[Downloaded from NASA Spacelink]

USMP-2 Public Affairs Status Report #10
4:00 p.m. CST, March 14, 1994
10/08:07 MET
Spacelab Mission Operations Control
Marshall Space Flight Center
Huntsville, Ala.

After more than nine days of around-the-clock research in fundamental
solidification and fluid physics, the second United States Microgravity Payload
(USMP-2) successfully concluded planned science activities late last night, and
the Columbia was maneuvered to support other mission objectives.  However,
three instruments will continue to gather data until the end of the flight.

"The USMP-2 mission has gone extraordinarily well," Dr. Peter Curreri, USMP-2
Mission Scientist, said. "We've achieved our primary science for all our
payloads.  We have made basic science discoveries that we had not anticipated.
It has been, in my opinion, a fantastically rich mission scientifically."

IDGE

 "The Isothermal Dendritic Growth Experiment was a resounding success," Dr.
Martin Glicksman, principal investigator, said. "The investigation exceeded
virtually every expectation regarding flawless operation of the instrument and
delivered a figurative 'goldmine' of scientific data."

Television images from the experiment revealed that the dendrites developed
more quickly than anticipated.  This allowed additional mission time for
observing growing dendrites under varying conditions. "'Telescience' and
time-critical commanding permitted full use of quality microgravity time,"
Glicksman said.

The IDGE team had the opportunity to observe the tip splitting of dendrites at
extremely small temperature differences below the freezing point, which they
believe have never been observed on Earth. Scientists received considerably
more data than they anticipated before Columbia took off.

"These discoveries and their subsequent development simply could not have been
accomplished without going into low-Earth orbit, where gravity is reduced up to
a million times," Glicksman said. "We are certain that the basis of current
theories about dendritic growth are seriously corrupted by convective effects
due to gravity.  It will require a lot of thinking by many scientists and
engineers to explore fully this scientific goldmine."

He added, "We are confident that the images and data collected during the IDGE
experiment will become 'the standard' for the scientific field for some time to
come." These data will permit refinement of theoretical and practical
mathematical models for terrestrial solidification of metals.

ZENO

"We have gone where no one has gone before," said Dr. Robert Gammon, principal
investigator for the Critical Fluid Light Scattering Experiment, nicknamed
Zeno. Gammon is referring to the fact that he has been able to make accurate
measurements over 100 times closer to xenon's critical point than is possible
on Earth. At the critical point, a material is neither a gas nor a liquid, it
is both; more precisely, the material rapidly changes back and forth from one
state to another so that either state is indistinguishable.  Materials at this
sensitive point exhibit very interesting behavior, but scientists on the ground
have been unable to study it so closely in normal gravity.  On USMP-2, however,
Gammon and his team "have explored the responses of the xenon sample with
unprecedented precision."

The microgravity environment produced by the Shuttle has allowed Gammon to
perform measurements in a uniform, uncompressed sample, that cannot be made on
Earth, and to see things that he has "spent his career waiting to see."

Sending commands from the ground, Gammon has been able to manually fine-tune
and adjust experiment parameters to find and study the critical point.
"Telescience" is allowing Gammon to extend his data range, gathering more
information than he previously expected.

Scientists use their observations from experiments like Zeno to explain
phenomena ranging from small scales, such as atomic interactions, to global
scales, such as weather warming.  Information gathered from this experiment can
strengthen the physics theories that may form the foundation for changes of
state such as the magnetization of an iron bar, as well as how electrons can be
arranged into superconducting materials.  For Gammon, it is "a dream realized."

MEPHISTO

"The first Seebeck signals of dendritic crystals grown in microgravity were
captured by the MEPHISTO directional solidification furnace," Dr. Reza
Abbaschian, principal investigator, said.  MEPHISTO is a acronym for Material
pour L'Etude des Phenomenes Interessant la Solidification sur Terre et en
Orbite.

The joint U.S.-French team also was able to get real-time information on the
motion of the liquid-solid interface as it responded to imposed growth
conditions.  This is very important information to the crystal growth process,
Abbaschian explained.

The furnace's "telescience" capability allowed a great deal of flexibility in
operating the furnace.  Scientists have been able to use remote commanding to
adjust their procedures in real time to enhance the quality of data they
received.

Cross-sectional analysis of these samples after they are returned to Earth will
give additional information on the shape of the solid-liquid interface and
crystal growth process for study by the science and technical communities to
improve processes for making materials ranging from heavy metals to airplane
turbine blades and electronic equipment on Earth.

AADSF

Dr. Sandor Lehoczky, principal investigator for the Advanced Automated
Directional Solidification Furnace (AADSF), is also pleased with his results.
"Our theories suggest that the Shuttle environment was just right to solidify,
under precisely controlled low gravity conditions, the longest semiconducting
crystal of this type grown to date in space," he said.  Analysis of the
downlinked data indicated that the temperature distribution in the furnace
during growth was exactly as predicted for the necessary seven days.

"Our sophisticated high-temperature furnace is operating perfectly in
microgravity.  In fact, the experiment has gone so well we were able to use
'telescience' to create a demarcation, or reference point, on the crystal at a
critical time in our growth process," Lehoczky said.  The marker will help
determine the position and shape of the solid-liquid growth interface.

After Columbia lands, the crystal will be sliced and polished for study .
These findings will help scientists learn about the effect of convection -- the
movement of fluids caused by gravity - during growth of crystals on Earth for
advanced electronics use in the photo electronics industry.

SAMS

During its ninth flight, the Space Acceleration Measurements System (SAMS) "has
run flawlessly" according to Ron Sicker, SAMS program manager.  SAMS is
designed to monitor and record the onboard accelerations and vibrations
experienced during Shuttle orbital flight.  Since knowledge of the acceleration
environment aboard the Shuttle is essential for the experiments on this
mission, SAMS data is downlinked in real-time as well as stored for post-flight
analysis.

"It is exciting to look at data while it is happening," Sicker said.
Scientists are particularly interested in measurements made during specific
Shuttle maneuvers, crew activity and operations using the robot arm.  Armed
with this SAMS data and 'telescience', researchers can "time their experiments
and conserve resources."

Since the scientists will learn what types of accelerations affected their
experiments, they can make new designs for future missions which take these
into account.

"This is what it's all about!" Dave Jarrett, USMP-2 Program Manager, said.
"Watching the USMP-2 principal investigators getting the data they've worked so
long and hard to get is really inspiring and makes all the hard work everyone
has done seem that much more worthwhile."