USML-2 Public Affairs Status Report #14
6:00 a.m. CDT, Oct. 28, 1995
7/21:07 MET
Spacelab Mission Operations Control
Marshall Space Flight Center

Mission Specialist Cady Coleman and Payload Specialist Fred Leslie 
took turns conducting investigations within the European Space 
Agency's versatile Glovebox enclosure as the second United States 
Microgravity Laboratory-2 mission reached its half-way point.

Leslie worked with two Glovebox investigations sponsored by NASA's 
Lewis Research Center in Cleveland, Ohio.  First, he photographed 
several containers holding different concentrations of microscopic 
plastic spheres suspended in liquid for the Colloidal Disorder-
Order Transition experiment.  Dr. Paul Chaikin of Princeton 
University hopes to determine at which concentration the 
collisions between the spheres change the mixture from a 
disordered fluid state, with the spheres moving haphazardly, to an 
ordered crystalline state in which they are arranged in a 
symmetrical way.

"We are studying the most fundamental transition between liquid 
and solid states, to find what is really important in the 
formation of solids and crystals," said Chaikin.  The behavior of 
the spheres in space, essentially free from the disruption of 
gravity, is a basic model for the way atoms interact with one 
another.  All physical properties of matter such as weight, 
hardness and color are determined by the kind of atoms present and 
how they interact.

Leslie's next Glovebox activity, the Interface Configuration 
Experiment, studied the behavior of a fluid in microgravity as it 
filled a specially shaped chamber.  Glovebox Investigator Dr. Paul 
Concus of the University of California at Berkeley and Co-
Investigators Dr. Robert Finn of Stanford University, and Mark 
Weislogel of NASA's Lewis Research Center watched live video as 
ruby-tinted fluid began flowing into three containers, each with 
slightly different internal angles.  The scientists were able to 
see definite differences in the way the fluid adhered to chamber 
walls in the various containers, and some of the behavior was 
different from that predicted by the classic mathematical model.  

"This shows that we cannot rely completely on the current theory 
of how surfaces form in low gravity, which is based on an equation 
developed in the 1800's," said Weislogel.  "We saw that physical 
factors which are not included in the purely mathematical theory 
do indeed play a significant role."  Insights will aid design of 
fluid systems for space such as those for liquid fuels.

Coleman activated more proteins for the Glovebox Protein Crystal 
Growth experiment, this time using larger drops of protein 
solution.  She has initiated growth of new protein samples during 
several recent shifts, adjusting conditions based on the progress 
of previously activated crystals.  This hands-on involvement of 
crew members will help Dr. Larry DeLucas of the University of 
Alabama at Birmingham determine the best growth methods for 
various proteins during future Shuttle and Space Station 
experiments.  

Mission Specialist Mike Lopez-Alegria deactivated a crystal growth 
chamber for a portion of Dr. Dan Carter's Protein Crystallization 
for Microgravity Apparatus experiment.  This was one of eight 
chambers, activated early in the flight, which contain two salt 
solutions rather than actual proteins.  The two solutions, with 
different concentrations of salt, will gradually diffuse into one 
another until the salt concentration is uniform.  The crew is 
deactivating one container about every two days to detect the 
point in time when the diffusion is completed.  Carter will use 
results to estimate the rate at which solutions will diffuse 
during actual protein crystal growth experiments in microgravity.

"We know that proteins grow more slowly in space than on Earth, 
but we don't know why," said protein specialist Brenda Wright of 
Marshall Space Flight Center.  "We've wanted to do an experiment 
for a long time that would help us predict the rate at which 
certain crystals will grow, so we can be more efficient with these 
valuable proteins and our time in orbit.  But up until now, we 
haven't had the room to fly anything but actual proteins."  
Because Carter's apparatus holds many times more samples in the 
same volume of space than traditional crystallization facilities, 
room was available for the test on USML-2 .  Scientists use the 
well-formed crystals grown in space to analyze protein structures, 
a key to determining how these "building blocks of life" function 
in the human body and other biological systems.

Early this morning, Lopez-Alegria rolled  the orbiter's position 
about 17 degrees to put its left wing directly into the path of 
flight, an attitude the Geophysical Fluid Flow Cell (GFFC) 
experiment scientists believe might further reduce disturbances to 
its experiment.  The Shuttle will maintain that orientation until 
about 8 a.m. CDT.  The fluid flow cell team is running solar 
atmosphere simulations at a slower rotation, to determine if the 
special Shuttle attitude makes a discernible difference.  The 
facility uses a combination of rotation, temperature and 
gravitational variables to simulate fluid flows in the atmospheres 
of the sun and planets.

The Suppression of Transient Acceleration by Levitation 
Experiment, or STABLE, completed its final run for the mission 
during the Shuttle maneuver.  After the mission, a Marshall Center 
team will analyze video of a small experiment inside the 
levitation device to see if STABLE isolated the experiment from 
disturbances as the orbiter changed position.

Later today crew members will remove the three crystals which have 
already been processed in Crystal Growth Furnace, replacing them 
with three more before melting the next sample.  The crew will 
also work with Glovebox Protein Crystal Growth and Surface Tension 
Driven Convection Experiments.

Note to reporters:  Hours at the Spacelab News Center at the 
Marshall Space Flight Center are being adjusted to 6 a.m. to noon 
on Saturday and Sunday.  There will be no 6 p.m. Spacelab status 
report today.  The next report will be issued at 6 a.m. Sunday.

Status reports are issued from Johnson Space Center's Mission
Control at 8 a.m. and 5 p.m.; and from Marshall Space Flight
Center's Spacelab Mission Operations Control at 6 a.m. and 6
p.m. weekdays, 6 a.m. on weekends.  For additional information, see
the Internet USML-2 payload homepage,
http://liftoff.msfc.nasa.gov/spacelab/usml2/welcome.html and the
STS-73 Shuttle homepage, http://shuttle.nasa.gov