STS-87 Mission Science Report # 6s
Tuesday, November 25, 1997, 7:00 a.m. CST
Researchers at Marshall Space Flight Center in Huntsville, Ala., continued during the past 24 hours with the scientific investigations to study metallic crystal formation and the properties of materials for future electronics -- even as Space Shuttle Columbia’s crew successfully retrieved the Spartan satellite.
“During the intensive part of the space walk, we had to pause some of our experiments,” said USMP-4 Assistant Mission Manager Jimmie Johnson. “But we picked them right back up after the satellite was captured and secured,” Johnson said.
He added that the Spartan recovery did not have a major impact on the mission’s original plan and that it primarily involved shifting the order of some events. “The original flight plan included a spacewalk to practice International Space Station assembly procedures,” he said. “So after this short break, we’re continuing on with our planned timeline.”
The next nine days of the mission are designated as the prime period for the microgravity science experiments. And, beginning on Wednesday, Columbia will be oriented in the optimum attitude for one of the microgravity facilities, the Advanced Automated Solidification Furnace.
This morning, preparations were under way to use the furnace for melting of a mercury, cadmium and telluride alloy sample. Dr. Donald C. Gillies of the Marshall Center, co-investigator of that experiment, said “The furnace is operating normally and we’re looking forward to the experiment run. We’ve changed the furnace settings and by Wednesday afternoon, we will bring it up to our experiment temperature of over 1,800 degrees Fahrenheit.” The experiment is called “Growth of Solid Solution Single Crystal.”
The almost 70-hour melting and solidification experiment is designed to produce a single, unique electrical crystal with exceptional compositional uniformity. Researchers hope to improve metallic crystal structure and to enhance their performance in electronics, computers and infrared detectors.
On Tuesday, in anticipation of the Shuttle’s thrusters firing and vibrations associated with the space walk, the Confined Helium Experiment team cycled through a slow cooling period. “We don’t want to cool too fast, otherwise we lose accuracy,” said Dr. Talso Chui, a co-investigator from the Jet Propulsion Laboratory in Pasadena, Calif.
The experiment “squeezes” helium very flat until it becomes two-dimensional. “We are studying the novel properties of matter when it becomes very thin,” said Chui. “Hopefully, we’ll learn some secrets of nature,” he said. Through this study of helium, researchers hope to understand the effects of miniaturization and how electrical performance is affected by sheer size, thickness and surface irregularities. Results may lead to even smaller electronic devices.
The MEPHISTO team also used the spacewalk time to their advantage by entering a melting cycle of their bismuth and tin sample in the furnace experiment. “When we’re melting, we want to mix the sample really well so that it is homogeneous and all the astronaut activity actually helped,” said William Foster, project manager from NASA Lewis Research Center in Cleveland, Ohio. “But,” he added, “when we solidify a sample, we need a low G-level with no disturbances.”
By early this morning, the shuttle crew ended their day and Foster’s team began their almost two-hour solidification cycle.
MEPHISTO is a French acronym describing the metal-mixing experiment that is helping researchers understand what happens when materials go from a liquid to a solid. They want to know how to control this process to improve the quality of semiconductors and electronic structures. The experiment is a cooperative United States, French and Australian effort.
The Isothermal Dendritic Growth Experiment continued with growth of their tiny dendrite crystals aboard Columbia, during the space walk. Researchers are studying the dendrite formations for better understanding of new ways to manufacture steel, aluminum and superalloys for use in automobile and airplane construction.
In addition to remotely monitoring and controlling the orbiting Shuttle experiment from Rensselaer Polytechnic Institute in Troy, N.Y., the dendrite-growth team began hosting school group visits to their control center at Rensselaer.
“The experiment’s visitors room provides the opportunity for us to speak directly to teachers and their students,” said the dendrite-growth investigation’s lead scientist, Dr. Matthew Koss of Rensselaer. “We share with them the excitement of NASA space flight operations. At the same time we’re teaching them the rudiments of microgravity and materials science,” said Koss.
Looking ahead to the next 24 hours ...
Columbia’s crew will resume investigations in the Microgravity Glovebox. Tonight, they will start with three and four hour sessions of melting and solidifying composite metal materials in the Particle Engulfment and Pushing by a Solid/Liquid Interface experiment. Understanding the results from this research could lead to new processing techniques for the blood supply, new composite materials, and advances for the auto and aerospace industry.
And, USMP-4 researchers will continue the metal mixing experiments in the MEPHISTO furnace and in the Advanced Automated Directional Solidification Furnace.
The next scheduled Public Affairs status report will be issued at approximately 7 a.m., Wednesday, Nov. 26. For more information call the Spacelab Newscenter at Marshall Space Flight Center at (205) 544-0034 or visit the web sites: For USMP-4 payload and science information: http://liftoff.msfc.nasa.gov/shuttle/usmp4/ and http://science.msfc.nasa.gov/usmp4/usmp4.htm For STS-87 information: http://www.shuttle.nasa.gov
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