A new generation of ultra-sensitive electrostatic accelerometers for GRACE Follow-on and towards the next generation gravity missions

Abstract The sensor core configuration of the electrostatic accelerometers of the CHAMP, GRACE and GOCE missions has been especially designed for space applications and so optimized in regard to the weak level of acceleration to sustain and measure in orbit. The return of experience of these three gravity space missions which demonstrate the robustness and the performances of this family of space instruments, allows a better optimization of the design of the accelerometer in terms of thermal stability and operation reliability for the near future missions as GRACE follow-on. The paper presents the improvement of the GRACE-FO accelerometer with respect to the still in-orbit previous models and a status of its development. Nevertheless because the next generation of low-low satellite to satellite tracking missions will take advantage of interferometer laser ranging methods to improve their performance, the noise level of the accelerometer has also to be lowered, especially in the low frequency bandwidth. In addition to the measurement of the surface forces exerted on the spacecraft by the atmospheric drag, by the Sun radiation and by the Earths albedo and infrared pressures, the accelerometer instrument becomes a major part of the attitude and orbit control system by acting as a drag free sensor and by accurately measuring the angular accelerations. Onera proposes a new configuration much more compact with performances in a better adequacy with a next generation of small but drag compensated micro-satellites or geodesy missions.