Apollo-Derived Terminal Control for Bank-Modulated Mars Entries with Altitude Maximization

Abstract

This paper studies the performance of an Apollo-derived Entry Terminal Point Controller when used to fly bank-modulated entry trajectories at Mars. The trajectories have been optimized to achieve maximum altitude at a given Mach number, accounting for human-class entry constraints. Provided that typical entries at Mars result in high supersonic terminal velocities, the optimal trajectories considered in this paper are of interest to conduct entry, descent and landing of human-class payloads because final altitude maximization −a fair surrogate for time-to-ground maximization− is believed to be an interesting feature for the use of, yet undeveloped, non-propulsive deceleration systems. The guidance performance is evaluated under nominal and dispersed conditions for a variety of vehicle ballistic coefficients and lift-to-drag ratios. Overall, although the designed optimal trajectories accomplish their goal to a fair certainty, they present a number of guidance and control challenges. This paper presents those challenges and potential ways to address them.