Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session L4: Invited Symposium: The Role of Physics in NASA's Vision for Space Exploration |
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Sponsoring Units: DMP Chair: Darrell Jan, NASA JPL Room: LACC 515A |
Tuesday, March 22, 2005 2:30PM - 3:06PM |
L4.00001: Icosahedral Order in Undercooled Metallic Liquids - Impact on the Crystal Nucleation Barrier and Thermophysical Properties Invited Speaker: Over a half-century ago, Charles Frank argued that metallic liquids could be undercooled because of developing icosahedral short-range order (ISRO) in the liquid that is incompatible with the translational periodicity of crystal phases. Our recent high-energy x-ray diffraction and nucleation undercooling studies of electrostatically levitated droplets of a Ti-Zr-Ni liquid produced the first experimental proof of this hypothesis. In addition to coupling to the nucleation barrier for the ordered phase, the icosahedral order can significantly influence the thermophysical properties of the liquid. A sharp decrease in the specific heat that is correlated with the growing ISRO indicates a rapidly decreasing configurational entropy in the liquid, at temperatures far above the glass transition temperature. Surprisingly, our studies demonstrate that ISRO is evident even above the liquidus temperature in the Ti-Zr-Ni liquid as well as in liquid Ni. It is significantly distorted in liquid Ti, consistent with an increasing importance of the covalent character of the 3-d bonding, which frustrates the development of ISRO. Supported by NASA under contract NAG8-1682, and by the National Science Foundation under grant DMR 03-07410. [Preview Abstract] |
Tuesday, March 22, 2005 3:06PM - 3:42PM |
L4.00002: Inertial Navigation Invited Speaker: |
Tuesday, March 22, 2005 3:42PM - 4:18PM |
L4.00003: Microgravity Research: A Retrospective of Accomplishments Invited Speaker: During the early days of human spaceflight U.S. National Aeronautics and Space Administration (NASA) began giving researchers the ability to perform experiments under extremely low gravity conditions (microgravity). Early microgravity experiments were rudimentary and discovery driven. The limitations of such an approach were clear and in the early 1990s, NASA broadened its program significantly beyond those experiments that were destined to be flown to include a ground- based program that contained both experimental and theoretical investigations. The ground-based program provided a source of carefully designed microgravity experiments. This led to the program in the Physical Sciences Division that involved research in, for example, fluids, materials and low temperature physics. The impact of the microgravity research program has been the focus of a recent National Research Council report titled “Assessment of Directions in Microgravity and Physical Sciences Research at NASA.” We found that there have been numerous high impact ground-based and flight investigations. For example, NASA funding has been instrumental in elucidating the nature of surface-tension-driven fluid flows, dendritic crystal growth and the thermodynamics of phase transitions near critical points. Using this report as a basis, a discussion of the impact of microgravity research on the fields in which it is a part will be given. [Preview Abstract] |
Tuesday, March 22, 2005 4:18PM - 4:54PM |
L4.00004: Advanced Systems for Air and Water Quality Monitoring in Long Duration Human Flight Invited Speaker: Any space mission involving extended astronaut travel time must have an accompanying system for monitoring the quality of the onboard air and water. These systems must not only meet the detection criteria for undesirable species, at the detection limits set by NASA and the National Academy of Sciences. They must also meet generic requirements such as having low mass, volume, and power; requiring minimal astronaut assistance, and having minimal need for consumables. We will briefly review the criteria for acceptable air and water contamination levels. We will then review the monitoring methods presently in use, and those being developed. These methods include, for example, GCMS, ion mobility spectrometry, the ``electronic nose,'' infrared absorption, and solid phase extraction with colorimetry. [Preview Abstract] |
Tuesday, March 22, 2005 4:54PM - 5:30PM |
L4.00005: Panel Participant Invited Speaker: |
Tuesday, March 22, 2005 5:30PM - 6:06PM |
L4.00006: Panel member Invited Speaker: |
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