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Wednesday, July 16, 1997 7 a.m. CDT
STS-94 Mission Science Report # 23s

As the orbiting Microgravity Science Laboratory (MSL) nears the end of its mission, scheduled for Thursday morning, the crew of Space Shuttle Columbia is wrapping up Spacelab experiments in the areas of combustion science, fluid physics, materials science and biotechnology.

Mission Specialist Dr. Donald Thomas and Pilot Susan Still transferred the Astro/Plant Generic Bioprocessing Apparatus from the EXPRESS Rack to the Shuttle middeck Tuesday morning. The plant growth experiment had been moved from the middeck to the EXPRESS Rack early in the mission. The EXPRESS Rack is designed to speed and ease the transportation of experiments to the International Space Station and the MSL mission is testing the design, development and adaptability of the rack. “Lessons learned from this flight will be implemented to improve the EXPRESS Rack for the Space Station,” said hardware developer Annette Sledd of NASA’s Marshall Space Flight Center in Huntsville, Ala.

The plants will continue to grow in the middeck. "Things are going great,” said lead scientist Dr. Louis Stodieck of the University of Colorado in Boulder. “We’ve gotten data showing that the plants are very healthy. I’m very enthused and looking forward to the Shuttle landing and the opportunity to analyze the plants."

The plant growth experiment is studying the effect of space on various types of plants. The investigation examines the production of lignin, essential for the formation and joining of woody cell walls in plants; the production of secondary metabolites, necessary for generating energy to sustain vital life processes; and changes which occur in the sugars and starches of vegetable plants.

Researchers are interested in determining if these plant processes are interrelated and how they might be manipulated to improve plant growth and production on Earth. Findings may also verify evidence that plants grown in microgravity require less metabolic energy to produce lignin, permitting greater production of secondary metabolites, a source of many medicinal drugs. Secondary metabolites may also be used to attract, repel or poison insects.

Plants being studied aboard Space Shuttle Columbia, include a species of sage native to Southeast Asia which is a source of the antimalarial drug artemisinin; one which produces vinca alkaloids, used in chemotherapy treatment of cancer; the loblolly pine, used widely in the paper and lumber industries; and a variety of spinach.

One of the combustion experiments, the Structure of Flame Balls at Low-Lewis Number, or SOFBALL, completed its final run Tuesday morning. Payload Specialist Dr. Greg Linteris conducted the run in the Combustion Module. The experiment gathered data on the burning processes of weak fuel-air mixtures in near-zero gravity.

The last run, which used a mixture of hydrogen, oxygen and carbon dioxide, was a repeat of a test performed earlier in the mission. Sparking the mixture resulted in six balls of flame. “We got a few more flame balls than we expected,” said project scientist Dr. Karen Weiland of NASA’s Lewis Research Center in Cleveland, Ohio. “Earlier in the mission when we ran this test point, we only got four. We’ll be able to compare this run to the earlier one to understand the different behaviors of flame balls when there are more of them present.”

The flame ball experiment completed more runs than originally scheduled, and the science team wrapped up early, making time for four additional runs of a study of soot properties. Payload Commander Dr. Janice Voss conducted the runs last night. The Laminar Soot Processes experiment, led by Dr. Gerard Faeth of the University of Michigan in Ann Arbor, is collecting information on flame shape, the type and amount of soot produced under various conditions and the temperature of soot components. Information gathered from this study may lead to a better understanding of how to contain unwanted fires and reduce harmful pollutants from fires.

Two runs of a diffusion of liquid metals study were conducted in the Large Isothermal Furnace Tuesday. Thomas initiated the first run Tuesday morning. Processing was ended when the science team reported unexpected readings from the sample. The cartridge was changed out for another and processing resumed.

Payload Specialist Dr. Roger Crouch initiated the experiment’s final run Tuesday afternoon. Diffusion is the process by which liquid metals mix without stirring. The investigation is aimed at determining the diffusion coefficient -- a fundamental quantity which describes the diffusion process -- of molten salts. Headed by Dr. Tsutomu Yamamura of Tohoku University in Sendai, Japan, the experiment is designed to also reveal the ideal conditions for electrolysis of molten salts. Electrolysis is the use of an electrical current to break down a dissolved substance into its constituent components. Findings may benefit basic science and engineering processes on Earth. After the final sample completed processing, Thomas deactivated the Large Isothermal Furnace early this morning.

NASA Administrator Dan Goldin and Tennessee Senator Dr. Bill Frist spoke to crew members Voss, Crouch and Mission Specialist Dr. Michael Gernhardt by telephone Tuesday. Frist asked questions on behalf of school students and expressed his personal appreciation for a job well done.

The final runs of the Coarsening in Solid-Liquid Mixtures experiment were conducted Tuesday in the Glovebox, completing all nine planned runs of the experiment. The investigation which is led by Dr. Peter Voorhees of Northwestern University in Chicago, Ill., could provide a better understanding as to what causes metals to weaken or fail.

Crouch spent most of the evening Tuesday deactivating the protein crystal growth experiments -- the Protein Crystallization Apparatus for Microgravity, Second-generation Vapor Diffusion Apparatus and Hand-held diffusion test cells. The microgravity environment of space allows researchers to grow larger and more perfect protein crystal specimens. Once back on Earth, scientists perform X-ray diffraction studies on the specimens to determine their structures. Better understanding of a protein’s structure could allow scientists to design more effective drugs to treat diseases such as cancer, diabetes, alcoholism, AIDS and Alzheimer’s.

After a sample of zirconium completed processing in the TEMPUS levitating furnace, an experiment to investigate undercooling of an aluminum-copper-iron alloy was conducted. Undercooling is when a liquid remains fluid when cooled below its normal freezing point. The investigation, led by Dr. D.M. Herlach of the German Aerospace Research Establishment in Cologne, Germany, could shed light on nucleation, the point at which solidification from the melted state begins. This research could lead to improved techniques for processing materials on Earth and in turn, better products.

This morning, Linteris began the final run of the Capillary-driven Heat Transfer Device in the Middeck Glovebox. The study is aimed at improving the performance of these devices for future use in spacecraft. Similar devices may be used to transfer heat from electrical systems to radiators. Capillary-heat transfer is attractive for use in space because it requires no power to operate and such devices cost less because they weigh less. This study has already provided insight into how these devices work and is offering explanations as to why they occasionally fail in spacecraft applications. The experiment’s lead investigator is Dr. Kevin Hallinan of the University of Dayton, Ohio.

Today, Thomas will deactivate the Physics of Hard Spheres Experiment in the EXPRESS Rack before powering down the facility. Linteris will complete the capillary heat transfer experiment and later, Thomas will shut down the Middeck Glovebox. Before completing his shift around noon today, Linteris will shut down the TEMPUS facility.

The final Microgravity Science Laboratory -1 summary status report will be issued at approximately 6 p.m., July 16.


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