests indicate that these umbilicals resonate at frequencies outside the ARIS controller’s bandwidth at levels of potential concern for certain microgravity experiments. Reduction in the umbilical resonant frequencies could help to address this issue. This work documents the development and verification of equations for the in-plane deflections and flexibilities of an idealized umbilical (thin, flexible, inextensible, cantilever beam) under end-point, in-plane loading (inclined-force and moment). The effect of gravity is neglected due to the on-orbit application. The analysis assumes an initially curved (not necessarily circular), cantilevered umbilical with uniform cross-section, which undergoes large deflections with no plastic deformation, such that the umbilical slope changes monotonically. The treatment is applicable to the ARIS power and vacuum umbilicals under the indicated assumptions.
Keywords: carbon-carbon composites, carbon fibers, reinforcing materials, ablation, abort trajectories, temperature effects, erosion, silicon carbides, silicon dioxides, oxidation
Abstract: Reusable, oxidation-protected reinforced carbon-carbon (RCC) has been successfully flown on all Shuttle Orbiter flights. Thermal testing of the silicon carbide-coated RCC to determine its oxidation characteristics has been performed in convective (plasma Arc-Jet) heating facilities. Surface sealant mass loss was characterized as a function of temperature and pressure. High-temperature testing was performed to develop coating recession correlations for predicting performance at the over-temperature flight conditions associated with abort trajectories. Methods for using these test data to establish multi-mission re-use (i.e., mission life) and single mission limits are presented.
Keywords: TOCA, water recovery system, Space Station, potable water supply, RFI
Abstract: This report summarizes the review and analysis of the proposed solutions submitted to meet the water quality monitoring requirements. Proposals were to improve upon the functionality of the existing Space Station Total Organic Carbon Analyzer (TOCA) and monitor additional contaminants in water samples. The TOCA is responsible for in-flight measurement of total organic carbon, total inorganic carbon, total carbon, pH, and conductivity in the Space Station potable water supplies. The current TOCA requires hazardous reagents to accomplish the carbon analyses. NASA is using the request for information process to investigate new technologies that may improve upon existing capabilities, as well as reduce or eliminate the need for hazardous reagents. Ideally, a replacement for the TOCA would be deployed in conjunction with the delivery of the Node 3 water recovery system currently scheduled for November 2007.
Keywords: near infrared sprectroscopy, elevated skin blood flow, supine rest, NIRS, SBF, sketal muscle, LDV, NIRD
Abstract: Near infrared spectroscopy is a non-invasive technique that allows determination of tissue oxygenation/blood flow based on spectro-photometric quantitation of oxy- and deoxyhemoglobin present within a tissue. This technique has gained acceptance as a means of detecting and quantifying changes in tissue blood flow due to physiological perturbation, such as that which is elicited in skeletal muscle during exercise. Since the NIRS technique requires light to penetrate the skin and subcutaneous fat in order to reach the muscle of interest, changes in skin blood flow may alter the NIRS signal in a fashion unrelated to blood flow in the muscle of interest. The aim of this study was to determine the contribution of skin blood flow to the NIRS signal obtained from resting vastus lateralis muscle of the thigh.
Keywords: bioastronautics, aerospace environments, critical path method, research, resource allocation
Abstract: The Bioastronautics Critical Path Roadmap is the framework used to identify and assess the risks to crews exposed to the hazardous environments of space. It guides the implementation of research strategies to prevent or reduce those risks. Although the BCPR identifies steps that must be taken to reduce the risks to health and performance that are associated with human space flight, the BCPR is not a “critical path” analysis in the strict engineering sense. The BCPR will evolve to accommodate new information and technology development and will enable NASA to conduct a formal critical path analysis in the future. As a management tool, the BCPR provides information for making informed decisions about research priorities and resource allocation. The outcome-driven nature of the BCPR makes it amenable for assessing the focus, progress and success of the Bioastronautics research and technology program. The BCPR is also a tool for communicating program priorities and progress to the research community and NASA management.
Keywords: heat transfer; temperature distribution; body temperature; heat stress; liquid-cooling garment; reentry; cabin temperature; skin temperature
Abstract: Current flight rules restrict maximum cabin temperature during reentry and landing to protect crewmembers from heat stress. Cabin temperature is affected by the amount of hardware in operation during these activities. To allow for additional operations, the maximum cabin temperature limit must be raised. Crewmembers wear a liquid-cooling garment (LCG) under their Suit during reentry and landing to protect against heat stress. The purpose of our project was to determine whether the LCG could adequately cool when cabin temperature was allowed to reach 80°F. Eight subjects underwent a simulated cabin temperature profile in an environmental chamber. Subjects completed a 10-minute stand test as an assessment of orthostatic tolerance before and after the chamber stay. The secondary objective was to determine whether there was a graded effect of cabin temperatures when the maximums were 75, 80, and 85F. Four suited subjects underwent the simulated temperature profile at these temperatures. Ratings were measured in 15-minute intervals on a 10-minute stand test. No discernible pattern was observed in core or skin temperatures. There appeared to be higher subjective ratings of comfort and heat across the temperature profiles. However, the subjects were able to control sufficiently their body temperatures with self-selected flow rates during these tests.
Keywords: Cosmic Dust, particles, interplanetary dust, luster, size, shape, transparence, color.
Abstract: Since May 1981, NASA has used aircraft to collect cosmic dust particles from Earth’s stratosphere. Specially designed dust collectors are prepared for flight and processed after flight in an ultraclean (class-100) laboratory constructed for this purpose at the Lyndon B. Johnson Space Center in Houston, Texas. Particles are individually retrieved from the collectors, examined and cataloged, and then made available to the scientific community for research. Cosmic dust thereby joins lunar samples and meteorites as an additional source of extraterrestrial materials for scientific study. This catalog summarizes preliminary observations on particles retrieved from many collection surfaces. These surfaces were flat plate collectors, which were coated with silicone oil (dimethyl siloxane) and then flown aboard NASA U-2, ER-2 and WB-57F aircraft. All of the collectors were installed in specially constructed wing pylons which ensured that the necessary level of cleanliness was maintained between periods of active sampling. During successive periods of high altitude (20 km) cruise, the collectors were exposed in the stratosphere by barometric controls and then retracted into sealed storage containers prior to descent. This catalog does not describe new particles; rather, we have revisited all previous catalogued cluster particles, and ascertained how much of each remains for allocation. http://www-curator.jsc.nasa.gov/curator/dust/cdcat16/index.htm
Keywords: arc jet engines, atmospheric entry, structural analysis, tiles, silicon rectifiers, spacecraft maintenance, emissivity, thermal stability, shrinkage.
Abstract: Arc jet tests of candidate tile repair materials and baseline Orbiter uncoated reusable surface insulation (RSI) were performed in the Johnson Space Center’s (JSC) Atmospheric Reentry Materials and Structures Evaluation Facility (ARMSEF) from June 23, 2003, through August 19, 2003. These tests were performed to screen candidate tile repair materials by verifying the high temperature performance and determining the thermal stability. In addition, tests to determine the surface emissivity at high temperatures and the geometric shrinkage of bare RSI were performed. In addition, tests were performed to determine the surface emissivity at high temperatures and the geometric shrinkage of uncoated RSI.arc
Keywords: manned spacecraft, space suits, pressure suits, atmospheres, controlled atmospheres, life support systems.
Abstract: The selection of spacecraft and space suit atmospheres for future human space exploration missions will play an important, if not critical, role in the ultimate safety, productivity, and cost of such missions. Internal atmosphere pressure and composition (particularly oxygen concentration) influence many aspects of spacecraft and space suit design, operation, and technology development. Optimal atmosphere solutions must be determined by iterative process involving research, design, development, testing, and systems analysis. A necessary first step in this process is the establishment of working bounds on the atmosphere design space.
Keywords: Weightlessness, weightlessness simulation, parabolic flight, zero gravity, aerospace medicine, astronaut performance, bioprocessing, space manufacturing.
Abstract: This document represents a summary of medical and scientific evaluations conducted aboard the KC-135 from June 23, 2004 to June 27, 2005. Included is a general overview of KC-135 activities manifested and coordinated by the Human Adaptation and Countermeasures Office. A collection of brief reports that describe tests conducted aboard the KC-135 follows the overview. Principal investigators and test engineers contributed significantly to the content of the report describing their particular experiment or hardware evaluation. This document concludes with an appendix that providesbackground information concerning the KC-135 and the Reduced-Gravity Program.
Keywords: cognition; exploration, space flight; risk; management, human resources; responses, physiological; sensory perception; perception; human performance
Abstract: "Cognition in Space Workshop I: Metrics and Models" was the first in a series of workshops sponsored by NASA to develop an integrated research and development plan supporting human cognition in space exploration. The workshop was held in Chandler, Arizona, October 25–27, 2004. The participants represented academia, government agencies, and medical centers. This workshop addressed the following goal of the NASA Human System Integration Program for Exploration: to develop a program to manage risks due to human performance and human error, specifically ones tied to cognition. Risks range from catastrophic error to degradation of efficiency and failure to accomplish mission goals. Cognition itself includes memory, decision making, initiation of motor responses, sensation, and perception. Four subgoals were also defined at the workshop as follows: (1) NASA needs to develop a human-centered design process that incorporates standards for human cognition, human performance, and assessment of human interfaces; (2) NASA needs to identify and assess factors that increase risks associated with cognition; (3) NASA needs to predict risks associated with cognition; and (4) NASA needs to mitigate risk, both prior to actual missions and in real time. This report develops the material relating to these four subgoals.
Keywords: probability distribution functions; galactic cosmic rays; solar radiation; morality; radiation effects; radiation shielding; radiation; cancer; mission planning
Abstract: This document addresses calculations of probability distribution functions (PDFs) representing uncertainties in projecting fatal cancer risk from galactic cosmic rays (GCR) and solar particle events (SPEs). PDFs are used to test the effectiveness of potential radiation shielding approaches. Monte-Carlo techniques are used to propagate uncertainties in risk coefficients determined from epidemiology data, dose and dose-rate reduction factors, quality factors, and physics models of radiation environments. Competing mortality risks and functional correlations in radiation quality factor uncertainties are treated in the calculations. The cancer risk uncertainty is about four-fold for lunar and Mars mission risk projections. For short-stay lunar missins (<180 d), SPEs present the most significant risk, but one effectively mitigated by shielding. For long-duration (>180 d) lunar or Mars missions, GCR risks may exceed radiation risk limits. While shielding materials are marginally effective in reducing GCR cancer risks because of the penetrating nature of GCR and secondary radiation produced in tissue by relativisitc particles, polyethylene or carbon composite shielding cannot be shown to significantly reduce risk compared to aluminum shielding. Therefore, improving our knowledge of space radiobiology to narrow uncertainties that lead to wide PDFs is the best approach to ensure radiation protection goals are met for space exploration.
Keywords: Kalman filters, algorithms, space rendezvous, state vectors
Abstract: A new derivation of an algorithm which fuses the outputs of two Kalman filters is presented. Unlike other works, this derivation clearly shows the combination of estimates to be optimal, minimizing the trace of the fused covariance matrix. The algorithm assumes that the filters use identical models, and are stable and operating optimally with respect to their own local measurements. Evidence is presented which indicates that the error ellipsoid derived from the covariance of the optimally fused estimate is contained within the intersections of the error ellipsoids of the two filters being fused. Modifications which reduce the algorithm's data transmission requirements are also presented, including a scalar gain approximation, a cross-covariance update formula which employs only the two contributing filters' autocovariances, and a form of the algorithm which can be used to reinitialize the two Kalman filters. A sufficient condition for using the optimally fused estimates to periodically reinitialize the Kalman filters in this fashion is presented and proved as a theorem. When these results are applied to an optimal spacecraft rendezvous problem, simulated performance results indicate that the use of optimally fused data leads to significantly improved robustness to initial target vehicle state errors. Two other applications of estimate fusion methods to spacecraft rendezvous are also described: state vector differencing, and redundancy management.
Keywords: space debris; miss distance; predictions; forecasting; energy dissipation; shielding; collision avoidance; radar cross sections; inclination, orbits; circular orbits
Abstract: A responsibility of the Trajectory Operations Officer is to ensure that the International Space Station (ISS) avoids colliding with debris. United States Space Command (USSPACECOM) tracks and catalogs a portion of the debris in Earth orbit, but only objects with a perigee less than 600 km and a radar cross section (RCS) greater than 10 cm—objects that, in fact, represent only a small fraction of the objects in Earth orbit. To accommodate for this, the ISS uses shielding to protect against collisions with smaller objects. This study provides a better understanding of how quickly, and to what degree, USSPACECOM projections tend to converge to the final, true miss distance. The information included is formulated to better predict the behavior of miss distance data during real-time operations. It was determined that the driving components, in order of impact on miss distance fluctuations, are energy dissipation rate (EDR), RCS, and inclination. Data used in this analysis, calculations made, and conclusions drawn are stored in Microsoft Excel log sheets. A separate log sheet, created for each conjunction, contains information such as predicted miss distances, apogee and perigee of debris orbit, EDR, RCS, inclination, tracks and observations, statistical data, and other evaluation/orbital parameters.
Keywords: Human performance, abilities; life support systems; systems engineering; Medical science, cardiology; aerospace medicine; communication; exploration
Abstract: The 2004 Johnson Space Center (JSC) National Aeronautics and Space Administration Faculty Fellowship Program (NFFP) was conducted by Texas A&M University and JSC. The program was funded by the Office of Education, NASA Headquarters, Washington, D.C. and by JSC. Each faculty Fellow spent at least 10 weeks at JSC (or the White Sands Test Facility) engaged in a research project in collaboration with a NASA/JSC colleague. This document is a compilation of the final reports on the research projects done by the Fellows during the summer of 2004. Volume 1 contains reports 1 through 12 and Volume 2 contains reports 13 through 22.
Keywords: Aerospace medicine, radiation, gravitational physiology, space psychlogy, weightliessness, biomedical data.
Abstract: The paper describes what we have learned from the first four years of research on ISS relative to the exploration mission, the on-going research being conducted in this regard, and our current understanding of the major exploration mission risks that the ISS can be used to address. Specifically, we discuss research carried out on the ISS to determine the mechanisms by which human health is affected on long-duration exploration missions. We also discuss how targeted technological developments can enable mission design trade studies. We discuss the relationship between the ultimate number of human test subjects available on the ISS to the quality and quantity of results of NASA's efforts over the past year to realign the ISS research programs to support a product-driven portfolio that is directed towards reducing the major risks of exploration.
Keywords: Weightlessness, astronaut performance, bone demineralization,
Abstract: Prolonged exposure to weightlessness associated with spaceflight provokes profound physiological changes in humans. Two areas of significant concern are bone loss and neuromuscular deconditioning. Changes in lower-limb neuromuscular activation patterns have raised concern about the ability of astronauts to escape from their spacecraft in an emergency landing situation. Countermeasures that stimulate bone maintenance and locomotor control are vital to the success of human spaceflight. It has been hypothesized that, to help maintain the bone mineral density that an astronaut has in normal gravity, the ground reaction force (GRF) achieved during locomotion in weightlessness should mimic the GRF that occurs on Earth. Currently, a crewmember exercising on the treadmill recieves an external load by means of an upper-body harness that attaches to the SLD via extender straps or bungees. GRF is imparted as the SLD pulls the crewmember toward the treadmill surface during locomotion. The primary objective of this investigation was to determine if gait, GRF, an kinematics during locomotion at 0G, using a simulated ISS treadmill and SLD, are significantly different from those found during locomotion at 1G. The secondary objective of this investigation was to quantify the load magnitude, variability, and stiffness of the external load applied to the crewmember by the SLD during locomotion at -G.
Keywords: International Space Station, Space Shuttle, knowledge capture, knowledge management, human space vehicles
Abstract: The incorporation of knowledge capture and knowledge management strategies early in the development phase of an exploration program is necessary for safe and successful missions of human and robotic exploration vehicles of the life of a program. Following the transition from the development to the flight phase, loss of underlying theory and rationale governing design and requirements occur through a number of mechanisms. This degrades the quality of engineering work resulting in increased life cycle costs and risk to mission success and safety of flight.Application of advanced information technology to perform knowledge capture and management would be most effective if program-wide requirements are defined at the beginning of a program.
Keywords: satellite breakup, human tended vehicles, SBRAM, shuttle, satellite
Abstract: There have been 30 known satellite breakups from First Element Launch in November 1998 to June 2005. While breakups have been studied, the threat they cause to human space flight is not well understood. Previous studies simply assessed the probability of collision per square meter and never considered different particle diameters or vulnerable areas of vehicles. Also, no flight rules exist to aid the crew and flight control team in response to a satellite breakup, causing concern for the safety of crew members and vehicles. This study fills the gaps left by previous tests and provides information that will be used to create flight rules that will increase safety during human spaceflight.
Keywords: International Space Station, Space Shuttle, lessons learned, X-38
Abstract: This document is a collection of writings concerning the application of GPS technology to the International Space Station, Space Station, and X-38 vehicles. An overview of how GPS technology was applied is given for each vehicle, including rationale behind the integration architecture and rationale governing the use or non-use of GPS data during flight.
Keywords: ALS, metric, SIMA
Abstract: This document provides the official calculation of the Advanced Life Support (ALS) Research and Technology Development Metric (the Metric) for Fiscal Year 2005. As such, the values herein are primarily based on Systems Integration, Modeling, and Analysis (SIMA) Element approved software tools or reviewed and approved reference documents.
Keywords: exercise physiology, locomotion, physiological effects, Aerospace medicine, astronaut performance, bone demineralization, gravitational effects.
Abstract: The purpose of this investigation was to evaluate locomotion on the Russian BD-1 non-motorized treadmill under three conditions weightlessness (0G) without a simulated subject positioning device, or horizontal restraint strap (RS), normal gravity (1G) without a RS, and 1G with a RS. Various outcome measures were evaluated, including the applied external load (EL), vertical ground reaction force (GRF), the ability to achieve specific locomotion speeds, and joint kinematics. The goal of this research was to better understand how locomotion and the related forces experienced by the musculoskeletal system during non-motorized treadmill locomotion in 0G compare to locomotion on the same device in 1G.
Keywords: space debris; Gamma Ray Observatory; environment effects; penetration; flux; maneuvers; aerospace environments
Abstract: A joint simulation was performed by the NASA Johnson Space Center (JSC) and United States Space Command (USSPACECOM) to obtain information concerning the current space debris population for debris avoidance operations. Simulation results, which are extrapolated within this document, are intended for use in future space station operations. The simulation, performed from September 1992 to March 1993, used the Gamma Ray Observatory (GRO)--orbiting at 28.5-deg orbital inclination, and substituting for a space station orbital inclination--as a target vehicle. As the simulation was carried out, USSPACECOM used the database maintained by its tracking network to search for conjunctions between the GRO and the tracked debris, and then transmitted results of the simulation to JSC for analysis. Over the entire altitude band studied, the debris flux and frequency of penetration of space shuttle orbiter "alert" and "maneuver" boxes were found to be much lower than the predictions of current models. However, if a maneuver box similar to that used for the space shuttle is used for a future space station, the number of maneuvers to avoid orbital debris will be prohibitive. Results of this study showed a very dynamic debris environment over the time period and altitudes covered.
Keywords: motion, human performance, video data, image analysis, image processing, underwater photography
Abstract: Video-based motion analysis systems are widely employed to study human movement, using computers to capture, store, process, and analyze video data. This data can be collected in any environment where cameras can be located. One of the NASA facilities where human performance research is conducted is the Weightless Environment Training Facility (WETF), a pool of water which simulates zero-gravity with neutral buoyance. Underwater video collection in the WETF poses some unique problems. This project evaluates the error caused by the lens distortion of the WETF cameras. A grid of points of known dimensions was constructed and videotaped using a video vault underwater system. Recorded images were played back on a VCR and a personal computer grabbed and stored the images on disk. These images were then digitized to give calculated coordinates for the grid points. Errors were calculated as the distance from the known coordinates of the points to the calculated coordinates. It was demonstrated that errors from lens distortion could be as high as 8%. By avoiding the outermost regions of a wide-angle lens, the error can be kept smaller.
