TSS-1R/USMP-3 Public Affairs Status Report #09 6:00 a.m. CST, Feb. 27, 1996 4/15:42 MET Spacelab Mission Operations Control Marshall Space Flight Center The third United States Microgravity Payload (USMP-3) has completed its first night of full-up operations in orbit aboard the Space Shuttle Columbia. The Marshall-managed payload's activities are greatly enhanced by the science teams' ability to conduct "telescience," the process of monitoring and changing experiment activities from ground sites to take full advantage of the time on orbit. Last night, the science team for the Middeck Glovebox Facility developed procedures for continued Glovebox operations in the event that the facility's gas sensor warning light activates during experiment investigations. Earlier in the day, the gas sensors, which monitor the Glovebox's ability to absorb experiment combustion products, had raised some concerns when their sensor lights activated. The Glovebox team concluded that the sensors were activated either by cleaning solution or packing material residues. Because all such materials have been flight qualified, and all combustion samples to be burned in the Glovebox have a zero toxicity rating, the gas sensor lights do not indicate a hazardous condition. For the STS-75 mission, the Glovebox, managed by Marshall's Science and Applications Projects Office, provides an area of containment to conduct combustion experiments. These experiments include the Radiative Ignition and Transition to Spread Investigation, the Forced Flow Flamespreading Test and the Comparative Soot Diagnostics experiment. The first of the Glovebox's experiment runs will begin Wednesday afternoon, 24 hours after a test of the facility's video equipment. The MEPHISTO directional solidification furnace began its first experiment run for the STS-75 mission last night. MEPHISTO is flying for the third time on a USMP mission in a series of cooperative investigations between NASA, the French CNES and the French Atomic Energy Commission. MEPHISTO studies the behavior of metals as they solidify. It is allowing scientists to closely monitor its first 32-hour- long cycle of solidification and remelting of its three tin- bismuth alloy samples by taking real-time temperature and resistance readings at the point where the molten and solid metals meet called the solid-liquid interface. Because the molten material is not transparent, researchers monitor electronic impulses to gain detailed information about conditions occurring at this interface. These data should provide scientists with greater insights into other, more subtle influences that impact solidification of materials. Ultimately, the MEPHISTO experiments may bring dramatic improvements in materials production on Earth. The Isothermal Dendritic Growth Experiment (IDGE), developed by Rensselaer Polytechnic Institute, is taking advantage of full real-time data collection. Now that USMP-3 is receiving the majority of the mission's science data flow, IDGE is gathering all its information in real-time downlink and assembling data that will test theories concerning the effects of gravity-driven fluid flows on solidification of molten materials. The experiment records photographs and video images of dendrites, or Christmas tree-shaped crystals, grown in the absence of gravity. Photographs are taken each time a dendrite is grown. The photographs, together with slow-scan television images, have produced comprehensive microgravity data that will provide a standard for testing solidification theories and mathematical models. Microgravity research such as this will lead to manufacturing improvements on Earth in metals and alloys that display dendrite formation. The Space Acceleration Measurement System (SAMS), developed by the NASA Lewis Research Center, continues to measure the microgravity environment of the USMP-3 equipment carrier in support of the four major onboard experiments. Measurements are made at specific times when microgravity disturbances are caused by events such as crew exercise and repositioning the Shuttle's Ku-band antenna. A related system, the Orbital Acceleration Research Experiment (OARE), is also managed by NASA's Lewis Research Center. It proves very useful on missions such as USMP-3, where it is important to accurately depict a wide variety of disturbances in the microgravity environment. Working closely with SAMS, the OARE records low-frequency activity such as the Shuttle's friction with the upper atmosphere. SAMS is more suitable for recording higher-frequency activity such as crew exercise. The OARE instrument continues to process data in support of the USMP-3 experiments, and team members say all is going well. Science activities for USMP-3 over the next twelve hours will continue, as STS-75 enters its sixth day in orbit. Status reports are issued from Marshall Space Flight CenterŐs Spacelab Mission Operations Control at 6 a.m. and 6 p.m. weekdays, and at 6 a.m. on weekends; and from Johnson Space CenterŐs Mission Control at 8 a.m. and 5 p.m. For additional information, see the USMP-3 payload Internet homepage at http://liftoff.msfc.nasa.gov/sts-75/usmp-3/usmp- 3.html, the TSS-1R payload Internet homepage at http://liftoff.msfc.nasa.gov/sts-75/tss-1r/tss-1r.html and the STS-75 Shuttle Mission Internet homepage at http://www.ksc.nasa.gov/ shuttle/missions/sts-75/mission-sts-75.html.