A surface-layer representation of the lunar gravitational field

A surface-layer representation of the lunar gravitational field has been derived dynamically from the analysis of Doppler observations on both polar and equatorial lunar orbiters. The force model contained 600 discrete masses located on the mean lunar surface between the approximate boundaries of ±60° latitude and ±95° longitude. The derived major mascons were generally in agreement with a model based on polar orbits alone. A technique for combining the discrete mass gravitational field for the front side with a spherical harmonics expansion for the back side is described. Harmonic analysis of the resultant field shows that the higher end of the power spectrum roughly follows the decay rule predicted by W. M. Kaula in Nicolaides et al. [1963].