Abstract
view Abstract Citations (5) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Laboratory Photometric Studies Relevent to the Lunar Surface. Hapke, Bruce W. Abstract Optical characteristics of a variety of rock and rock powder surfaces have been investigated with the obj ective of better understanding the photometric properties of the lunar surface. The characteristics measured were: the intensity, polarization and albedo of the surfaces as a function of angle and color. The effects of the following properties or treatments have been studied: particle size, compaction, chemical composition, irradiation by ~ rays and by H and He ions of solar wind energies. Only rock powders with particle size less than about 5 iL appear to be able to simultaneously match several of the optical characteristics of the moon. These fine powders need not be sifted to give the correct photometric function, as previously supposed (Hapke and Van Horn, Geophys. Rcs. 68, 4545, 1963); indeed, complex surfaces with high backscatter qualities can be produced by dropping the powder in a vacuum. Untreated rock powders do not match the moon; however, irradiation by 100 Conl/cm2 of 2 keV H or He ions darkens and reddens all fine rock powders and otherwise brings their photometric properties close to those of the moon. The primary cause of darkening appears to be due to the formation of coatings of nonstoichiometric compounds on the undersurfaces of the particles by the sputtering action of the solar wind. Doses of 106 R of ~ radiation have no noticeable effects. Chemical composition has only minor effects on properties of ion-bombarded fine powders. Generally, irradiated acidic rock powders are lighter than irradiated basic powders, but their properties are otherwise similar. Irradiated chrondritic meteorite powder has too large a polarization and insufficient color to match the moon, probably because of the large metallic Fe content. Publication: The Astronomical Journal Pub Date: 1965 DOI: 10.1086/109534 Bibcode: 1965AJ.....70Q.322H full text sources ADS |
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