Lunar Laser Ranging Contributions to Relativity and Geodesy

Abstract

Lunar laser ranging (LLR) is used to conduct high-precision measurements of ranges between an observatory on Earth and a laser retro-reflector on the lunar surface. Over the years, LLR has benefited from a number of improvements both in observing technology and data modeling, which led to the current accuracy of post-fit residuals of ~2 cm. Today LLR is a primary technique to study the dynamics of the Earth-Moon system and is especially important for gravitational physics, geodesy and studies of the lunar interior. LLR is used to perform high-accuracy tests of the equivalence principle, to search for a time-variation in the gravitational constant, and to test predictions of various alternative theories of gravity. On the geodesy front, LLR contributes to the determination of Earth orientation parameters, such as nutation, precession (including relativistic precession), polar motion, and UT1, i.e. especially to the long-term variation of these effects. LLR contributes to the realization of both the terrestrial and selenocentric reference frames. The realization of a dynamically defined inertial reference frame, in contrast to the kinematically realized frame of VLBI, offers new possibilities for mutual cross-checking and confirmation. Finally, LLR also investigates the processes related to the Moon's interior dynamics. Here, we review the LLR technique focusing on its impact on relativity and give an outlook to further applications, e.g. in geodesy. We present results of our dedicated studies to investigate the sensitivity of LLR data with respect to the relativistic quantities. We discuss the current observational situation and the level of LLR modeling implemented to date. We also address improvements needed to fully utilize the scientific potential of LLR.

12 pages, 15 figures, 2 tables. To appear in proceedings of the 359th WE-Heraeus Seminar on "Lasers, Clocks, and Drag-Free: Technologies for Future Exploration in Space and Tests of Gravity," ZARM, Bremen, Germany, May 30-June 1, 2005

References in corpus (3)

• Progress in Lunar Laser Ranging Tests of Relativistic Gravity
• Improving LLR Tests of Gravitational Theory
• Potential Capabilities of Lunar Laser Ranging for Geodesy and Relativity

Cited by in corpus (6)

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• Perturbation of the metric around a spherical body from a nonminimal coupling between matter and curvature
• Prospects in the orbital and rotational dynamics of the Moon with the advent of sub-centimeter lunar laser ranging
• Opportunities for Probing Fundamental Gravity with Solar System Experiments
• A Nonminimal Coupling Model and its Short-Range Solar System Impact
• Proposal for combined use of parallax and lunar laser ranging for Michelson-Morley experimentation