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 Centers Spacelab 
Mission Operations Control at 6 a.m. and 6 p.m. weekdays, and at 6 a.m. 
on weekends; and from Johnson Space Centers 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.