STS-73 Day 14 Highlights

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On Thursday, November 2, 1995, 8 a.m. CST, STS-73 MCC Status Report # 26 reports:

Columbia, with both payload bay doors fully open, currently is in its third thermal conditioning session designed to warm the underside of the orbiter. It will remain in the "belly to sun" attitude until about 2 p.m. Thursday afternoon.

On Thursday, November 2, 1995, 6 a.m. CST, STS-73 Payload Status Report # 22 reports: (12/22:07 MET)

"Things are going fantastically well, and we're just looking forward to getting as much science in the remaining time as we can," explained USML-2 Alternate Payload Specialist Glynn Holt early this morning in an interview for Mutual NBC Radio as fluid physics and combustion science took center stage on the thirteenth night of the second United States Microgravity Laboratory mission.

Spacelab systems and facilities continued to operate well and gather good data. The crew worked with the Fiber Supported Droplet Combustion experiment in the Glovebox, performed the fission experiment in the Drop Physics Module, monitored fluid flows for the Geophysical Fluid Flow Cell experiment, and initiated the last run of the Supression of Transient Acceleration by Levitation Evaluation (STABLE) vibration isolation system.

"Fred gets an A+ in combustion theory," exclaimed investigators for the Fiber Supported Droplet Combustion experiment (FSDC), offering Payload Specialist Fred Leslie "a collective high-five" for his "outstanding work" in the Glovebox facility. Leslie had been placing drops of fuel on a thin fiber, using needles in the experiment module, and igniting them with a hot wire. Earlier in the evening, Leslie worked closely with the FSDC science team to successfully troubleshoot difficulties with clogged drop accumulators, and then performed a series of excellent burns, varying the quantities of methanol and methanol/water fuel with each run. Also varied were fiber size and air flow rates. These experiments resulted in some droplet extinction diameters (the size of the drop as it burns out) larger than any initial droplet size capable of being studied on Earth. The science team was very pleased with what they described as the "textbook quality" data received and expressed their appreciation for the crew's hard work and persistence. Leslie showed his enthusiasm for the work when he humorously responded, "I don't get to play with fire much up here. I'm kind of enjoying it."

The NASA Lewis Center's FSDC investigation consists of new hardware and is on its first flight. The primary objective for this research is to provide scientists new fundamental insights into the dynamics of droplet burning which will be compared to state of the art analytic and numerical models.

"It did fission, and I got some good data," announced Mission Specialist Cady Coleman referring to the initial drop fissioning runs in the Drop Physics Module. Coleman used sound waves to manipulate rotating drops of silicone oil until they split, or underwent fission. Project Scientist Arvid Croonquist and his science team worked with Coleman throughout the night, uplinking instructions and watching downlink video. They were testing one set of theories that describes the breaking apart of distorted, or pre-flattened, drops while varying the viscosity (or thickness) of the fluid.

Drop Dynamics Experiment Principal Investigator Taylor Wang and his co-investigators from Vanderbilt University observed and analyzed conditions at which drops of various sizes and viscosities split, and he described Coleman's first run of the procedure as "a very successful drop fission." Also, during this run, the science team was able to get good pictures of the ligament, or thread of fluid, connecting the two halves of the drop as it passed through its critical "saddle" point while splitting in two.

On the first USML mission, Wang's team used the Drop Physics Module to confirm a theory that was more than 100 years old. Using fluids ranging from water to oils, the module spun single drops until they formed a dog-bone, or two lobe shape. All the drops changed into the same shape at the same point and at exactly the point that had been predicted over a century ago by fluid dynamics pioneer Lord Raleigh. Results from USML-2 are helping to develop theoretical models for the drop fission process.

Troubleshooting continues on the High Data Rate Recorder (HDRR), which began experiencing intermittent data degradation between MET 12/14:30 and 12/14:58. Scientific data is being stored on the Orbiter's recorder during loss of signal periods and downlinked via Hi-Pac TV.

The Space Acceleration Measurement System (SAMS) and the Orbital Acceleration Research Experiment (OARE) continued to track accelerations caused by movements and variations within the Shuttle, as well as by Shuttle maneuvers and atmospheric drag. The Principal Investigator Microgravity Services Project team, of NASA's Lewis Research Center, is at the Spacelab Mission Operations Control Center to help scientists evaluate the effects of accelerations on sensitive microgravity experiments. Both instruments make continuous records of accelerations for analysis after the flight. In addition, OARE is providing data on the relatively steady, or low-frequency, accelerations that occur in the Shuttle. This information is being provided to the USML-2 Principal Investigators in real-time throughout the mission.

The crew also activated the STABLE instrument, and unattended monitoring continued during the final run of the device. The STABLE system was developed by NASA's Marshall Space Flight Center jointly with McDonnell Douglas to test a device designed to isolate small science experiments from high-frequency accelerations, including Shuttle maneuver operations and crew activity.

On Thursday, November 2, 1995, 4 p.m. CST, STS-73 MCC Status Report # 27 reports:

What flight controllers believe to be an occasional glitch with two of Columbia's small steering jets reoccurred today, resulting in a temporary shutdown of the two small, or vernier, jets located on the tail of the spacecraft. The glitch has occurred twice before during the mission, and has been resolved each time by turning the shuttle's autopilot off and on. The same actions restored the jets function during this afternoon's problem, and they are now functioning normally. The glitch poses no problem for the mission, since Columbia's 38 primary jets are all in good working order. The small vernier jets are only used to minimize interference with sensitive experiments ongoing in the lab module.

