Lunar global figure from mare surface elevations

Laser altimetry data from the Apollo 15, 16, and 17 missions show that the ringed maria surfaces lie on one particular reference surface and that the center of gravity is definitely displaced from the optical center. If these extensive surfaces are assumed to be near-hydrostatic surfaces, then there must have existed a time in lunar history when lunar tides, internal processes, or both were much different than they are today.