Gross Estimates of the Conductivity, Dielectric Constant, and Magnetic Permeability Distributions in the Moon

Abstract

Sources of direct information on the electrical parameters of the moon include earth‐based astatic radar, earth‐satellite bistatic radar, lunar‐lander astatic radar, earth‐based radiothermic measurements, lunar orbital magnetic field measurements, and lunar‐lander magnetic attraction experiments. These pieces of information, when fitted to a reasonable geological model of the moon, permit estimation of the depth profiles of electrical conductivity, dielectric constant, and magnetic permeability. At lunar surface dc conductivities as low as 10‐12 mho/m may occur, and conductivities as high as 10 mhos/m appear possible for the deep lunar interior. It is demonstrated that interpretation of the Explorer 35 lunar satellite magnetometer data is at present based on such inadequate theory that the above range of values of conductivity could be quite consistent with the orbital magnetic field data. Anomalous ‘dc’ dielectric constants as high as 1010 could exist in the lunar interior if pore water and metallic minerals are present in juxtaposition. Magnetic permeabilities as large as 1.7 can be present in the lunar surface rocks. Typical depth profiles of conductivity and dielectic constant that fall within the extremes noted above are presented.