Assessing Propellant-Optimal Guidance for Crewed Lunar Descent

In this paper the propellant performance advantages of modern propellant-optimal powered descent guidance in a crewed lunar mission is accessed. Two recently developed indirect-method based optimal powered descent guidance algorithm are deployed in this study, one using the conventional bang-bang thrust solution, the other utilizing an optimal constant-thrust solution. The reduction of propellant usage by employing the optimal powered descent guidance approaches is shown to be substantial and meaningful in the context of the historical data from various Apollo lunar landing missions. Moreover, it is demonstrated in this paper that propellant-optimal and Apollo-era lunar descent guidance methods can be integrated to achieve the combined strengths of propellant efficiency and autonomous operations of the new technology, and robustness and high readiness level of legacy technology. The findings in this work could serve as references to the planning and design of a forthcoming crewed lunar mission.