Thruster Pointing Constrained Optimal Control for Satellite Servicing using Indirect Optimization

Future space missions such as in-space assembly of telescopes and on-orbit servicing require planning rendezvous and proximity operation trajectories that avoid thruster induced contamination of delicate components onboard the client spacecraft. Many spacecraft contain sensitive instruments or payloads which are prone to contamination by the thruster plumes of the servicing craft (chaser) and extreme care must be taken when performing rendezvous, proximity operations and docking during the servicing and assembly parts of the mission. In this work we introduce a thruster pointing constraint into an optimal control problem and solve it using indirect optimization techniques. The approach is simple to extend to different dynamical systems and the resulting (locally) fuel optimal trajectory significantly reduces the plume induced contamination, enabling a host of future space missions. In this work we present results of rendezvous trajectories under Clohessy-Wiltshire dynamics with a minimum thruster pointing constraint of 28 degrees with respect to the target.