Keywords: micrometeoroids; space debris; damage assessment; risk; impact damage; environment protection; environment simulation
Abstract: STS-111 was the eighteenth flight for the Space Shuttle Endeavour. This UF-2 mission to the International Space Station (ISS) involved a crew rotation and the delivery of new supplies and experiments in the multi-purpose logistics module. The mission, which took place between June 5 and June 19, 2002, had an orbital inclination of 51.6 deg and an altitude of about 389 km (210 n. mi.). This report on the meteoroid/orbital debris (M/OD) experienced during the mission of STS-111 is divided into two sections: The "As-Flown Assessment" section compares the results of a risk analysis using postflight attitude data with postflight damage observations and preflight risk predictions; and the "Postflight Damage Inspection" section documents the M/Od that was observed during inspections at Kennedy Space Center following the mission. Preflight and postflight assessments were performed using BUMPER-II code with the ORDEM 2000 orbital debris environment and the SSP-30425 meteoroid environment. At Shuttle/ISS altitudes, the new environment predicts a higher number of particles in the 0.01-mm-to-4-mm-diameter range and a fewer number of particles in the 4-mm-to-10-cm diameter range.
Keywords: Human factor engineering, Exercise physiology: muscular tonus, physical fitness, weightlessness, Space manufacturing,
Abstract: The interim Resistive Exercise Device (iRED) is currently being flown aboard the International Space Starion to mitigate the loss of muscle mass and muscular strength associated with long-duration exposure to microgravity. However, iRED is limited in the maximal loads that it can provide, and thus, is viewed as an interim solution to the loss of muscular strength. Thus, NASA has initiated the design and construction of the Advanced Resistive Exercise Device (ARED as a long-term solution to the preservation of muscle strength during extended habitation of microgravity environments. The ARED is designed to provide greater exercise capability than iRED. The primary resistance mechanism in the ARED is a pair of vacuum cylinders containing pistons. Preliminary life cycle testing indicates that the ARED will endure over one million cycles without critical failure. However, life cycle testing is much different than human subject testing. Often, humans put unique forces on devices that are not present during machine testing. Thus, the purpose of this evaluation was to test the functionality durability and reliability of the ARED during exercise executed by human subjects.
Keywords: galactic cosmic rays; terrestrial radiation; deoxyribonucleic acid; simulation; energy transfer; chromosomes; ions; models
Abstract: The high-charge high-energy (HZE) ion components of the galactic cosmic rays when compared to terrestrial forms of radiations present unique challenges to biological systems. In this paper we present a deoxyribonucleic acid (DNA) breakage model to visualize and analyze the impact of chromatin domains and DNA loops on clustering of DNA damage from X rays, protons, and HZE ions. Our model of DNA breakage is based on a stochastic process of DNA double-strand break (DSB) formulation that includes the amorphous model of the radiation track and a polymer model of DNA packed in the cell nucleus. Our model is a Monte-Carlo simulation based on a randomnly located DSB cluster formulation that accomodates both high- and low-linear energy transfer radiations. We demonstrate that HZE ions have a strong impact on DSB clustering, both along the chromosome length and in the nucleus volume. The effects of chromosomal domains and DNA loops on the DSB fragment-size distribution and the spatial distribution of DSB in the nucleus were studied. We compare our model predictions with the spatial distribution of DSB obtained from experiments. The implications of our model predictions for radiation protection are discussed.
Keywords: education; teaching; International Space Station; instructors; mathematics principles; engineering; science; instructions
Abstract: One important objective of NASA has always been to inspire the next generation. NASA and human space flight have a unique ability to capture the imaginations of both students and teachers. The presence of humans onboard the International Space Station (ISS) for more than five years now has provided a foundation for numerous educational activities aimed at capturing the interest and motivating study in the sciences, technology, engineering, and mathematics. Yet even before the Expedition 1 crew arrived at station in November 2000, experiments with student participation were being conducted onboard ISS in support of NASA missions. One of NASA's protein crystal growth experiments had been delivered to station by the shuttle Atlantis during STS-106 in September 2000 and was returned to Earth six weeks later aboard the shuttle Discovery during the STS-92 mission. From very early on it was recognized that students would have a strong interest in the ISS, and that this would provide a unique opportunity for them to get involved and participate in science and engineering projects on ISS. It should be noted that participation is not limited to U.S. students but involves the 16 International Partner countries and various other countries under special commercial agreements.
Keywords: extravehicular mobility unit; extravehicular activity; spacesuits; training analysis; symptomology; injuries, impairment; injuries, systems engineering
Abstract: The purpose of this study was to characterize the symptoms and injuries experienced by NASA astronauts during extravehicular activity (space walk) spacesuit training at the Neutral Buoyancy Laboratory at Ellington Field, Houston, Texas. We identified the frequency and incident rates of symptoms by each general body location and characterized mechanisms of injury and effective countermeasures. Based on these findings a comprehensive list of recommendations was made to improve training, test preparation, and current spacesuit components, and to design the next-generation spacesuit. At completion of each test event a comprehensive questionnaire was produced that documented suit symptom comments, identified mechanisms of injury, and recommended countermeasures. As we completed our study we found that most extravehicular mobility unit suit symptoms were mild, self-limited, and controlled by available countermeasures. Some symptoms represented the potential for significant injury with short- and long-term consequences regarding astronaut health and inteference with mission objectives. The location of symptoms and injuries that were most clinically significant was in the hands, shoulders, and feet. Correction of suit symptoms issues will require a multidisciplinary approach to improve prevention, early medical intervention, astronaut training, test planning, and suit engineering.
Keywords: Global positioning system, position indicators, orbit determination, space navigation, software engineering, software reliability.
Abstract: The international Space Station global positioning system (GPS) receiver was activated in April 2002. Since that time, numerous software anomalies surfaced that had to be worked around. Some of the software problems required waivers, such as the time function, while others required extensive operator intervention, such as numerous power cycles. Eventually enough anomalies surfaced that the three pieces of code included in the GPS unit have been re-written and the GPS units upgraded. The technical aspects of the problems are discussed, as well as the underlying causes that led to the delivery of a product that has had so many problems. The technical aspects of the problems included physical phenomena that were not well understood, such as the affect that the ionosphere would have on the GPS measurements. The underlying causes were traced to inappropriate use of legacy software, changing requirements, inadequate software processes, unrealistic schedules, incorrect contract type, and unclear ownership responsibilities.
Keywords: One of the most versatile tools designed for use on the International Space Station (ISS) is the Special Purpose Dexterous Manipulator (SPDM) robot. Operators for this system are trained at NASA Johnson Space Center using a robotic simulator, the Dexterous Manipulator Trainer (DMT), which performs most SPDM functions under normal static Earth gravitational forces. The SPDM is controlled from a standard Robotic Workstation. A key feature of the SPDM and DMT is the Force/Moment Accommodation (FMA) system, which limits the contact forces and moments acting on the robot components, on its payload – an Orbital Replaceable Unit (ORU) – and on the receptacle for the ORU. The FMA system helps to automatically alleviate any binding of the ORU as it is inserted or withdrawn from a receptacle, but it is limited in its correction capability. A successful ORU insertion generally requires that the reference axes of the ORU and receptacle be aligned to within approximately 0.25 inch and 0.5 degree of nominal values. The only guides available for the operator to achieve these alignment tolerances are views from any available video cameras. No special registration markings are provided on the ORU or receptacle, so the operator must use the intrinsic features in the video display to perform the pre-insertion alignment task. Since optimum camera views may not be available and dynamic orbital lighting conditions may limit viewing periods, long times are anticipated for performing some ORU insertion or extraction operations. This study explored the feasibility of using augmented reality (AR) to assist with SPDM operations. Geometric graphical symbols were overlaid on the end effector camera view to afford cues to assist the operator in attaining adequate pre-insertion ORU alignment.
Abstract: One of the most versatile tools designed for use on the International Space Station (ISS) is the Special Purpose Dexterous Manipulator (SPDM) robot. Operators for this system are trained at NASA Johnson Space Center using a robotic simulator, the Dexterous Manipulator Trainer (DMT), which performs most SPDM functions under normal static Earth gravitational forces. The SPDM is controlled from a standard Robotic Workstation. A key feature of the SPDM and DMT is the Force/Moment Accommodation (FMA) system, which limits the contact forces and moments acting on the robot components, on its payload – an Orbital Replaceable Unit (ORU) – and on the receptacle for the ORU. The FMA system helps to automatically alleviate any binding of the ORU as it is inserted or withdrawn from a receptacle, but it is limited in its correction capability. A successful ORU insertion generally requires that the reference axes of the ORU and receptacle be aligned to within approximately 0.25 inch and 0.5 degree of nominal values. The only guides available for the operator to achieve these alignment tolerances are views from any available video cameras. No special registration markings are provided on the ORU or receptacle, so the operator must use the intrinsic features in the video display to perform the pre-insertion alignment task. Since optimum camera views may not be available and dynamic orbital lighting conditions may limit viewing periods, long times are anticipated for performing some ORU insertion or extraction operations. This study explored the feasibility of using augmented reality (AR) to assist with SPDM operations. Geometric graphical symbols were overlaid on the end effector camera view to afford cues to assist the operator in attaining adequate pre-insertion ORU alignment.
Keywords: Global positioning system, position indicators, orbit determination, space navigation, software engineering, software reliability.
Abstract: A three-dimensional (3-D) tissue-like assembly (TLA) of human bronchial-tracheal mesenchymal (HBTC) cells with an overlay of human bronchial epithelial (BEAS-2B) cells was constructed using a NASA Bioreactor to survey the infectivity of SARS-CoV. This TLA was inoculated with a low passage number Urbani strain of SARS-CoV. At selected intervals over a 10-day period, media and cell aliquots of the 3-D TLA were harvested for viral titer assay and for light and electron microscopy examination. All viral titer assays were negative in both BEAS-2B two-dimensional monolayer and TLA. Light microscopy immunohistochemistry demonstrated antigen–antibody reactivity with anti-SARS-CoV polyclonal antibody to spike and nuclear proteins on cell membranes and cytoplasm. Coronavirus Group 2 cross-reactivity was demonstrated by positive reaction to anti-FIPV 1 and anti-FIPV 1 and 2 antibodies. TLA examination by transmission electron microscopy indicated increasing cytoplasmic vacuolation with numerous electron-dense bodies measuring 45 to 270 nm from days 4 through 10. There was no evidence of membrane blebbing, membrane duplication, or fragmentation of organelles in the TLAs. However, progressive disruption of endoplasmic reticulum was observed throughout the cells. Antibody response to SARS-CoV specific spike and nucleocapsid glycoproteins, cross-reactivity with FIPV antibodies, and the cytoplasmic pathology suggests this HBTE TLA model is permissive to SARS-CoV infection.
Keywords: Weightlessness, weightlessness simulation, parabolic flight, zero gravity, aerospace medicine, astronaut performance, bioprocessing, space manufacturing.
Abstract: This document represents a summary of medical and scientific evaluations conducted aboard the C-9 or other NASA-sponsored aircraft from June 30, 2005, to June 30, 2006. Included is a general overview of investigations manifested and coordinated by the Human Adaptation and Countermeasures Office. A collection of brief reports that describe tests conducted aboard the NASA-sponsored aircraft follows the overview. Principal investigators and test engineers contributed significantly to the content of the report, describing their particular experiment or hardware evaluation. Although this document follows general guidelines, the format of individual reports varies to accommodate differences in experiment design and procedures. This document concludes with an appendix that provides background information concerning the Reduced Gravity Program.
Keywords: Apollo, lunar dust, exploration vision, lessons learned, lunar module, command modlue, contamination
Abstract: The Apollo Mission Reports and Technical Debriefs were used to identify problems, solutions, and lessons learned. These documents were chosen because they were prepared immediately after the missions, while crewmembers memories of their lunar experience were still fresh. This report intentionally did not include later documentation and statements by crews, because memories fade and change, this methodology should produce a historically factual report. This report should be considered a starting point.
Keywords: Exercise Physiology, Laboratory Equipment, Physiological Tests, Treadmills, Ergometers, Body Measurement (Biology)
Abstract: This manual, based on procedures used in the Exercise Countermeasures Project at the Johnson Space Center, is intended as a reference for exercise physiology laboratories in developing their individual procedures. Included are brief discussions of laboratory safety and equipment calibration, assembly, and cleaning. The administration of graded exercise tests is described, and detailed procedures are given for measurement of body composition and physiological changes during exercise.
Keywords: space stations, workstations, human factors engineering, man machine systems, productivity, remote manipulator system, control systems, control boards
Abstract: Previous development testing for the Space Station Remote Manipulator System Workstation controls determined the need for hardware controls for the emergency stop, brakes on/off, and some camera functions. This report documents the results of an evaluation to further determine control implementation requirements, requested by the Canadian Space Agency (CSA) to close outstanding review item discrepancies. This test was conducted at the Johnson Space Center's Space Station Mockup and Trainer Facility in Houston, Texas, with nine NASA astronauts and one CSA astronaut as operators. This test evaluated camera iris and focus, back-up drive, latching end effector release, and autosequence controls, using several types of hardware and software implementations. Recommendations resulting from the testing included providing guarded hardware buttons to prevent accidental actuation; providing autosequence controls and back-up drive controls on a dedicated hardware control panel; and that "latch on/latch off", or on-screen software, controls not be considered. Generally, the operators preferred hardware controls although other control implementations were acceptable. The results of this evaluation will be used along with further testing to define specific requirements for the Workstation design.
Keywords: International Space Station; research facilities; bioastronautics; space technology experiments; biology; physical science, space flight, technology assessment
Abstract: This report summarizes research accomplishments on the International Space Station (ISS) through the first ten Expeditions. When research programs for early Expeditions were established, five administrative organizations were executing research on ISS: bioastronautics research, fundamental space biology, physical science, space product development, and space flight. The Vision for Space Exploration led to changes in NASA's administrative structures, so we have grouped experiments topically by scientific themes--human research for exploration, physical and biological sciences, technology development, observing the Earth, and educating the inspiring the next generation--even when those do not correspond to the administrative structure at the time at which they were completed. The research organizations at the time at which the experiments flew are preserved in the appendix of this document. These early investigations on ISS have laid the groundwork for research planning for Expeditions to come. Humans performing scientific investigations on ISS serve as a model for the goals of future Exploration missions. The success of a wide variety of investigations is an important hallmark of early research on ISS. Of the investigations summarized here, some are completed with results released, some are completed with preliminary results, and some remain ongoing.
Keywords: Manned Spacecraft, Apollo Spacecraft, Vostok spacecraft, Voskhod manned spacecraft, crew workstations
Abstract: This thesis presents a frame work for a crew station handbook and includes samples of the broader areas which such a handbook should cover. The completed sections of this thesis serve as extensive treatments of the topics covered. The content of the individual sections of Chapters I and II varied with my experience and knowledge.
Keywords: long duration space flight, workloads (psychophysiology), fatigue, human performance, mental performance, physical work, stress, work capacity.
Abstract: The daily Skylab timelines have been reduced to categorical activities and the crew day has been broken down into man-hours expended in each of three separate categories: self sustenance activities, operational activities, and payload activities. The analysis shows that the average day aboard Skylab consisted of 14 hours of self sustenance activity, 6 1/2 hours of payload activity, and 3 1/2 hours of operational activity. The 10 hour workday represented by the combined payload and operational activity is recommended as the baseline workday for future manned missions. Additionally, until further experience or data indicates the feasibility of more than 90-day orbital stay times, the 90-day crew rotation is recommended as the baseline for planning long duration orbital projects.
Keywords: Weightlessness, weightlessness simulation, parabolic flight, zero gravity, aerospace medicine, astronaut performance, bioprocessing, space manufacturing.
Abstract: The Science Crew Operations and Utility Testbed (SCOUT) project is focused on the development of a rover vehicle that can be utilized by two crewmembers during extra vehicular activities (EVAs) on the moon and Mars. The current SCOUT vehicle can transport two suited astronauts riding in open cockpit seats. Among the aspects currently being developed is the cockpit design and layout. This process includes the identification of possible locations for a socket to which a crewmember could connect a portable life support system (PLSS) for recharging power, air, and cooling while seated in the vehicle. The spaces in which controls and connectors may be situated within the vehicle are constrained by the reach and vision capabilities of the suited crewmembers. Accordingly, quantification of the volumes within which suited crewmembers can both see and reach relative to the vehicle represents important information during the design process.
Keywords: medical equipment; telemedicine; risk; clinical medicine; patients; microgravity applications
Abstract: The feasibility of ultrasonic imaging in human space flight has been demonstrated on NASA and Russian spacecraft. Several ultrasound systems have been successfully operated by both physician and non-physician astronauts and cosmonauts in pre-International Space Station (ISS) space flights, yielding valuable scientific information. A multipurpose ultrasound system was adapted for space and installed aboard ISS to continue human research in microgravity environments at a new level of sophistication and fidelity. Alone or in combination with other components of the Human Research Facility (HRF), this system provides a research capability never before available in space. The system can operate in B, M, Color Doppler, Power Angiography, Flow Propagation, Pulsed Spectral Doppler, and Continuous Wave Doppler modes and their combinations. Thus, the HRF Ultrasound System allows the realization of the great scientific potential of ultrasound imaging in conditions of space flight, acquiring morphological/morphometric and physiological/functional information from virtually every area or organ system of the human body. This will now allow ultrasound to be used in space for medical risk mitigation and has driven the medical concept of operations to recognize and treat as many medical conditions as possible while on orbit, delaying or avoiding return to a definitive medical care facility.
Keywords: Spacecraft Performance, spacecraft rendezvous, spacecraft guidance
Abstract: Much can be learned from well-written descriptions of the technical and organizational factors that lead to an accident. Subsequent analysis by third parties of investigation reports and associated evidence collected during the investigations can lead to additional insight. Much can also be learned from documented close calls that do not result in loss of life or a spacecraft, such as the Mars Exploration Rover Spirit software anomaly, the SOHO mission interruption, and the NEAR burn anomaly. Seven space shuttle incidents fall into the latter category: Rendezvous Target Failure On STS-41B; Rendezvous Radar Anomaly and Trajectory Dispersion-STS-32 ;Rendezvous Lambert Targeting Anomaly-STS-49; Rendezvous Lambert Targeting Anomaly-STS-51; Zero Doppler Steering Maneuver Anomaly-STS-59; Excessive Propellant Consumption During Rendezvous-STS-69; Global Positioning System Receiver and Associated Shuttle Flight Software Anomalies-STS-91 Procedural work-arounds or software changes prevented them from threatening mission success. Extensive investigations, which included the independent recreation of the anomalies by multiple Shuttle Program organizations, were the key to determining the cause, accurately assessing risk, and identifying software and software process improvements. Lessons learned from these incidents not only validated long-standing operational best practices, but serve to promote discussion and mentoring among Program personnel and are applicable to future space flight programs.
Keywords: Solid propellant rocket engines,space shuttle boosters, space debris
Abstract:
Through an intensive collection and assimilation effort of SRM related data and resources, the author offers a resolution to the uncertainties surrounding SRM particulate generation, sufficiently so to enable a first-order incorporation of SRMs as a source term in space debris environment definition. The following five key conclusions are derived:
1) The emission of particles in the size regime of greatest concern from an orbital debris hazard perspective (D >100 µm), and in significant quantities, occurs only during the Tail-off phase of SRM burn activity.
2) The velocity of these emissions is correspondingly small - between 0 and 100 m/s.
3) The total Tail-off emitted mass is between approximately 0.04 and 0.65% of the initial propellant mass.
4) The majority of Tail-off emissions occur during the 30 second period that begins as the chamber pressure declines below approximately 34.5 kPa (5 psia).
5) The size distribution for the emitted particles ranges from 100 µm
Keywords: ignition, combustion, oxygen-enriched environment, oxygen hazards analysis
Abstract: Understanding and preventing fire hazards is necessary when designing, maintaining, and operating oxygen systems. Ignition risks can be minimized by controlling heat sources and using materials that will not ignite or will not support burning in the end-use environment. Because certain materials are more susceptible to ignition in oxygen-enriched environments, a compatibility assessment should be performed before the component is introduced into an oxygen system. This document provides an overview of oxygen fire hazards and procedures that are consistent with the latest versions of American Society for Testing and Materials (ASTM) Standards G63 (1999) and G94 (2005) to address fire hazards associated with oxygen systems. This document supersedes the previous edition, NASA Technical Memorandum 104823, Guide for Oxygen Hazards Analyses on Components and Systems (1996). The step-by-step oxygen compatibility assessment method described herein (see Section 4) enables oxygen-system designers, system engineers, and facility managers to determine areas of concern with respect to oxygen compatibility and, ultimately, prevent damage to a system or injury to personnel.
