STS-73 Day 8 Highlights

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On Friday, October 27, 1995, 8 a.m. CDT, STS-73 MCC Status Report # 15 reports:

Flight controllers in Houston had a quiet shift last night as orbiter systems continue to perform well, allowing work on board the Space Shuttle Columbia continue uninterupted.

Red Team members are now spending their their eighth day in space. Earlier this morning, Commander Ken Bowersox and Payload Commander Kathy Thornton took a moment to talk to ABC's World News Now about the progress of the flight and life on board Columbia. In response to a question about the living conditions on the orbiter, Thorton explained that the extra space provided by the Spacelab laboratory module and the fact that the crew is split into two teams for 24-hour payload operations, makes the living space quite comfortable.

On Friday, October 27, 1995, 6 a.m. CDT, STS-73 Payload Status Report # 12 reports: (6/21:07 MET)

"We feel like we're back home at Marshall in the Payload Crew Training Complex," said Mission Specialist Cady Coleman last night, referring to the Marshall Space Flight Center Spacelab mockup where she and her crewmates spent many hours preparing for the second United States Microgravity Laboratory mission. Overnight, Coleman and Payload Specialist Fred Leslie performed now-familiar duties with protein crystal growth and fluid flow experiments, and also tested a new vibration- isolation facility.

Coleman completed the mission's first technical demonstration with the Suppression of Transient Acceleration by Levitation Evaluation, or STABLE. Developed cooperatively by the Marshall Space Flight Center and McDonnell Douglas, STABLE is the first facility to use electromagnetic levitation to isolate sensitive experiments from disturbances in the Shuttle.

Coleman activated a simple experiment within the levitation device by heating a fluid-filled cell, then observed it with a laser light. To the delight of the science team in Huntsville, the experiment's small optical system recorded the resulting heat diffusion. This experiment, known as "CHUCK," was designed in Marshall's Space Sciences Lab as a small, simple system to study materials processes in microgravity that are applicable to crystal growth mechanics. For the first run, the STABLE platform floated free through the action of electromagnets. The platform was locked in place for a repeat run. Comparisons should help determine the effectiveness of STABLE for reducing background vibrations.

Both STABLE and CHUCK were produced in less than five months, from the time designers got the go-ahead for construction this past January until they delivered the equipment to Kennedy Space Center.in June. Engineers on these projects were working under a new NASA committment to streamline the development of lower cost space hardware.

Later in the shift, Coleman examined growing protein crystals under the Glovebox microscope. Commercial Protein Crystal Growth team members watched downlink video of the magnified crystals from their home lab at the University of Alabama in Birmingham. Coleman reported that the crystals were bigger and seemed to be growing in isolation rather than in clumps. One crystal in particular was so well-formed that the fist look at it elicited applause from the Birmingham team. Coleman then activated more samples of the same proteins based on observations of growth progress thus far. She jokingly told the experiment team that she has given up caffeinated coffee just for them, "since you have to be so careful with these things," referring to the delicate handling required for protein crystals.

The Glovebox protein crystal growth evaluation is one of several USML-2 experiments aimed at determining the best methods for growing protein crystals. In the middeck, the European Space Agency's Advanced Protein Crystallization Facility is growing protein crystals by three different methods. An internal camera is recording video images of the growing crystals. After the mission, researchers will study development of the crystals in microgravity to determine why and how proteins nucleate and begin to form crystals.

A decade of Shuttle protein crystal growth experiments has led to improved methods for ground-based experiments, as well as producing well-ordered crystals which have allowed the structures of several proteins to be determined. Understanding the structures of proteins, such as those related to diseases, is important for developing custom- tailored molecules, such as drugs, to interact with them.

As has been true for the majority of the mission, Leslie spent most of his shift working with the Surface Tension Driven Convection Experiment. The Lewis Research Center investigation is gathering extyensive new data on subtle fluid flows created by surface temperature variations. In a typical operation, Leslie drew down the volume of silicone oil within a 1-1/4 inch (3 centimeter) cylinder until it formed a deeply concave surface -- a surface shape possible only in microgravity with a container this large . Leslie heated the fluid, first very steadily, and again in several pronounced steps. The Case Western Reserve University science team reported seeing distinct differences in the heating power levels at which fluid flows became unsteady, or began to oscillate, with the two heating scenarios. A thorough understanding of fluid physics forms a valuable base for improvements in sophisticated materials processing.

Also last night, Coleman reset a Drop Physics Module circuit breaker which tripped yesterday when some film jammed, and the facility is ready for experiment operations later today. More Surface Tension Driven Convection Experiment runs are also scheduled. Growth of a gallium arsenide semiconductor within the Crystal Growth Furnace will continue until early tomorrow morning.

On Friday, October 27, 1995, 5 p.m. CDT, STS-73 MCC Status Report # 16 reports:

Systems on board the Space Shuttle Columbia continue to work well despite a temporary glitch concerning two steering jets. About 1:15 p.m. CDT two vernier jets - R5R and R5D - failed off at the same time. However, about 40 minutes later, after ground controllers reviewed data, the crew hot fired the jets and they were recovered. There was no loss of science data and minimal impact on the day's activities.

