07.16.97

Wednesday, July 16, 1997 6 p.m. CDTSTATUS REPORT: STS-94-24s

STS-94 MISSION SCIENCE REPORT # 24S



As researchers aboard the first Microgravity Science Laboratory 
mission prepared for Columbia’s return to Earth Thursday, their 
counterparts at Spacelab Mission Operations Control Center in 
Huntsville, Ala., began tallying the mission’s research 
accomplishments -- which often surpassed expectations.



"We've done better than anybody expected,” said Mission 
Scientist Dr. Michael Robinson, looking back at the wealth of science 
information collected during the course of this 16-day mission, set 
to end Thursday at 5:47 a.m. CDT when the Space Shuttle lands at 
Kennedy Space Center in Florida.



“A highlight of the mission is that everything worked so 
well,” said Robinson, of the Marshall Space Flight Center in 
Huntsville, where the microgravity science mission is managed. 
“All orbiter, Spacelab and payload systems have performed 
superbly. We are very pleased to have been able to take full 
advantage of this reflight opportunity,” added Mission Manager 
Teresa Vanhooser, also of Marshall:



This record-setting mission provided fundamental new knowledge in the 
principal scientific fields of combustion, biotechnology and 
materials processing.



More than 200 fires, or combustion experiment runs were conducted on 
MSL-1. Only 144 had been scheduled for the mission.



A study of the phenomena of soot resulted in discovery of a new 
mechanism of flame extinction caused by radiation of soot. Scientists 
found that the flames emit soot sooner than expected. These findings 
have direct impact on spacecraft fire safety, as well as the theories 
predicting the formation of soot -- which is a major factor as a 
pollutant and in the spread of unwanted fires.



Seventeen tests were completed in the soot study -- three more than 
originally scheduled -- on this mission and the shortened April 
Shuttle flight. “Every one worked and yielded good data,” 
said lead scientist Dr. Gerard Faeth of the University of Michigan at 
Ann Arbor. “That’s beyond my wildest dreams.”



Another combustion study -- this one on spherical flame structures, or 
flameballs -- resulted in the MSL-1 crew igniting the weakest flames 
ever burned either in space or on Earth. Flameball powers are as low 
as one watt -- or 1/50th the power of a birthday candle. The study 
also resulted in the longest burning flames ever ignited in space, 
burning for the entire 500-second duration of the experiment run. 
These tests provide new information for models of weak combustion 
processes needed to develop cleaner, more fuel- efficient internal 
combustion engines.



From the experiment, said lead investigator Dr. Paul Ronney of the 
University of Southern California in Los Angeles, “we can learn 
the burning limits of fuel mixtures. It gives us an idea of just how 
lean a fuel can be -- and still burn. It may lead to better gas 
mileage and less auto emissions.” Other benefits include 
improved fire safety for future spacecraft.



Experiments processed in MSL-1’s unique, levitating furnace 
facility known as TEMPUS yielded the first measurements of specific 
heat and thermal expansion of glass-forming metallic alloys. These 
measurements -- never taken before on Earth -- are fundamental 
measurements necessary for modeling industrial materials systems 
needed to manufacture new and better products.



The study has resulted in more than 120 melting cycles with zirconium, 
with a maximum temperature of 2,000 degrees Centigrade and was able 
to undercool to 340 degrees -- the highest temperature and largest 
undercooling ever achieved in space. The TEMPUS investigators also 
have provided the first measurements of viscosity of 
palladium-silicon alloys in the undercooled liquid alloy which are 
not possible on Earth. One TEMPUS lead investigator, Robert J. 
Bayuzick of Vanderbilt University in Nashville, said, 
“I’ll go out on a limb and say this is the most 
successful mission in microgravity research that’s ever been 
flown. It went perfectly.” His study focused on the changes 
that certain metals undergo as they are cooled from a liquid to a 
solid state in a containerless environment. “What we 
showed,” he said, “in this particular regime is that 
relative to one another, there’s no difference in the effect on 
nucleation between the moderate flow and the turbulent flow 
conditions. That’s a unique result. This kind of experiment has 
never been performed before, ever, in history.”



