Progress in Lunar Laser Ranging Tests of Relativistic Gravity

Analyses of laser ranges to the Moon provide increasingly stringent limits on any violation of the equivalence principle (EP) ; they also enable several very accurate tests of relativistic gravity. These analyses give an EP test of (M₆/M₈) ₄₏= (-1. 01. 4) 10^-13. This result yields a strong equivalence principle (SEP) test of (M₆/M₈) ₒ₄₏= (-2. 02. 0) 10^-13. Also, the corresponding SEP violation parameter is (4. 44. 5) 10^-4, where =4--3 and both and are post-Newtonian parameters. Using the Cassini, the result yields -1= (1. 21. 1) 10^-4. The geodetic precession test, expressed as a relative deviation from general relativity, is K₆₏=-0. 00190. 0064. The search for a time variation in the gravitational constant results in G/G= (49) 10^-13 yr^-1; consequently there is no evidence for local (1 AU) scale expansion of the solar system.