Keywords: Materials, fractures, tests, reaction control
Abstract: In April 2004, the Space Shuttle Orbiter Reaction Control System (RCS) thruster serial number (S/N) 120’s injector was found to be cracked while undergoing a nozzle retrofit at the White Sands Test Facility (WSTF). The RCS is composed of safety-critical propulsion hardware elements used to control the attitude of the space shuttle orbiter during virtually all operational mission phases. Since a failure resulting from an RCS thruster burn-through (initiated from a crack) could be catastrophic, an official flight constraint was issued until flight safety could be adequately demonstrated. One recommendation was to reproduce the cracking in the laboratory to understand fully the driving environments. The Johnson Space Center (JSC) Materials & Processes (M&P) Branch initiated an effort starting in January 2005 to reproduce the cracking in the niobium injector. The results were successful. The specific conditions necessary to cause cracking were explicitly established and bounded. Each of the following conditions is necessary in combination: 1. A mechanically disturbed/cold-worked free surface (plastic deformation from machining, handling, fastener installation, etc.) 2. An externally applied sustained tensile stress near yield strength 3. Presence of fluorine-containing fluids on exposed tensile/cold-worked free surfaces 4. Sustained exposure to temperatures greater than 400°F
Keywords: Human factors engineering, human factors laboratories
Abstract: This six-month gap analysis included literature reviews, database searches, interviews with NASA personnel, and then, a survey of NASA program and project managers as stakeholders. The primary focus of the GAP was on tools and methods to aid in the development of requirements and guidelines for the Crew Exploration Vehicle, since there was an immediate need for such information. However, the GAP is seen as a long-term effort and, therefore, future lunar and Mars exploration missions, as well as ground support needs for all missions, were also considered. The project was divided into four parts, two phases for data gathering, and two for compiling and prioritizing results. The Human Factors Background Review focused on the results of space program literature searches, review of human factors documents, and interviews of human factors personnel. The Field User Review focused on interviewing people outside the human factors area, but who work with crew interfaces. The results from these phases were then compiled and categorized into logical human factors topic areas. Using this compiled list, the Gap Evaluation phase began. In this phase the categories and description of potential research topics were rated by GAP personnel on seven different factors to create a reduced list to present to stakeholders. A more concise list of topic areas were then sent to NASA stakeholders to obtain their prioritization and buy-in of the important areas for human factors research. Last, the identified gaps were prioritized using four factors: CEV need, interview significance, stakeholder rating, and relevance to the Exploration Systems Architecture Study.
Keywords: projectile cratering; impact damage; hypervelocity impact; Teflon; thermal protection
Abstract: Impact experiments in Teflon targets were conducted to reproduce craters and penetration holes in thermal protective blankets that were exposed to space on board the long duration exposure facility, to understand the relationships between projectile size and the resulting crater or penetration-hole diameter over a wide range of impact velocities. Powder propellant and light-gas guns were used to launch soda-lime glass spheres into pure Teflon targets at velocities ranging from 1 to 7 km/s. Target thickness (T) was varied over more than three orders of magnitude from infinite halfspace targets to very thin films. Cratering and penetration of massive Teflon targets is dominated by brittle failure and the development of extensive spall zones. Mass removal by spallation at the back side of Teflon targets may be so severe that the absolute penetration-hole diameter can become larger than that of a standard crater at relative target thicknesses of Dp/T = 0.6-0.9. The crater diameter in infinite halfspace Teflon targets increases with encounter velocity by a factor of V 0.44. In contrast, the penetration-hole size in very thin foils is essentially unaffected by impact velocity. Penetrations at target thicknesses intermediate to these extremes will scale with variable exponents of V. Our experimental matrix is sufficiently systematic and complete to make reasonable recommendations for the velocity scaling of Teflon craters and penetrations. We suggest that cratering behavior and associated equations apply to all impacts in which the shock-pulse duration of the projectile is shorter than that of the target.
Keywords: Space debris, obstacle avoidance, Global Tracking Network, space surveillance, exclusion
Abstract: Both the “exclusion volume” and “maneuver threshold” methods have been carefully investigated by performing detailed calculations of debris risk over time and debris avoidance maneuver rate for the Space Transportation System Orbiter and the International Space Station. The underlying mathematics of the two methods is identical. Also, conjunction screening is based upon an exclusion volume; the efficiency of the screening exclusion volume is the limiting efficiency of the debris avoidance process, whether the threshold method or the exclusion box method is employed in the final decision process. This analysis shows the threshold method to have the advantages of somewhat better risk reduction and far fewer maneuvers. All computations are based on empirically determined covariance distributions for STS and the orbital debris population. The covariance of the ISS is assumed to be that of an orbital debris object, subject to the same atmospheric drag as the ISS. State vector covariances for STS were determined from recent tracking data for 2, 4, 8, and 12-hour propagation times for low, moderate, and high vehicle activity. These covariances were combined with the debris covariances, to determine the maneuver rate and fractional residual risk associated with different screening box shapes and sizes and different collision probability maneuver thresholds.
Keywords: Space debris, obstacle avoidance, Global Tracking Network, space surveillance, maneuvers
Abstract: The decision for the International Space Station to perform a maneuver to avoid orbital debris will be based upon a predicted collision probability. The collision probability will be calculated using real-time best estimates of the debris and ISS position state and position error covariance, propagated to the anticipated time of conjunction, or time of closest approach (TCA). If the computed collision probability exceeds a threshold value, the Red Threshold, a maneuver will be performed unless prevented by other operational considerations. The debris position and its uncertainty, propagated to TCA, will be supplied by United States Space Command, by processing observations from its Space Surveillance Network. Given the distribution of position errors for a space vehicle and the debris population, it is possible to calculate both the anticipated maneuver rate and the residual risk resulting from the choice of a maneuver threshold. The lower the probability threshold, the more maneuvers will be performed. However, no matter how many maneuvers are performed, risk can never be completely eliminated. Further, the performance of a debris avoidance maneuver disrupts the operation of the ISS micro-gravity laboratory and also complicates altitude management for ISS. Clearly the need is to achieve the maximum possible risk reduction while maintaining a sustainable maneuver rate.
Keywords: Sensorimotor performance, physiological tests, vestibular tests
Abstract: This short report provides a brief history of space flight, serves as a valuable resource for neurovestibular and sensorimotor space flight experiments conducted by all countries through 2005, and finally, it provides a comprehensive set of space flight physiology references with an emphasis on sensorimotor documents. Therefore, the intent and purpose of this historical overview of neuroscience and space flight is two-fold: First to equip researchers with a single, common reference document, and second, to allow those who helped create this history, a record of accomplishment.
Keywords: physical work; psychological factors; astronaut performance; space flight stress; emotional factors; human factors engineering; training analysis
Abstract: Long-duration space missions place on crewmembers unique physical, environmental, and psychological demands that directly affect their ability to live and work in space. A growing body of research on crews working for extended periods in isolated, confined environments reveals the existence of psychological and performance problems in varying degrees of magnitude. Research has also demonstrated that although the environment plays a cathartic role, many of the problems encountered are due to interpersonal frictions that affect individuals differently. Consequently, crewmembers often turn to maladaptive behaviors as coping mechanisms, resulting in decreased productivity and psychological discomfort. From this research, critical skills have been identified that can help a crewmember better navigate the psychological challenges of long-duration spaceflight. Although most people lack several of these skills, the majority can be learned, so a training program can be designed to teach crewmembers effective leadership, teamwork, and self-care strategies that will help minimize the emergence of maladaptive behaviors. The purpose of this report is to review the training literature to help determine the optimal instructional methods to use in delivering psychological skill training to the U.S. Astronaut Expedition Corps, and to detail the structure and content of the proposed Astronaut Expedition Corps Psychological Training Program.
Keywords: MMRB, fluid dynamics, CFD, computational fluid dynamics, Laser Doppler
Abstract: A modification of the Modular Rotating Bioreactor concept (MMRB) as described in the June 22, 2003, patent disclosure by John Muratore, Thomas Goodwin, Tuan Troung, and Carol Evans was evaluated with respect to the fluid dynamic implications of the proposed vessel geometry. A range of jet geometries was investigated using computational fluid dynamics (CFD) to provide an initial evaluation of the use of fluid jets injected directly into the cell culture volume as a means of providing mixing of oxygen and fresh perfused media, while keeping the fluid shear levels at acceptable values. The CFD results were verified with Laser Doppler Velocimeter measurements on a working model of the MMRB.
Keywords: Space suits, protective clothing, Mars exploration
Abstract: The MarsSuit Project is an innovative research initiative that will engage multiple universities in a coordinated and synergistic effort to assist NASA in the formidable task of designing a lightweight, blue-collar Mars Extravehicular Mobility Unit for human exploration of the Mars. It is a revolutionary and evolutionary project, using a collaborative design Web site to link 16 university teams with NASA, industry, and other external institutions in a virtual organization mirroring an NASA Project Office. The MarsSuit Project will add to, focus, and galvanize the efforts of other universities into a nationwide program that will involve technology identification, assessment, and development; systems engineering; systems design; and education enhancing opportunities for participants. It will partner underrepresented minority institutions with established universities having a rich legacy of NASA research experiences. To assure relevance to NASA’s requirements there will be a strong NASA presence through a NASA MarsSuit Advisory Panel led by the EVA Program Office; Joseph J. Kosmo, JSC’s Senior EVA Project Engineer; and Astronaut Dr. Michael Gernhardt. To assure reality in the design and its ability to be reproduced by industry, an Industry Advisory Panel will be established as well, with representation from Hamilton Sundstrand and ILC Dover, leaders in the design and development of NASA space suits.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency
Abstract: The NASA Deputy Administrator charted an internal NASA planning group to develop the rationale for exploration beyond low-Earth orbit. This team, termed the Exploration Blueprint, performed architecture analyses to develop roadmaps for how to accomplish the first steps beyond Low-Earth Orbit through the human exploration of Mars. Following the results of the Exploration Blueprint study, the NASA Administrator asked for a recommendation on the next steps in human and robotic exploration. Much of the focus during this period was on integrating the results from the previous studies into more concrete implementation strategies in order to understand the relationship between NASA programs, timing, and resulting budgetary implications. This resulted in an integrated approach including lunar surface operations to retire risk of human Mars missions, maximum use of common and modular systems including what was termed the exploration transfer vehicle, Earth orbit and lunar surface demonstrations of long-life systems, collaboration of human and robotic missions to vastly increase mission return, and high-efficiency transportation systems (nuclear) for deep-space transportation and power. The data provided in this summary presentation was developed to begin to address one of the key elements of the emerging implementation strategy, namely how lunar missions help retire risk of human missions to Mars. During this process the scope of the activity broadened into the issue of how testing in general, in various venues including the moon, can help reduce the risk for Mars missions.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency spacecraft design, aerospace engineering
Abstract: n June 1999, the NASA Administrator chartered an internal NASA task force, termed the Decadal Planning Team, to create new integrated vision and strategy for space exploration. The efforts of the Decadal Planning Team evolved into the Agency-wide team known as the NASA Exploration Team (NEXT). This team was also instructed to identify technology roadmaps to enable the science-driven exploration vision, established a cross-enterprise, cross-center systems engineering team with emphasis focused on revolutionary not evolutionary approaches. The strategy of the DPT and NEXT teams was to “Go Anywhere, Anytime” by conquering key exploration hurdles of space transportation, crew health and safety, human/robotic partnerships, affordable abundant power, and advanced space systems performance. During the DPT and NEXT study cycles, several architectures were analyzed including missions to the Earth-Sun Libration Point, the Earth-Moon Gateway and Earth-Moon Libration Point, the lunar surface, Mars (both short and long stays), one-year round trip Mars, and near-Earth asteroids. Although there was much emphasis placed on utilization of existing launch capabilities, the team concluded that missions in near-Earth space are only marginally feasible and human missions to Mars were not feasible without a heavy lift launch capability. In addition, the team concluded that missions in Earth’s neighborhood, such as to the moon, can serve as stepping-stones toward further deep-space missions in terms of proving systems, technologies, and operational concepts.
Keywords: Space Shuttle Orbiter, aerothermodynamics, boundary layer transition
Abstract: The Space Shuttle Orbiter Aerothermodynamic Test, MH-13, was performed at Calspan/University of Buffalo Research Center in the Large Energy National Shock Tunnels facility. A highly instrumented 0.018 scale Orbiter model was tested at several flight-like reentry conditions. Data were collected for basic environmental trends, including Reynolds number and Mach number sweeps, and configuration trends, including angle of attack, side slip, and control surface deflection sweeps. Studies were also completed on windward side and wing leading edge (in the area of the shock-shock interaction) boundary layer transition. The resulting data will be used for computational data comparison and possible improvements in real-time flight support analysis methodology.
Keywords: Exploration, space flight, lunar exploration, Mars exploration, experimentation, risk contingency spacecraft design, aerospace engineering
Abstract: The material contained in this report was compiled to capture the work performed by the National Aeronautics and Space Administration’s (NASA’s) Exploration study team in the late 2002 timeframe. The “Exploration Blueprint Data Book” documents the analyses and findings of the 90-day Agency-wide study conducted from September – November 2002. The NASA Deputy Administrator requested that a study be performed with the following objectives: Develop the rationale for exploration beyond low-Earth orbit, roadmaps for how to accomplish the first steps through humans to Mars, design reference missions as a basis for the roadmaps and make recommendations on what can be done now to effect this future This planning team performed architecture analyses to develop roadmaps for how to accomplish the first steps beyond LEO through the human exploration of Mars. The reference missions resulting from the analysis performed by the Exploration Blueprint team formed the basis for requirement definition, systems development, technology roadmapping, and risk assessments for future human exploration beyond low-Earth orbit. Emphasis was placed on developing recommendations on what could be done now to effect future exploration activities. The team embraced the “Stepping Stone” approach to exploration where human and robotic activities are conducted through progressive expansion outward beyond low-Earth orbit. Results from this study produced a long-term strategy for exploration with near-term implementation plans, program recommendations, and technology investments.
Keywords: computer systems design, software engineering, program verification, computer programs, computer systems performance, design analysis, reliability analysis
Abstract: This handbook documents the three software analysis processes the Space Station Software Analysis team uses to assess Space Station software, including their backgrounds, theories, tools, and analysis procedures. Potential applications of these analysis results are also presented. The first section describes how software complexity analysis provides quantitative information on code, such as code structure and risk areas, throughout the software life cycle. Software complexity analysis allows an analyst to understand the software structure; identify critical software components; assess risk areas within a software system; identify testing deficiencies; and recommend program improvements. Performing this type of analysis during the early design phases of software development can positively affect the process, and may prevent later, much larger, difficulties. The second section describes how software reliability estimation and prediction analysis, or software reliability, provides a quantitative means to measure the probability of failure-free operation of a computer program, and describes the two tools used by JSC to determine failure rates and design tradeoffs between reliability, costs, performance, and schedule.
Keywords: bodyweight, human body locomotion, physical exercise
Abstract: The purpose of this investigation was to determine if increasing body mass while maintaining bodyweight would affect ground reaction forces and joint kinetics during walking and running. It was hypothesized that performing gait with increased mass while maintaining body weight would result in greater ground reaction forces, and would affect the net joint torques and work at the ankle, knee and hip when compared to gait with normal mass and bodyweight. Vertical ground reaction force was measured for ten subjects (5M/5F) during walking and running on a treadmill. Subjects completed one minute of locomotion at normal mass and bodyweight and at four added mass conditions (10%, 20%, 30% and 40% of body mass) in random order. Three-dimensional joint position data were collected via videography. The addition of mass resulted in several effects. Peak impact forces and loading rates increased during walking, but decreased during running. Peak propulsive forces decreased during walking and did not change during running. Stride time increased and hip extensor angular impulse and positive work increased as mass was added for both styles of locomotion. Work increased at a greater rate during running than walking. The adaptations to additional mass that occur during walking are different than during running. Increasing mass during exercise in microgravity may be beneficial to increasing ground reaction forces during walking and strengthening hip musculature during both walking and running.
Keywords: Ergometers, exercise physiology.
Abstract: The purpose of this study was to compare the U.S. and Russian cycle ergometers, focusing on the mechanical differences of the devices and the physiological differences observed while using the devices. First, the mechanical loads provided by the U.S. Cycle Ergometer with Vibration Isolation System (CEVIS) and the Russian Veloergometer were measured using a calibration dynamometer. Results were compared and conversion equations were modeled to determine the actual load provided by each device. Second, 10 male subjects experienced with both cycling and exercise testing completed a standardized submaximal exercise test protocol on CEVIS and Veloergometer. The exercise protocol involved eight submaximal workloads each lasting three minutes for a total of 24 minutes per session, or until the end of the stage when the subject reached 85% of peak oxygen consumption or age-predicted maximum heart rate. The workload started at 50 watts (W), increased to 100 W, and then increased 25 W every three minutes until reaching a peak workload of 250 W. Physiological variables were then compared at each workload by repeated measures Analysis of Variance (ANOVA) or paired t-tests (p<0.05). While both CEVIS and Veloergometer produced significantly lower workloads than the displayed workload, CEVIS produced even lower loads than Veloergometer (p<0.05) at each indicated workload. Despite this fact, the only physiological variables that showed a significant difference between the ergometers were expired ventilation (125 – 250W), oxygen consumption (175 and 250 W), and carbon dioxide production (175 W). All other physiological data were not statistically different between CEVIS and Veloergometer.
Keywords: Aerospace medicine, exploration
Abstract: Medical requirements for the future Crew Exploration Vehicle (CEV), Lunar Surface Access Module (LSAM), advanced Extravehicular Activity (EVA) suits and Lunar habitat are currently being developed. Crews returning to the lunar surface will construct the lunar habitat and conduct scientific research. Inherent in aggressive surface activities is the potential risk of injury to crewmembers. Physiological responses to and the operational environment of short forays during the Apollo lunar missions were studied and documented. Little is known about the operational environment in which crews will live and work and the hardware that will be used for long-duration lunar surface operations.Additional informantion is needed regarding productivity and the events that affect crew function such as a compressed timeline. The Space Medicine Division at the NASA Johnson Space Center (JSC) requested a study in December 2005 to identify Apollo mission issues relevant to medical operations that had impact to crew health and/or performance. The operationally oriented goals of this project were to develop or modify medical requirements for new exploration vehicles and habitats, create a centralized database for future access, and share relevant Apollo information with the multiple entities at NASA and abroad participating in the exploration effort.
Keywords: Aerospace medicine, exploration
Abstract: The Medical Informatics and Health Care Systems group in the Office of Space Medicine at NASA Johnson Space Center (JSC) has been tasked by NASA with improving overall medical care on the International Space Station and providing insights for medical care for future exploration missions. A three day Operational and Research Musculoskeletal Summit was held on August 23-25, 2005, at Space Center Houston to review NASA’s current strategy for preflight health maintenance and injury screening, current treatment methods in-flight, and risk mitigation strategy for musculoskeletal injuries or syndromes that could occur or impact the mission. Additionally, summit participants provided a list of research topics NASA should consider to mitigate risks to astronaut health. Prior to the summit, participants participated in a web-based pre-summit forum to review the NASA Space Medical Conditions List of musculoskeletal conditions that may occur on ISS as well as the resources currently available to treat them. Data from the participants were compiled and integrated with the summit proceedings. Summit participants included experts from the extramural physician and researcher communities, and representatives from NASA Headquarters, the astronaut corps, JSC Medical Operations and Human Adaptations and Countermeasures Offices, Glenn Research Center Human Research Office, and the Astronaut Strength, Conditioning, and Reconditioning group. The recommendations in this document are based on a summary of summit discussions and the best possible evidence-based recommendations for musculoskeletal care for astronauts while on the ISS, and include recommendations for exploration class missions.
Keywords: Weightlessness, weightlessness simulation, parabolic flight, zero gravity, aerospace medicine, astronaut performance, bioprocessing, space manufacturing.
Abstract: This document represents a summary of medical and scientific evaluations conducted aboard the C-9 or other NASA-sponsored aircraft from June 30, 2006, to June 30, 2007. Included is a general overview of investigations manifested and coordinated by the Human Adaptation and Countermeasures Office. A collection of brief reports that describe tests conducted aboard the NASA-sponsored aircraft follows the overview. Principal investigators and test engineers contributed significantly to the content of the report, describing their particular experiment or hardware evaluation. Although this document follows general guidelines, each report format may vary to accommodate differences in experiment design and procedures. This document concludes with an appendix that provides background information about the Reduced Gravity Program.