Each orbiter has 38 primary thrusters and six smaller vernier thrusters which provide vehicle steering. Shortly after the two vernier jets failed this afternoon, the crew took the orbiter from a gravity gradient attitude, which requires sporadic firing of steering jets, to free drift. Columbia had been flying in a gravity gradient attitude - which has the tail of the orbiter facing the Earth and its nose facing deep space - to minimize shuttle movement in support of science operations in the Spacelab, particularly the growth of protein crystals. The temporary loss of the two vernier jets occurred while crystals growing in the Spacelab were cooling down so there was no impact on the experiment.

Early this afternoon crew members also downlinked views of a ding in one of the orbiter's front windows. There are six windows along the front of the orbiter, three on the commander's side and three on the pilot's side. The ding was in the center window on the commander's side or the second window from the left.

Shuttle windows encounter dings from orbital debris or natural material such as meteoroids from time to time. The dings are analyzed by scientists after the shuttle has landed to determine size and material source. JSC debris scientists said the largest ding returned on a shuttle window thus far occurred on STS-59 in April 1994. The ding measured one-half an inch in diameter and was caused by an orbiting paint chip. Based on what they saw in the downlinked video, scientists estimated the Columbia's ding was most likely no larger than about one-eighth of an inch across, but said exact measurements and a determination of the source material would have to await the shuttle's return to Earth.

Columbia is in a 169 by 165 mile orbit, completing a revolution of the Earth every 90 minutes.

On Friday, October 27, 1995, 6 p.m. CDT, STS-73 Payload Status Report # 13 reports: (7/09:07 MET)

Lead scientists for two USML-2 investigations, Astroculture and the Geophysical Fluid Flow Cell Experiment, showed experiment pictures to the crew early this morning, via the new Ground-to-Air Television uplink being tested on this mission as STS 73 completed its first week in space.

"This is the first time that crop plants have been grown to produce edible food in space," observed Astroculture co- investigator Dr. Theodore Tibbitts. Also, for the first time, scientists have been able to obtain data on respiratory cycles and starch accumulation for plants in a NASA controlled space environment. Starch is an important nutrient in plants, and these measurements will tell whether space-grown potato tubers have the same nutritional value as their Earth-grown counterparts. The benefits of having plants in space go well beyond providing a food source. Plants will provide a naturally recycling life support system in space by helping remove excess carbon dioxide and replenishing oxygen, and by providing a natural way to purify water in a space-borne habitat.

Astroculture Principal Investigator Dr. Raymond Bula of the University of Wisconsin in Madison pointed out leaf patterns in a photo of potato plants growing in the plant growth chamber aboard the Shuttle. "The thing that's been exciting to us is that, in the three images that have come down at different times, the leaves are in the same position. This means that the plants are healthy. If they had been having problems, the leaves would have shifted," Bula said.

"This is all kind of new and exciting stuff," explained Dr. John Hart of the University of Colorado in Boulder, principal investigator for the Geophysical Fluid Flow Cell, while showing the crew a time lapse movie of simulated solar atmospheric flows. The movie was made from the still photo images, snapped every 45 seconds, of fluid flows within the facility's rotating hemisphere. "You can see a lot of the evolution of these solar dynamic flows we've been interested in, and we've seen some surprising turbulence," Hart told the crew. "We are comparing these results with our computer simulations and other theoretical ideas to understand the extensive turbulence which starts near the polar region and spreads rapidly toward the equator." This morning, the GFFC simulated the long-term changes that will eventually occur in the Sun.

Payload Specialist Dr. Al Sacco began his shift operating the Surface Tension Driven Convection Experiment Apparatus. Throughout the day, researchers on the ground relayed instructions for Sacco and Thornton to manipulate the temperature of the silicon oil surface in order to study the change from thermocapillary fluid flows to unsteady flows. This investigation could one day lead to better, stronger high-tech crystals, metals, alloys and ceramics.

Working in the Glovebox, Sacco had an opportunity to demonstrate the device's versatility, growing protein crystals in the morning then switching to zeolites in the afternoon. The system can offer one or two levels of containment for toxic materials, liquids and particles. It can operate with gloves for full containment, sleeves for more sensitive surgical glove operation or with all doors removed as an open workbench observation platform. Al Sacco is principal investigator for two USML-2 investigations into the growth of zeolite crystals, widely used as catalysts and filters in the chemical processing industry.

A crystal of the semiconductor material gallium arsenide has finished the crystal growing portion of the processing cycle in the Crystal Growth Furnace. The crystal grew to more than two inches in length and will continue cooling until being removed tomorrow morning. After cooling, the crystal will be removed from the furnace and stored using a flexible glovebox. Gallium arsenide is used in high-speed digital circuits, solid-state lasers, and a variety of other applications.

Al Sacco worked at the Drop Physics Module, manipulating liquid drops treated with a surfactant, or substance that changes the properties of liquid surfaces. Two drops were deployed and brought together until they coalesced, or merged to form a single drop. The surfactant, called Bovine Serum Albumin, is an organic protein typically used in chemical processing. Sacco twice succeeded in making the drops coalesce. "These are the first and best drop coalescences we've ever had," said DPM co-investigator Dr. Eugene Trinh of NASA's Jet Propulsion Laboratory, adding, "it went very nicely." The Drop Physics Module allows investigators to study large drops in which dynamic phenomena (such as coalescence) are slowed down and more easily seen. They can observe how flows inside a drop and the drop's surface interact to provide a variety of dynamic events. This fundamental knowledge can be beneficial for a variety of industries on Earth, from pharmacology to industrial chemistry.

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