Testing general relativity with satellite laser ranging and the laser ranged satellites experiment (LARASE) research program: current results and perspectives

LARASE aims to perform reliable measurements of the gravitational interaction in the weak-field and slow-motion limit of General Relativity (GR) by means of the laser tracking of the two LAGEOS and LARES satellites. These satellites are orbiting the Earth at a rather high altitude and their trajectory is known with an accuracy of a few cm level. By a least-squares fit of the ranging data it is possible to extract the GR effects on the orbital elements, namely in the Euler angles that define the orientation in space of the orbit, and by means of suitable combinations of such observables it is therefore possible to obtain the measurements of the GR precessions that arise from the Earth's gravitoelectric and gravitomagnetic fields, as well as from the de Sitter effect. These measurements represent the first step to obtain constraints of selected post-Newtonian parameter values in the field of the Earth, as well as to check the predictions of GR with respect to those of other theories for the gravitational interaction. In order to obtain these precise measurements of relativistic effects it is of primary importance to provide a reliable error budget based on an accurate evaluation of the main systematic error sources due to gravitational and nongravitational perturbations. In this talk the various ongoing LARASE activities will be presented and discussed, along with the current results regarding satellites dynamics modeling improvements, precise orbit determination and preliminary measurements of relativistic effects, with the perspectives for the final goals of this research program.