Initial Results of a New Method for Optimizing Low-Thrust Gravity-Assist Missions

Kurzfassung

Further exploring our solar system is continuously becoming more challenging, thus gravity-assists and low-thrust propulsion are typical mission enablers. Combining both has the potential to improve performance even more. Typically, optimization for low-thrust gravity-assist missions is conducted only for the trajectory. To improve results, it is however desirable to include finding the gravity-assist in the optimization. This paper presents a method, able to evaluate a large number of mission candidates, defined by gravity-assist maneuvers and the trajectories in between, with the gravity-assist partner as one control variable. A heuristic search is conducted under application of a shape based trajectory model. The paper explains the structure of the control variables and their repercussions on the optimization and presents the initial results obtained for three major questions: Is the method overall usable? Can the search space be pruned with constraints based on the maximum obtainable Δv and the pool of possible gravity-assist partners? Can evolutionary algorithms be used to optimize such missions with the given method? The basic method has been effective in finding optimal gravity-assist partners for single-gravity-assist missions and shows potential for multi-gravity-assist missions as well. Derived from the optimization performance some conclusions about the search space topography are drawn.