Keywords: Exercise physiology, fitness, ergometers, pulmonary functions
Abstract: Aerobic deconditioning occurs during long-duration spaceflight despite the use of exercise countermeasures. As a part of International Space Station (ISS) medical operations, periodic tests designed to estimate aerobic capacity are performed prior to, during, and after missions of greater than 30 days in duration. These tests track changes in aerobic fitness and determine the effectiveness of exercise countermeasures. The purpose of this investigation was to compare exercise metabolic gas analysis measurements (including oxygen consumption) obtained by the Pulmonary Function System (PFS) to those collected using a reference metabolic gas analysis system: the ParvoMedics TrueOne© 2400 system (ParvoMedics, Salt Lake City, UT). This system has been extensively validated and is currently utilized by the NASA’s Exercise Physiology Laboratory for pre- and post-flight testing astronauts assigned to ISS flights. Laboratory evaluation of the PFS demonstrated that it provides similar results to those measured by the reference metabolic gas analysis system. It is recommended that the PFS be incorporated into the standard periodic fitness evaluation testing performed onboard the ISS
Keywords: Exploration, space flight, planetary aerial vehicles, planetary environments, long term space flight
Abstract: NASA has recently formed the Constellation Program to achieve the objectives of maintaining American presence in low Earth orbit, returning to the moon for purposes of establishing an outpost, and laying the foundation to explore Mars and beyond in the first half of the 21st century. The Constellation Program’s heritage rests on the successes and lessons learned from NASA’s previous human spaceflight programs: Mercury, Gemini, Apollo, Space Shuttle and International Space Station (ISS). This paper describes the rationale behind the formulation of the Constellation Program, including organizational structure, and workforce structure, as well as the approaches to requirements generation, budget formulation, operational philosophies, and procurement strategies.
Keywords: Physiology, thermoregulation, tolerances.
Abstract: This study, conducted on behalf of the EVA Physiology, Systems and Performance Project at NASA-JSC, was initiated to verify and correlate mathematical models used to predict the thermal limits of crewmembers practicing rescue techniques aboard the International Space Station (ISS) during Extravehicular Activity (EVA). While the impetus for this work came from excessive heat storage predictions by an existing EMU SINDA model, the resulting correlations and results have potential benefits for a wide range of safety-of- flight operations performed by astronauts during nominal and contingency operations.
Keywords: extravehicular activiy, medical equipment
Abstract: PURPOSE: To determine how the use of a shoulder harness during Extravehicular Activity (EVA) training activities subjectively and objectively affects the likelihood of shoulder discomfort and injury by assessment of shoulder motion and subject comfort during task performance. Data were collected during two separate phases. In phase 1, video and verbal data were collected from subjects during inverted operations at the Neutral Buoyancy Laboratory (NBL). Discomfort ratings were collected during shoulder maneuvers, and comments were recorded regarding subjective evaluations before, during, and after movements. In phase 2, sensors measured the load distribution and average pressure on the shoulders during simulated inversion in the laboratory. A force equal to the subjects’ body weight was placed on each subjects’ shoulders, and pressures were recorded during shoulder motions. During actual inversion in the NBL, subjects reported lower pain ratings while using the harness than without the harness. Subjects reported a sense of decreased shoulder range of motion while using the harness, although video records do not suggest that range of motion was affected. In general, subjects reported that the decreased sense of range of motion was the cost for the increased comfort. With both harness and no harness conditions, however, the reports of pain and discomfort were evident, suggesting that the harness may reduce discomfort, but not eliminate it.
Keywords: Radiation shielding, radiation measurement, radiation protection
Abstract: The ray-tracing technique is a powerful scientific tool that enables the analysis of radiation shielding properties of a spacecraft based on a geometry model. We discuss a method to describe spacecraft geometry as defined by one of the modern computer-aided drafting tools, ProE. A suite of software tools, called Fishbowl, is presented to convert the spacecraft geometric data to the areal density map, which is used for space radiation shielding analysis in the habitable area of the spacecraft. This tool allows users to create elaborate models of spacecraft. The areal density map is given as a function of the ray position originating from a given point inside a spacecraft or human body. The map is then input to the high-charge-and-energy transport computer program (HZETRN) code developed at NASA. The HZETRN code calculates energy spectra of high-energy particles passing through the spacecraft material of a certain thickness and takes into account fragments created by nuclear reactions. The flux at a dose point can be determined with this tool, as well as a false color ball displaying "hot" and "cold" spots of radiation penetrating the spacecraft wall, which can be useful for suggesting more efficient spacecraft geometries for radiation shielding. In other words, the directionality of the received radiation is described for the analysis of the spacecraft design to make it more optimal for radiation protection. Two examples of the validation of the ProE-based model with a simpler OpenGL/C++ in-house tool are presented. Several dose rate data are presented at points within the Lunar Transfer Vehicle and within the astronaut’s body received from space radiation. A human phantom model constructed from several parts was introduced in ProE too. Examples of radiation shielding calculations for lunar mission are described.
Keywords: booster rocket engines, space shuttle boosters, launch vehicles, solid propellant rocket engines, recoverable launch vehicles, booster recovery
Abstract: The concept of a flyback booster has been around since early in the Shuttle program. The original two-stage Shuttle concepts used a manned flyback booster. These boosters were eliminated from the program for funding and size reasons. The current Shuttle uses two redesigned solid rocket motors (RSRMs), which are recovered and refurbished after each flight; this is one of the major cost factors of the program. Replacement options have been studied over the past ten years. The conclusion reached by the most recent study is that the liquid flyback booster (LFBB) is the only competitive option from a life-cycle cost perspective. The purpose of this study was to assess the feasibility and practicality of LFBBs. The study provides an expansion of the recommendations made during the aforementioned study. The primary benefits are the potential for enhanced reusability and a reduction of recurring costs. The potential savings in vehicle turnaround could offset the up-front costs. Development of LFBBs requires a commitment to the Shuttle program for 20 to 30 years. LFBBs also offer enhanced safety and abort capabilities. Currently, any failure of an RSRM can be considered catastrophic, since there are no intact abort capabilities during the burn of the RSRMs. The performance goal of the LFBBs was to lift a fully loaded Orbiter under optimal conditions, so as not to be the limiting factor of the performance capability of the Shuttle. In addition, a final benefit is the availability of growth paths for applications other than Shuttle. Participants included JSC, KSC, and MSFC. If it is determined that a more detailed study is warranted, a new study would be initiated to obtain baseline requirements, which would lead the way for detailed vehicle designs and a reference concept with bottoms-up cost.
Keywords: Kinematics, exercise physiology, fitness
Abstract: Purpose: Determine how External Load (EL) type affects locomotion patterns and muscular activity on the enhanced Zero-gravity Locomotion Simulator (eZLS) when using bungees or a linear motor subject loading device. Eight subjects were suspended on the eZLS while walking at 3 mph and running at 7 mph. The EL was provided by either bungees or a linear motor subject loading device (LM-SLD) at approximately 55% and 90% of body weight during the exercise. Joint kinematics, ground reaction forces (GRF), and electromyographical activity of lower body musculature were measured during each condition. Repeated measures analysis of variance were tested for differences between EL types within load levels on eZLS. There were few differences in locomotion patterns and muscular activity between loading mechanisms. GRF were greater with the LM-SLD than with bungees during eZLS locomotion. GRF magnitudes for both devices were lower than previously reported values obtained during upright locomotion in normal gravity, but similar to those found in actual microgravity. Greater GRF with the LM-SLD suggests that use of a constant-force SLD may be of potential benefit during treadmill exercise because locomotion patterns do not change, but subjects experience increased force magnitude and loading rates applied at the feet.
Keywords: decompression sickness; extravehicular activity; Crew Exploration Vehicle; Lunar Surface Access Module; long-term surface habitats; microgravity, impacts of
Abstract: To limit the risk of fire and reduce the risk of decompression sickness and prebreathe time to support frequent activities on the moon and Mars, a hypobaric and mildly hypoxic living environment is considered for the Crew Exploration Vehicle, Lunar Surface Access Module, and long-term surface habitats. Superimposed on physiological adjustments to living in a hypobaric hypoxia (HH) environment are those associated with adaptation to microgravity (mG). Outward manifestations of physiological adaptations may present as signs and symptoms of Acute Mountain Sickness (AMS). The signs and symptoms of AMS are undesirable, as they would impact crew health and performance. A literature review suggests that: (1) there is an absolute pressure effect per se on AMS, so the higher the altitude for a given computed hypoxic alveolar oxygen (O2) partial pressure (PAO2) the greater the AMS response; (2) about 25% of adults would experience AMS near 2,000 m altitude; (3) there is no direct evidence that HH synergizes with adaptive changes during simulated mG to dramatically increase hematocrit and blood viscosity; and (4) only susceptible astronauts would develop mild and transient AMS with exposure to 8.0 psia (16,000 ft) while breathing 32% O2 and simultaneously adapting to mG.
Keywords: Suits, comfort, field of vision
Abstract: The primary objective of the Launch Suit Test was to evaluate crewmember comfort in two planetary suit concepts during 1-g launch conditions similar to those to be experienced in the Crew Exploration Vehicle. This report addresses suit wear in a launch pad configuration; however, the overarching question is: “Should planetary suits be further considered for launch/entry suits?” The test plan outlined four objectives: assess crewmember comfort in the Advanced Crew Escape Suit (ACES), Mark III and the Rear Entry ILC Dover Suit (REI-Suit) in a recumbent position (with helmet); determine the visibility envelope of crewmembers while in the ACES, Mark III, and REI-Suit in a recumbent position (with helmet); determine the ability of crewmembers to sit and stand from a recumbent position unassisted while in the ACES, Mark III, and REI-Suit (with helmet); and determine the reach envelope and motion capability for the ACES, Mark III, and REI-Suit in a recumbent position (with helmet). This report addresses objectives 1 through 3. The findings support further study of the planetary suit for use as a potential launch/entry suit.
Keywords: International Space Station; payload stations; access control; JEM; Columbus-EPF; Express Logistics Carrier; U.S. truss
Abstract: External payload accommodations are provided at attachment sites on the U.S.-provided Express Logistis Carrier, U.S. truss, Japanese Experiment Module-Exposed Facility (JEM-EF), and Columbus-EPF (External Payload Facilities). The integrated truss segment attaches solar and thermal control arrays to the International Space Station (ISS), houses cable distribution trays and spacewalk support equipment, and provides for extravehicular robotic accommodations. The JEM-EF accommodates up to eight payloads, which can be serviced via the JEM PM airlock and dedicated robotic arm. The Columbus-EPF can accommodate two zenith- and nadir-looking payloads. The ISS command and data handling (C&DH) system consists of hardware and software that provide services for command, control, and data distribution for all ISS systems, subsystems, and payloads. The system-level C&DH architecture contains redundant command and control (C&C) multiplexers/demultiplexers (MDMs) and MIL-STD-1553B control buses. The payload service includes the payload MDM for low-rate data link (LRDL) data and command distribution, and a high-rate data link (HRDL) for payload-to-payload communication and data-downlink service. LRDL data are downlinked via the HRDL to the ground. Safety-related data are routed via the C&C MDM to S-band data services for downlink. The Personal Computer System is used by the crew for command and display interface.
Keywords: epithelium, respiratory, cells, cell culturing, cultured cells, in vitro methods and tests
Abstract: In vitro three-dimensional (3D) human lung epithelio-mesenchymal tissue-like assemblies (3D hLEM TLAs), from this point forward referred to as TLAs, were engineered in rotating wall vessel technology to mimic the characteristics of in vivo tissues, thus providing a tool to study human respiratory viruses and host cell and viral interactions. The TLAs were bioengineered onto collagen-coated cyclodextran microcarriers using primary human mesenchymal bronchial-tracheal cells as the foundation matrix and an adult human bronchial epithelial immortalized cell line as the overlying component. The resulting TLAs share significant characteristics with in vivo human respiratory epithelium including polarization, tight junctions, desmosomes, and microvilli. The presence of tissue-like differentiation markers including villin, keratins, and specific lung epithelium markers, as well as the production of tissue mucin, further confirm that these TLAs differentiated into tissues functionally similar to in vivo tissues. Increasing virus titers for human respiratory syncytial virus and the detection of membrane bound glycoproteins over time confirm productive infection with the virus. Therefore, we assert TLAs mimic aspects of the human respiratory epithelium and provide a unique capability to study the interactions of respiratory viruses and their primary target tissue independent of the host’s immune system.
Keywords: meteorites; robotics; Mars exploration; lunar exploration; comets; electric batteries; atmospheric entry; artificial gravity; robot sensors; oxygen analyzers
Abstract: The Biennial Research and Technology Development Report is a compilation of advances in research and technology accomplished by Johnson Space Center (JSC) engineers and scientists. It contains astromaterials research and exploration science, space life science, engineering, extravehicular activity, White Sands Test Facility (WSTF), and education and center operations. Examples of astromaterials research and exploration science demonstrate major improvements in handling and analysis of extremely small solar and asteroid particles. Space life sciences research includes neurovestibular research and arterial and cardiac function in six-degree head-down tilt bed rest. Engineering research includes the designing of a prototype ultra-wide-band tracking system for lunar operations where navigation tools are not available. JSC is also studying ramifications of applying laser peening to friction stir welding for space operations. The extravehicular program is developing medical and engineering practices to maintain a productive healthy crew during difficult and dangerous work situations. WSTF’s research on ignition testing on multiple spacesuit materials placed in various oxygen concentrations is critical for future exploration missions. JSC’s commitment to science, technology, engineering, and math educational programs for elementary schools through post-doctorate programs is strong. Finally, advances in technology are needed for JSC’s work with the community, and for facilitating space center operations.
Keywords: Space debrisd, environmental effects, fragments,
Abstract: Orbital debris is a concern to all nations that use satellites or launch space vehicles. The debris field scattered near Earth’s geosynchronous orbit (GEO) poses a threat to anything residing in or passing through it. To mitigate risk and minimize this environment’s expansion, the threat must be understood. NASA has been using the Charged-Coupled Device Debris Telescope (CDT), a transportable 32-cm Schmidt telescope located near Cloudcroft, New Mexico, to help characterize the debris environment in GEO. Using the CDT, researchers conducted systematic searches of the GEO environment as part of an international measurement campaign under the auspices of the Inter-Agency Space Debris Coordination Committee (IADC). The objectives for this survey are to determine the extent and character of debris in GEO, specifically by obtaining distributions for the brightness, inclination, right ascension of ascending node (RAAN), and mean motion for the debris. Tests using the CDT for this campaign took place in late 1997 and data collection began in January 1998. This report describes the data taken and all of the data reduction details to make it a standalone report on the Calendar Year (CY) 2000 activities.
Keywords: Space debris, environmental effects, fragments,
Abstract: Orbital debris is a concern to all nations that use satellites or launch space vehicles. The debris field scattered near Earth’s geosynchronous orbit (GEO) poses a threat to anything residing in or passing through it. To mitigate risk and minimize this environment’s expansion, the threat must be understood. NASA has been using the Charged-Coupled Device Debris Telescope (CDT), a transportable 32-cm Schmidt telescope located near Cloudcroft, New Mexico, to help characterize the debris environment in GEO. Using the CDT, researchers conducted systematic searches of the GEO environment as part of an international measurement campaign under the auspices of the Inter-Agency Space Debris Coordination Committee (IADC). The objectives for this survey are to determine the extent and character of debris in GEO, specifically by obtaining distributions for the brightness, inclination, right ascension of ascending node (RAAN), and mean motion for the debris. Tests using the CDT for this campaign took place in late 1997 and data collection began in January 1998. This report describes the data taken and all of the data-reduction details to make it a stand-alone report on the Calendar Year (CY) 2001 activities.
Keywords: Space debris, environmental effects, fragments,
Abstract: Understanding the evolving debris environment is essential if the human race continues to venture into space. Of particular importance is the geosynchronous environment in which satellites have been placed since the 1960s. Debris in geosynchronous Earth orbit (GEO) has an enhanced potential for collision with operational satellites due to the extremely long lifetimes of the debris. The Charged Coupled Device (CCD) Debris Telescope (CDT) conducted systematic searches of the GEO environment to help characterize and determine the extent of the debris found in this volume of near-Earth space. The observations provided distributions in brightness, mean motion, inclination, range, and Right Ascension of Ascending Node (RAAN) of detected debris. Yearly reports (NASA/Johnson Space Center (JSC) publications) described details of the observing program and observed distributions (Jarvis et al., 2001, 2002, 2007a, 2007b). In this final report, a summary and comparison of the observations is conducted. All observed magnitudes have been corrected for standard solar distance, a Lambertian phase function at phase angle 0°, and an observed range, when possible. Orbital elements were derived from two or more astrometric positions based on the assumption of a circular orbit (eccentricity = 0°). We define the dimensions of a GEO environment to be between 34,000 km and 40,000 km and between 0° and 17° inclination based on the assumed circular orbit (ACO) elements of the observations. The scope of the paper is limited to the population distributions of objects found in this defined GEO environment.
Keywords: deconditioning; physical exercise; orthostatic tolerance; bone demineralization; treadmills, physical exercise; treadmills, physical fitness
Abstract: Space flight-induced deconditioning includes the loss of aerobic exercise capacity, orthostatic tolerance, muscle strength and endurance, and bone mineral density. These reductions may compromise crew members’ ability to perform mission-critical activities and prolong the return to activities of daily living postlanding. Further, altered locomotion and neuromuscular activation patterns following space flight may impair the ability of space travelers to ambulate during extraterrestrial activities, emergency egress, or normal activities upon return to Earth. Although lacking the orthostatic stress of upright exercise in normal gravity (1g), it is believed that treadmill exercise during microgravity protects exercise and metabolic capacities, simulates 1g loads to the musculoskeletal system, and stimulates neuromuscular patterns required for locomotion. It is currently employed as a countermeasure to space flight deconditioning during long-duration missions aboard the station. The purpose of this study is to compare the acute metabolic and cardiovascular responses to, as well as the kinetic and kinematic aspects of, short-duration TVIS-M, TVIS-NM, and BD-1 treadmill exercise in relation to a standard laboratory treadmill exercise. Study findings will provide valuable information regarding ongoing use of treadmill exercise as a countermeasure to musculoskeletal and cardiovascular deconditioning associated with space flight and assist in the development of future treadmill exercise prescriptions.
Keywords: human performance, human factors engineering, habitability, SpaceHab-1
Abstract: SpaceHab-1 (STS-57) was the first of six scheduled Commercial Middeck Augmentation Module (CMAM) missions seeking to offer entrepreneurial companies an opportunity to use the resource of microgravity. The SpaceHab module, which occupies about one-fourth of the payload bay, is approximately 2-3/4 m long and 4 m diameter. It provides a shirtsleeve environment and contains the storage space equivalent of 50 middeck lockers. A modified Spacelab tunnel links the SpaceHab module to the middeck. While in orbit, the Orbiter payload bay doors remain open. The crew for SpaceHab-1 was comprised of four males and two females, each of whom participated in some part of the human factors assessment (HFA) evaluation. The HFA was one of over twenty experiments manifested on this maiden flight of the SpaceHab module. HFA consisted of HFA-EPROC, HFA-LIGHT, HFA-SOUND, HFA-QUEST, and HFA-TRANS. The goal of HFA-EPROC was to assess the advantages and disadvantages of paper versus computer presentation for procedural tasks. The second of two evaluations investigated the modules' lighting and acoustic environment. HFA-TRANS sought to evaluate the design of the SpaceHab tunnel and to characterize translation through it. HFA-QUEST represented a consolidation of the in-flight questions generated by the HFA principal investigators involved in the acoustic, lighting and translation studies.
Keywords: hypervelocity impact, metal foams, composite materials, sandwich structures, honeycomb structures, shielding
Abstract: A series of hypervelocity impact (HVI) tests were conducted by the NASA Johnson Space Center (JSC) Hypervelocity Impact Technology Facility (HITF), building 267 (Houston, Texas) between January 2003 and December 2005 to test the HVI performance of metal foams, as compared to the metal honeycomb panels currently in service. The HITF testing was conducted at the NASA JSC White Sands Test Facility in Las Cruces, New Mexico. Eric L. Christiansen, Ph.D., and NASA Lead for micrometeoroid orbital debris (MMOD) protection requested these HVI tests as part of shielding research conducted for the JSC Center Director Discretionary Fund project. The structure tested is a metal foam sandwich structure; a metal foam core between two metal facesheets. Aluminum and titanium metals were tested for foam sandwich and honeycomb sandwich structures. Aluminum honeycomb core material is currently used in orbiter vehicle radiator panels and in other places in space structures. It has many desirable characteristics and performs well by many measures, especially when normalized by density. Aluminum honeycomb does not perform well in HVI testing. This is a concern, as honeycomb panels are often exposed to space environments and take on the role of MMOD shielding. Therefore, information on possible replacement core materials that perform adequately in all necessary functions of the material would be useful. In this report, HVI data are gathered for these two core materials in certain configurations and compared to gain an understanding of the metal foam HVI performance.
