LUNAR LASER RANGING - A CONTINUING LEGACY OF THE APOLLO PROGRAM

On 21 July 7 1969, during the first manned lunar mission, Apollo 11, t he first retroreflector array was placed on the moon, enabling highly accurate measurements of the Earth-moon separation by means of laser r anging. Lunar laser ranging (LLR) turns the Earth-moon system into a l aboratory for a broad range of investigations, including astronomy, lu nar science, gravitational physics, geodesy, and geodynamics. Contribu tions from LLR include the three-orders-of-magnitude improvement in ac curacy in the lunar ephemeris, a several-orders-of-magnitude improveme nt in the measurement of the variations in the moon's rotation, and th e verification of the principle of equivalence for massive bodies with unprecedented accuracy. Lunar laser ranging analysis has provided mea surements of the Earth's precession, the moon's tidal acceleration, an d lunar rotational dissipation. These scientific results, current tech nological developments, and prospects for the future are discussed her e.