Earth Rotation and Lunar Laser Ranging (LLR)
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.
For the improvement of the gravitational interaction of Earth and Moon the Model of the Earth Gravity Filed was replaced by the more precise Model EGM2008. In the current approach the coefficients of the Gravity Field LP165P up to degree 4 are now used. Beside this, the Modelling of the athmospheric delays of the Laser Beam between the ground and the moon stations is improved by using the current Satellite laser Ranging (SLR) Model. To avoid upcomming systematic effects introduced by unexact rotation parameters and to improve the determination of Nutation coefficients, an approach is analysed by modelling one additional Rotation Transformation between the Quasar fixed and Earth fixed co-ordinate system.
A possible inconsistency of the equivalence principle, parameterized by the Nordtvedt Parameter η as well as the unifomity of the gravitational constant g was analysed, using the present LLR Data series from 1970 to 2010 as well as the before mentioned improved approach.
The Nordtvedt Parameter η could be determined by an accuracy of 5.2⋅10-4 and a possible linear drift of the gravitational constant of 4⋅10-31. These values are hard below the limit of injury of Einstein's Gravity Theory.
In March 2010 the station MRLO (Matera, Italy) restart measurements to the moon. At the same time a successful measuring to the reflector of the lunochod-1 Rover could be carried out after 40 years. As the LLR Analysis Software package of IfE was reviewed, the additional data could be used for the Determination of the Earth Rotation Parameters.
Research Projects | Earth Rotation and Lunar Laser Ranging
Within the Research Field of Earth Rotation and Lunar Laser Ragning current projects with and international relevance are perfomed. The important knowledge, origine from the observation of our near satellite, the moon, develop our comprehension of the Earth's system. Please follow the Link below for further information.