Improved modelling of the Earth-Moon system

The successful realisation of Lunar Laser Ranging (LLR) measurements with infrared wavelength in recent years has led to an increase in highly accurate LLR data. In order to make the best possible use of the potential of the high-precision observations, the evaluation of the data must be adapted accordingly. This includes, on the one hand, a refined modelling of the involved reference frames (e.g. for reflector coordinates and lunar ephemeris) as well as the investigation of the effects of a possible solid inner lunar core on the lunar libration and the extension of the simplified time delay model for the lunar tides to a model with frequency-dependent components, similar to that of the Earth. On the other hand, unmodelled effects such as geocentre variations, non-tidal station motions and solar mass loss have to be included in the LLR analysis. In the end, an improved LLR analysis model will be available that includes all the effects and features mentioned above. It will then be the basis for the evaluation of differential LLR observations as well as for a further investigation of relativistic quantities. Furthermore, the usefulness for the realisation of reference systems will be investigated if accurate clock measurements on the lunar surface are available.