Aerocapture Guidance, Navigation, and Control for Uranus Orbiter and Probe

The 2022 Planetary Science Decadal Survey identified the Uranus Orbiter and Probe (UOP) mission as the flagship mission for the 2020s decade. The current UOP design requires a Jupiter flyby and fully propulsive orbit insertion at Uranus but may be infeasible due to delays in development and launch opportunities. Aerocapture, an orbit insertion maneuver that utilizes atmospheric forces, can alleviate these challenges while providing a solution flexible to different launch opportunities. While individual technologies that aerocapture leverages have been flight-proven, aerocapture has not been validated through a complete systems test. Aerocapture has been studied for many decades in three-degree-of-freedom (3-DOF) simulations but rarely in higher-fidelity six-degree-of-freedom (6-DOF) simulations. This paper presents the novel development of a 6-DOF closed-loop guidance, navigation, and control simulation framework allowing bank angle guidance commands and trim attitude to be achieved with reaction control system jet firings and closed-loop navigation feedback using inertial measurement unit data. The framework is used to assess the robustness of Uranus aerocapture in the presence of large environmental model uncertainties. Nominal and Monte Carlo trajectory results are compared to 3-DOF solutions to understand the higher-fidelity performance of the aerocapture design.