Sensitivity Reduction and Lifetime Extension of Power-Limited Low-Thrust Trajectories

Planetary protection requirements and the need for robustness to unplanned temporary loss of control is a significant design concern for low-thrust missions in highly perturbed orbital environments. The purpose of this paper is to provide two easily implementable techniques for reducing the sensitivity and extending the lifetime of variable specific impulse low-thrust trajectories subject to temporary loss of control. Both methods leverage current trajectory design schemes based on optimal control. The first method aims at sensitivity reduction of the trajectory to control errors and is based on minimizing the angle between the controlled and the uncontrolled vector fields. The second technique focuses on extending a measure of trajectory lifetime and is based on inverse dynamics and backpropagation of an optimal trajectory. Simulation results in both the Earth–moon and the Jupiter–Europa system demonstrate the applicability and ease of implementation of the proposed methods.