The contribution of a large baseline intersatellite link to relativistic metrology

The precise estimation of helio- and fundamental physics parameters is essential for an accurate modeling of the solar system. The enhancement of radio tracking performances will enable unprecedented measurements of celestial mechanics, approaching the ultimate limits attainable with a single planetary mission. We report in this study the results of our numerical simulations with a novel interplanetary mission configuration composed of two probes at different planets able to establish, apart from a classical ranging link with the Earth, an inter-satellite ranging link. It is shown how this configuration allows constraining planetary positions much more tightly compared with the case of Earth-based measurements only, leading to a very precise retrieval of fundamental and heliophysics parameters. Through the analysis of an extensive set of simulations we investigate the applicability and the beneficial effects that a large baseline intersatellite link introduces in the estimation process and we show that such a mission concept performs better than any other single-probe planetary mission with the same measurement accuracy. In particular we demonstrate that over short timescales (<2 years) the gain in terms accuracy in the retrieval of the parameters of interest is considerable and might lead to unprecedented improvements in terms of fundamental physics and solar system modeling.