Corner-cube retro-reflector instrument for advanced lunar laser ranging
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Corner-cube retro-reflector instrument for advanced lunar laser ranging 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
Received: 27 September 2012 / Accepted: 29 October 2012 / Published online: 14 December 2012 © Springer Science+Business Media Dordrecht 2012
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 ground-based laser ranging facilities, the present LLR measurement accuracy is limited by the retro-reflectors currently on the lunar surface, which are arrays of small corner-cubes. 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 corner-cube could have a clear advantage. In addition, after nearly four decades of successful operations the retro-reflectors 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 retro-reflector 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 1-mm in a single pulse while being subjected to significant thermal variations
S. G. Turyshev () · J. G. Williams · W. M. Folkner · G. M. Gutt · R. T. Baran · R. C. Hein · R. P. Somawardhana Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-0899, USA e-mail: [email protected] J. A. Lipa · S. Wang Hansen Experimental Physics Laboratory, Department of Physics, Stanford University, Stanford, CA 94305-4085, USA
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Exp Astron (2013) 36:105–135
present on the lunar surface, and will have low mass to allow robotic deployment. Here we report on our design results and instrument development effort. Keywords Lunar laser ranging · Laser corner-cube retro-reflector · Moon
1 Introduction Since its initiation in 1969, lunar laser ranging (LLR) has contributed significantly to our understanding of the Moon’s internal structure and the dynamics of the Earth– Moon system. After initial deployment of the Apollo 11 corner cube retro-reflector (CCR) array [1, 2] two more CCR packages were set up by Apollos 14 and 15 (Figs. 1 and 2). In addition, two French-built CCR arrays were on the Lunokhod 1 and 2 rovers placed on the Moon by the Soviet Luna 17 and 21 missions, respectively (Fig. 3). Figure 4 shows the five LLR re
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