Keywords: Risk, forecasting, operations research, predictions, strategy
Abstract: Identification, resolution, and avoidance of technical and programmatic issues are important for ensuring safe and successful space missions.1,2 Although the importance of applying lessons learned to reduce risk is frequently stressed, there is little material available to help technical and management personnel research and document lessons learned. Collecting, researching, identifying, and documenting lessons learned that will be useful to current and future management and engineering personnel is not always a straightforward task. This white paper presents lessons learned and best practices concerning the research and documentation of technical and organizational lessons learned. It is intended to enable organizations to initiate or improve lessons learned research and documentation efforts. The content of this white paper is based on four technical lessons learned projects conducted by the United Space Alliance (USA) Flight Design and Dynamics Department, in support of the NASA/Johnson Space Center (JSC) Flight Design and Dynamics Division. Each project published a report, titled as follows: GPS Lessons Learned From the ISS, Space Shuttle and X-38 4; Lessons Learned From Seven Space Shuttle Missions 5; Space Shuttle Rendezvous and Proximity Operations Experience Report; and Navigation Technical History with Lessons Learned
Keywords: Human behavior, human performance
Abstract: This document defines Human Behavior and Performance (HBP) competencies that are recommended to be included as requirements to participate in international long duration missions. They were developed in response to the Multilateral Crew Operations Panel (MMOP) request to develop HBP training requirements for the International Space Station (ISS). The competency model presented here was developed by the ITCB HBPT WG and forms the basis for determining the HBP training curriculum for long duration crewmembers.
Keywords: Human behavior, human performance
Abstract: This document defines Human Behavior and Performance (HBP) competencies that are recommended to be included as requirements to participate in international long duration missions. They were developed in response to the Multilateral Crew Operations Panel (MMOP) request to develop HBP training requirements for the International Space Station (ISS). The competency model presented here was developed by the ITCB HBPT WG and forms the basis for determining the HBP training curriculum for long duration crewmembers.
Keywords: Space debris, fragments, satellite breakup, satellite fragmentation
Abstract: Since the first serious satellite fragmentation occurred in June 1961 (which instantaneously increased the total Earth satellite population by more than 400%) the issue of space operations within the finite region of space around the Earth has been the subject of increasing interest and concern. The prolific satellite fragmentations of the 1970s and the marked increase in the number of fragmentations in the 1980s served to widen international research into the characteristics and consequences of such events. Continued events in all orbits in later years make definition and historical accounting of those events crucial to future research. Large, manned space stations and the growing number of operational robotic satellites demand a better understanding of the hazards of the dynamic Earth satellite population.
Keywords:
Abstract: This paper describes proposed environmental atmospheres for future long-duration spacecraft, spacesuits, and lunar and Mars habitats. Several atmospheric design points for the Constellation missions have been developed by the Environmental Atmosphere Working Group, ranging from normoxic to moderately hypoxic while simultaneously hypobaric. These environments were analyzed to achieve a balance among the risk of decompression sickness, the overhead required to perform an exploration extravehicular activity (EVA), short- and long-term human performance at less than normoxic levels of partial pressure of oxygen, and the fire hazard. Atmospheres in future vehicles for exploration missions will likely be less than standard atmospheric pressure, with an ambient inspired ppO2 less than an Earth sea-level equivalent of 3.07 pounds per square inch, absolute, or 159 mmHg. A hypobaric and reduced-oxygen environment will be the integrated solution to safety, engineering, operational, and medical concerns that have as their goal routine and safe exploration of the lunar or martian surface. Constellation Program goals and proposed mission architecture emphasize EVA with exploration of planetary surfaces as the central driving operation. However, human physiology, materials, and equipment factors pose important limits that must be considered when choosing these atmospheric parameters.
Keywords: Space Shuttles, Wind Tunnel Tests, Aerodynamic Characteristics, Heat Transfer, Dynamic Structural Analysis, Aerothermodynamics
Abstract: Development of the Space Shuttle necessitated an extensive wind tunnel test program, with the cooperation of all the major wind tunnels in the United States. The result was approximately 100,000 hours of Space Shuttle wind tunnel testing conducted for aerodynamics, heat transfer, and structural dynamics. The test results were converted into Chrysler DATAMAN computer program format to facilitate use by analysts, a very cost effective method of collecting the wind tunnel test results from many test facilities into one centralized location. This report provides final documentation of the Space Shuttle wind tunnel program. The two-volume set covers the evolution of Space Shuttle aerodynamic configurations and gives wind tunnel test data, titles of wind tunnel data reports, sample data sets, and instructions for accessing the digital data base.
Keywords: Space Shuttles, Wind Tunnel Tests, Aerodynamic Characteristics, Heat Transfer, Dynamic Structural Analysis, Aerothermodynamics
Abstract: Development of the Space Shuttle necessitated an extensive wind tunnel test program, with the cooperation of all the major wind tunnels in the United States. The result was approximately 100,000 hours of Space Shuttle wind tunnel testing conducted for aerodynamics, heat transfer, and structural dynamics. The test results were converted into Chrysler DATAMAN computer program format to facilitate use by analysts, a very cost effective method of collecting the wind tunnel test results from many test facilities into one centralized location. This report provides final documentation of the Space Shuttle wind tunnel program. The two-volume set covers the evolution of Space Shuttle aerodynamic configurations and gives wind tunnel test data, titles of wind tunnel data reports, sample data sets, and instructions for accessing the digital data base.
Keywords: International Space Station; Japanese Experiment Module; Advanced Lower Body Extremities Restraint Test; manipulators; Space Station payloads; constraints
Abstract: The current International Space Station configuration includes a Japanese Experiment Module which relies on a large manipulator and a smaller dexterous manipulator to operate outside the pressurized environment of the experiment module. The module's flight demonstration is a payload that will be mounted in the aft flight deck on STS-87 for evaluation. Since the payload operations entail two 8-hour scenarios on consecutive days, adequate operator restraint at the workstation will be critical to the payload's perceived success or failure. Simulations in reduced gravity environment on the KC-135A allowed evaluation of the restraint systems and workstation configuration. Two astronaut and two non-astronaut operators evaluated the restraint system. Results indicated that access to the switch panels was difficult and manipulation of the hand controllers forced operators too low for optimal viewing of the aft flight deck monitors. The workstation panel should be angled for better visibility, and infrequently used switches should be moved. Pitch angle and placement of the hand controllers should optimize the operator's eye position. The lower body restraint was preferred over foot loops because it allowed operators to maintain a more relaxed posture, its height adjustability allowed better viewing of monitors, and it provided better restraint for reacting forces imparted at the workstation. The foot loops provide adequate restraint.
Keywords: Mir Space Station, Salyut Space Station, Soyuz Spacecraft, Zond Space Probes, Spacecraft Docking, Space Stations, Soviet Spacecraft
Abstract: The heritage of the major Mir complex hardware elements is described. These elements include Soyuz-TM and Progress-M; the Kvant, Kvant 2, and Kristall modules; and the Mir base block. Configuration changes and major mission events of the Salyut 6, Salyut 7, and Mir multiport space stations are described in detail for the period 1977-1994. A comparative chronology of U.S. and Soviet/Russian manned spaceflight is also given for that period. The 68 illustrations include comparative scale drawings of U.S. and Russian spacecraft as well as sequential drawings depicting missions and mission events.
Keywords: virtual reality; artificial intelligence; robotics
Abstract: The Fourth International Symposium on Measurement and Control in Robotics (ISMCR '94) Topical Workshop on Virtual Reality was organized to respond to the growing interest and importance of the niche area of virtual reality in the field of telerobotics and supervised autonomous robotics. The Symposium, organized by IMEKO Technical Committee 17, sponsored by the AIAA/IEEE/ISA, and hosted by the Clear Lake Council of Technical Societies and the NASA Johnson Space Center attempts to bring together a comprehensive international overview of the rapidly moving advanced technology which comprises the field of virtual reality. This focused Symposium deals with each of the critical technology areas in an integrated fashion, such that advances, problems and issues which cut across technologies can be viewed and evaluated from an integrated, common perspective. Papers in the areas of rendering, tracking sensors, displays, sensory feedback, and applications are included in the six sequential sessions of the Symposium. It is felt that this Symposium provides an important and timely indepth look at the interaction of these technologies as they apply to the applications of virtual reality to robotics.
Keywords: Lunar Exploration, Manned Mars Missions, Instrument Packages, Payloads
Abstract: This catalog collects and describes science payloads considered for future robotic and human exploration missions to the Moon and Mars. The science disciplines included are geosciences, meteorology, space physics, astronomy and astrophysics, life sciences, in-situ resource utilization, and robotic science. Science payload data is helpful for mission scientists and engineers developing reference architectures and detailed descriptions of mission organizations. One early step in advanced planning is formulating the science questions for each mission and identifying the instrumentation required to address these questions. The next critical element is to establish and quantify the supporting infrastructure required to deliver, emplace, operate, and maintain the science experiments with human crews or robots. This requires a comprehensive collection of up-to-date science payload information--hence the birth of this catalog. Divided into lunar and Mars sections, the catalog describes the physical characteristics of science instruments in terms of mass, volume, power and data requirements, mode of deployment and operation, maintenance needs, and technological readiness. It includes descriptions of science payloads for specific missions that have been studied in the last two years: the Scout Program, the Artemis Program, the First Lunar Outpost, and the Mars Exploration Program.
Keywords: robotics, robots, computers, computer programming, artificial intelligence
Abstract: The AIAA/NASA Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS '94) was originally proposed because of the strong belief that America's problems of global economic competitiveness and job creation and preservation can partly be solved by the use of intelligent robotics, which are also required for human space exploration missions. It was also recognized that there are a far greater set of common problems and solution approaches in field, factory, service, and space applications to be leveraged for time and cost savings than the differences in details would lead one to believe. This insight made a continuing series of conferences to share the details of the common problems and solutions across these different fields not only a natural step, but a necessary one. Further, it was recognized that a strong focusing effort is needed to move from recent factory-based technology into robotic systems with sufficient intelligence, reliability, safety, flexibility, and human/machine interoperability to meet the rigorous demands of these fields, the scope of which is beyond the capability of any one area. The papers in these proceedings are evidence that users in each field, manufacturers and integrators, and technology developers are rapidly increasing their understanding of integrating robotic systems on Earth and in space to accomplish economically important tasks requiring mobility and manipulation. The 21 sessions of technical papers in 7 tracks plus 2 plenary sessions cover just the tip of this major progress, but reveal its presence nonetheless.
Keywords: Weightlessness, Biodynamics, Orthostatic tolerance, Space flight stress, Cardiovascular system, Exercise physiology, Osteoporosis, Deconditioning
Abstract: Exercise countermeasures have been a part of long-duration space flight for both the U.S. and Russian programs. In this regard, the Exercise Countermeasures Project (ECP) sponsored a workshop entitled, "Countering Space Adaptation with Exercise: Current Issues." The workshop proceedings represent an update to the problems associated with living and working in space and the possible impact exercise would have on helping reduce risk. The meeting provided a forum for NASA scientists, engineers, and technicians to discuss and debate contemporary issues in exercise science and medicine as they relate to manned space flight with outside investigators. These outside investigators are experts who have performed investigations relating to exercise and its effect on the deconditioning process before, during, and after space flight or its analog. This meeting also afforded an opportunity to introduce the current status of the ECP science investigations and inflight hardware and software development. In addition, techniques for physiological monitoring and the development of various microgravity countermeasures were discussed. This document is a collection of the papers presented, abstracts submitted, and Socratic debates held at the NASA Johnson space Center.
Keywords: microwave, biotechnology, intelligent systems, software analysis, automation, bioinstrumentation, software engineering, advanced avionics and robotics
Abstract: This document contains papers presented at the Dual-Use Space Technology Transfer Conference and Exhibition held at the Johnson Space Center February 1-3, 1994. Possible technology transfers covered during the conference were in the areas of information access; innovative microwave and optical applications; materials and structures; marketing and barriers; intelligent systems; human factors and habitation; communications and data systems; business process and technology transfer; software engineering; biotechnology and advanced bioinstrumentation; communications signal processing and analysis; new ways of doing business; medical care; applications derived from control center data systems; human performance evaluation; technology transfer methods; mathematics, modeling, and simulation; propulsion; software analysis and decision tools; systems/processes in human support technology; networks, control centers, and distributed systems; power; rapid development; perception and vision technologies; integrated vehicle health management; automation technologies; advanced avionics; and robotics technologies. More than 77 papers, 20 presentations, and 20 exhibits covering various disciplines were presented by experts from NASA, universities, and industry.
Keywords: information transfer, research , research projects, urban research, engineering, science, universities, university program
Abstract: The JSC NASA/ASEE Summer Faculty Fellowship Program was conducted by Texas A&M University and JSC. The objectives of the program, which began nationally in 1964 and at JSC in 1965, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of participants' institutions; and (4) to contribute to the research objectives of the NASA centers. Each faculty fellow spent at least 10 weeks at JSC engaged in a research project in collaboration with a NASA/JSC colleague. This document is a compilation of the final reports on the research projects completed by the faculty fellows during the summer of 1993.
Keywords: mass, orbital assembly, space logistics, space erectable structures, orbital servicing, weight (mass), maintenance, scheduling
Abstract: To prepare for Space Station Alpha's on-orbit assembly, maintenance, and resupply, NASA requires information about the crew members' ability to move heavy masses on orbit. Ease of movement in microgravity and orbiter stay time constraints may change the Space Station equipment and outfitting design requirements. Therefore, the time and effort required to perform a particuar task and how and where the forces and torque should be applied become critical in evaluating the design effort. Thus, the three main objectives of this investigation were to: 1) quantify variables such as force and torque as they relate to heavy mass handling techniques; 2) predict the time required to perform heavy mass handling tasks; and 3) note any differences between males and females in their ability to manipulate a heavy mass.
Keywords: man-computer interface; computer programs; software engineering; software tools; computer systems design
Abstract: The characteristics of this field guide approach address the problems of designing innovative software to support user tasks. The requirements for novel software are difficult to specify a priori, because there isn't sufficient understanding of how the user's tasks should be supported, and there aren't obvious pre-existing design solutions. When the design team is in unfamiliar territory, care must be taken to avoid rushing into detailed design, requirements specifications, or implementing the wrong product. The challenge is to get the right design and requirements in an efficient, cost-effective manner. This document's purpose is to describre the methods we are using to design human interactions with intelligent systems that support Space Shuttle flight controllers in the Mission Control Center. Although these software systems usually have some intelligent freatures, the design challenges arise primarily from the innovation needed in the software design. While these methods are tailored to our specific context, they should be extensible, and helpful to designers of human interaction with other types of automated systems. We review the unique features of this context so you can determine how to apply these methods to your project. Throughout this field guide, we discuss goals of the design methods. This should help designers understand how a specific method might need to be adapted to the project at hand.
Keywords: Mission Planning, Hubble Space Telescope, Postmission Analysis (Spacecraft), Operations Research, Management Planning
Abstract: To ensure the success of the complex Hubble Space Telescope servicing mission, STS-61, NASA established a number of independent review groups to assess management, design, planning, and preparation for the mission. One of the resulting recommendations for mission success was that an overall Mission Director be appointed to coordinate management activities of the Space Shuttle and Hubble programs and to consolidate results of the team reviews and expedite responses to recommendations. This report presents pre-mission events important to the experience base of mission management, with related Mission Director's recommendations following the event(s) to which they apply. All Mission Director's recommendations are presented collectively in an appendix. Other appendixes contain recommendations from the various review groups, including Payload Officers, the JSC Extravehicular Activity (EVA) Section, JSC EVA Management Office, JSC Crew and Thermal Systems Division, and the STS-61 crew itself. This report also lists mission events in chronological order and includes as an appendix a post-mission summary by the lead Payload Deployment and Retrieval System Officer. Recommendations range from those pertaining to specific component use or operating techniques to those for improved management, review, planning, and safety procedures.
Keywords: robotic missions, Mars missions, specific impulse, constant power, plasma propulsion, trajectory optimization, Mars probes, propulsion system performance
Abstract: The operational characteristics of the Exhaust-Modulated Plasma Rocket are described. Four basic human and robotic mission scenarios to Mars are analyzed using numerical optimization techniques at variable specific impulse and constant power. The device is well suited for "split-sprint" missions, allowing fast, one-way low-payload human transits of 90 to 104 days, as well as slower, 180-day, high-payload robotic precursor flights. Abort capabilities, essential for human missions, are also explored.
Keywords: spacecraft components, array deployment; robotics; end effectors; actuators; dampers; reaction compensation; pointing mechanisms; antenna deployment; booms
Abstract: The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft.
Keywords: Expert Systems, Artificial Intelligence, Computer Systems Programs, Monitors, Real Time Operation, Manuals
Abstract: This reference guide for developers of intelligent monitoring systems is based on lessons learned by developers of the DEcision Support SYstem (DESSY), an expert system that monitors Space Shuttle telemetry data in real time. DESSY makes inferences about commands, state transitions, and simple failures. It performs failure detection rather than in-depth failure diagnostics. A listing of rules from DESSY and cue cards from DESSY subsystems are included to give the development community a better understanding of the selected model system. The G-2 programming tool used in developing DESSY provides an object-oriented, rule-based environment, but many of the principles in use here can be applied to any type of monitoring intelligent system. The step-by-step instructions and examples given for each stage of development are in G-2, but can be used with other development tools. This guide first defines the authors' concept of real-time monitoring systems, then tells prospective developers how to determine system requirements, how to build the system through a combined design/development process, and how to solve problems involved in working with real-time data. It explains the relationships among operational prototyping, software evolution, and the user interface. It also explains methods of testing, verification, and validation. It includes suggestions for preparing reference documentation and training users.
Keywords: Electric Batteries, Primary Batteries, Safety Factors, Handbooks
Abstract: This handbook provides engineers and safety personnel with guidelines for the safe design or selection and use of primary batteries in spaceflight programs. Types of primary batteries described are silver oxide zinc alkaline, carbon-zinc, zinc-air alkaline, manganese dioxide-zinc alkaline, mercuric oxide-zinc alkaline, and lithium anode cells. Along with typical applications, the discussions of the individual battery types include electrochemistry, construction, capacities and configurations, and appropriate safety measures. A chapter on general battery safety covers hazard sources and controls applicable to all battery types. Guidelines are given for qualification and acceptance testing that should precede space applications. Permissible failure levels for NASA applications are discussed.
Keywords: human factors engineering, man machine systems, manned spaceflight
Abstract: The purpose of this report is to characterize the process of Human-Rating as employed by NASA for human spaceflight. An Agency-wide committee was formed in November 1992 to develop a Human-Rating Requirements Definition for Launch Vehicles based on conventional (historical) methods. The committee members were from NASA Headquarters, Marshall Space Flight Center, Kennedy Space Center, Stennis Space Center, and Johnson Space Center. After considerable discussion and analysis, committee members concluded that human-rating is the process of satisfying the mutual constraints of cost, schedule, mission performance, and risk while addressing the requirements for human safety, human performance, and human health management and care.
Keywords: Ion Motion, Mass Spectrometers, Gas Chromatography, Chemical Analysis, Ion Mobility Spectrometry, Conferences
Abstract: Basic research in ion mobility spectrometry has given rise to rapid advancement in hardware development and applications. The Third International Workshop on Ion Mobility Spectrometry (IMS) was held October 16-19, 1994, at Johnson Space Center to provide a forum for investigators to present the most recent results of both basic and applied IMS research. Presenters included manufacturers and various users, including military research organizations and drug enforcement agencies. Thirty papers were given in the following five sessions: Fundamental IMS Studies, Instrument Development, Hyphenated IMS Techniques, Applications, and Data Reduction and Signal Processing. Advances in hardware development, software development, and user applications are described.
