In the USA, a new Lunar Laser Ranging (LLR) station will realise a novel measurement concept, namely differential LLR measurements. It can provide a new kind of observable, i.e., the range difference of two consecutive ranges (measured at time t1 and t2) got by fast switching of the measurement from one station to two or more reflectors. This previously unavailable observation will have an expected high accuracy of ~30 µm, resulting mainly from reducing Earth’s atmospheric error. This technique makes it possible to carry out more precise investigations of the lunar interior and of Einstein's theory of relativity, and the uncovering of remaining systematics in the analysis and modelling of the LLR measurements.

The main goal of this project is to prepare the use of the precise data from new differential LLR observations. For this purpose, the existing software has to be modified and extended accordingly. In the end, a joint evaluation of classical LLR data and differential LLR observations should be possible in order to combine the advantages of both measurement methods in the best possible way. As long as no real data are available, corresponding data are to be simulated via the institute's own software LUNAR.