Design of guidance laws for lunar pinpoint soft landing

Future lunar missions ask for the capability to perform precise Guidance, Navigation and Control (GNC) to the selected landing sites on the lunar surface. This paper studies the guidance issues for the lunar pinpoint soft landing problem. The primary contribution of this paper is the design of descent guidance law based on the Pontryagin maximum principle. The simulation shows that the proposed polynomial guidance law can achieve precise pinpoint landing. However it is sensitive to the selection of several parameters. Suggestions on lunar pinpoint soft landing strategies are also given according to the simulation results.