Bound On Lunar Plate Motion

We analyzed high accuracy time delays of laser signals sent from the Earth to the retroreflector arrays on the Moon in conjunction with several other sets of solar-system astrometric data. Using especially the lunar laser ranging data obtained from the Apache Point Observatory telescope site in New Mexico and the Apollo 11 and Apollo 14 retroreflectors on the Moon, we have set a bound on their relative motion along the connecting great circle of 4 mm/yr over a 14-year period.