Lunar gravity: the first farside map.

A global lunar gravity field has been determined from data on the long-term motion of the Apollo 15 and Apollo 16 subsatellites and Lunar Orbiter 5. The nearside gravity map resolves major mascon basins and, in general, is in excellent agreemnent with the results of Muller and Sjogren. The farside gravity map is characterized by broad positive gravity in the highland regions with interspersed, localized, negative anomalies corresponding to major ringed basins. A comparison between global gravity and topography indicates that a thicker farside crust could be responsible for these gravitational differences between the two lunar hemispheres.