Density and porosity of the lunar crust from gravity and topography

Abstract

Newly obtained gravity and topography data of the Moon, combined with a lithospheric flexure model that considers both surface and subsurface loading, are used to place constraints on the density of the upper crust from a localized spectral admittance analysis. Subsurface loads are found to be relatively unimportant in the highlands, and when subsurface loads are neglected, the best fitting bulk densities for a number of highland regions are found to vary from 2590 to 2870 kg m−3, with a mean value of 2691 kg m−3. Crustal rock densities estimated from geochemical considerations and global iron and titanium abundances imply somewhat greater densities, which we interpret as porosity affecting the gravity‐derived bulk density estimates. The average porosity in the upper few kilometers of crust is calculated to be about 7.7%, which is consistent with porosity estimates of impact‐fractured meteorites and terrestrial impact craters.