IML-2 Status Report #19
 
IML-2 Public Affairs Status Report #19
6:00 p.m. CDT, July 17, 1994
9/6:17 MET
Spacelab Mission Operations Control
Marshall Space Flight Center
 
    Today, IML-2 crew members assisted science teams with ground-commanded
materials experiments, attempted to repair the Free Flow Electrophoresis Unit,
and got a few well-deserved hours of rest.  NASA Administrator Dan Goldin
surprised the crew with a telephone call from Mission Control in Houston. He
praised their hard work, saying it would help lay the groundwork for future
space exploration.
 
    Payload Commander Rick Hieb volunteered two blocks of his free time today
to perform maintenance procedures on the Japanese space agency's Free Flow
Electrophoresis Unit. Assisted by Pilot Jim Halsell this morning, Hieb twice
replaced all the distilled water in the unit's fluid cooling system to flush
out air bubbles in the line.  The unit reached its normal activation state and
ran well for an hour and 20 minutes, then automatically shut off.  Not willing
to give up, Hieb tried the procedure for a third time just before his pre-sleep
period.  Thus far, the unit continues to operate within specifications.  If
this remains to be the case, the blue shift crew will prepare for a chromosome
DNA separation experiment in the unit.
 
    Payload Specialist Chiaki Mukai worked closely with ground controllers to
perform a run of Dr. Klaus Leonartz' solidification study in the NIZEMI slow-
rotating centrifuge.  A transparent, two-component material which mimics the
behavior of metal alloys was melted, then slowly resolidified, as the
centrifuge turned to simulate various levels of gravity.  The NIZEMI microscope
gave Mukai and experiment scientists a clear view of the point where the liquid
was turning into a solid, called the solidification front. "Using the NIZEMI,
we can observe fluid flows and detect the gravity levels at which they begin,"
explained Leonartz. "We can also determine the effect of the fluid flow on the
solid.  If we can learn how to make semiconductors or metals more homogenous,
we can improve their properties.  By determining gravity thresholds, we can
learn how to use other methods, such as electromagnetic forces, to surpress
fluid flows during processing on Earth."
 
    Another fluid-flow experiment was conducted in the Bubble, Drop and
Particle Unit this morning.  An experiment container holding three layers of
immiscible (non-mixing) fluids was heated from the top and the bottom.  Dr.
Jean-Claude Legros of Brussels, Belgium, watched downlinked video as resulting
tension differences where the fluids contacted one another began to create
flows within the layers.  The team will use the observations to verify
numerical calculations they had made to predict the velocity and direction of
the fluid flows in the middle layer. "The rough data we received from our
remote support center in Belgium seems to match our predictions," said Legros.
The calculations could help researchers develop methods for controlling fluid
flows during the manufacture of sophisticated materials, such as silicon and
metal alloys for the electronics industry.
 
    The current Bubble, Drop and Particle Unit experiment, which continues
until late tonight, uses vapor bubbles in a liquid refrigerant to study the
process of evaporation and condensation where the liquid and vapor form common
surfaces.  It should provide a better understanding of boiling processes and
the behavior of fluids at a liquid-vapor interface.  Principal investigator for
the experiment is Dr. Johannes Straub of the Technical University of Munich,
Germany.
 
    The TEMPUS electromagnetic containerless processing facility levitated,
melted and solidified an aluminum-copper-cobalt alloy this morning.  After the
mission, investigators will study the preserved sample to determine its atomic
arrangement.  They will be looking for "quasicrystals," a recently discovered
atomic structure that can give materials a high degree of hardness, as well as
novel electrical and physical properties.  The study aims for a better
understanding of how and why quasicrystals form.
 
    The flight crew suspended orbiter thruster firings for a short period this
afternoon, providing the most stable environment possible as the TEMPUS
facility melted a sphere of pure zirconium.  The strong, ductile metal was
heated to more than 3,600 degrees Fahrenheit (2,000 degrees Celsius), several
hundred degrees higher than any for any previous melt in space.  The sample was
levitated for about 10 seconds, then cooled down and solidified.
 
    The Japanese space agency's Large Isothermal Furnace processed two
cartridges of tungsten-nickel-iron alloys for Dr. Randall German's liquid phase
sintering experiment.  The material was heated so the iron and nickel formed a
liquid, surrounding the uniformly dispersed powered tungsten.  The method is
used extensively on Earth to combine dissimilar materials, but researchers
suspect gravity plays a role in distorting the microstructure of such alloys.
German, of Pennsylvania State University, will compare seven different
compositions of the space-processed alloy, heated for different periods of
time, with similar alloys processed on Earth. He will look for differences in
shape, texture, density and high-temperature strength.
 
    Mission Specialists Don Thomas and Leroy Chiao will each get four hours off
tonight.  The assignments during work hours include NIZEMI, Biorack and TEMPUS
experiments.
 
NASA issues four status reports daily on STS-65/IML-2 activities: science
operations reports from Spacelab Mission Operations Control in Huntsville at
approximately 6 a.m. and 6 p.m., and orbiter operations reports from Mission
Control in Houston at approximately 8 a.m. and 5 p.m.