Trajectory Design and Maneuver Performance of the OSIRIS-REx Low-Altitude Reconnaissance of Bennu

With more than a year of asteroid proximity operations, the OSIRIS-REx team was able to identify one primary and one backup site for sample collection. The next step was to finalize on-board, localized image libraries and site-specific terrain information prior to attempting sample acquisition. Collecting this information required additional, low-altitude asteroid flyby reconnaissance activities. These activities, referred to as ‘sorties’, involved special maneuver and trajectory designs, unique from any other OSIRIS-REx maneuver activity. In order to minimize time between flybys and decrease the total number of maneuvers required, this trajectory design departed from and returned to a frozen Sun-terminator plane orbit within the span of a few hours. This work discusses the trajectory design and performance of the four flybys that were used to collect key topographic science observations of the primary and backup sample sites, which helped lead to a successful sample collection.