Orion Reentry Guidance with Extended Range Capability Using PredGuid

Abstract

[Abstract] A reentry and precision landing algorithm using bank angle modulation control that enables precision landing for target locations between 2,400 km and 10,000 km downrange of Entry Interface (EI) was designed for the Orion spacecraft. The algorithm is general enough to be applicable to variations in Orion vehicle design. The algorithm was tested against various reentry scenarios including perturbations in initial entry conditions, vehicle mass, aerodynamic properties, and atmospheric density. The algorithm was shown to be robust to these uncertainties to allow a delivery error of less than 3.5 km for the entire 2,400 km – 10,000 km landing footprint. The guidance algorithm is based on the Apollo entry guidance algorithm and upgraded using PredGuid, a numeric predictor-corrector aerocapture algorithm developed by Draper Laboratory for the Aero-assist Flight Experiment in the late 1980’s. The upgrades were sufficient to allow precision landing of skip reentry trajectories for target ranges of up to 10,000 km. In addition, it was shown that skip trajectory shaping can be controlled by modulating the time at which the PredGuid guidance phase takes over.