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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Petrology of Apollo 11 regolith breccias

Petrographic and mineral chemical data for 16 Apollo 11 regolith breccias show that: (1) the regolith breccias differ from soil 10084 with respect to agglutinate content, glass population, plagioclase compositions, and proportions of high-K mare and low-K mare basalt components; (2) the A-11 breccias and soil have highland components that are similar both in abundance and petrology; and (3) lunar regolith breccias provide a better comparison with howardites than do lunar soils. The data and observations are consistent with formation of the regolith breccias from immature soil. It appears that little or no highland material has been added to the Tranquillitatis regolith since the formation of the breccias.

Simon, S. B.↗
NASA NTRS2010

Complex Role of Secondary Electron Emissions in Dust Grain Charging in Space Environments: Measurements on Apollo 11 and 17 Dust Grains

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions. Knowledge of the dust grain charges and equilibrium potentials is important for understanding of a variety of physical and dynamical processes in the interstellar medium (ISM), and heliospheric, interplanetary, planetary, and lunar environments. The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. It has been well recognized that the charging properties of individual micron/submicron size dust grains are expected to be substantially different from the corresponding values for bulk materials and theoretical models. In this paper we present experimental results on charging of individual dust grains selected from Apollo 11 and Apollo 17 dust samples by exposing them to mono-energetic electron beams in the 10- 400 eV energy range. The charging rates of positively and negatively charged particles of approximately 0.2 to 13 microns diameters are discussed in terms of the secondary electron emission (SEE) process, which is found to be a complex charging process at electron energies as low as 10-25 eV, with strong particle size dependence. The measurements indicate substantial differences between dust charging properties of individual small size dust grains and of bulk materials.

Abbas, M. M.↗