A Lunar Laser Ranging Retroreflector Array for the 21st Century

To date, lunar laser ranging to the Apollo retroreflector arrays, which are still operational after four decades, has produced some of the best tests of General Relativity. Since the ground Observatories have improved their accuracy by a factor of 200, the lunar hardware, due to the lunar librations, now limits the ranging accuracy. The Lunar Laser Ranging Retroreflector Array for the 21st Century program plans to deploy new packages that will improve the ranging accuracy by a factor of ten to one hundred in the next few years.