Approach and Maintenance Along the Sunlight for Spacecraft Based on the Impulsive Control

This paper investigates the impulsive control of spacecraft for close proximity approach and maintenance along the sunlight. The concept of approach along the sunlight means that a spacecraft approaches a target, with its position kept on the line connecting the target and the Sun. Firstly, the close proximity relative dynamics is established between the spacecraft and the target. Then the geometrical definition of the sunlight corridor is presented. By transforming the path constraint to the position constraint, a nonlinear programming (NLP) model is developed to describe the optimal impulsive control for the approaching. The time constrained fuel optimal strategy is obtained through solving the NLP model. In addition, the long term variations of the line connecting the target and the Sun are analyzed in the target’s local vertical local horizontal (LVLH) coordinate frame. And an impulsive control strategy is proposed for position maintenance along the sunlight, which is based on the sampling of impulse epochs and positions as well as the dynamical fitting technique. Finally, numerical simulations are conducted to verify the proposed control strategies. The results indicate that the spacecraft can successfully conduct the approach and maintenance, with the sunlight corridor constraint satisfied.