Testing Einstein's theory of gravity by analyzing lunar laser ranging data

Lunar Laser Ranging (LLR) data of more than 20 years have been used to accurately determine parameters of the Earth-Moon system (e.g., the mass of the system, the lunar tidal acceleration etc.), the station-reflector geometry, and other physical parameters like the solar quadrupole moment J₂^⊙. In addition to these, parameters suitable for testing metric theories of gravity in the first post-Newtonian approximation have been determined with great accuracy. These are the PPN (parameterized post-Newtonian) parameters γ and β, the Nordtvedt parameter ç, the geodetic precession of the lunar orbit Ω_GP, as well as a possible time variation of the gravitational constant G.