Low-Thrust Trajectory Design for Controlled Deorbiting and Reentry of Space Debris

Space debris pose a serious threat to the safety and operations of space assets. Debris removal strategies and post-mission disposal operations are becoming more pertinent due to the catastrophic collisions and explosions that have occurred in orbit in the past two decades. An important aspect of any debris removal mission or post-mission disposal maneuver is the ability of debris object to deorbit and reenter into Earth's atmosphere in a controlled manner over an uninhabited area. This is considered one of the safest options since a controlled reentry can ensure the object falls in specific low-populated or unpopulated regions (e.g., South Pacific Ocean Uninhabited Area). In this work, an approach is detailed for designing controlled deorbiting and reentry trajectories for a small satellite equipped with a hybrid propulsion system. The maneuver is comprised of two phases: a) bringing the debris object from its initial orbit to a deorbit altitude using a low-thrust propulsion system and a set of optimum steering angles, and b) reentering the debris into Earth's atmosphere through an impulsive maneuver over the intended “splashdown” zone. The reentry and splashdown phases are investigated considering the uncertainties in the atmospheric model as well as the dynamics of the debris object's motion through the atmosphere. Due to the uncertainties in atmospheric dynamics, the splashdown area is identified through the inclusion of variations in atmospheric density and wind speed during the reentry maneuver. A number of simulation scenarios are provided in order to investigate the feasibility of the proposed approach for controlled removal and reentry of debris objects from orbit using a hybrid propulsion system.