Analytical Lunar Descent Guidance Algorithm

The desire to return humans to the moon has motivated the evaluation of existing lunar descent guidance algorithms and the development of new ideas. This paper outlines a design for a targeting algorithm that quickly and reliably generates a two-dimensional reference trajectory and a real-time three-dimensional guidance algorithm that can use this or any reference trajectory as its basis. The targeting algorithm is analytical in nature and allows for updates to the reference in real time. Monte Carlo analysis demonstrates the reliable performance of the algorithms in both a general sense and for retargeting once the lunar descent has been initiated.