Research > Earth Rotation and LLR

Earth Rotation and Lunar Laser Ranging (LLR)

Present 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.


A portion of the Apollo 15 lunar laser ranging retroreflector array, as placed on the Moon and photographed by D. Scott. Source: NASA/D. Scott.
A portion of the Apollo 15 lunar laser ranging retroreflector array, as placed on the Moon and photographed by D. Scott. Source: NASA/D. Scott.

The work on the Improvement of the existing Models and the Lunar Laser Rangign Analysis Software Packages were contnued by  Dipl.-Ing. Liliane Biskupek (DFG) and Dipl.-Ing. Franz Hofmann (QUEST).

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.

DFG-Research Group Earth Rotation and global dynamic Processes

Link to the web pages of the DFG-Research Group Earh Rotation  and globale dynamic Processes

QUEST University Hannover

Earth Rotation and Lunar Laser Ranging

International Earth Rotation and Reference System Service (IERS)

International Earth Rotation and Reference Frame Service
Last Change: 23.04.2013
 
Editorial Responsibility IfE web service