Lunar moments, tides, orientation, and coordinate frames

To determine the lunar moments of inertia (A < B < C) it is necessary to determine three quantities. (C − A)B and (B − A)C come from Lunar Laser Ranging (LLR) measurement of the lunar orientation Spacecraft or lunar orbit perturbations provide J2 Combining five reported J2 results gives a normalized polar moment of inertia CMR2 = 0.3929 ± 0.0009 Solid-body tides displace the surface about 0.1 m, but can perturb the orbit of a Moon-orbiting spacecraft. The selenocentric coordinates of four lunar retroreflectors are accurately known and can serve as reference points. The orientation and orbit of the Moon are very well known for the time span of the LLR data.