STS-73 Day 12 Highlights
Back to STS-73 Flight Day 11 Highlights:
- On Tuesday, October 31, 1995, 8 a.m. CST, STS-73 MCC Status Report # 22
- With all orbiter systems and payload activities continuing to run
smoothly, members of the STS-73 Red Team are taking a break today from
their busy schedule. STS-73 Commander Ken Bowersox and Payload
Specialist Al Sacco had their off-duty time during the first part of
the Red Team's shift, while Pilot Kent Rominger and Payload Commander
Kathy Thornton will have some free time during the second half of the
team's day. These "off duty" times are used by the flight control team
to keep the crew well rested for the duration of the 16-day mission.
- Columbia is nearing the end of a 14-hour thermal conditioning period
designed to warm the underside of the orbiter and increase the landing
gear tire pressure. For the United States Microgravity Laboratory-2
mission, Columbia usually flies in a stable gravity gradient attitude
with its tail pointing toward the Earth and its port wing pointing in
the direction of travel. The gravity gradient attitude requires only
minimal thruster firings to maintain the orbiter's position, but
shades the underside of the orbiter where the landing gear is housed.
- On Tuesday, October 31, 1995, 6 a.m. CST, STS-73 Payload Status Report # 18
reports: (10/22:07 MET)
- The second United States Microgravity Laboratory added to an already
bulging "portfolio" of scientific information as it completed an
eleventh day in space. "It's really great to be collecting all this
data that we've been planning on for so long," said Mission Specialist
Cady Coleman as she sent video views of USML-2 experiment facilities
to scientists on the ground.
- Last night's Particle Dispersion Experiment confirmed a theory about
the behavior of dust and particle clouds proposed by Glovebox
Investigator Dr. John Marshall, who works with the SETI Institute and
NASA's Ames Research Center in California. Payload Specialist Fred
Leslie agitated several small transparent chambers inside the
Glovebox, dispersing particles of volcanic material, rounded quartz,
angular quartz or copper within the various chambers. Marshall
watched Glovebox video as dispersed particles in each of the chambers
gradually clumped together, or aggregated, due to electrostatic
- This validates Marshall's hypothesis that aggregation occurs in all
dust clouds: the planetary nebulae which coalesce to form stars,
global dust storms on Mars, dust clouds from a meteor impact on Earth
(such as the one some believe led to extinction of the dinosaurs), and
clouds of dust and ash flung into Earth's atmosphere during volcanic
eruptions. The particles are drawn together by static electrical
charges. Because the resulting clumps are heavier than individual
particles, they fall to the ground to cleanse the atmosphere (or move
to the center to form stars) more rapidly than would be predicted by
gravitational theory alone.
- The USML-2 investigation built on results of a technology study on
USML-1, which tested methods for dispersing small particles in
microgravity. "Because of the success of the USML-1 investigation, we
were able to flesh out our science objectives and test variables like
particle size, density of the cloud, and type of material. All the
materials showed a similar propensity to aggregate," said Marshall.
- Leslie conducted several more runs for the Glovebox Oscillatory
Thermocapillary Flow Experiment, this time using a very shallow
silicone oil chamber to see how the shallow depth affects the onset of
unstable fluid flows. A few small bubbles, introduced into the oil as
Leslie filled the chamber, moved in concert with aluminum tracer
particles to illustrate fluid flow patterns in the last experiment
run. The Glovebox investigation complements the Surface Tension
Driven Convection Experiment's probe into the conditions which cause
heat-induced fluid flows to become unsteady, or oscillate.
- Geophysical Fluid Flow Cell Experiment controllers began their first
observation scenario simulating the atmosphere of the planet Jupiter.
The giant gas planet radiates more heat than it receives from the sun,
making its atmosphere of particular interest to Principal Investigator
Dr. John Hart and other atmospheric scientists. "These early runs
show dramatic changes in flow types with very small variations in the
instrument settings," said University of Colorado Team Member Scott
Kittelman. Investigations for the remainder of the flight will
concentrate on atmospheres like those of the gaseous planets Jupiter,
Saturn and Uranus. Hart feels that lessons learned by studying these
"gas giants" can be brought forward to apply to fluid flows on the
- Early in Coleman's shift, she stretched a "bridge" of liquid between
Drop Physics Module injector tips, in an operation designed to profile
the chamber's acoustic characteristics. The Jet Propulsion Laboratory
facility's four loudspeakers produce precisely balanced sound waves,
used to position and manipulate liquid drops within the chamber. The
acoustics system was upgraded after USML-1, and the experiment team
used last night's runs to refine their understanding of how various
acoustic controls affect drop manipulation in microgravity.
- Mission Specialist Mike Lopez-Alegria made several adjustments to
bring fuel deployment needles closer together in the Fiber Supported
Droplet Combustion experiment hardware. Glovebox investigators hope
this will make it possible to deposit fuel drops onto a stretched
fiber during upcoming experiment runs. Yesterday's planned combustion
study was thwarted when the needles would not come close enough to the
fiber for the fuel to adhere to it.
- The Crystal Growth Furnace has cooled down, after processing Dr.
David Matthiesen's gallium arsenide semiconductor crystal. The
furnace is beginning to melt the next sample, another cadmium zinc
telluride semiconductor crystal for Dr. David Larson. This sample is
contained in a modified ampoule designed to force the crystal to
adhere evenly to chamber walls, further reducing defects.