The four crew members on the Red Team handed over to the Blue Team at 2:38 p.m. CST. The three Blue Team crew members will be on duty till 2:38 a.m. Friday when they hand over to the Red Team. Early in the afternoon Pilot Kent Rominger, and payload specialists Kathryn Thornton and Al Sacco conducted experiments in space and answered questions from students in Worcester, Massachusetts, and Louisville, Kentucky. The experiments and questions focused on surface tension and combustion concepts. Students were involved in ground based adaptation experiments that have enabled them to work alongside their counterparts in space.

To demonstrate surface tension in space, Sacco squeezed out a ball of orange juice which immediately formed a sphere. The demonstration was designed to illustrate how surface tension can make a fluid form a sphere when it doesn't have to contend with gravity. Shortly after the demonstration, Sacco drank the experimental orange juice sphere.

The surface tension experiment studies the transition between steady fluid flows to unstable fluid flows. Scientists are interested in such studies because of their applications in areas of materials processing such as the production of high-tech crystals, metals, alloys and ceramics. The combustion experiments will give scientists insight into the dynamics of burning fuel.

After completing its third thermal conditioning period earlier today, Columbia returned to a "gravity gradient" attitude with the orbiter tail pointing towards the Earth and the port wing pointing in the direction of travel. Because the gravity gradient attitude shades portions of the orbiter, thermal conditioning periods are needed to warm the underside of the orbiter and subsequently increase the landing gear tire pressure. One more warm-up period is expected on Friday morning.

On Thursday, November 2, 1995, 6 p.m. CST, STS-73 Payload Status Report # 23 reports: (13/10:07 MET)

As the past 12 hours unfolded on the second United States Microgravity Laboratory mission, Payload Commander Kathryn Thornton and Payload Specialist Al Sacco spent a good portion of their shift working on experiments in the Glovebox facility.

Investigators for the Fiber Supported Droplet Combustion Glovebox experiment saw something this morning they hadn't expected. Hydrocarbon-mix droplets deployed in the facility burned slower and produced more soot than drops of an alcohol-mix. Researchers also learned that larger drops burned longer, as expected. These tests, which study combustion behavior in microgravity, were conducted using various fuel mixtures in different-sized drops and changing air flow rates to see how quickly the drops ignite and extinguish. Throughout the morning, Thornton deployed the drops onto thin fibers, and ignited them by placing an electrical hot wire near the drop. The longest burn, that of a large hydrocarbon-mixed drop, lasted for about 40 seconds.

Scientists will analyze their data post-mission to learn more about the chemistry of the combustion process, information which will aid in the development of combustion experiments for the International Space Station. Research in this field could spark a totally new approach in the design of space- based safety equipment, such as fire alarms. It could also aid in cleaner fuel use on Earth.

The first crystal growth experiment ever designed to produce a crystal without the growing portion touching its container wall has been completed in the Crystal Growth Furnace. Principal Investigator Dr. David Larson hopes to bring home an almost defect-free cadmium zinc telluride crystal thanks to the unique container apparatus, designed to grow the crystal as a liquid bridge. The two-inch (five centimeter) crystal, which grew for about 30 hours, is the sixth of eight semiconductor crystal growths planned for the versatile, high-temperature furnace. Growing these semiconductors in microgravity is necessary for a more uniform distribution of chemicals in order to obtain crystals with a more perfect structure. Cadmium zinc telluride crystals are used to make infrared detectors.

The next sample set for processing in the Crystal Growth Furnace is a crystal of gallium doped germanium. Growing this material, which has well-known properties, provides an engineering test of a new Crystal Growth Furnace capability to mark the boundary between the melted and solidified portions of a crystal at given time intervals. The marks make post-flight analysis of crystal growth more precise.

Today's experiment runs of the Particle Dispersion Experiment increased Principal Investigator Dr. John Marshall's data base for future Shuttle and International Space Station aerosol dispersion investigations. Performed in the Glovebox facility, the experiment demonstrates how fine natural particles, such as dust, disperse within an atmosphere, then assemble back together (or reaggregate) into larger clusters. Earlier this week the experiment confirmed a theory that aggregation occurs in all dust clouds.

Investigators for the Geophysical Fluid Flow Cell Experiment today set their experiment parameters to create flows mimicking those of the sun's interior. Information from this experiment run will be used to validate data collected earlier in the mission on this same phenomena. Rotation rate, temperature and voltage within the facility are varied to simulate specific atmospheric conditions. The fluid flows that result are relevant to the study of oceans, planetary atmospheres, and stars Ð- information could one day aid in weather forecasting.

Protein crystals activated earlier in the mission continue to grow, ensuring investigators that there will be ample data for post-mission analysis. One of these experiments, the Protein Crystallization Apparatus for Microgravity, holds more than six times as many samples as are normally accommodated in the same amount of space. These crystals are being grown using the vapor diffusion method. In vapor diffusion, liquid evaporates from a protein solution and is absorbed by a reservoir solution in a wicking material. As the protein concentration rises, the proteins form crystals.

These experiments are a precursor to long-duration crystallization investigations aboard the International Space Station, which would greatly benefit from the ability to control crystal growth times of up to approximately six months in length. Proteins play important roles in daily life, from providing nourishment to fighting disease.

When the blue shift comes on duty, Mission Specialist Catherine Coleman and Payload Specialist Fred Leslie will devote the majority of their time to Drop Physics Module and Glovebox experiments.

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