Keywords: Lunar Landing Sites; Lunar Topography; Lunar Maps; Lunar Photography; Lunar Orbiter; Lunar Probes
Abstract: Among the hazards that must be negotiated by lunar-landing spacecraft are blocks on the surface of the Moon. Unfortunately, few data exist that can be used to evaluate the threat posed by such blocks to landing spacecraft. Perhaps the best information is that obtained from Surveyor photographs, but those data do not extend to the dimensions of the large blocks that would pose the greatest hazard. Block distributions in the vicinities of the Surveyor I, III, VI, and VII sites have been determined from Lunar Orbiter photography and are presented here. Only large (i.e., greater than or equal to 2.5 m) blocks are measurable in these pictures, resulting in a size gap between the Surveyor and Lunar Orbiter distributions. Nevertheless, the orbital data are self-consistent, a claim supported by the similarity in behavior between the subsets of data from the Surveyor I, III, and VI sites and by the good agreement in position (if not slopes) between the data obtained from Surveyor III photography and those derived from the Lunar Orbiter photographs. Confidence in the results is also justified by the well-behaved distribution of large blocks at the surveyor site. Comparisons between the Surveyor distributions and those derived from the orbital photography permit these observations: (1) in all cases but that for Surveyor III, the density of large blocks is overestimated by extrapolation of the Surveyor-derived trends, (2) the slopes of the Surveyor-derived distributions are consistently lower than those determined for the large blocks, and (3) these apparent disagreements could be mitigated if the overall shapes of the cumulative lunar block populations were nonlinear, allowing for different slopes over different size intervals. The relatively large gaps between the surveyor-derived and Orbiter-derived data sets, however, do not permit a determination of those shapes.
Keywords: umbras, quaternions, iteration methodology/process, terminator lines
Abstract: A method for calculating orbital shadow terminator points is presented. The current method employs the use of an iterative process which is used for an accurate determination of shadow points. This calculation methodology is required, since orbital perturbation effects can introduce large errors when a spacecraft orbits a planet in a high altitute and/or highly elliptical orbit. To compensate for the required iteration methodology, all reference frame change definitions and calculations are performed with quaternions. Quaternion algebra significantly reduces the computational time required for the accurate determination of shadow terminator points.
Keywords: Corrosion, Space Shuttle Orbiters, Histories, Life (durability)
Abstract: The Orbiter Corrosion Control Review Board is preparing a set of reports concerning orbiter corrosion. This report summarizes past corrosion issues experienced by the NASA Space Shuttle Orbiter fleet. Design considerations for corrosion prevention and inspection methods are reviewed. Significant corrosion issues involving structures and subsystems are analyzed, including corrective actions taken. Notable successes and failures of corrosion mitigation systems and procedures are discussed. The projected operating environment used for design is contrasted with current conditions in flight and conditions during ground processing.
Keywords: terminal ballistics, hypervelocity, space debris
Abstract: The cratering and penetration behavior of annealed aluminum 1100 targets, with thickness varied from several cm to ultra-thin foils < 1 micro-m thick, were experimentally investigated using 3.2 mm dia. spherical soda-lime glass projectiles at velocities from 1 to 7 km/s. The objective was to establish quantitative, dimensional relationships between initial impact conditions (impact velocity, projectile dia., and target thickness and the dia. of the resulting crater or penetration hole). Such dimensional relationships and calibration experiments are needed to extract diameters and fluxes of hypervelocity particles from space-exposed surfaces and to predict performance of certain shields. The cratering behavior of aluminum 1100 is fairly well predicted, but crater depth is modestly deeper for our silicate impactors than the canonical value based on aluminum projectiles and aluminum 6061-T6 targets. The ballistic-limit thickness was also different. These differences attest to the great sensitivity of detailed crater geometry and penetration behavior on the physical properties of both the target and impactor. Each penetration experiment was equipped with a witness plate to monitor the nature of the debris plume emanating from the rear of the target. Both penetration hole and witness-plate spray patterns systematically evolve in response to projectile diameter/target thickness. The relative dimensions of the projectile and target totally dominate the experimental products documented in this report; impact velocity is an important contributor as well, but is of subordinate significance for the witness-plate spray patterns.
Keywords: information transfer, research, research projects, urban research, engineering, science, universities, university program
Abstract: The JSC NASA/ASEE Summer Faculty Fellowship Program was conducted by Texas A&M University and JSC. The objectives of the program, which began nationally in 1964 and at JSC in 1965 are to (1) further the professional knowledge of qualified engineering and science faculty members, (2) stimulate an exchange of ideas between participants and NASA, (3) enrich and refresh the research and teaching activities of participants' institutions, and (4) contribute to the research objectives of the NASA centers. Each faculty fellow spent at least 10 weeks at JSC engaged in a research project in collaboration with a NASA JSC colleague. This document is a compilation of the final reports on the research projects completed by the faculty fellows during the summer of 1994.
Keywords: information transfer, research, research projects, urban research, engineering, science, universities, university program
Abstract: The JSC NASA/ASEE Summer Faculty Fellowship Program was conducted by Texas A&M University and JSC. The objectives of the program, which began nationally in 1964 and at JSC in 1965 are to (1) further the professional knowledge of qualified engineering and science faculty members, (2) stimulate an exchange of ideas between participants and NASA, (3) enrich and refresh the research and teaching activities of participants' institutions, and (4) contribute to the research objectives of the NASA centers. Each faculty fellow spent at least 10 weeks at JSC engaged in a research project in collaboration with a NASA JSC colleague. This document is a compilation of the final reports on the research projects completed by the faculty fellows during the summer of 1994.
Keywords: photographic film, radiation effects, spaceborne photography
Abstract: The Shuttle and its cargo are occasionally exposed to an amount of radiation large enough to create nonimage forming exposures (fog) on photographic flight film. The television/photography working group proposed a test plan to quantify the sensitivity of photographic films to space radiation. This plan was flown on STS-37 and was later incorporated into a detailed supplementary objective (DSO) which was flown on STS-48. This DSO addressed the effects of significant space radiation on representative samples of six highly sensitive flight films. In addition, a lead-lined bag was evaluated as a potential shield for flight film against space radiation.
Keywords: Polyphenyls, Fibers, Polymer Blends, Materials Tests
Abstract: Woven and braided Polybenzoxazole (PBO) structures have been developed for aerospace applications. The properties of PBO fibers are compared to those of other high performance fibers. PBO is unique for combining excellent flammability properties with the highest tensile strength and modulus of all synthetic organic fibers. The PBO structures are specifically developed to be compared to similar Kevlar structures. The physical, mechanical, thermal, and oxidative properties of the PBO woven and braided structures are determined. The resistance to various chemicals and to UV light is evaluated. Recommendations for specific aerospace applications are given with comments for further development and industrial applications.
Keywords: body fluids, astronauts, sicknesses, electrolyte metabolism, plasma
Abstract: Fluid loading with salt and water is a countermeasure used after spaceflight to restore body fluids. However, gastrointestinal side effects have been frequently reported in persons taking similar quantities of salt and water in ground-based studies. We compared the effectiveness of the Shuttle fluid-loading countermeasure (8 gms salt, 0.97 liters of water) to Astro-ade (an isotonic electrolyte solution), to maintain plasma volume (PV) during 4.5 hrs of resting fluid restriction. Three groups of healthy men (n=6) were studied: a Control Group (no drinking), an Astro-ade Group, and a Salt Tablet Group. Changes in PV after drinking were calculated from hematocrit and hemoglobin values. Both the Salt Tablet and Astro-ade Groups maintained PV at 2-3 hours after ingestion compared to the Control Group, which had a 6% decline. Side effects (thirst, stomach cramping, and diarrhea) were noted in at least one subject in both the Astro-ade and Salt Tablet Groups. Nausea and vomiting were reported in one subject in the Salt Tablet Group. We conclude that Astro-ade may be offered as an alternate fluid-loading countermeasure but further work is needed to develop a solution that is more palatable and has fewer side effects.
Keywords: Thermal Vacuum Tests, Heat Radiators, Tubes, Temperature Control, Lunar Bases
Abstract: Spacecraft thermal control systems are essential to provide the necessary environment for the crew and equipment to function adequately on space missions. The Ultralight Fabric Reflux Tube (UFRT) was developed by Pacific Northwest Laboratory (PNL) as a lightweight radiator concept to be used on planetary-type missions (e.g., Moon, Mars). The UFRT consists of a thin-walled tube (acting as the fluid boundary), overwrapped with a low-mass ceramic fabric (acting as the primary pressure boundary). The tubes are placed in an array in the vertical position with the evaporators at the lower end. Heat is added to the evaporators, which vaporizes the working fluid. The vapor travels to the condenser end above and cools as heat is radiated to the environment. The fluid condensed on the tube wall is then returned to the evaporator by gravity. The primary objectives for the fiscal year 1994 program included the design and fabrication of prototype UFRTs and thermal/vacuum chamber testing of these test articles. Six UFRTs, with improved titanium liners, were successfully manufactured and provided to the Johnson Space Center in July 1994. Five were tested in a thermal/vacuum chamber in September 1994. Data obtained to characterize the performance of the UFRTs under simulated lunar conditions demonstrated the design concept successfully. In addition, a trade study showed that an optimized/improved UFRT could achieve as much as a 25% mass savings in the heat rejection subsystem of future planetary-type thermal control systems.
Keywords: Hyperbaric Medicine; Space Station Freedom; Decompression Sickness; Space Medicine; Treatment of Decompression Sickness
Abstract: In September 1991, a previously established working group convened to discuss aspects of hyperbaric medical care for Space Station Freedom (SSF). A vigorous extravehicular activity schedule planned for SSF construction and maintenance led to the inclusion of an on-orbit hyperbaric treatment facility known as the Hyperbaric Airlock (HAL). This presented several technical and procedural challenges requiring expert consultation. The Ad Hoc Committee for Space Hyperbaric Medicine, which had been involved since the early planning stages of SSF, had been formed to address these issues. Seven highly experienced and world-renowned specialists in hyperbaric medicine and decompression related disorders, representing a wide experience base in the aviation and undersea environments, have participated. This latest meeting at the Johnson Space Center, which involved five of these specialists, was the third convening of this group. The meeting enjoyed heavy support and participation from local hyperbaric and space medicine specialists from the NASA community. Specific topics addressed included the risk of on-orbit decompression sickness (DCS), treatment options for DCS on orbit, overviews of the HAL layout and operation, crew duty constraints following DCS, and specific hazards of hyperbaric treatment on orbit. Over the course of several formal presentations and panel discussions, decompression disorders and the role of hyperbaric medicine in manned space flight were covered thoroughly. These proceedings reflect this enormously productive meeting, and will serve as a benchmark for further work in this highly specialized and critical aspect of manned space flight.
Keywords: Global Positioning System, multipath, transmission, differential interferometry, diffraction, Geometrical Theory of Diffraction, carrier waves, signal reflection, ray tracing
Abstract: Two computational techniques are used to calculate differential phase errors on Global Positioning System (GPS) carrier wave phase measurements due to certain multipath-producing objects: a rigorous computation electromagnetics technique called Geometric Theory of Diffraction (GTD) and a simple ray tracing method. GTD has been used successfully to predict microwave propagation characteristics by taking into account the dominant multipath components due to reflections and diffractions from scattering structures. The ray tracing technique only solves for reflected signals. The results from the two techniques are compared to GPS differential carrier phase measurements taken on the ground using a GPS receiver in the presence of typical International Space Station (ISS) interference structures. The calculations produced using GTD compared to the measured results better than the ray tracing technique. The agreement was good, demonstrating that the phase errors due to multipath can be modeled and characterized using GTD and characterized to a lesser fidelity using the DECAT technique. However, some discrepancies were observed. Most occurred at lower elevations and were due to antenna phase center deviations, the background multipath environment, or the receiver itself. Selected measured and predicted differential carrier phase error results are presented and compared. Results indicate that reflections and diffractions caused by the multipath producers can produce phase shifts greater than 10 mm and as high as 95 mm.
Keywords: cancer, ISSA, space station, galactic cosmic rays, galactic radiation, radiation dosage, extraterrestrial radiation
Abstract: Excess cancer risks resulting from exposures to space radiation are estimated for various orbits of the International Space Station (ISS). Organ exposures are computed with the transport codes, BRYNTRN and HZETRN, and the computerized anatomical male and computerized anatomical female models. Cancer risk coefficients in the National Council on Radiation Protection and Measurements report No. 98 are used to generate lifetime excess cancer incidence and cancer mortality after a one-month mission to ISS. The generated data are tabulated to serve as a quick reference for assessment of radiation risk to astronauts on ISS missions.
Keywords: laminar flow, laminar boundary layer, boundary layer transition, turbulent boundary layer, surface roughness effects
Abstract: Several Space Shuttle flights experienced earlier than expected laminar to turbulent boundary layer transition. These have often been asymmetric, which results in unplanned control requirements and higher localized heating. It was noted that evidence of roughness elements was generally a common factor for the flights experiencing the unexpected early transition. We conducted a test in the Arnold Engineering and Development Center's Von Karman Facility Tunnel B to determine the effect of specific discrete roughness element heights and locations on the transition of the Orbiter boundary layer from laminar to turbulent at various Reynolds numbers. We limited angle of attack to 35 and 40 deg, which are most representative of the flight experience. The major objectives were to verify that off-design changes to the thermal protection system could cause roughness-induced early transition consistent with flight experience and to determine which sizes and locations of roughness elements would cause early transition. Test results indicate that, while a single roughness element on the windward centerline near the nose region could induce early transition over most of the windward surface, a single roughness element off to the side of the windward centerline could result in a turbulent boundary layer occurring on a major portion of one side of the windward surface with the other side remaining laminar. Increasing the height of the roughness element on the windward centerline and cooling the model resulted in transition at lower freestream Reynolds numbers.
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: This report highlights specific research and technology projects at Johnson Space Center for 1995. Emerging technologies in these major disciplines are summarized: solar system sciences, life sciences, technology transfer, computer sciences, space technology, and human support technology. These NASA advances have a range of potential applications for industry, from improved filters for blood collection devices to an environmentally safe replacement solvent for ozone-depleting Freon.
Keywords: Radiation, Measuring Instruments, sensitometry
Abstract: A joint U.S./Russian film test was conducted during MIR Mission 18 to evaluate the effects of radiation on photographic film during long-duration space flights. Two duplicate sets of film were flown on this MIR mission: one set was processed and evaluated by the NASA/JSC Photographic Laboratory, and the other by the RKK Energia's Photographic Laboratory in Moscow. This preliminary report includes only the results of the JSC evaluation (excluding the SN-10 film which was not available for evaluation at the time this report was written). The final report will include an evaluation by JSC of the SN-10 film and an evaluation of the test data by the RKK Energia. JSC's evaluation of the test data showed the positive film flown was damaged very little when exposed to approximately 8 rads of radiation. Two of the three negative films were significantly damaged and the third film was damaged only moderately.
Keywords: space suits; Shuttle; motion; garments, thermal micrometeoroid; strength; model, computer; extravehicular mobility unit
Abstract: In this study the strength of subjects suited in extravehicular mobility units (EMUs) - or Space Shuttle suits - was compared to the strength of unsuited subjects. The authors devised a systematic and complete data set that characterizes isolated joint torques for all major joints of EMU-suited subjects. Six joint motions were included in the data set. The joint conditions of six subjects were compared to increase our understanding of the strength capabilities of suited subjects. Data were gathered on suited and unsuited subjects. Suited subjects wore Class 3 or Class 1 suits, with and without thermal micrometeoroid garments (TMGs). Suited and unsuited conditions for each joint motion were compared. From this the authors found, for example, that shoulder abduction suited conditions differ from each other and from the unsuited condition. A second-order polynomial regression model was also provided. This model, which allows the prediction of suited strength when given unsuited strength information, relates the torques of unsuited conditions to the torques of all suited conditions. Data obtained will enable computer modeling of EMU strength, conversion from unsuited to suited data, and isolated joint strength comparisons between suited and unsuited conditions at any measured angle. From these data mission planners and human factors engineers may gain a better understanding of crew posture, and mobility and strength capabilities. This study also may help suit designers optimize suit strength, and provide a foundation for EMU strength modeling systems.
Keywords: torsion problems, Legendre polynomials, boundary value problems, Lame functions, finite element method, equilibrium equations, shear stress
Abstract: A new treatment of the classical beam torsion boundary value problem is applied. Using the p-version finite element method with shape functions based on Legendre polynomials, torsion solutions for generic cross-sections comprised of isotropic materials are developed. Element shape functions for quadrilateral and triangular elements are discussed, and numerical examples are provided.
Keywords: information transfer, research, research projects, engineering, science, university program
Abstract: The JSC NASA/ASEE Summer Faculty Fellowship Program was conducted at JSC, including the White Sands Test Facility, by Texas A&M University and JSC. The objectives of the program, which began nationally in 1964 and at JSC in 1965, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participants' institutions; and (4) to contribute to the research objectives of the NASA centers. Each faculty fellow spent at least 10 weeks at JSC engaged in a research project in collaboration with a NASA/JSC colleague. In addition to the faculty participants, the 1995 program included five students. This document is a compilation of the final reports on the research projects completed by the faculty fellows and visiting students during the summer of 1995. The reports of two of the students are integral with that of the respective fellow. Three students wrote separate reports.
Keywords: human factors engineering, protective clothing, gloves, manual control, astronaut performance, extravehicular activity
Abstract: One of the reasons for reduction in performance when gloves are donned is the lack of tactile sensitivity. It was argued that grasping force for a weight to be grasped will be a function of the weight to be lifted and the hand conditions. It was further reasoned that the differences in grasping force for various hand conditions will be a correlate of the tactile sensitivity of the corresponding hand conditions. The objective of this experiment, therefore, was to determine the effects of glove type, pressure, and weight of load on the initial grasping force and stable grasping force. It was hypothesized that when a person grasps an object, he/she grasps very firmly initially and then releases the grasp slightly after realizing what force is needed to maintain a steady grasp. This would seem to be particularly true when a person is wearing a glove and has lost some tactile sensitivity and force feedback during the grasp. Therefore, the ratio of initial force and stable force and the stable force itself would represent the amount of tactile adjustment that is made when picking up an object, and this adjustment should vary with the use of gloves. A dynamometer was fabricated to measure the grasping force; the tests were performed inside a glove box. Four female and four male subjects participated in the study, which measured with four variables: load effect, gender effect, glove type, and pressure variance. The only significant effects on the peak and stable force were caused by gender and the weight of the load lifted. Neither gloves nor pressure altered these forces when compared to a bare-handed condition, as was suspected before the test. It is possible that gloves facilitate in holding due to coefficient of friction while they deter in peak grasp strength.
Keywords: ignition, combustion, oxygen-enriched environment, oxygen hazards analysis
Abstract: Because most materials, including metals, will burn in an oxygen-enriched environment, hazards are always present when using oxygen. Most materials will ignite at lower temperatures in an oxygen-enriched environment than in air, and once ignited, combustion rates are greater in the oxygen-enriched environment. Many metals burn violently in an oxygen-enriched environment when ignited. Lubricants, tapes, gaskets, fuels, and solvents can increase the possibility of ignition in oxygen systems. However, these hazards do not preclude the use of oxygen. Oxygen may be safely used if all the materials in a system are not flammable in the end-use environment or if ignition sources are identified and controlled. These ignition and combustion hazards necessitate a proper oxygen hazards analysis before introducing a material or component into oxygen service. The objective of this test plan is to describe the White Sands Test Facility oxygen hazards analysis to be performed on components and systems before oxygen is introduced and is recommended before implementing the oxygen component qualification procedure. The plan describes the NASA Johnson Space Center White Sands Test Facility method consistent with the ASTM documents for analyzing the hazards of components and systems exposed to an oxygen-enriched environment. The oxygen hazards analysis is a useful tool for oxygen-system designers, system engineers, and facility managers. Problem areas can be pinpointed before oxygen is introduced into the system, preventing damage to hardware and possible injury or loss of life.
Keywords: two-phase systems, heat pumps, heat pipes, heat radiators, radiators, heat exchangers, missions, lunar bases, space transportation system, thermal analysis
Abstract: The Johnson Space Center (JSC) initiated a dynamic study to determine possible improvements available through advanced technologies (not used on previous or current human vehicles), identify promising development initiatives for advanced active thermal control systems (ATCSs), and help prioritize funding and personnel distribution among many research projects by providing a common basis to compare several diverse technologies. Some technologies included were two-phase thermal control systems, light-weight radiators, phase-change thermal storage, rotary fluid coupler, and heat pumps. JSC designed the study to estimate potential benefits from these various proposed and under-development thermal control technologies for five possible human missions early in the next century. The study compared all the technologies to a baseline mission using mass as a basis. Each baseline mission assumed an internal thermal control system; an external thermal control system; and aluminum, flow-through radiators. Solar vapor compression heat pumps and light-weight radiators showed the greatest promise as general advanced thermal technologies which can be applied across a range of missions. This initial study identified several other promising ATCS technologies which offer mass savings and other savings compared to traditional thermal control systems. Because the study format compares various architectures with a commonly defined baseline, it is versatile and expandable, and is expected to be updated as needed.
