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Lunar Laser Ranging Status: IfE acts as one of only four Lunar Analysis Centres of the International Laser Ranging Service (ILRS) worldwide, with strong concentration on relativistic effects in the Earth-Moon system. In the ILRS, Prof. Müller is LLR representative in the Governing Boar and member of the analysis working group. In the framework of the DFG research group "Earthrotation and Global Dynamic Process" (www.erdrotation.de) earth orientation parameters are determine and the LLR data are analysed.

Lunar Laser Ranging (LLR) basics: (download pdf-file) Lunar Laser Ranging (LLR) has provided observations for more than 36 years. There is enormous science potential of LLR to further our understanding of the dynamics of the Earth-Moon system (e.g. Earth orientation parameters or the secular increase of the Earth-Moon distance: 3.8 cm/year) and to determine relativistic quantities such as the equivalence principle or any time variation of the gravitational constant. The model is fully relativistic and complete up to first post-Newtonian (1/c2) level (see, e.g., Müller and Nordtvedt 1998 or Müller 2000, Müller et al. 2006 and references therein). Using LLR data, various tests of Einstein's theory of relativity can be performed. In particular, the following selected post-Newtonian parameters can be derived (for a more complete description see Müller et al., 2006). The nominal values for general relativity are given in parentheses:

Determinations for relativistic parameters and error limits from recent analysis at the IfE are given in Table 1 (see Müller et al. 2006, for more details). LLR has become the strongest tool for testing Einstein's theory of gravitation in the solar system with improving limits, as new data are being acquired. No violations of general relativity have been found so far. With respect to geodetic parameters, solutions for combined EOP series and the realisation of various reference frames (e.g. the ITRF2000) were provided. The Moon orbit itself serves as highly accurate dynamic realisation of an inertial reference system. LLR data were also used in the computation of solar system ephemeris. The reflector coordinates on the lunar surface contributed to the realisation of a selenocentric system and in combination with high resolution images to accurate lunar maps.

Observatories : Grasse (France), McDonald (USA), Wettzell (Germany) und Hawai (USA). Links: ILRS:  http://www.dgfi.badw-muenchen.de/edc/ilrs/ilrs.gsfc.nasa.gov/index.html ITRF:  http://lareg.ensg.ign.fr/ITRF/ IERS:  http://www.iers.org/ FESG: http://tau.fesg.tu-muenchen.de/~fesg/web/index.php

For further informations contact: Prof. Dr.-Ing. Jürgen Müller Dipl.-Ing. Lilliane Biskupek

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