Cornercube retroreflector instrument for advance

Authors: Slava G Turyshev James G Williams William M Folkner Gary M Gutt Richard T Baran Randall C Hein Ruwan P Somawardhana John A Lipa Suwen Wang

Publish Date: 2012/12/14

Volume: 36, Issue: 1-2, Pages: 105-135

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Abstract

Lunar laser ranging LLR has made major contributions to our understanding of the Moon’s internal structure and the dynamics of the Earth–Moon system Because of the recent improvements of the groundbased laser ranging facilities the present LLR measurement accuracy is limited by the retroreflectors currently on the lunar surface which are arrays of small cornercubes Because of lunar librations the surfaces of these arrays do not in general point directly at the Earth This effect results in a spread of arrival times because each cube that comprises the retroreflector is at a slightly different distance from the Earth leading to the reduced ranging accuracy Thus a single wide aperture cornercube could have a clear advantage In addition after nearly four decades of successful operations the retroreflectors arrays currently on the Moon started to show performance degradation as a result they yield still useful but much weaker return signals Thus fresh and bright instruments on the lunar surface are needed to continue precision LLR measurements We have developed a new retroreflector design to enable advanced LLR operations It is based on a single hollow corner cube with a large aperture for which preliminary thermal mechanical and optical design and analysis have been performed The new instrument will be able to reach an Earth–Moon range precision of 1mm in a single pulse while being subjected to significant thermal variations present on the lunar surface and will have low mass to allow robotic deployment Here we report on our design results and instrument development effortWe thank Leon Alkalai W Bruce Banerdt Hamid Hemmati Michael Shao and Michael Werner of JPL for their interest support and encouragement during the work We also thank David Arnold Douglas Currie and Thomas W Murphy Jr for helpful conversations The work described in this report was performed at the Jet Propulsion Laboratory California Institute of Technology under a contract with the National Aeronautics and Space Administration

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