Keywords: pyrotechnics, hexanitrostilbene, detonators, shaped charges, fuses, deterioration, life (durability)
Abstract: Determining deterioration characteristics of the Space Shuttle crew escape system pyrotechnic components loaded with hexanitrostilbene would enable us to establish a hardware life-limit for these items, so we could better plan our equipment use and, possibly, extend the useful life of the hardware. We subjected components to accelerated-age environments to determine degradation characteristics and established a hardware life-limit based upon observed and calculated trends. We extracted samples using manufacturing lots currently installed in the Space Shuttle crew escape system and from other NASA programs. Hardware included in the study consisted of various forms and ages of mild detonating fuse, linear shaped charge, and flexible confined detonating cord. The hardware types were segregated into 5 groups. One was subjected to detonation velocity testing for a baseline. Two were first subjected to prolonged 155°F heat exposure, and the other two were first subjected to 255°F, before undergoing detonation velocity testing and/or chromatography analysis. Test results showed no measurable changes in performance to allow a prediction of an end of life given the storage and elevated temperature environments the hardware experiences. Given the lack of a definitive performance trend, coupled with previous tests on post-flight Space Shuttle hardware showing no significant changes in chemical purity or detonation velocity, we recommend a safe increase in the useful life of the hardware to 20 years, from the current maximum limits of 10 and 15 years, depending on the hardware.
Keywords: global positioning system; space rendezvous; real time operation; Kalman filters
Abstract: A real-time global positioning system (GPS) Kalman filter has been developed to support automated rendezvous with the International Space Station (ISS). The filter is integrated with existing Shuttle rendezvous software running on a 486 laptop computer under Windows*. In this work we present real-time and postflight results achieved with the filter on STS-69. The experiment used GPS data from an Osborne/Jet Propulsion Laboratory TurboRogue receiver carried on the Wake Shield Facility (WSF) free-flyer and a Rockwell Collins 3M receiver carried on the Orbiter. Real-time filter results, processed onboard the Shuttle and replayed in near-real time on the ground, are based on single-vehicle mode operation and on 5 to 20 minute snapshots of telemetry provided by WSF for dual-vehicle mode operation. Postflight results were achieved by running the filter in real-time mode using data recorded during the mission. Orbiter and WSF state vectors calculated using our filter compare favorably with precise reference orbits determined by the University of Texas Center for Space Research. The lessons learned from this experiment will be used in conjunction with future experiments to mitigate the technology risk posed by automated rendezvous and docking to the ISS.*Trademark
Keywords: human factors engineering; man-computer interface; posture
Abstract: The Posture Video Analysis Tool* (PVAT) has been developed by the Human Factors and Ergonomics Laboratory (HFEL) engineers at the NASA Johnson Space Center in response to the need for a low cost, reliable method of collecting postural data from nonscientific mission video footage. The PVAT is an interactive Macintosh menu and button driven SuperCard* prototype consisting of a setup and an analysis screen. Since its creation, PVAT has undergone a series of usability evaluations. The testing accomplished thus far has assisted the PVAT designers in improving the interface with both subtle and sweeping changes. The results of these iterative evaluations demonstrated that the PVAT is a promising initial step in identifying and quantifying "limiting microgravity postures" and related workstation design concerns. Furthermore, it is also anticipated that the PVAT will be applicable in a host of nonaerospace industries with little or no modification. If funding is available, further evaluations will be conducted to refine its graphical user interface and demonstrate its industrial applications. *Trademark
Keywords: oxygen; oxygen regulators; oxygen supply equipment; relief valves; check valves; manual valves; operational hazards; fibers; oxygen regulators; hoses; intensifiers; safety factors
Abstract: Although oxygen is a chemically stable element, it is not shock sensitive, will not decompose, and is not flammable. Oxygen use therefore carries a risk that should never be overlooked, because oxygen is a strong oxidizer that vigorously supports combustion. Safety is of primary concern in oxygen service. To promote safety in oxygen systems, the flammability of materials used in them should be analyzed. At the NASA White Sands Test Facility (WSTF), we have performed configurational tests of components specifically engineered for oxygen service. These tests follow a detailed WSTF oxygen hazards analysis. The stated objective of the tests was to provide performance test data for customer use as part of a qualification plan for a particular component in a particular configuration, and under worst-case conditions. In this document - the "Guide for Oxygen Component Qualification Tests" - we outline recommended test systems, and cleaning, handling, and test procedures that address worst-case conditions. It should be noted that test results apply specifically to: manual valves, remotely operated valves, check valves, relief valves, filters, regulators, flexible hoses, and intensifiers. Component systems are not covered.
Keywords: space debris; orbital mechanics
Abstract: A semi-empirical orbital debris model has been developed which combines direct measurements of the environment with the output and theory of more complex orbital debris models. This model is computer based. It approximates the environment with six different inclination bands. Each band has a unique distribution of semi-major axis, for near circular orbits, and a unique perigee distribution, for highly elliptical orbits. In addition, each inclination band has unique size distributions which depend on the source of debris. Collision probability equations are used to relate the distributions of orbital elements to the flux measured on a spacecraft or to the flux measured through the field of view of a ground sensor. The distributions of semi-major axis, perigee, and inclination are consistent with the U.S. Space Command catalogue for sizes larger than about 10 cm, taking the limitations of the sensors into account. For smaller sizes, these distributions are adjusted to be consistent with the flux measured by ground telescopes, the Haystack radar, and the Goldstone radar as well as the flux measured by the LDEF satellite and the Space Shuttle. The computer program requires less than 1 second to calculate the flux and velocity distribution for a given size debris relative to an orbiting spacecraft.
Keywords: illuminating, luminaires, bidirectional reflectance, reflectance, spread reflection, computerized simulation, space environment simulation
Abstract: Task illumination has a major impact on human performance: What a person can perceive in his environment significantly affects his ability to perform tasks, especially in space's harsh environment. Training for lighting conditions in space has long depended on physical models and simulations to emulate the effect of lighting, but such tests are expensive and time-consuming. To evaluate lighting conditions not easily simulated on Earth, personnel at NASA's JSC Graphics Research and Analysis Facility (GRAF ) have been developing computerized simulations of various illumination conditions using the ray-tracing program, Radiance (Greg Ward, Lawrence Berkeley Laboratory). Because these computer simulations are only as accurate as the data used, accurate information about the reflectance properties of materials and light distributions is needed. JSC personnel gathered material reflectance properties for a large number of paints, metals, and cloths used in the Space Shuttle and Space Station programs, and processed these data into reflectance parameters needed for the computer simulations. They gathered lamp distribution data for most light sources used and validated the ability to accurately simulate lighting levels by comparing predictions with measurements for ground-based tests. The result is a database of material reflectance properties for a wide variety of materials, and lighting information for most of the standard light sources used. The combination of the Radiance program and GRAF's graphics capability form a validated computerized lighting simulation capability for NASA.
Keywords: computer programs, computers, computer systems programs, software engineering, reliability analysis, program verification (computers)
Abstract: As software is maintained or reused, it undergoes an evolution which tends to increase the overall complexity of the code. To understand the effects, we brought in statistics experts and leading researchers in software complexity, reliability, and interrelationships. These experts' project has resulted in our ability to statistically correlate specific code complexity attributes, in orthogonal domains, to errors found over time in the HAL/S flight software which flies in the Space Shuttle. Although only a prototype-tools experiment, the result of this research appears to be extendable to all other NASA software, given appropriate data similar to that logged for the Shuttle onboard software. Our research has demonstrated that a more complete domain coverage can be mathematically demonstrated, thereby ensuring full insight into the cause-and-effects relationship between the complexity of a software system and the fault density of that system. We can characterize the dynamic effects of software path complexity under this same approach. We now have the ability to measure specific attributes which have been statistically demonstrated to correlate to increased error probability, and to know which actions to take, for each complexity domain. Shuttle software verifiers can now monitor the changes in the software complexity, assess the added or decreased risk of software faults in modified code, and determine necessary corrections. The reports, tool documentation, user's guides, and new approach that have resulted from this research effort represent advances in the state of the art of software quality and reliability assurance. Details describing how to apply this technique to other NASA code are contained in this document.
Keywords: human factors engineering, man-computer interface, software engineering, computer systems programs, software tools, program verification (computers)
Abstract: The Usability Testing and Analysis Facility (UTAF) at the NASA Johnson Space Center has identified and evaluated a potential automated software interface inspection tool capable of assessing the degree to which space-related critical and high risk software system user interfaces meet objective human factors standards across each NASA program and project. Testing consisted of two distinct phases. Phase I compared analysis times and similarity of results for the automated tool and for human-computer interface (HCI) experts. In Phase II, HCI experts critiqued the prototype tool's user interface. Based on this evaluation, it appears that a more fully developed version of the tool will be a promising complement to a human factors-oriented Independent Verification and Validation (IV&V) process.
Keywords: Mars; manned Mars missions; Mars surface; mission planning; exploration; space
Abstract: This document describes current expectations for the activities of human and robotic crews, and the associated support equipment, that will occur as they explore the surface of Mars. These descriptions, made at a functional level, were prepared assuming a split-mission architecture. It should be noted that these descriptions can, in general, be used in conjunction with other mission approaches. The Mars Surface Reference Mission is a tool used by the Exploration Team and the exploration community to compare and evaluate approaches to surface activities. Intended to identify and clarify system drivers, or significant sources of cost, performance, risk, and schedule variation, it does not represent a final or recommended approach. The Exploration Team is currently studying alternative scenarios, including technical approaches to solving mission and technology challenges, and human exploration missions to the Moon, asteroids, or other targets beyond Earth orbit. Comparing alternative approaches in this way provides the basis for continual improvement to technology investment plans and a general understanding of future human exploration missions. This document has been divided into several major sections. The first provides an overview of the split-mission approach, to provide a framework for the surface mission. The remainder is devoted to a series of vignettes describing key activities or functions that will be a part of the surface mission. This document represents a “snapshot” of work in progress in support of planning through October 1998 for future human exploration of the Martian surface. Publications of revisions to this document are planned.
Keywords: cyogenics, plume flow fields, catalycity, hypersonic flow, thermal radiation, and aerothermal, thermal, structural, and fluid analysis
Abstract: This document contains papers presented at the Eighth Annual Thermal and Fluids Analysis Workshop (TFAWS) on spacecraft analysis and design. The workshop was sponsored by the Johnson Space Center. It was held on September 8-11, 1997 at the University of Houston - Clear Lake. Seminars were hosted and technical papers were provided in fluid and thermal dynamics. Seminars were also given on GASP, SINDA, SINAPS Plus, TSS, and PHOENICS. Seventeen papers were presented.
Keywords: Hubble Space Telescope, solar arrays, photogrammetry, solar dynamic power systems
Abstract: This report documents the photogrammetric assessment of the Hubble Space Telescope (HST) solar arrays conducted by the NASA Johnson Space Center Image Science and Analysis Group during the second Servicing Mission (SM-2) on STS-82 in February of 1997. Two types of solar array analyses were conducted during the mission using Space shuttle payload bay video: (1) measurement of solar array motion due to induced loads, and (2) measurement of solar array static or geometric twist caused by the cumulative array loading. The report describes premission planning and analysis technique development activities conducted to acquire and analyze solar array imagery data during SM-2. This includes analysis of array motion obtained during SM-1 as a proof-of-concept of the SM-2 measurement techniques. The report documents the results of real-time analysis conducted during the mission and subsequent analysis conducted post-flight. This report also provides a summary of lessons learned on solar array imagery analysis from SM-2 and recommendations for future on-orbit measurements applicable to HST SM-3 and to the International Space Station. This work was performed under the direction of the Goddard Space Flight Center HST Flight Systems and Servicing Project.
Keywords: aerogel, space debris, cosmic dust, cometary atmospheres, deceleration, hypervelocity impact, impact melts
Abstract: Recent impact experiments conducted at the Johnson Space Center supported a space-exposed flight instrument called the orbital debris collector (ODC) to see whether SiO2 aerogel performed adequatedly as a collector to capture cosmic dust particles and/or manmade debris, or whether additional develpment is needed. The first ODC was flown aboard the Mir for 18 months, while the second will be flown aboard a spacecraft (Stardust, to be launche in 1999) that will encounter the comet Wild 2 and return to Earth. Aerogels are highly porous materials that decelerate high-velocity particles without substantial melting or modifications to the particle components. In other denser materials, these particles would melt or vaporize upon impact. The experimental data in this report must be considered somewhat qualitative because they are characterized by substantial, if not intolerable, scatter, possibly caused by experimental difficulties in duplicating given setes of initial impact conditions. Therefore, this report is a chronological guide of our attempts, difficulties, progress, and evaluations for future tests.
Keywords: long duration spaceflight, planetology, trajectory, Mars, martian
Abstract: The human exploration of Mars will be a complex undertaking. From 1992 through 1994, personnel representing several NASA field centers met to formulate a "Reference Mission" addressing human exploration of Mars. This report summarizes their work and describes a plan for the first human missions to Mars, using approaches that are technically feasible, have reasonable risks, and have relatively low costs. The architecture for the Mars Reference Mission builds on previous work, principally on the work of the Synthesis Group and Zubrin's concepts for the use of propellants derived from the martian atmosphere. In defining the Reference Mission, choices have been made. In this report, the rationale for each choice is documented; however unanticipated technology advances or political decisions might change the choices in the future. One principal use of the Reference Mission is to lay the basis for comparing different approaches and criteria in order to select better ones. The Reference Mission is not implementable in its present form. It involves assumptions and projections, and it cannot be accomplished without further research, development, and technology demonstrations. It is also not developed in the detail necessary for implementation, which would require a systematic development of requirements through the system engineering process. The primary purpose of this report is to stimulate further thought and development of alternative approaches.
Keywords: manned Mars missions, Mars, extraterrestrial resources, utilization, site selection
Abstract: As a planet with striking similarities to Earth, Mars is an important focus for scientific research aimed at understanding the processes of planetary evolution and the formation of our solar system. Fortunately, Mars is also a planet with abundant natural resources, including accessible materials that can be used to support human life and to sustain a self-sufficient martian outpost. Resources required include water, breathable air, food, shelter, energy, and fuel. Through a mission design based on in situ resource development, we can establish a permanent outpost on Mars beginning with the first manned mission. This paper examines the potential for supporting the first manned mission with the objective of acheiveing self-suffeiciency throuhg well understood resource development and a program of rigorous scientific research aimed at extending that capability. We examine the potential for initially extracting critical resources from the martian environment, and discuss the scientific investigations required to identify additional resources in the atmosphere, on the surface, and within the subsurface. We also discuss our current state of knowledge of Mars, technical considerations of resource utilization, and using unmanned missions' data for selecting an optimal site. The primary goal of achieving self-sufficiency on Mars would accelerate the development of human colonization beyond Earth, while providing a robust and permanent martian base from which humans can explore and conduct long-term research on planetary evolution, the solar system, and life itself.
Keywords: exercise physiology, physical exercise, weightlessness, muscular strength, bones
Abstract: This demonstration project assessed the crew members' compliance to a portion of the exercise countermeasures planned for use on board the International Space Station (ISS) and the outcomes of their performing these countermeasures. Although these countermeasures have been used separately in other projects and investigations, this was the first time they'd been used together for an extended period (60 days) in an investigation of this nature. Crew members exercised every day for six days, alternating every other day between aerobic and resistive exercise, and rested on the seventh day. On the aerobic exercise days, subjects exercised on an electronically braked cycle ergometer using a protocol that has been previously shown to maintain aerobic capacity in subjects exposed to a space flight analogue. On the resistive exercise days, crew members performed five major multijoint resistive exercises in a concentric mode, targeting those muscle groups and bones we believe are most severely affected by space flight. The subjects favorably tolerated both exercise protocols, with a 98% compliance to aerobic exercise prescription and a 91% adherence to the resistive exercise protocol. After 60 days, the crew members improved their peak aerobic capacity by an average 7%, and strength gains were noted in all subjects. These results suggest that these exercise protocols can be performed during ISS, lunar, and Mars missions, although we anticipate more frequent bouts with both protocols for long-duration spaceflight. Future projects should investigate the impact of increased exercise duration and frequency on subject compliance, and the efficacy of such exercise prescriptions.
Keywords: flow measurement, flow, axisymmetric flow, parabolic bodies, shock layers, viscous flow, heat flux
Abstract: A technique is implemented for computing hypersonic aeroheating, shear stress, and other flow properties on the windward side of a three-dimensional (3D) blunt body. The technique uses a 2D/axisymmetric flow solver modified by scale factors for a corresponding equivalent axisymmetric body. Examples are given in which a 2D solver is used to calculate the flow at selected meridional planes on elliptic paraboloids in reentry flight. The report describes the equations and the codes used to convert the body surface parameters into input used to scale the 2D viscous shock layer equations in the axisymmetric viscous shock layer code. Very good agreement is obtained with solutions to finite rate chemistry 3D thin viscous shock layer equations for a finite rate catalytic body.
Keywords: Mars, exploration, human, space transportation, propulsion
Abstract: This Addendum to the Mars Reference Mission was developed as a companion document to the NASA Special Publication 6107, "Human Exploration of Mars: The Reference Mission of the NASA Mars Exploration Study Team." It summarizes changes and updates to the Mars Reference Mission that were developed by the Agencywide Exploration Team since the final draft of SP 6107 was printed in early 1998. The Reference Mission is a tool used by the exploration community to compare and evaluate approaches to mission and system concepts that could be used for human missions to Mars. It is intended to identify and clarify system drivers, significant sources of cost, performance, risk, and schedule variation. Several alternative scenarios, employing different technical approaches to solving mission and technology challenges, are discussed in this Addendum. Comparing alternative approaches provides the basis for continual improvement to technology investment plans and a general understanding of future human missions to Mars. The Addendum represents a snapshot of work in progress in support of planning future human exploration missions through May 1998.
Keywords: exercise physiology, laboratories, physiological tests
Abstract: This manual describes the laboratory methods used to collect flight crew physiology performance data at the Johnson Space Center. The Exercise Countermeasures Project Laboratory is a standard physiology laboratory; only the application to the study of human physiological adaptations to space flight is unique. In the absence of any other recently published laboratory manual, this manual should be a useful document for the staffs and students of other laboratories.
Keywords: Research Projects, Research and Development, NASA Programs, Technology Utilization, Space Technology Experiments
Abstract: This report highlights key projects and technologies at Johnson Space Center for1997. The report focuses on the commercial potential of the projects and technologies and is arranged by CorpTech Major Products Groups. Emerging technologies in these major disciplines are summarized: solar system sciences, life sciences, technology transfer, computer sciences, space technology, and human support technology. These NASA advances have a range of potential commercial applications, from a school internet manager for networks to a liquid metal mirror for optical measurements. For general commercial information or commercialization information about a specific tehcnology, contact the NASA JSC Office of Technology Transfer and Commercialization at: NASA JSC, mail code HA, 2101 NASA Rd 1, Houston, TX, 77058-3696; Tel: (281) 483-3809; Fax: (281) 244-8452; E-mail: commercialization@jsc.nasa.gov; Web page: http://technology.jsc.nasa.gov
Keywords: restraints, optimization, human factors engineering
Abstract: The zero-gravity environment creates a need for a proper human body restraint system to maintain a comfortable posture with less fatigue and to maximize productivity. In addition, restraint systems must be able to meet the loading demands of maintenance and assembly tasks performed on orbit. The Shuttle's primary intravehicular astronaut restraint system is currently a foot loop design that attaches to flat surfaces on the Shuttle, allowing for varying mounting locations and easy egress and ingress. However, this design does not allow for elevation, pitch, or foot loop length adjustment. Several prototype foot restraint systems are being evaluated for use aboard the Space Station and the Space Shuttle. The JSC Anthropometry and Biomechanics Laboratory initiated this study to quantify the maximum axial forces and moments that would be induced on a foot loop type of restraint while operators performed a torque wrench task, also allowing for angling the restraint pitch angle to study yet another effect. Results indicate that the greatest forces into the torque wrench and into the foot restraint system occur while the operator performs an upward effort. This study did not see any significant difference in the operators' force due to pitch orientation. Thus, in a work environment in which hand holds are available, no significant influence of the pitch angle on forces imparted to the restraint system existed.
