During the entry phase of a human lunar mission, an entry guidance algorithm is used to safely steer the return vehicle through the atmosphere to a target landing site. The PredGuid entry guidance algorithm is enhanced to improve performance and satisfy a set of assumed mission requirements. The enhanced algorithm utilizes an improved numeric predictor-corrector (NPC) to perform precision targeting and generate steering commands for direct, loft, and skip entry scenarios. Analyses show that an energy management approach for short-range targets was is required. The Enhanced PredGuid algorithm is tested and compared to previous versions of the PredGuid algorithm using high-fidelity six-degree-of-freedom simulation of vehicle dynamics. The enhanced algorithm features robust precision landing capability for target ranges from 2000 km to 10000 km and adequate deceleration management for target ranges greater than 2000 km.
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