Solar-Sail trajectory optimization for close proximity operations and rendezvous of space debris

Active debris removal (ADR) is recognized as one of the most effective strategies to address the ever-increasing problem of space debris. This thesis highlights the potential of solar sailing as a propellant-free propulsion method that offers an unlimited ΔV budget suitable for multiple debris removal missions. Traditional proximity operations are considered and their feasibility when using a solar sail is established for Low Earth Orbit (LEO) scenarios where space debris density is higher. Given the unique dynamics of solar sails, the study explores alternative trajectories such as Hold trajectories and Walking Safety Ellipses for target inspection, which improve passive safety by maintaining a collision-free path even in the event of sail failure. The transfer from a far-range phase point to an Inspection Loop is then examined. GPOPS-II, a software based on direct collocation methods, is employed to optimise these trajectories and to evaluate the effectiveness of these methods in addressing optimisation challenges specific to close-proximity operations. The results demonstrate that the proposed Hold and Inspection Loop Trajectories enable a safe approach to target debris, potentially reducing overall ADR mission costs due to the sailcraft’s propellantless nature.