Keywords: space debris, environmental effects, reentry effects, collision rates, debris, orbit decay, histories, bibliographies
Abstract: This chronology covers the 37-year history of orbital debris concerns. It tracks orbital debris hazard creation, research, observation, experimentation, management, mitigation, protection, and policy. Included are debris-producing events; UN orbital debris treaties; Space Shuttle and space station orbital debris issues; ASAT tests; milestones in theory and modeling; uncontrolled reentries; detection system development; shielding development; geosynchronous debris issues, including reboost policies; returned surfaces studies; seminal papers, reports, conferences, and studies; the increasing effect of space activities on astronomy; and growing international awareness of the near-Earth environment.
Keywords: Mir Space Station, Spacecraft Docking, Space Stations, Spacecraft Configurations
Abstract: Dockings, module additions, configuration changes, crew changes, and major mission events are tracked for Mir missions 17 through 21 (November 1994 through August 1996). The international aspects of these missions are presented, comprising joint missions with ESA and NASA, including three U.S. Space Shuttle dockings. New Mir modules described are Spektr, the Docking Module, and Priroda.
Keywords: spectrometers, cosmic rays, antimatter, International Space Station, observatories, calorimeters, accelorators, extraterrestrial radiation
Abstract: In 1994 the NASA Administrator selected the first high-energy particle physics experiment for the International Space Station (ISS), the alpha magnetic spectrometer (AMS), to place a magnetic spectrometer in Earth orbit and search for cosmic antimatter. A natural consequence of this decision was that NASA would begin to explore cost-effective ways through which the design and implementation of AMS might benefit other promising payload experiments. The first such experiment to come forward was Advanced Cosmic-Ray Composition Experiment for Space Station (ACCESS) in 1996. It was proposed as a new mission concept in space physics to attach a cosmic-ray experiment of weight, volume, and geometry similar to the AMS on the ISS, and replace the latter as its successor when the AMS is returned to Earth. This was to be an extension of NASA's suborbital balloon program, with balloon payloads serving as the precursor flights and heritage for ACCESS. The balloon programs have always been a cost-effective NASA resource since the particle physics instrumentation for balloon and space applications are directly related. The next step was to expand the process, pooling together expertise from various NASA centers and universities while opening up definition of the ACCESS science goals to the international community through the standard practice of peer review. This process is still ongoing, and the accommodation study presented here will discuss the baseline definition of ACCESS as we understand it today.
Keywords: research projects, research and development, NASA programs, technology utilization, space technology experiments
Abstract: This report describes 61 projects funded through the NASA Research and Technology Operating Plan (RTOP). Emerging technologies in 12 disciplines are summarized: automation, biotechnology, computer hardware, energy, environmental, advanced materials, medical, photonics, software, subassemblies and components, telecommunications, and transportation. Although these projects focus on support of human spacecraft design, development, and safety, most have wide civil and commercial applications in areas as varied as advanced materials, digital imaging, high-performance computers, medical devices and diagnoses, environmental concerns, and human factors engineering.
Keywords: escape systems; spacecraft; spacecraft configurations; spacecraft design; ingress; weightlessness
Abstract: This project aimed to develop a methodology for evaluating performance and acceptability characteristics of the pressurized crew module volume suitability for zero-gravity (g) ingress of a spacecraft and to evaluate the operational acceptability of the NASA crew return vehicle (CRV) for zero-g ingress of astronaut crew, volume for crew tasks, and general crew module and seat layout. No standard or methodology has been established for evaluating volume acceptability in human spaceflight vehicles. Volume affects astronauts' ability to ingress and egress the vehicle, and to maneuver in and perform critical operational tasks inside the vehicle. Much research has been conducted on aircraft ingress, egress, and rescue in order to establish military and civil aircraft standards. However, due to the extremely limited number of human-rated spacecraft, this topic has been unaddressed. The NASA CRV was used for this study. The prototype vehicle can return a 7-member crew from the International Space Station in an emergency. The vehicle’s internal arrangement must be designed to facilitate rapid zero-g ingress, zero-g maneuverability, ease of one-g egress and rescue, and ease of operational tasks in multiple acceleration environments. A full-scale crew module mockup was built and outfitted with representative adjustable seats, crew equipment, and a volumetrically equivalent hatch. Human factors testing was conducted in three acceleration environments using ground-based facilities and the KC-135 aircraft. Performance and acceptability measurements were collected. Data analysis was conducted using analysis of variance and nonparametric techniques.
Keywords: arc jet engines; arc discharges; impact damage; hypervelocity impact; impact prediction; computerized simulation; impact tests; debris; space debris; oxidation
Abstract: This paper presents results from arc jet tests conducted at the NASA Johnson Space Center on reinforced carbon-carbon (RCC) samples subjected to hypervelocity impact. The RCC test specimens are representative of RCC components used on the Space Shuttle Orbiter. The arc jet testing established the oxidation characteristics of RCC when hypervelocity projectiles, simulating meteoroid/orbital debris, impact the RCC material. In addition to developing correlations for use in trajectory simulations, we discuss analytical modeling of the increased material oxidation in the impacted area using measured hole growth data. Entry flight simulations are useful in assessing the increased Space Shuttle RCC component degradation as a result of impact damage and the hot gas flow through an enlarging hole into the wing leading-edge cavity.
Keywords: Polymer combustion, microgravity, flammability test methods
Abstract: NASA Glenn Research Center conducted a cooperative program with the Russian Space Agency Keldysh Research Center, with technical support provided by NASA Johnson Space Center White Sands Test Facility, to investigate polymer combustion in ventilated microgravity in a small combustion tunnel operated on the orbital station Mir. Reported here are ground test results on flammability characteristics of the test materials for verification of the data and conclusions of the space measurements. It was found that very low forced convective flows can sustain polymer combustion in microgravity. Shutoff of the flow, however, is likely to suppress the combustion, particularly if the fire is in the incipient phase and the oxygen concentration is sufficiently low. Relative flammability rankings obtained in ground tests focusing on limiting oxygen index and cone calorimeter heat-release tests would not apply to microgravity environments if the ranking criterion is the minimum forced-flow velocity required for sustained combustion. Convective flows caused by buoyancy in the ground NASA STD 6001 Test 1 far exceeded the minimum forced convective flows required to sustain microgravity combustion. Results indicate that this test provided conservative results for the materials tested in microgravity by sustaining their combustion in less severe oxygen concentration and total pressure conditions than those in which extinguishment occurred in quiescent microgravity environments.
Keywords: skin temperature; heat transfer; thermal cooling; spaceflight stress; flight clothing
Abstract: The two flight suits currently worn by crew members during Shuttle launch and landing, the launch and entry suit and the advanced crew escape suit, are designed to protect crew members in case of an emergency. Although the liquid cooling garment worn under the flight suits was designed to counteract the heat storage of the suits, the suits may increase thermal stress and limit the astronaut's egress capabilities. The purpose of this study was to assess the thermal loads experienced by crew members during a simulated emergency egress before and after spaceflight. Comparisons of skin temperatures were made between the preflight unsuited and suited conditions, between the pre- and postflight suited conditions, and between the two flight suits.
Keywords: International Space Station; extravehicular activity; physical exercise; exercise physiology; decompression sickness; oxygen consumption; heart rate
Abstract: Decompression sickness (DCS) is a serious risk to astronauts performing extravehicular activity (EVA). To reduce this risk, the addition of ten minutes of moderate exercise (75% VO2pk) during prebreathe has been shown to decrease the total prebreathe time from 4 to 2 hours and to decrease the incidence of DCS. The overall purpose of this pilot study was to develop an exercise protocol using flight hardware and an in-flight physical fitness cycle test to perform prebreathe exercise before an EVA. Eleven subjects volunteered to participate in this study. The first objective of this study was to compare the steady-state heart rate (HR) and oxygen consumption (VO2) from a submaximal arm and leg exercise (ALE) session with those predicted from a maximal ALE test. The second objective was to compare the steady-state HR and VO2 from a submaximal elastic tube and leg exercise (TLE) session with those predicted from the maximal ALE test. The third objective involved a comparison of the maximal ALE test with a maximal leg-only (LE) test to conform to the in-flight fitness assessment test. The 75% VO2pk target HR from the LE test was significantly less than the target HR from the ALE test. Prescribing exercise using data from the maximal ALE test resulted in the measured submaximal values being higher than predicted VO2 and HR. The results of this pilot study suggest that elastic tubing is valid during EVA prebreathe as a method of arm exercise with the flight leg ergometer and it is recommended that prebreathe countermeasure exercise protocol incorporate this method.
Keywords: decompression sickness; decompression; manned Mars missions; manned space flight; nitrogen; oxygen; argon; space habitats
Abstract: A cost-effective approach for Mars exploration is to use available resources, such as water and atmospheric gases. Nitrogen (N2) and argon (Ar) are available and could form the inert gas component of a habitat atmosphere at 8.0, 9.0, or 10.0 pounds per square inch (psia). The habitat and space suit are designed as an integrated system: a comfortable living environment about 85% of the time and a safe working environment about 15% of the time. A goal is to provide a system that permits unrestricted exploration of Mars, but the risk of decompression sickness (DCS) during the extravehicular activity in a 3.75-psia suit, after exposure to any of the three habitat conditions, may limit unrestricted exploration. I evaluate here the risk of DCS since a significant proportion of a trinary breathing gas in the habitat might contain Ar. I draw on past experience and published information to extrapolate into untested, multivariable conditions to evaluate risk. A rigorous assessment of risk as a probability of DCS for each habitat condition is not yet possible. Based on many assumptions about Ar in hypobaric decompressions, I conclude that the presence of Ar significantly increases the risk of DCS. The risk is significant even with the best habitat option: 2.56 psia oxygen, 3.41 psia N2, and 2.20 psia Ar. Several hours of prebreathing 100% O2, a higher suit pressure, or a combination of other important variables such as limited exposure time on the surface or exercise during prebreathe would be necessary to reduce the risk of DCS to an acceptable level. The acceptable level for DCS risk on Mars has not yet been determined. Mars is a great distance from Earth and therefore from primary medical care. The acceptable risk would necessarily be defined by the capability to treat DCS in the Rover vehicle, in the habitat, or both.
Keywords: Carbon dioxide production, water vapor production, regenerable carbon dioxide removal system (RCRS)
Abstract: The current environmental control device in the Shuttle uses lithium hydroxide (LiOH) filter canisters to remove carbon dioxide (CO2) from the cabin air, requiring several bulky filter canisters that can only be used once and must be changed frequently. To alleviate a stowage problem and decrease launch weight, the Crew and Thermal Systems Division (CTSD) at the NASA Johnson Space Center has been researching a system to be used on future Shuttle missions. This system uses two beds of solid amine material to absorb CO2 and water, later desorbing them to space vacuum. In this way the air scrubbing medium is regenerable and reusable. To identify the efficacy of this regenerable CO2 removal system (RCRS), CTSD began investigations in the Shuttle mockup. The purpose of this investigation was to support the CTSD program by determining mean levels of carbon dioxide and water vapor production in normal, healthy males and females age-matched with the astronaut corps. Subjects' responses were measured at rest and during exercise at intensity levels equivalent to normal Shuttle operation activities. The results were used to assess the adjustments made to RCRS and are reported as a reference for future investigations in Shuttle environmental control.
Keywords: dynamic models; information adaptive system; data systems; database management systems; feasability analysis
Abstract: This paper describes a methodology to efficiently construct feasible systems, then modify feasible systems to meet successive goals by selecting from alternative components; a problem recognized to be n-p complete. The methodology provides a means to catalog and model alternative components. A presented system modeling structure is robust enough to model a wide variety of systems and provides a means to compare and evaluate alternative systems. These models act as input to a methodology for selecting alternative components to construct feasible systems and modify feasible systems to meet design goals and objectives. The presented algorithm’s ability to find a restricted solution, as defined by a unique set of requirements, is demonstrated against an exhaustive search of a sample of proposed Shuttle modifications. The utility of the algorithm is demonstrated by comparing results from the algorithm with results from three NASA Shuttle evolution studies using their value systems and assumptions.
Keywords: life sciences; body measurement; temperature measurement; measurement; bioinstrumentation; bioassay; flight stress; thermoregulation; exercise
Abstract: The purpose of this study was to determine if intestinal temperature (Tin) might be an acceptable alternative to esophageal (Tes) and rectal temperature (Trec) to assess thermoregulation during supine exercise. We hypothesized that Tin would have values similar to Tes and a response time similar to Trec, but the rate of temperature change across time would not be different between measurement sites. Seven subjects completed a continuous supine protocol of 20 min of rest, 20 min of cycle exercise at 40% peak oxygen consumption (VO2pk), 20 min of cycle exercise at 65% VO2pk, and 20 min of recovery. Tes, Trec, and Tin were recorded each min throughout the test. Temperatures were not different after 20 min of rest, but Trec was less than the Tes and Tin at the end of the 40% and 65% VO2pk stages. After 20 min of recovery, Tes was less than either Trec or Tin, which were not different from each other. Time to threshold for increased temperature from rest was greater for Trec than Tes but not different from Tin. Time to reach peak temperature was greater for Tin and Trec than Tes. Similarly, time to a decrease in temperature after exercise was greater for Trec than Tes, but not different from Tin. The rate of temperature change from threshold to the end of the 40% VO2pk stage was not different between measurement sites. However, the rate of change during recovery was more negative for Tes than Tin and Trec, which were different from each other. Measurement of Tin may be an acceptable alternative to Tes and Trec with an understanding of its limitations.
Keywords: manned space flight; space stations; Mercury; Gemini; Apollo; Skylab; Mir
Abstract: Biomedical issues have presented a challenge to flight physicians, scientists, and engineers ever since the advent of high-speed, high-altitude airplane flight in the 1940s. In 1958, preparations began for the first manned space flights of Project Mercury. The medical data and flight experience gained through Mercury's six flights, the Gemini, Apollo, and Skylab projects, as well as subsequent space flights comprised the knowledge base which was used to develop and implement the Extended Duration Orbiter Medical Project (EDOMP). In addition, a significant amount of hardware was developed and tested under the EDOMP which was designed to improve data gathering capabilities and maintain crew physical fitness while minimizing the overall impact to the microgravity environment. The biomedical findings as well as the hardware development results realized from the EDOMP have been important to the continuing success of extended Space Shuttle flights and have formed the basis for medical studies of crewmembers living for three to five months aboard the Russian space station, Mir. EDOMP data and hardware are also being used in preparation for the construction and habitation of International Space Station.
Keywords: airports, air defense, military aircraft, aircraft design, aircraft pilots, airport planning, armed forces (United States)
Abstract: This document details the chronological history of an air field in Southeast Texas that currently serves as an adjunct to NASA Johnson Space Center as well as a civilian/military air field. The field was built early in the 20th century, soon after airplane flight became a recognized factor in American military applications, was central to a wide variety of military uses throughout this century, and remains viable for such purposes in addition to serving a vital role in NASA's training of astronauts.
Keywords: Hubble Space Telescope; portable foot restraint; loads (forces); solar collectors
Abstract: The Hubble Space Telescope (HST) was deployed from the Space Shuttle Discovery on April 25, 1990. It is capable of performing observations in the visible, near-ultraviolet, and near-infrared (1150 A to 1 mm). The HST weighs 12 tons, and collects light with an 8-ft-diameter mirror. The attitude control and maneuvering is performed by four of six gyroscopes, or reaction wheels. The HST contains fine guidance sensors that lock onto guide stars to reduce the spacecraft drift and increase the pointing accuracy. The HST was designed to last 15 years, with crewed service missions approximately every three years. The first service mission, STS-61, took place in 1993. The second service mission took place in 1997. In 1999, the STS-103 crew performed the third service mission to the HST. This mission’s purpose was to replace the right sensor units and make improvements on the fine guidance sensors. To perform these tasks on the HST, the STS-103 crewmembers used a portable foot restraint to anchor themselves to the HST in the zero-gravity environment. The solar arrays currently used on the telescope are second-generation, and therefore susceptible to loads placed on the telescope. The crew and Mission Operations Directorate worried about the damage that the crew could possibly cause during ingress and egress of the PFR and by transferring loads to the solar arrays. The purpose of this study is to inform the crewmembers of the loads they are imparting on the HST, and train them to decrease these loads to a safer level. Minimizing these loads will significantly decrease the chance of crewmembers causing damage to the solar arrays while repairing the HST.
Keywords: photographic film, radiation, sensitometry, degradation, International Space Station, solar radiation
Abstract: We conducted this film test to evaluate several manufacturers’ photographic films for their ability to acquire imagery on the International Space Station. We selected 25 motion picture, photographic slide, and negative films from three different film manufacturers. We based this selection on the fact that their films ranked highest in other similar film tests, and on their general acceptance by the international community. This test differed from previous tests because the entire evaluation process leading up to the final selection was based on information derived after the original flight film was scanned to a digital file. Previously conducted tests were evaluated entirely based on 8x10s that were produced from the film either directly or through the internegative process. This new evaluation procedure provided accurate quantitative data on granularity and contrast from the digital data. This test did not try to define which film was best visually. This is too often based on personal preference. However, the test results did group the films by good, marginal, and unacceptable. We developed, and included in this report, a template containing quantitative, graphical, and visual information for each film. These templates should be sufficient for comparing the different films tested and subsequently selecting a film or films to be used for experiments and general documentation on the International Space Station.
Keywords: magnetic field, magnetoplasma, specific impulse, magnetostatics, symmetry
Abstract: This paper examines the accuracy and calculation speed for the magnetic field computation in an axisymmetric electromagnet. Different numerical techniques, based on an adaptive nonuniform grid, high order finite difference approximations and semi-analitical calculation of boundary conditions are considered. These techniques are being applied to the modeling of the Variable Specific Impulse Magnetoplasma Rocket. For high-accuracy calculations, a fourth-order scheme offers dramatic advantages over a second-order scheme. For complex physical configurations of interest in plasma propulsion, a second-order scheme with nonuniform mesh gives the best results. Also, the relative advantages of various methods are described when the speed of computation is an important consideration.
Keywords: microelectronics; microminiaturization; microniniaturized electronic devices; encapsulated microcircuits; reliability; reliability analysis
Abstract: Microelectromechanical systems (MEMS) are a broad and rapidly expanding field that is currently receiving a great deal of attention because of the potential to significantly improve the ability to sense, analyze, and control a variety of processes, such as heating and ventilation systems, automobiles, medicine, aeronautical flight, military surveillance, weather forecasting, and space exploration. MEMS are very small and are a blend of electrical and mechanical components, with electrical and mechanical systems on one chip. This research establishes reliability estimation and prediction for MEMS devices at the conceptual design phase using neural networks. At the conceptual design phase, before devices are built and tested, traditional methods of quantifying reliability are inadequate because the device is not in existence and cannot be tested to establish the reliability distributions. A novel approach using neural networks is created to predict the overall reliability of a MEMS device based on its components and each component’s attributes. The methodology begins with collecting attribute data (fabrication process, physical specifications, operating environment, property characteristics, packaging, etc.) and reliability data for many types of microengines. The data are partitioned into training data (the majority) and validation data (the remainder). A neural network is applied to the training data (both attribute and reliability); the attributes become the system inputs and reliability data (cycles to failure), the system output. After the neural network is trained with sufficient data, the validation data are used to verify the neural networks provided accurate reliability estimates. Now, the reliability of a new proposed MEMS device can be estimated by using the appropriate trained neural networks developed in this work.
Keywords: propellant, zirconium-potassium perchlorate; initiator, NASA standard; mixtures, blending techniques; precipitation, blending method
Abstract: This paper discusses processes employed in manufacturing zirconium-potassium perchlorate propellant for the NASA standard initiator. It provides both a historical background on the NSI device - detailing problem areas and their resolution - and on propellant blending techniques. Emphasis is placed on the precipitation blending method. The findings on mixing equipment, processing, and raw materials are described. Also detailed are findings on the bridgewire slurry operation, one of the critical steps in the production of the NASA standard initiator.
Keywords: propellant, NASA standard initiator; propellant, manufacture; propellant, Viton; precipitation cycle; mixtures, bridgewire slurry
Abstract: This paper discusses some of the properties of Viton that are relevant to its use as a pyrotechnic binder in a NASA standard initiator (NSI) propellant. Nearly every aspect of NSI propellant manufacture and use is impacted by the binder system. The effect of Viton’s molecular weight on solubility, solution viscosity, glass transition temperature, and strength characteristics as applied to NSI production and performance are reviewed. Emphasis is placed on the Viton fractionation that occurs during the precipitation cycle and its impact on bridgewire functions. Special consideration is given to the production of bridgewire slurry mixtures.
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