(101955) Bennu is a small, near-Earth asteroid that passes close to Earth about every six years. It was the target of NASA’s OSIRIS-REx mission to collect an asteroid sample and bring it to Earth.
This work focuses on periodic orbits in the vicinity of the asteroid (101955) Bennu. These orbits were computed and analyzed using a constant-density polyhedron model based on measurements from the OSIRIS-REx mission. Moreover the planar retrograde and direct families, orbit families emanating from equilibria, and families emanating from bifurcation points in other families were identified and analyzed. The authors claim that portions of the orbit families presented in this work were first identified by the second author et al. in [The dynamics about asteroid (101955) Bennu. Techn. Rep. AIAA 2022–2468, AIAA SCITECH 2022 Forum (2022; doi:10.2514/6.2022-2468)], but they were incomplete. Additionally, with respect to the aforementioned paper, here the authors consider slight modifications to the Bennu shape model.
One of the new features of this work is the use of the estimates of Bennu’s characteristics and shape based on measurements from the OISRIS-REx mission. The specific shape model used by the authors is the image-based stereophotoclinometry (SPC) v42 model (see [O. S. Barnouin et al., Nat. Geosci. 12, No. 4, 247–252 (2019; doi:10.1038/s41561-019-0330-x)]), which can be found in the JHUAPL Small Body Mapping Tool (SBMT).
Overall, there were many similarities to the structures identified using this model and the structures identified using simplified models like the homogeneous rotating gravitating tri-axial ellipsoid. While the asteroid does not have any perfect symmetry, a number of the orbit structures identified were nearly symmetric. Furthermore, many of the structures identified in this analysis were very similar to each other, and one expects a number of these structures evolve in similar ways. Ten distinct families were identified in this set, and many of the orbit structures were similar (e.g., the vertical families emanating from the equilibria behaved in similar ways), and several of these structures were connected to each other. By using numerical continuation, the authors identified 12 distinct families emanating from bifurcation points in the initial families. These 12 families could be classified into four types. Even though the model of Bennu had no exact symmetry, many nearly symmetric structures were identified. There were also many similarities to structures identified using simplified models like the homogeneous rotating gravitating triaxial ellipsoid.