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 Delta(M-G/M-I)(EP)=(-1.0+/-1.4)x10(-13). This result yields a strong equivalence principle (SEP) test of Delta(M-G/M-I)(SEP)=(-2.0+/-2.0)x10(-13). Also, the corresponding SEP violation parameter eta is (4.4+/-4.5)x10(-4), where eta=4beta-gamma-3 and both beta and gamma are post-Newtonian parameters. Using the Cassini gamma, the eta result yields beta-1=(1.2+/-1.1)x10(-4). The geodetic precession test, expressed as a relative deviation from general relativity, is K-gp=-0.0019+/-0.0064. The search for a time variation in the gravitational constant results in G/G=(4+/-9)x10(-13) yr(-1); consequently there is no evidence for local (similar to1 AU) scale expansion of the solar system.