11.21.97

Friday, Nov. 21, 1997, 7:00 a.m. CSTSTATUS REPORT: STS-87-02s

STS-87 MISSION SCIENCE REPORT # 2S



Aboard Space Shuttle Columbia Thursday, furnaces were fired up for 
several research studies, and other experiments were supercooled as 
scientific research in the microgravity of space proceeded in 
earnest.



With most all of Columbia&rsquo;s science payload &mdash; known as the 
U.S. Microgravity Payload-4 &mdash; activated, and its experiments 
under way, important findings are already exciting researchers. 
&ldquo;From preliminary results,&rdquo; said Assistant Mission 
Manager Jimmie Johnson, &ldquo;it looks like we&rsquo;re going to 
have a great science mission. We&rsquo;ve gotten a good start on 
science for this 16-day mission, and all of our systems are 
performing well.&rdquo; The science goals of the mission include a 
study of materials used by industry, research into the unwanted 
extinction of flames, and the continued miniaturization of computer 
chips.



Early Thursday afternoon, Mission Specialists Dr. Kalpana Chawla and 
Dr. Takao Doi performed the first materials science experiment inside 
a thermal chamber in the Microgravity Glovebox. Researchers are 
looking at how to create a uniform mixture of the liquids that form 
certain metal alloys, such as those used in simple bearings or 
complex superconductors. These alloys are made up of two liquids that 
do not mix well.



When such metals are processed on Earth, gravity causes the liquids to 
separate &mdash; much the same way as water and oil. This separation 
causes weaknesses in metal structures. Previous tests of these alloys 
conducted in the low gravity of space revealed unexpected separation 
of their components into layers. Scientists expect that one possible 
cause of the separation is droplet wetting &mdash; or coating &mdash; 
along container walls. The experiment initiated Thursday is designed 
to study ways to control this wetting behavior. Developing a method 
to eliminate the separation will help create better materials, 
leading to many benefits on Earth.



Dr. Barry Andrews of the University of Alabama at Birmingham, who 
leads the experiment, said late Thursday, &ldquo;The first two 
experiment samples were processed with fascinating results.&rdquo; 
Andrews said those initial samples consisted of compositions where 
preferential wetting of the gasket material had not been previously 
observed during processing on Earth. The flight samples indicated a 
noticeable tendency toward wetting &mdash; even for compositions with 
the lowest content of a colorless crystalline material known as 
succinonitrile. &ldquo;This result,&rdquo; said Andrews, &ldquo;was 
completely unexpected and will provide substantial information on the 
importance of wetting tendencies.&rdquo;



Scientists on Earth Thursday pored over video images, transmitted from 
Columbia, clearly showing the continuing growth of dendritic crystals 
&mdash; structures which look much like miniature pine trees. In this 
experiment, materials are melted and resolidified to observe the 
growth of dendrites. Metal alloys form dendrites when they 
crystallize, ultimately creating the strong materials used in 
production of automobiles and jet engines. Results of this study may 
improve manufacturing of steel, aluminum and super alloys.



Because Earth&rsquo;s gravity distorts dendrites as they grow, 
dendrite crystals produced in the low-gravity of space reveal new 
information about dendrite formation. The experiment&rsquo;s 
principal investigator, Dr. Martin Glicksman of the Rensselaer 
Polytechnic Institute at Troy, N.Y., said late Thursday that 
information already gathered from the experiment &ldquo;is providing 
extremely valuable insight into microgravity solidification behavior 
of pivalic acid &mdash; our primary test substance.&rdquo; Glicksman 
was especially impressed with the high quality of the video 
downlinked from Columbia Thursday. &ldquo;It will doubtless lead to 
new scientific findings about dendrite growth dynamics,&rdquo; he 
added.



A furnace onboard Columbia was heated up Thursday to 750 degrees 
Celsius &mdash; or 1,382 degrees Fahrenheit &mdash; in a joint 
experiment between NASA and the French Space Agency studying crystal 
growth in space. Samples processed in the furnace, known as MEPHISTO, 
will help researchers understand how gravity-driven convection 
affects production of metals -- including alloys -- and electronic 
materials. Precise temperature control allows the crystals to grow 
gradually &mdash;without the effects of Earth&rsquo;s gravity. The 
result is large, nearly perfect crystals. For electronic 
applications, better crystals reduce power needs and increase data 
handling rates. In metals, more perfect crystals result in improved 
strength and durability. Three different sample cartridges containing 
the metal bismuth, with small additions of tin, will be processed in 
the furnace using directional solidification &mdash; a common method 
for growing semiconductors and metal alloys. The temperature, speed 
of growth, and the shape of the crystals solidifying within each 
sample are to be measured in three different ways to identify the 
internal structure of the crystal.



Project scientist and co-investigator of the study, Henry C. de Groh 
III of NASA&rsquo;s Lewis Research Center in Cleveland, Ohio, said 
early Friday morning, &ldquo;We&rsquo;re completing our first 
solidification and melt cycle now. Everything is going great. This is 
one data point. We solidify and melt at one velocity, and then we 
will do several other velocities. Ultimately, we will produce new 
results on solidification.&rdquo;



During the next 24 hours, the Spartan solar physics spacecraft is to 
be deployed from Columbia. Deployment had been scheduled on Thursday, 
but was delayed due to a problem with SOHO &mdash; the Solar and 
Heliospheric Observatory. That delay resulted in a number of science 
experiments, originally scheduled Friday, to be conducted Thursday. 
Also ahead: The Automated Directional Solidification Furnace will be 
reactivated for an upcoming crystal growth experiment, and another 
metal alloy sample will be processed in the MEPHISTO furnace.



The next scheduled Public Affairs status report will be issued at 
approximately 7 a.m., Saturday, Nov. 22. For more information call 
the Spacelab Newscenter at Marshall Space Flight Center at (205) 
544-0034 or visit the web sites: For USMP-4 payload and science 
information: http://liftoff.msfc.nasa.gov/shuttle/usmp4/ and 
http://science.msfc.nasa.gov/usmp4/usmp4.htm For STS-87 information: 
http://www.shuttle.nasa.gov

	
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