Space-based tests of gravity with laser ranging

Existing capabilities of laser ranging, optical interferometry, and metrology, in combination with precision frequency standards, atom-based quantum sensors, and drag-free technologies, are critical for space-based tests of fundamental physics; as a result of the recent progress in these disciplines, the entire area is poised for major advances. Thus, accurate ranging to the Moon and Mars will provide significant improvements in several gravity tests, namely the equivalence principle, geodetic precession, PPN parameters beta and., and possible variation of the gravitational constant G. Other tests will become possible with the development of an optical architecture that allows one to proceed from meter to centimeter to millimeter range accuracies on interplanetary distances. Motivated by anticipated accuracy gains, we discuss the recent renaissance in lunar laser ranging and consider future relativistic gravity experiments with precision laser ranging over interplanetary distances.