Microgravity Science Laboratory -1 Status Report July 11, 6p.m.

MSL Public Affairs Status Report #18
6:00 p.m. CDT, July 11, 1997
MET 10/4:58
Spacelab Mission Operations Control
Marshall Space Flight Center, Huntsville, Ala.


The crew aboard the Space Shuttle Columbia has had another busy day
conducting materials and combustion experiments in the Spacelab. 

Today, crew members worked in the Glovebox to conduct additional Fiber
Supported Droplet Combustion experiment.  Mission Specialist Dr. Don
Thomas spent most of the morning, and Payload Specialist Dr. Roger Crouch
spent the afternoon, conducting the experiment to study the combustion
process of large droplets of fuel. 

"In this experiment we're burning heptane and hexadecane -- hydrocarbon
fuels which are similar to gasoline," said co-investigator Dr. Benjamin
Shaw of the University of California in Davis, Calif.  "Hexadecane has a
much higher boiling point than heptane and when you mix these two together
some peculiar things happen." 

"Specifically we're looking to see whether the fuel drop will have a
bubble that will grow inside and then shatter the drop.  Sometimes these
flames will pulsate and we want to know when that pulsation occurs because
that tells us what is going on within the droplet itself," said Shaw. 

The Fiber Supported Droplet Combustion experiment allows scientists to
study the burning of fuel droplets nearly one-quarter inch in diameter.
The experiment will shed light on the role that convection plays in
burning by introducing a controlled air-flow into the flame environment
during the experiment. 

Results of this experiment, led by Dr. Forman Williams of the University
of California in San Diego, could lead to the efficient utilization of
fossil fuels and reduction of air pollution. 

This morning Linteris set up the Combustion Module -1 and conducted
another run of the flame ball or Structure at Low Lewis-number experiment. 
This run of the experiment used a fuel mixture of hydrogen, oxygen and
sulfur hexafluoride at one atmospheric pressure -- the same as on Earth. 
Linteris sparked the fuel mixture in the test chamber, producing one
burning ball of flame.  Upon a reburn attempt, another flame ball was
ignited. 

"We had a very successful burn and reburn this morning," said project
scientist Dr. Karen Weiland.  The initial flame ball burned steadily for
the duration of the experiment -- 500 seconds. 

The flame ball experiment is designed to determine under what conditions a
stable flame ball can exist and if heat loss is responsible for the
stabilization of the flame ball during burning.  The experiment also
examines how various mixture properties, such as fuel/oxidizer
concentrations and temperature, affect the flame-ball's stability and
existence. 

Around noon, Thomas initiated a nickel sample from an experiment led by
Dr. D.M. Herlach of the German Aerospace Research Establishment in Cologne
in the TEMPUS levitation facility.  This experiment studies the
solidification velocity of dendrites -- tiny branching structures -- that
form as metals solidify.  The size, shape and structure of the dendrites
have a major effect on the strength and usefulness of an alloy. 

Measurements of the speed of dendritic solidification can be used to test
and refine modeling of dendritic growth behavior.  This type of experiment
must be performed in microgravity because crystal growth can be greatly
affected by connective fluid flow or buoyancy-driven motion, in molten
metal.  The low-acceleration environment in space effectively eliminates
convection.  Comparing space experiment data to those obtained on Earth
will allow researchers to learn more about the effect convection has on
dendrite growth.  Information gained from this experiment could have
applications in welding and casting. 

Before taking a scheduled half-day break, Payload Commander Dr. Janice
Voss performed a procedure to fix the top-view camera in the TEMPUS
facility. The camera had stopped working earlier in the mission.  The
proceedure was a success, and the camera is operational.  The side-view
camera has remained operational throughout the mission and investigators
have been able to receive data despite the malfunction of the top-view
camera. 

This afternoon, Crouch initiated the sixth and last sample run of the
diffusion in molten semiconductors experiment in the Large Isothermal
Furnace.  This is the first time diffusion in semiconductors has been
studied in space.  Results of the experiment could improve semiconductors
used in electronic components. 

Ahead Payload Commander Dr. Janice Voss will perform a run of the flame
ball experiment and Crouch will continue to perform the Fiber Supported
Droplet Combustion experiment. 

The next scheduled Public Affairs status report will be issued at
approximately 6 a.m., July 12. 

For more information call the Spacelab Newscenter at Marshall Space Flight
Center at (205) 544-6535 or visit our web sites. For Spacelab payload
information: http://liftoff. msfc.nasa.gov/shuttle/msl and for science
information: http://www.ssl.msfc.nasa.gov/ msl1/msl1hframe.htm