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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A least-square mixing model incorporating mare basalts, KREEP basalts, anorthosites, anorthositic gabbros, ultramafics, granites, and meteorites was used to estimate the abundances of rock components in lunar soil from the Apollo 11, 12, 15, Luna 16, and Surveyor 5 and 6 landing sites. The predominance of iron-rich mare basalt at the sites is indicated.
The thermal inertia of the Fra Mauro formation limits its rate of cooling. The calculations of Jaeger (1961) for the cooling of an extrusive sheet are used to estimate the time required for a central temperature drop of 10%. This time is found to be about 45 years. For a 90% temperature drop, the time is about 200 years. Analytical methods used in the investigations are discussed together with the diffusion of Rb and Sr within lunar basalt. Isochron diagrams for various minerals are presented.
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The terrestrial planets aggregated essentially from small particles, to begin as solid cool bodies with the same general compositions, and there is no possibility of an iron-core developing within any of them at any stage. Their differing internal and surface properties receive ready explanation from their different masses which determine whether the pressures within are sufficient to bring about phase-changes. The claim that the terrestrial core can be identified by means of shock-wave data as nickel-iron is based on theoretical misconception, whereas the actual seismic data establish an uncompressed-density value much lower than any such mixture could have. The onset of the Ramsey phase-change in the earth takes the form of a rapid initial collapse to produce a large core in metallic state which thereafter continues to grow secularly as a result of radioactive heating and leads to reduction of surface-area at long last adequate to account for folded and thrusted mountain-building.
Using a balloon borne double dE/dx total energy telescope, we have determined the isotopic composition of cosmic ray Li, Be and B nuclei in the energy range 100-250 MeV/nuc. The measured mass resolution for these nuclei is about 0.3 AMU. The observed isotopic composition is in agreement with that predicted on the basis of interstellar fragmentation with the exception of a deficiency of Be-10. If the low abundance of Be-10 is attributed to the decay of this radioactive isotope, we obtain a mean cosmic ray lifetime of 3.4 (plus 3.4 or minus 1.3) m.y.
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Men and materials performing in the environment of an operating nuclear reactor require shielding from the escaping neutron particles and gamma rays. For efficient shielding from gamma rays, dense, high atomic number elements such as iron, lead, or tungsten are required, whereas light, low atomic number elements such as hydrogen, lithium, or beryllium are required for efficient neutron shielding. The use of lithium hydride (LiH) as a highly efficient neutron-shielding material is considered. It contains, combined into a single, stable compound, two of the elements most effective in attenuating and absorbing neutrons.
The ratio Be/B depends on whether the confinement time of cosmic rays in the Galaxy is long or short compared to the radioactive half-life of Be-10. We report observations of this ratio which were obtained with a dE/dx-Cerenkov detector launched into a polar orbit on OGO-6 as part of the Caltech Solar and Galactic Cosmic Ray Experiment. Be/B ratios were determined for various rigidity thresholds up to 15 GV. We find no statistically significant rigidity dependence of the ratio, which is 0.41 plus or minus 0.02 when averaged over all observed cutoffs. Additional calculations suggest that if the present fragmentation parameters are correct, then the lifetime of cosmic rays in the Galaxy is less then 10 m.y.
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International cooperation in space programs is discussed. Early international efforts, such as the establishment of tracking station networks and utilization of communications and weather satellites, are outlined, and the Apollo-Soyuz Test Project and the Spacelab-Shuttle project are cited as major cooperative ventures. The ATS-6, Helios, and ERTS projects - which demonstrate the importance of international ties to the space program - are detailed.
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The investigation reported continues a study conducted by Tera et al. (1974). An attempt is made to summarize all of the data currently available in the literature on terra materials and to discuss the implications of the upper intersection with the concordia curve. Data on total rocks and some plagioclase separates are presented in a graph. The data appear to give further support to a model of a terminal lunar cataclysm associated with intense global bombardment at about 3.9 aeons.
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