Integrated strategy of stationkeeping, autonomous navigation, and real-time geodetical recovery of gravity fields: application into asteroid Lutetia mission

An integrated strategy is proposed for asteroid orbiting, consisting of stationkeeping, autonomous navigation, and real-time geodetical recovery. It is designed to maintain the spacecraft on its nominal trajectory under some uncertainties from the spacecraft and the asteroid. Furthermore, it performs adaptive estimations on the mass and thruster of spacecraft, as well as the spherical harmonic coefficients and spin rate of the gravity field of asteroid. These estimations are then substituted into an extended Kalman filter for autonomous navigation, which has significantly reduced positioning errors. Inheriting the original idea of sliding mode control, the integrated strategy is designed to be adaptive and robust with control saturation. The accuracy and distribution of real-time geodetical recovery of Lutetia’s gravity fields are investigated by Monte Carlo simulations. Numerical simulations show that the proposed strategy can rapidly decrease the control errors and accurately estimate the aforementioned parameters.