STS-75 Day 11 Highlights
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- On Sunday, March 3, 1996, 6 a.m. CST, STS-75 Payload Status Report # 16
reports: (9/15:42 MET)
- As "telescience," or remote controlled, operations for the third
United States Microgravity Laboratory (USMP-3) continue, the crew has
been actively conducting combustion experiments. While the four
primary USMP-3 investigations depend on remote commanding from the
ground, the three combustion investigations require, and benefit from,
intensive crew involvement. To ensure safety, these are conducted in
the enclosed Middeck Glovebox work area.
- Combustion plays a key role in energy production, air pollution,
transportation, propulsion, global environmental heating, materials
processing and waste incineration. Two experiments -- the Radiative
Ignition and Transition to Spread Investigation (RITSI) and the
Forced-Flow Flamespreading Test (FFFT) -- study how fires behave in
the low-gravity environment of space, so that they can be prevented
and controlled. The third experiment -- Comparative Soot Diagnostics
(CSD) -- is designed to determine how soot produced by flames in
microgravity can be detected by on- board fire detectors. CSD may
also help researchers better understand this major industrial
- Many space experiments require human interaction but contain
irritating substances or potentially hazardous conditions. The
Marshall-managed Middeck Glovebox provides a controlled and safe work
environment for these operations. Project Scientist Dr. Donald
Reiss, of NASA's Marshall Space Flight Center, says that scientists
use the Glovebox to simulate experiments done in their ground-based
laboratories but that their experiment samples behave quite
differently than they do on Earth. The facility also provides power,
light, data collection, air and particle filtration, and sensors for
gas, temperature, air pressure and humidity. The microgravity
environment of the Space Shuttle is itself an essential tool
- RITSI principal investigator Dr. Takashi Kashiwagi, of the National
Institute for Standards and Testing, got a boost in science return
thanks to the help of Mission Specialist Maurizio Cheli. During the
first RITSI run on Friday, Cheli was able to speed up a relatively
long process and complete half of a second run ahead of schedule.
This frees up a valuable time period for possible additional runs.
Early results from RITSI dramatically illustrate that flames produced
in space are quite different from those produced on Earth. "They were
upside down, completely the reverse of flames one usually sees,"
Dr. Kashiwagi explained. On Earth, warm air rises, and cool air falls
due to buoyancy-driven convection. In microgravity, the convective
process is virtually eliminated.
- The Forced Flow Flamespreading Test (FFFT) studies how air motion
affects flame spreading to be able to better prevent or control fires.
When a fire starts on Earth, flames spread due to the movement of air
around and through the flames. Air motion also supplies oxygen to the
fire, removes combustion products and controls how heat is released
and the flame is distributed. Dr. Kurt Sacksteder and his
investigator team from NASA's Lewis Research Center watched closely as
flat paper and cellulose cylinder fuel samples were heated and
ignited. The FFFT low-speed wind tunnel creates air movements of one
to four inches per second, much slower than can be properly studied on
Earth, where normal gravity causes air flows of at least ten inches
- As Pilot Scott Horowitz conducted an FFFT run, he adjusted the
Glovebox's camera angle and focus to give the science team a better
view of what he termed a "blue ball moving down the tube," referring
to the cylindrical ashless paper sample he had lit up. Horowitz also
reported seeing a "yellow flame inside the blue flame that is quite
spectacular. I've never seen anything like this." Dr. Sacksteder
said that the information his science team already has gathered will
take months to fully analyze.
- Dr. David Urban, also of the Lewis Center, is principal investigator
for the Comparative Soot Diagnostics experiment. He worked through
the Crew Interface Coordinator at Marshall who, in turn, sent up voice
commands to Commander Andrew Allen to "tweak" various parameters such
as fan speed and the ignition setting. Dr. Urban explained that
"microgravity is quite different from the laboratory on Earth where we
use models to guess the power it will take to ignite a material. In
orbit, we realized that we could reduce the ignition power settings."
- Over the next 24 hours, dedicated microgravity operations will
continue with both MEPHISTO experiment teams, at the French Space
Agency in Toulouse, France, and at the University of Alabama in
Huntsville, Alabama, processing real-time data from their furnace's
tin and bismuth alloy sample. The sample is again undergoing longer,
slower melting and re-solidification cycles to take advantage of the
best possible crystal growth conditions. Later today, the Advanced
Automated Directional Solidification Furnace (AADSF) team will
solidify their third lead-tin-telluride crystal. Meanwhile, the
Critical Fluid Light Scattering Experiment continues cooling its xenon
sample ever closer to its critical temperature. Also, tomorrow
morning, the Isothermal Dendritic Growth Experiment (IDGE) team will
shift its main remote control and data collection activities to the
Rensselaer Polytechnic Institute, the first time that a campus site
has ever sent remote commands to the Space Shuttle.
- On Sunday, March 3, 1996, 8 a.m. CST, STS-75 MCC Status Report # 20
- Flying 180 miles above the Earth, Columbia continues to provide a
stable platform for the experiments comprising the United States
Microgravity Payload mission with all orbiter systems performing well.
- Science investigations continued through the night without
interruption. Among the activities, crew members worked with an
experiment called the Forced Flow Flamespreading Test which studies
how flames react in the absence of gravity.
- This morning, Commander Andy Allen had some time to relax while Pilot
Scott Horowitz, Mission Specialist Maurizio Cheli, and Payload
Specialist Umberto Guidoni talked with Voice of America about the
progress of the flight so far. Later in the day, Horowitz, Cheli and
Guidoni will have a break from their payload activities while Allen
continues the scientific investigations.
- The Blue Team will wake for its next shift at shortly after 3
p.m. Central. Columbia continues to orbit the Earth in smooth fashion
at an altitude of 180 miles, completing one revolution of the Earth
every 90 minutes.
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