Optimal Control Problem for Low-Thrust Multiple Asteroid Tour Missions

The use of low-thrust propulsion systems makes very complex missions possible. Among them, multiple asteroid missions have not been the subject of much study. The design of such missions requires visiting a high number of targets. The mathematical problem is of large dimensionality, and to guarantee high accuracy, an efficient solution method should be proposed. This paper presents a possible formulation of the problem.An indirectmethod is used to formulate a multiple asteroid mission problem, which includes specific control constraints necessary for effective control and operations when approaching an asteroid for flyby. No a priori knowledge of the control structure is required. Special care is given to the Jacobian structure formaximum efficiency. The algorithm is implemented with parallelization for computational speed. Overall, the formulation demonstrates robustness in solving highdimensional optimal control problems using an indirect approach, which would mostly be impossible with direct methodswithout significantly impacting the solution accuracy. Interplanetary trajectories are presented as examples of the method. For instance, the method is applied to the problem of the fourth edition of the Global Trajectory Optimisation Competition, and it optimizes a mission scenario with as many as 42 asteroid flybys.