- As they have throughout the mission, the Space Acceleration
Measurement System (SAMS) and the Orbital Acceleration Research
Experiment (OARE) tracked accelerations caused by movements and
vibrations within the Shuttle, as well as by Shuttle maneuvers and
atmospheric drag. Both are part of the Lewis Research Center's
Principal Investigator Microgravity Services project, which provides
information to help space scientists evaluate effects of accelerations
on sensitive microgravity experiments. Both instruments make
continuous records of accelerations for analysis after the flight. In
addition, OARE is providing profiles of relatively steady, or
low-frequency, accelerations to the USML-2 mission scientist every 12
- A Spacelab video cassette recorder which malfunctioned briefly
yesterday morning is back to normal operations, with no loss to USML-2
science data collection.
- On Tuesday, October 31, 1995, 5 p.m. CST, STS-73 MCC Status Report # 23
- Shortly after 11 a.m. CST, crew members reported they were unable to
see the Cosmos 398 because of bright sunlight although the shuttle
passed within about 75 statute miles of the spacecraft. The Cosmos 398
is an old Soviet lunar module now circling the Earth at a lower orbit
than the shuttle. It was launched into orbit by the former Soviet
Union in 1971 and, due to program changes, was left in space.
- About 1:04 p.m. ended its 14-hour thermal conditioning period and
returned to a gravity gradient attitude. Tuesday's conditioning period
marked the second of four planned warm-up sessions. The thermal
conditioning periods are designed to warm the underside of the orbiter
and subsequently increase the landing gear tire presssure.
- For the United States Microgravity Laboratory-2 mission, Columbia
usually flies in a stable gravity gradient attitude with its tail
pointing toward the Earth and its port wing pointing in the direction
of travel. The gravity gradient attitude requires only minimal
thruster firings to maintain the orbiter's position, but shades the
underside of the orbiter where the landing gear is housed. The
remaining two warm-up sessions are targeted to occur on Thursday and
- The Red Team handed over mission activities to their colleagues on
the Blue Team at 2:38 p.m. CST and will resume their work at 2:38 a.m.
- On Tuesday, October 31, 1995, 6 p.m. CST, STS-73 Payload Status Report # 19
reports: (11/09:07 MET)
- USML-2's Crystal Growth Furnace has finished melting a second
sample of the semiconductor material cadmium zinc telluride, and the
crystal has begun to solidify. This crystal is being slowly
solidified in one direction, for a more perfect structural
arrangement. On Earth, cadmium zinc telluride is used as a substrate,
or base, for growing mercury cadmium telluride crystals, useful for
making infrared radiation detectors. The alloying element, zinc, is
added to minimize the strain where the two crystals join, thereby
reducing defects. Defects caused by gravity driven fluid flows on
Earth produce less perfect crystals and thus less perfect end
products. This is the sixth semiconductor crystal to be grown on
USML-2 in the Crystal Growth Furnace.
- This afternoon Payload Specialist Al Sacco continued changing
parameters in the Geophysical Fluid Flow Cell Experiment to produce a
variety of fluid flows which mimic those in planets, atmospheres and
stars. Today's experiments continued a series which study the
atmospheres of gaseous planets such as Jupiter and Saturn. Scientists
hope lessons learned from these studies can apply to fluid flows on
Earth. Researchers will use data from this experiment to build better
computer models of fluid behavior which could one day aid in
forecasting ocean flows and weather patterns.
- A demonstration used to isolate sensitive experiments from small
vibrations and disturbances in the Shuttle was deactivated today.
Earlier this week, the Suppression of Transient Acceleration by
Levitation Evaluation, or STABLE, was tested with an experiment called
"CHUCK," an investigation designed to study materials processes in
microgravity that are applicable to crystal growth mechanics.
Comparisons of these data will be made post-mission, and should help
determine the effectiveness of STABLE for reducing background
vibrations. The STABLE experiment was designed and developed by
McDonnell Douglas of Huntington Beach, Calif., and NASA's Marshall
Space Flight Center.
- Early in the blue shift, Mission Specialist Cady Coleman began
setting up the Drop Physics Module for an experiment run which will
involve positioning a drop of water in the center of a silicon oil
drop. Precise adjustments to sound waves within the drop chamber may
enable Coleman to maneuver the water drop to the oil's center. The
ability to deploy and manipulate compound drops is an important step
towards uniform encapsulation -- a technique which could aid
scientists in using polymer systems to study the encapsulation of
living cells aimed at the possible treatment of hormonal disorders
such as diabetes.
- In other Drop Physics Module activity, scientists obtained detailed
observations of the water drops and how they are affected by
surfactants, or chemicals, that change the surface tension. In
today's experiments, different concentrations of the same chemical
were added to the drops which Payload Commander Kathryn Thornton then
manipulated using sound waves. Principal Investigator Dr. Robert
Apfel of Yale University gathered a plethora of data on the
oscillations of the drops which were squeezed and then released so
their shapes, thanks to microgravity, repeated themselves over a
period of time.
- Surfactants change the properties of a liquid drop, and are of
interest to scientists for the role they play in countless industrial
processes, from the production of cosmetics, to the dissolution of
proteins in synthetic drug production. Another application could be
the production of new surfactants with more desirable properties.
- During the next 12 hours, crew members Coleman and Payload
Specialist Fred Leslie will alternate their four-hour breaks, working
with the Drop Physics Module, the Oscillatory Thermocapillary Flow
Experiment, and the Geophysical Fluid Flow experiment.
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