A Radio Science Experiment for the Ramses Mission to Apophis

This paper outlines the Radio Science Experiment (RSE) proposed for the RAMSES mission to asteroid (99942) Apophis, which will undergo a close Earth encounter in April 2029. This event provides a unique opportunity to study the asteroid's physical and dynamical changes under strong tidal forces. The experiment leverages a combination of Earth-based radiometric measurements, optical imaging, and inter-satellite links between the RAMSES mothercraft and deployable subcraft in proximity to Apophis. Using high-precision Doppler and optical navigation data, the RSE aims to estimate the asteroid's mass, gravity field, and spin state with unparalleled accuracy, furthering our understanding of near-Earth asteroid evolution and internal structure. Simulation results show the robustness of the proposed mission scenario, highlighting the critical role of multi-probe configurations and novel inter-satellite link technologies in achieving accurate gravity science results.