Sensitivity Analysis of the OSIRIS-REx Terminator Orbits to Maneuver Errors

OSIRIS-REx is NASA’s asteroid sample return mission that was launched in September of the year 2016 to Asteroid (101955) Bennu. The nominal orbit that is considered for large parts of the science phase of the mission is a Sun–terminator circular orbit. Sun–terminator orbits are quasi stable in environments where solar radiation pressure is the dominant perturbing force. However, because of highly non-Keplerian dynamics present in such an environment, small perturbations can lead to large deviations from the nominal trajectory. Such perturbations arise from errors in the maneuver executions, such as reaction wheel de-saturation maneuvers and orbit targeting maneuvers. In this study, analytical expressions that govern the secular motion of the perturbed orbit elements are derived. Furthermore, a set of Monte Carlo and numerical simulations is implemented to analyze the sensitivity of the terminator orbits to the maneuver execution errors and their uncertainties. Although this study focuses on the OSIRIS-REx mission terminator orbits, analytical derivations and conclusions of the study may be extrapolated to other terminator orbits about small bodies in an environment that is strongly perturbed by the solar radiation pressure.