Rapid Design of High-Fidelity Low-Thrust Transfers to the Moon

Abstract

Low-thrust trajectories to the moon are attractive for many proposed and selected SmallSat missions due to their low-fuel requirements and reduced launch cost. However, designing these trajectories is computationally expensive, making design space exploration prohibitively difficult for these low-budget missions. In this paper, we introduce a new method to rapidly produce near-optimal, high-fidelity trajectories in cislunar space using the Q-Law guidance algorithm. By combining forward- and backward-propagated Q-Law, we generate continuous trajectories from an Earth parking orbit to a target lunar orbit. The Q-Law result can then be refined using direct collocation. To demonstrate this process, we solve a problem inspired by the SMART-1 mission and compare to literature results. We then apply this method to two SmallSat mission scenarios and demonstrate that this technique can be used to efficiently explore the trajectory trade space and provide powerful initial guesses for direct optimization.