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Tuesday, July 15, 1997, 7 a.m. CDT
STS-94 Mission Science Report # 22s

As the First Microgravity Science Laboratory mission begins day 14 of its flight, crew members are working steadily to complete the remaining investigations scheduled for the 16-day mission. In a news conference from space last night Payload Commander Dr. Janice Voss summarized the purpose and success of the science experiments being conducted aboard Spacelab. “The nature of research in general is an evolutionary process, building on what has come before and feeding what comes after,” said Voss. “This is true with the experiments on this flight. They’re all contributing good science to the future of these research programs.”

One such effort which is providing a foundation for future space research in the area of combustion science is the flame ball experiment on Columbia, called SOFBALL. Two more runs of the experiment, which studies the burning processes of weak fuel-air mixtures in near-zero gravity, were conducted Monday. Payload Specialist Dr. Gregory Linteris conducted one run using a mixture of hydrogen, oxygen and carbon dioxide. Two flames balls resulted and burned for the full eight-plus minutes.

The second run, conducted by Voss last night, involved a mixture of remaining fuels from two previous runs. “This mixture bridged the gap between two other test points,” said investigator Dr. Paul Ronney of the University of Southern California in Los Angeles. Two flame balls resulted and burned for entire 500-second duration of the experiment.

The investigation is providing researchers with information necessary to improve theoretical models. A better understanding in this area will enable improving fuel efficiency and reducing pollution in combustion engines.

Crew members initiated another run of the Coarsening in Solid-Liquid Mixtures experiment in the Glovebox. The investigation studies a process that can severely degrade the strength of alloy products, such as turbine blades in aircraft engines. The experiment, led by Dr. Peter Voorhees of Northwestern University in Chicago, Ill., is providing insight into processes which can cause metals to weaken or fail.

The Droplet Combustion Experiment concluded in the Spacelab Monday evening as Voss burned the last drop of heptane fuel at one-quarter atmospheric pressure. “We’ve achieved our science objectives,” said principal investigator Dr. Forman Williams, of the University of California at San Diego. “We burned droplets of heptane over a range of pressures from one-quarter atmosphere to one atmosphere. We were even able to get some data which will provide a comparison for another combustion experiment that took place in the Glovebox.”

After that final fire investigation in the Droplet Combustion Apparatus, Voss removed the control computer, camcorder, camera and VCR and prepared the experiment for the trip back to Earth.

Alabama Senator Jeff Sessions visited the Spacelab Mission Operations Control Center at Marshall Space Flight Center in Huntsville, Ala., Monday. He spoke to crew members, offering his support and best wishes for the mission’s continued success. “All of America is proud of the good work you are doing,” said Sessions. “This is the beginning of a commercially feasible adventure into space exploration, characteristic of this nation -- a nation of explorers.”

Later, Payload Specialist Dr. Roger Crouch completed the fourth and final run of an undercooling of metallic alloys experiment in the TEMPUS levitating facility. The Alloy Undercooling Experiment, led by Dr. Merton Flemings of the Massachusetts Institute of Technology in Cambridge, Mass., is aimed at measuring how fast melted steel mixtures solidify. During the study, a spherical sample of iron, chromium and nickel is positioned in the facility, melted and then cooled. The science team said all four runs have gone well. Results of this research may improve steel strip casting and welding processes.

The undercooling run was the last planned TEMPUS experiment of the mission. Project scientist Dr. Jan Rogers of Marshall said the remaining time allocated for TEMPUS experiments is bonus time and will be used to process samples identified by scientists as good candidates for gathering additional scientific data.

Two samples of the experiment analyzing diffusion in liquid lead-tin-telluride were processed in the Large Isothermal Furnace over the last 24 hours, making a total of five runs for that investigation. The study, led by Ms. Misako Uchida of Ishikawajima-Harima Heavy Industries in Tokyo, Japan, is aimed at determining the diffusion coefficient -- a fundamental quantity which describes the diffusion process -- of liquid lead-tin-telluride. The alloy is a potential material for use in manufacturing infrared detectors and lasers.

Today, Thomas and Linteris will be wrapping up other experiments. Linteris will conduct runs of the flame ball experiment and the properties of soot experiment in the Combustion Module. Thomas will initiate the third and final run of an experiment in the Large Isothermal Furnace to study the diffusion process of impurities in molten salts. Later, Thomas and Pilot Susan Still will transfer the plant growth experiment from the EXPRESS rack to two lockers in the Middeck. The EXPRESS Rack is designed to speed and ease transportation of experiments to the International Space Station. The plant growth experiment was transferred to the EXPRESS Rack earlier in the mission to test its design development and adaptability.

The next scheduled Public Affairs status report will be issued at approximately 6 a.m., July 16.


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