A Lunar Laser Ranging Retroreflector Array for the 21st Century: Thermal and emplacement issues

Over the past 41 years, the Ranging Program to the Apollo Retroreflector Arrays has supplied the best accuracy for almost all of the tests of General Relativity and provided significant information on the composition and origin of the moon [1]. The Apollo arrays, the only experiment that is still in operation, initially contributed a negligible error. The ground stations have improved by more than two hundred so now the existing Apollo arrays contribute a significant fraction of the ranging errors. The University of Maryland, as the Principal Investigator for the original Apollo arrays, is now proposing a new approach [2], [3]. The investigation of this new techno logy, with Professor Currie as Principal Investigator, is currently being supported by two NASA programs. The new retroreflectors will support improved accuracy by a factor 10 to 100. In the array design, there are three major challenges: 1) Validate the ability to fabricate a Cube Corner Reflector (CCR) of the required specifications, which are significantly beyond the properties of current CCRs 2) Address the thermal and optical effects of solar radiation, reducing the transfer of heat from the CCR housing and 3) Validate an emplacement technique for the CCR package on the lunar surface.