SIMULATION COMPARISON OF ENTRY AND POWERED DESCENT GUIDANCE ALGORITHMS FOR A HUMAN-SCALE MARS MISSION

Large uncertainty in atmospheric conditions at Mars make entry, descent, and landing a challenging task for human-scale missions that require safe and precise landing. Since the knowledge of the actual conditions is limited by the navigation system of the vehicle, guidance algorithms capable of accommodating these types of dispersions are critical to develop future human missions to Mars. This paper focuses on the performance comparison of two state-of-the-art numerical predictor-corrector (NPC) entry guidance algorithms and guidance approaches: one uses direct-force control and the other the conventional bank-angle control. The algorithms are applied to a reference human-scale Mars mission. Both algorithms are implemented in the Program to Optimize Simulated Trajectories II at the Langley Research Center. Three degree-of-freedom end-to-end simulations of the low lift-to-drag ratio NASA reference entry vehicle are used to compare the performance of both algorithms. Monte Carlo simulations enable performance comparison by introducing dispersions that the guidance algorithms must accommodate. The results from this study provide a comparative assessment of the current EDL guidance capability for human-scale Mars Mission.