Studies conducted in the multipurpose Middeck Glovebox have 
demonstrated its value in supporting a variety of experiments in 
microgravity -- including those on this mission in the areas of 
liquid and bubble behavior, fluids-based heat transfer devices, and 
solid-liquid mixtures. In a testimony to the glovebox’s 
usefulness, the crew has performed well over 100 test runs in the 
facility -- more than double the number planned.



Real progress has been made during this mission in learning how to 
control and position liquid drops, according to Mission Scientist 
Robinson. Experiments on this mission have demonstrated that 
quiescent positioning and control of the rotation of a liquid drop 
can be achieved using acoustic levitation in the microgravity of 
space. The investigation of internal flows in a free drop has 
provided information on the dependence of acoustic torque on acoustic 
pressure and the internal flows in a liquid drop. This study is 
allowing researchers to assess a potential method of mixing which 
could lead to improvements in chemical manufacturing, petroleum 
technology, and the cosmetics and food industries.



In another glovebox study on MSL-1, researchers have obtained the 
first data for the nonlinear free decay frequency for a totally free 
drop, and the first accurate data for drop deformation as a function 
of acoustic pressure. This has lead to discovery of an effective 
method for bubble positioning and manipulation in microgravity. These 
findings could lead to techniques that eliminate or counteract the 
complications that bubbles cause during materials processing.



Large droplets of fuel were ignited and information collected on the 
burn rates, flame shape and radiation emitted in another glovebox 
experiment. This study resulted in the first microgravity experiment 
in which droplet arrays were burned.



In a novel and unplanned twist to this experiment, scientists -- 
pleased with the single-droplet tests -- decided to expand the study 
to run tests using two droplets. The pairs of drops were positioned 
on a fiber and ignited simultaneously. This provided a bonus to 
researchers as they observed the interaction of the droplets. The 
experiment’s lead investigator, Dr. Forman Williams of the 
University of California at San Diego, called the view of the two 
droplets “the most beautiful set of twins I’ve ever 
seen.” Only 52 test runs were planned on MSL-1. Yet 125 runs 
were completed -- a 240 percent science return. Information from the 
study is expected to improve theoretical models of combustion.



In the coarsening in solid-liquid mixtures experiment -- also in the 
glovebox -- researchers studied a process that can cause metals to 
weaken or fail in alloy products, such as turbine blades in aircraft 
engines. By examining this process in space, the design and control 
of metals processing on Earth may be improved.



In another experiment, researchers were able to take a very pure look 
at the combustion process without the effects of gravity. The Droplet 
Combustion Experiment has provided scientists with fundamental 
knowledge of the burning process -- and may provide a method for 
verifying which complex, chemical model accurately describes the 
process. It may also lead to cleaner and safer ways to burn fuels.



In this experiment, researchers pushed the envelope of knowledge of 
combustion by setting a fire at the lowest atmospheric pressure yet 
during a mission. The study’s lead investigator, Dr. Forman 
Williams of the University of California at San Diego, said, 
“On the ground, there have been a lot of studies on heptane. 
But all have been less than 2 millimeters in diameter. This is the 
first complete burn of a 3-millimeter diameter heptane 
droplet.” Williams said that “because in the atmosphere 
of normal air, we were able to observe a fuel droplet that burns for 
a longer period of time.” Additionally, as a fuel droplet 
burned in a spherical shape, the heat dissipated outward, and 
actually extinguished the flame before all the fuel vapor was 
completely burned away. This gave researchers that very pure look at 
the combustion process.



During MSL-1, samples were processed in the Large Isothermal Furnace 
to study the diffusion of tracers, or impurities, in melted germanium 
-- an element widely used as a semiconductor and alloying agent. This 
mission marks the first time diffusion in semiconductors has been 
studied in space. Findings may have applications for improving the 
performance of electronic components made from semiconductor 
materials, such transistors and integrated circuits.



The Physics of Hard Sphere experiment, which examined changes that 
occur during transition of a substance from liquid to solid and solid 
to liquid, could improve the design of metallic alloys and processing 
techniques. Initial findings from this mission show model crystals in 
this experiment grew faster in space than on Earth. Also, the time 
scale for particle movement or diffusion is considerably different 
than in low-gravity.



