Microgravity Research Opportunities for the 1990s (1995) / Chapter Skim
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Microgravity Research Opportunities for the 1990s: Chapter 2
Microgravity Research Opportunities for the 1990s: Chapter 2
Pages 37-52
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From page 37... ...
Fluid and thermal systems and materials processes that are EXECUTIVE SUMMARY essential to mission-enabling technologies for extended space operations will PART I generally behave differently under reduced gravity conditions. Microgravity CHAPTER 1 research opportunities will frequently be driven by the technological needs of CHAPTER 2 NASA's programs.
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From page 38... ...
Fields that will benefit significantly less from a microgravity environment are polymers, epitaxial layer growth on single-crystal substrates, large single inorganic crystal growth, and ceramics and glasses. It is noted that the common and major theme among the five recommended areas is that of fluid mechanics and transport phenomena.
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From page 39... ...
The duration of experiments, the regime of parameters available to experimenters, and the ability to demonstrate reproducibility of results in many microgravity experiments create the need for extended-duration orbiting platforms. The recommendations have value, however, whether such platforms become available or the microgravity program continues only with existing facilities.
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From page 40... ...
Also, the reduction of gravitational body forces leads to dominance by other forces normally obscured in terrestrial environments such as surface tension and electrical forces. Because fluid mechanics and transport processes are involved in most of the areas of microgravity research, they represent a common theme for much of the subject.
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From page 41... ...
The following topics deserve attention not only for their intrinsic scientific importance but also to provide a knowledge base for space technologies and applications: Convective processes at low Reynolds number. Investigation of low Reynolds number flows with density variations at reduced gravity levels will reveal the altered nature of transport phenomena in a new range of parametric conditions.
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From page 42... ...
2. In fire research, several subfields of combustion need to be investigated under microgravity conditions.
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From page 43... ...
3. A dedicated effort should be made to evaluate the potential advantages of the microgravity environment for the study of cellular interactions, cell fusion, and multicellular assembly and to identify candidate cell systems that show maximum response to being cultured in such an environment.
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From page 44... ...
Topics in the metals and alloys area that might benefit from focused microgravity research include the following items listed in order of general priority: 1. Nucleation kinetics and the achievement of metastable phase states, such as metallic glasses and nanostructures, are areas that could benefit from achieving deep supercooling in the microgravity environment, from the elimination of container surfaces, and from the reduction of melt flows due to buoyancy-driven convection.
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From page 45... ...
Precise transport data will be particularly useful for fluid dynamics computations, which are rapidly improving for terrestrial melt and solution growth. Any experiments on bulk crystal growth must be judged by their potential to contribute to the scientific understanding of the fundamental processes of crystal growth.
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From page 46... ...
Furthermore, transport measurements in industrially important fluids may be an important microgravity application outside the realm of large inorganic crystal growth. Growth of Epitaxial Layers on Single-Crystal Substrates During the terrestrial growth of epitaxial layers by vapor deposition, an effort is made to minimize the effects of flow, buoyancy, and boundary layer uniformity by rotating or spinning substrates during the growth process.
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From page 47... ...
3. Mass transport and diffusion studies of glass and ceramic melts under microgravity conditions should generate more precise data than those available from terrestrial measurements.
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From page 48... ...
If a space station is to be a useful contributor to the area of fundamental science, access to liquid-helium facilities will be mandatory. GENERAL SCIENCE RECOMMENDATIONS FOR MICROGRAVITY RESEARCH Following are a number of general science recommendations that are important for microgravity research: The reproducibility of results is a crucial element of laboratory science, and flight investigators should be given the opportunity to address reproducibility in their research.
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From page 49... ...
Therefore, if a space station centrifuge is to be developed, it is desirable to evaluate shared utilization for microgravity research. NASA should categorize experiments according to their minimum facility requirements to maximize scientific return and cost-effectiveness.
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From page 50... ...
ADMINISTRATIVE RECOMMENDATIONS The following recommendations do not directly address scientific issues but instead summarize administrative issues that profoundly affect the quality and quantity of the science content of the microgravity program. Meaningful interaction should be maintained between the principal investigators and NASA staff during experiment development and integration, and communication among these groups must be continued following flight.
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From page 51... ...
NASA should organize and maintain an accessible archive of microgravity research results. This archive should contain a bibliography of all published scientific papers and reports on microgravity subjects and should preserve the original spaceflight data sets, such as photographs and electronically recorded data.
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From page 52... ...
National Academy Press, Washington, D.C. Last update 4/12/00 at 3:48 pm Site managed by Anne Simmons, Space Studies Board file:///C|/SSB_old_web/mgoppch2.htm (16 of 17)
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