A new general model for the evolution of the spin vector of the two LAGEOS satellites and LARES and the LARASE research program

We present a new general model to calculate the evolution of the spin of passive, conductive and spherical satellites such as the two LAGEOS and LARES. The knowledge of the spin, both in orientation and rate, is of fundamental importance to model correctly the thermal effects on the surface of these satellites, as in the case of the solar Yarkovsky-Schach effect and of the Earth's Thermal drag. These are very important non-gravitational perturbations that produce long-term effects on the orbit of the cited satellites. Therefore, the improvement of the accuracy of the models developed to handle these perturbations represents a very significant result. Such enhancements, with the possibility of a more reliable orbit determination for the satellites, will be very useful in the field of General Relativity measurements with laser-ranged satellites, as well as in the fields of space geodesy and of geophysics.