STS-94 Mission Science Report # 13s
Wednesday, July 9, 1997, 7 a.m. CDT
Aboard Spacelab last night, Payload Commander Dr. Janice Voss ignited the first flames of the flame ball experiment. The purpose of the investigation is to determine if stationary spherical flame structures can exist. “It was just fantastic,” said Microgravity Science Laboratory investigator Paul Ronney of the University of Southern California in Los Angeles. “We had two very successful burns. Everything worked great and we are just ecstatic.”
During both runs, mixtures of hydrogen, oxygen and sulfur hexafluoride burned in the chamber for the full 500-second duration of the test. This is significant because these mixtures will not burn on Earth. “These are the weakest flames ever burned,” said Ronney. “The typical power of these flames is about one watt, less than a flashlight.”
The experiment revealed new information about the role of buoyancy on flames. “The effect of gravity is weaker than we expected,” said Ronney. And that information, along with other findings from the study, may have important applications for improving fuel efficiency on Earth. “If we could burn weaker mixtures in engines, we could get higher efficiency with less pollutant emissions,” said Ronney.
This morning, after the crew shift change, Payload Specialist Dr. Gregory Linteris continued the flame ball experiment, reporting “phenomenally successful” runs.
Two runs of the Internal Flows in a Free Drop experiment were completed overnight in the Middeck Glovebox. Payload Specialist Dr. Roger Crouch conducted the first run late last night, and Mission Specialist Dr. Donald Thomas completed another run early this morning. The experiment examines techniques for controlling the position and motion of liquids in low-gravity. This study is allowing researchers to assess a potential method of mixing which could lead to improvements in chemical manufacturing, petroleum technology, and the cosmetics and food industries.
Late last night, Mission Specialist Mike Gernhardt performed a shear cell rotation of the sample processing in the Large Isothermal Furnace. A second rotation was performed by Thomas early this morning. This procedure is part of an experiment to study the diffusion process of tracers, or impurities, in melted germanium, an element widely used as a semiconductor and alloying agent. “It is a fundamental scientific study. We are trying to measure the fundamental thermophysical properties of this semiconductor,” said lead scientist Dr. David Matthiesen of Case Western Reserve University in Cleveland, Ohio.
Such knowledge is fundamental and findings from this study may have applications for improving the performance of electronic components made from semiconductor materials, such transistors and integrated circuits.
“We’re using samples of pure germanium and doped germanium, or one with an additive,” explained Matthiesen. “The first shear rotation brings samples into contact with other. After processing for a certain amount of time, the second rotates them back to break them into segments.” The segments are then cooled for post-flight analysis.
One thermocouple -- an electronic temperature sensor -- in the cartridges used for Matthiesen’s samples is not working. Researchers are working on a procedure to correct the connection between the facility and the thermocouple.
In the TEMPUS levitating facility, an investigation is underway to study nucleation, or the point at which solidification from the melted state begins, in undercooled liquid zirconium. Undercooling is when a liquid remains fluid when cooled below its freezing point. Researchers are interested in determining the temperatures at which nucleation, an important in metals casting processes, occurs.
According to researcher Dr. Robert Bayuzick of Vanderbilt University in Nashville, Tenn., the team is extremely pleased with last night’s test results. “The effort could be considered a complete success,” said Bayuzick. Collaborating on the study with Bayuzick are Dr. Merton Flemings and Dr. Gerardo Trapaga of the Massachusetts Institute of Technology in Cambridge, Mass. Results may help improve theoretical modeling.
Today, Thomas is slated to conduct a study in the Middeck Glovebox to examines the manipulation of bubble shape and movement in water under weightlessness conditions. He will also continue the diffusion in semiconductors experiment under way in the Large Isothermal Furnace. Linteris will continue the flame ball experiment in the Combustion Module and begin another undercooling of metallic alloys study in the TEMPUS facility.
The next scheduled Public Affairs status report will be issued at approximately 6 p.m., July 9.
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