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Sunday, July 6, 1997, 7:00 a.m. CDT
STS-94 Mission Science Report # 08s

The Microgravity Science Laboratory mission is paying off for crew members and science teams which have spent years preparing for their mission on the Space Shuttle and this opportunity to conduct fundamental scientific research in space. Experiments are yielding new information in the areas of biotechnology, combustion science, materials science and fluid physics, and researchers are hopeful their findings will find applications for improving life on Earth and the future of research in space.

Results from the first runs in a study of the capillary-driven heat transfer devices, conducted overnight in the Middeck Glovebox aboard Spacelab, are shedding new light on how these devices work. The experiment is examining their use to transfer heat away from a particular location. For instance, in spacecraft they may be used to transfer heat from electrical devices to radiators. They weigh less than conventional devices because they operate on evaporation and condensation, and because they do not require power, they are more economical, but there have been problems with their application for spacecraft systems.

Payload Specialist Dr. Roger Crouch conducted the first experiment run Saturday evening, and Mission Specialist Dr. Donald Thomas completed another run early this morning. During the experiment, when heat was added to the evaporator, it dried out. “That’s what we expected, but for another reason,” said principal investigator Dr. Kevin Hallinan of the University of Dayton in Dayton, Ohio. “We’re losing liquid. It’s condensing, but not in the condenser. The nice thing is we didn’t expect this. It offers insight into potential failure mechanisms that may not have been considered before. And we’re modifying our procedures to look at this failure mechanism as well as the one we anticipated.”

Over the last 24 hours, two series of burning fuel droplet runs were completed in the Droplet Combustion Apparatus. Payload Specialist Dr. Gregory Linteris completed one series Saturday morning, and Crouch completed another series in the afternoon. During the experiment, a heptane fuel droplet is burned in an atmosphere of helium and oxygen. The droplet is formed and deployed in the apparatus. Igniter wires are touched to each side of the droplet and then retracted to create a free burning droplet. Researchers are gathering information on the burning rates of flames, flame structures and conditions under which flames are extinguished. Findings from this study will provide a better understanding of the combustion process and may lead to cleaner and safer ways to burn fossil fuels as well as more efficient methods of generating heat and power on Earth.

Yesterday, Thomas powered up the Middeck Glovebox to conduct a study of the manipulation of bubble shape and bubble movement in water under weightlessness conditions. Many industrial processes, including solidification of metallic alloys, are adversely affected by bubbles. Findings from this investigation may improve materials processing techniques on Earth by eliminating or counteracting bubbles.

Linteris conducted a run of the Laminar Soot Processes experiment in the Combustion Module Saturday afternoon, and Payload Commander Dr. Janice Voss completed another run last night, giving up her free time to do so. During the runs, ethylene fuel was burned in the facility. Researchers are gathering information on flame shape, the type and amount of soot produced under various conditions and the temperature of soot components. Findings from this investigation may lead to a better understanding of how to contain unwanted fires, burn fuels more efficiently and reduce pollutants.

In the area of materials science, experiments are under way in the TEMPUS and Large Isothermal Furnace facilities. These investigations may find direct applications in improving techniques used on Earth to manufacture materials and in turn lead to better, higher-quality products.

In the TEMPUS facility, Thomas activated an experiment to measure the heat of undercooled liquid metals. Undercooling occurs when a solid is melted into a liquid then cooled below its normal freezing point without solidifying. The study, led by Dr. Hans Fecht of the Technical University Berlin in Germany, is aimed at determining the ability of certain zirconium-based alloys to form glass. Zirconium is a metallic element used chiefly in ceramic and refractory compounds as alloying agent.

“This is the first time that these particular alloys could be prepared and measured in this way,” said Fecht. “Undercooling to 200 degrees Celsius is a lot. We have excellent and very important data. We’re very excited.”

Early Sunday, Linteris activated the sample in the TEMPUS facility to begin another study of glass-forming metallic alloys. This research, led by Dr. W.I. Johnson of the California Institute of Technology in Pasadena, examines the thermophysical properties -- heat capacity, thermal conductivity, nucleation rates, surface tension, viscosity and thermal expansion -- of multi-component zirconium-based alloys.

“We are taking fundamental measurements of these alloys, in some cases for the first time,” said project scientist Dr. Jan Rogers of NASA’s Marshall Space Flight Center in Huntsville, Ala. “These measurements will be used to make better products on Earth. For instance, findings from metallic glass investigations may be used to improve sporting good products, such as golf clubs, because of their good elastic properties.”

Science operations in TEMPUS have continued successfully despite difficulties with the facility’s top-view video camera. The science team has developed a procedure to troubleshoot the problem and plans to perform it later in the mission.

In the Large Isothermal Furnace, Voss completed the second of five planned runs Saturday afternoon for the Diffusion of Liquid Metals study using the Large Isothermal Furnace. Diffusion is the process by which liquid metals mix without stirring -- similar to how the smell of baking bread, for instance, spreads from the oven throughout the house. The experiment is designed to reveal the diffusion coefficient -- a fundamental quantity which describes the diffusion process -- of liquid tin in relation to temperature.

During the fourth run, researchers noticed the helium consumption was greater than expected and ended the final rapid cooling step of the experiment early to conserve helium. Another run of the Liquid Phase Sintering experiment, which does not require helium, was activated in the facility, while researchers assess the helium consumption rate. The investigation under way examines the sintering process, or how particles bond when heated, in solid-liquid mixtures.

The EXPRESS Rack facility has been experiencing problems relaying housekeeping information, such as temperature, air pressure and water flow, to the ground. The crew is monitoring read-outs and voicing down information every two hours. Troubleshooting continues to determine the cause and corrective actions.

Today, Linteris is scheduled to conduct another test of the soot experiment, and another diffusion of liquid metals study will be activated in the Large Isothermal Furnace.

The next scheduled Public Affairs status report will be issued at approximately 6 a.m., July 7.


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