Osiris-Rex Post-Tag Observation Trajectory Design and Navigation Performance

NASA’s OSIRIS-REx spacecraft successfully collected a sample of asteroid regolith
from the surface of near-Earth asteroid Bennu in October of 2020. Subsequent
imaging of the sampler head showed material leaking from the collection
mechanism, thus stowage of the sample precluded execution of any planned maneuvers
in the following days. Optical navigation imaging also ceased in the days
following sample collection. The desire to image the sample site to investigate
the results of the spacecraft-to-surface interaction led to the Navigation team designing
a trajectory to return to Bennu after several months in order to image the
surface one final time. After several iterations a trajectory design was created that
satisfied the numerous constraints that were levied in order to place utmost importance
on the safety of the spacecraft and stowed sample, while also closely emulating
previously obtained imaging conditions to provide a close comparison of site
pre- and post-contact. Significant analysis was necessary in order to reliably reacquire
the asteroid after several months without optical navigation imagery. The
final design required five maneuvers to return the spacecraft to Bennu and perform
a final flyby of the asteroid at a distance of 3.8 kilometers. Successful execution of
the phase provided key insights regarding the performance of the sample collection
activities and the subsurface composition of the asteroid.