Reducing uncertainties in the determination of the Earth's GM

For the past fifty years, geodetic satellites have contributed to improve our knowledge on various Earth's physical behaviors. The purpose of this paper is to reassess the value of the geocentric gravitational constant (GM), defined by the product of the Earth's universal gravitational constant G and its mass M, from Satellite Laser Ranging (SLR) observations. Indeed, its relatively large uncertainty of 2.0 ppb (Ries et al., 1992) is not compatible with the final goal of the GENESIS MEO (Medium Earth Orbit) mission to realize the Terrestrial Reference Frame with an accuracy of 1 mm. The core of this analysis is based on the simultaneous estimation of the Earth's GM with laser station and satellite biases, taking the most of historical passive geodetic satellites, including three pairs of "twin" satellites to validate independently the accuracy of the newly derived GM value. Furthermore, by combining MEO and LEO (Low Earth Orbit) satellites, a consistent value of GM has been reassessed, this value being higher and less uncertain than the currently used reference value determined in 1992. In particular, the influence of errors in the modeling of the Earth radiation pressure and station coordinates on GM was evaluated.