Chance-Constraint Robust Trajectory Optimization with a Hybrid Multiple-Shooting Approach

During interplanetary flight, several sources of stochastic disturbances and dynamic uncertainties may deviate a spacecraft from its nominal trajectory. This paper proposes a systematic, robust trajectory design method, where quantitative information concerning uncertainty on the system dynamics and stochastic navigation errors are directly accounted for in the mission-planning process. A linear feedback control law is designed to steer the probability distribution of the spacecraft state toward a target distribution at an assigned final time, minimizing the propellant consumption while guaranteeing robustness to disturbance and uncertainties. A hybrid multiple-shooting approach is adopted, where the mean trajectory and the open-loop controls are optimized according to a multiple-shooting scheme, while a single-shooting scheme is adopted for propagating the first two statistical moments of the spacecraft state distribution. The proposed approach is applied to the analysis of the nominal interplanetary transfer phase of the future JAXA mission DESTINY+. The final dispersion on the state is expected to be reduced by a few orders of magnitude, with a small increase in fuel consumption.