Researchers have gained yet a better understanding through MSL-1 of 
what makes certain types of heat transfer devices fail in space. In a 
study involving the Capillary-driven Heat Transfer Device, scientists 
have examined the device’s ability to transfer heat away from a 
particular location. In the future, these devices may be used to 
transfer heat from electrical equipment to radiators on spacecraft.



The benefits of these systems are that they weigh less than 
conventional units because they operate on evaporation and 
condensation, and are more economical because they do not require 
power. The experiment’s lead investigator, Dr. Kevin Hallinan 
of the University of Dayton, Ohio, said, “With the science 
learned on this mission, we’ve been able to characterize 
boundaries of what we call unstable operations which accelerates this 
transition to this failed -- or disrupted state. We are closer to our 
goal of understanding why the Capillary-driven Heat Transfer devices 
have failed in space -- yet succeed in 1-G (on the ground). We are 
confident new designs can be rendered that will work.”



A plant growth experiment on MSL-1 is examining the effect of space on 
certain types of plants. Scientists hope the study reveals how to 
manipulate processes to improve plant growth on Earth. Findings may 
also verify evidence that plants grown in microgravity require less 
metabolic energy to produce lignin, permitting greater production of 
secondary metabolites -- a source of many medicinal drugs. Secondary 
metabolites also may be used to attract, repel or poison insects. 
Plants being studied aboard MSL-1 include a source of the 
antimalarial drug artemisinin; a plant used in chemotherapy treatment 
of cancer; and a species widely used in the paper and lumber 
industries.



More than 700 crystals of various proteins were grown on MSL-1 during 
its 16-day mission. Knowledge of protein structures is very important 
to our everyday lives, as many diseases involve proteins, either 
directly or indirectly. The microgravity environment of space allows 
researchers to grow larger and higher quality crystal specimens. Back 
on Earth, scientists will perform X-ray diffraction studies on the 
specimens to determine their structures. Better understanding of a 
protein’s structure could allow scientists to design more 
effective drugs to treat diseases such as cancer, diabetes, 
alcoholism, chagus, AIDS and Alzheimer’s



In addition to contributing new scientific knowledge, the first 
Microgravity Science Laboratory has served as a bridge to 
America’s future in space, spanning the gap between 
today’s Spacelab and tomorrow’s International Space 
Station. It has used Spacelab as a transition vehicle -- testing 
hardware, facilities and procedures that will be used on Space 
Station.



Flying for the first time on MSL-1, the EXPRESS Rack, designed and 
developed at Marshall, demonstrated quick and easy installation of 
experiment and facility hardware in orbit. The rack will be used on 
Space Station.



Two payloads -- the Physics of Hard Spheres experiment and the 
Astro/Plant Generic Bioprocessing Apparatus experiment -- were flown 
on MSL-1 to check the design, development and adaptation of EXPRESS 
hardware. During this mission, the two experiments were transferred 
from the Shuttle middeck to the EXPRESS Rack, operated, and then 
returned to the middeck. “The procedure went beautifully with 
no problems,” said Cindy Sanderson, EXPRESS Operations 
Controller at Marshall. “We're very satisfied with our 
demonstration of the EXPRESS rack,” said Mission Manager 
Vanhooser: “The goals we set were accomplished.”



In all, 25 primary experiments, four glovebox investigations and four 
accelerometer studies flew on this mission of Columbia. The 
experiments were contributed by scientists from four international 
space agencies -- NASA, the European Space Agency, the German Space 
Agency and the National Space Development Agency of Japan.



A gauge to the amount of science research conducted aboard this 
mission is the record number of commands sent from Spacelab Mission 
Operations Control Center at Marshall to experiments aboard Columbia. 
The more than 35,000 commands sent broke the previous record of 
25,837 set in 1994.



Now, said Mission Scientist Robinson, “as Columbia prepares to 
return to Earth -- its mission accomplished -- it is time for 
researchers to get down to the task of analyzing the data. 
That’s going to keep everybody very busy for quite a while."

	
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