Large Constellation De-Orbiting with Low-Thrust Propulsion

This paper deals with the propulsive phase of de-orbiting phase for coplanar satellites in large constellations. The design is conducted via two layers: the first layer is to design a time-optimal deorbiting trajectory for a single satellite; the second layer is to find the optimal de-orbit timing for each satellite to start the de-orbiting in order to minimize the total transfer time as well as the inner constellation collision risk. For the first layer, two de-orbit strategies are considered: the first strategy aims at lowering the perigee; the second strategy aims at reaching a natural de-orbiting corridor. For each strategy, the quasi time-optimal steering law is developed, and the secular variations of the orbital elements are derived by using the averaging technique. For the second layer, the inner constellation collision risk is evaluated by miss distance; the optimal de-orbit timings are found for different de-orbit sequences by using a multi-objective optimization technique.