Determination of Global Density Inhomogeneities and Stresses Inside the Moon

Abstract

The possible distribution of density and stress anomalies in the interior of the Moon is determined. For this purpose, we have developed a new solution of the incorrect inverse gravimetry problem developed by the authors, tested for the Earth and Mars. The idea of this solution is that the isostatic compensation depths are uniquely determined for the harmonics of the expansion of the relief heights in spherical functions based only on cosmic data on the gravitational field and the relief of the planet. We have shown that possible isostatic relief compensation is carried out in the depth range of 0–530 km. The most probable compensation depths in this range were determined and the distribution of compensation masses at these depths was found. For the remaining harmonics, two other compensation options were chosen: (1) compensation is carried out at two levels, the first of which is the mean depth of the crust of 2.7 km, corresponding to a layer of 0–10 km; the possible depths for the second level were determined from an analysis of the results obtained for isostatically compensated harmonics; (2) uncompensated harmonics of the relief lead to vertical stresses in the Moon’s lithosphere reaching the compressive strength (16 MPa) and tensile strength (15 MPa).