Volume 5, Number 2     March/April 1997

  Aerospace Technology Development

Discoveries From Shuttle Experiments Could Have Great Impact

IGNIFICANT SCIENTIFIC DISCOVERIES from experiments conducted on two recent Space Shuttle missions could greatly improve life on Earth. NASA researchers, astronauts and university scientists responsible for the space-based experiments outlined their discoveries at a recent conference at the National Academy of Sciences, in Washington, D.C., held to mark the one-year anniversaries of the second U.S. Microgravity Laboratory (USML-2) and the third U.S. Microgravity Payload (USMP-3) missions.

Their discoveries are expected to lead to better synthetic drugs, less expensive alloys and metal products, improved environmental cleanup, a greater understanding of weather and climate and a greater knowledge of how blood clots in the human body. For example, the study of the compound cadmium zinc telluride is expected to result in improved radiation detectors, sensors and other electronic products. Dr. David J. Larson of State University of New York at Stony Brook discovered that crystals grown in space without touching the walls of their containers are of markedly higher quality than Earth-grown crystals.

Dr. John Hart of the University of Colorado at Boulder sought to better understand the flows in oceans and the atmospheres of planets and stars in the experiment "Geophysical Fluid Flow Cell." The study showed "banded," rotational patterns of flows, such as those seen in the atmosphere of Jupiter. The observations are expected to be of great importance in understanding weather patterns and climatic conditions on Earth.

Dr. J.J. Favier of the French Center of Nuclear Studies sought to discover how small disturbances in gravity affect the production of alloys and metals. Favier found structural changes resulted during crystal production because of tiny disturbances that occurred when the Space Shuttle's control jets were fired. The study showed fluid flow damage to the crystals could be eliminated when the growing metal's orientation was carefully controlled. This and other findings are expected to improve manufacturing processes for alloys used in airplane-engine turbine blades and electronic materials. They ultimately could bring dramatic improvements in materials manufacturing.

Successful antithrombin crystal growth experiments by Dr. Daniel Carter of NASA's Marshall Space Flight Center made it possible to further define the protein crystal's molecular model and activities in the human body. The crystals, which control blood coagulation in human plasma, are very difficult to grow on Earth because of the forces of gravity.

An experiment by Dr. Robert Gammon of the Institute for Physical Science and Technology at University of Maryland, College Park, demonstrated that physical measurements can be made in the microgravity of space that cannot be done on Earth. This finding provides insight into a variety of physics problems, ranging from state changes in fluids to alterations in the magnetic properties of solids. The results will be valuable in such fields as superconductors and liquid crystals. Gammon studied the behavior of an elemental gas at critical point in the experiment. At critical point, liquid and vapor become one fluid. The fluid collapses under its own weight at critical point on Earth, preventing precise experimentation.

As molten materials solidify during the production of most commercially important metal alloys, they form tiny, pine-tree-shaped crystals called dendrites, which dictate the hardness and integrity of the material. Previous studies indicated that small variations in the growth rate of these patterns in metal were caused by the microgravity environment of space. However, Dr. Martin Glicksman of Rensselaer Polytechnic Institute discovered that variations are controlled instead by the specimen size—contrary to previous conclusions. His findings will lead to the production of less expensive and more reliable cast or welded metal and alloy products.

Dr. Robert Apfel of Yale University has examined the influence of surfactants— substances that alter the surface properties of a liquid. Soap with water is an example of a surfactant-liquid interaction. Apfel's experiment found that surfactants can change the hydrodynamics of droplets. The findings will lead to new and improved technologies in manufacturing cosmetics and synthetic drugs, as well as oil recovery and environmental cleanup.

Dr. Taylor Wang of Vanderbilt University hit droplets with sound. He found that the droplets lost symmetry and began to rotate. The findings from this study promise improved technologies in the chemical processing and pharmaceutical industries and a better understanding of rain formation and weather patterns.

For more information, contact Steve Roy at the Marshall Space Flight Center.
Call 205/544-0034,Fax 205/544-5852.
Please mention you read about it in Innovation.