The lunar sub-satellite experiment of the ESA MORO mission: goals and performances

Abstract The global properties of the lunar gravity field, as well as the local anomalies on the far side and polar regions, are still largely unknown. They can be determined by means of a satellite-to-satellite tracking experiment. A low-low configuration is proposed, with a sub-satellite to be deployed from a main spacecraft orbiting around the Moon. The required measurement is the range rate between the two satellites, with an accuracy comparable to the current state of the art for space-borne equipment. It is shown how this can be accomplished with a very low mass sub-satellite, carrying no active attitude and thermal control. This experiment is compatible with the constraints of the lunar remote sensing mission MORO, currently under study by ESA.