Human-Class Mars Entry, Descent, and Landing Trajectory Optimization Using Indirect Methods

Trajectory optimization problems involving entry, descent, and landing (EDL) on Mars are usually very difficult to solve, particularly for delivering human-class payloads to Mars. Previously, direct pseudospectral methods have been employed in solving one such human-class Mars EDL problem with HL-20 as a sample entry vehicle. Indirect methods had some numerical issues in solving this problem initially, which led to a several-year-effort in advancing these methods. This paper demonstrates the ability of the advanced indirect methods used in an optimization toolbox called Giuseppe for solving the complicated Mars EDL problem. HL-20 has been used in this study as a representative lifting body vehicle. A previously devised flying EDL technique involving dive, cruise, and loft phases is used in this paper. Using indirect methods the dive and cruise phases are found to be non-unique and are selected based on engineering judgement. Only the loft phase involves actual optimization and results in significant energy savings requiring lesser propellant for the terminal descent phase. Future work involves using indirect methods of optimization for maximizing the useful human-class payload delivered by a high-lifting parawing vehicle on the surface of Mars.