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The possible origin of the Near-Earth Asteroid Kamo’oalewa (469219) as Lunar ejecta

Presentation #321.08 in the session Asteroids: Origins (Oral Presentation)

Published onOct 23, 2023
The possible origin of the Near-Earth Asteroid Kamo’oalewa (469219) as Lunar ejecta

The Near-Earth Asteroid Kamo‘oalewa (469219) is exceptional among the small population of Earth’s co-orbitals due to its recurrent transitions between quasi-satellite and horseshoe orbital states, persisting over megayears as revealed by numerical simulations. The reflectance spectrum of this asteroid as measured by Sharkey et al. (2021), shows a similarity with lunar silicates, which, together with its very Earth-like orbit, suggests a possible origin of Kamo‘oalewa as a Lunar-Ejecta from a meteroidal impact. We explore with numerical simulations the dynamical behavior of particles with a large range of launch conditions from the surface of the Moon. These launched particles face a dynamical barrier for entry into Earth’s co-orbital space. However, a small fraction reach co-orbital states, some resembling Kamo‘oalewa’s orbital behavior with persistent transitions between quasi-satellite and horseshoe orbits. The favored launch conditions for such outcomes are launch velocities slightly above the lunar escape velocity, and launch locations from the Moon’s trailing hemisphere. Furthermore, we find that Kamo‘oalewa’s inclination may have been boosted by repeated close approaches with Earth. Our results lend support to the hypothesis that Kamo‘oalewa could indeed have originated as lunar ejecta. These findings also suggest that many lunar ejecta remain to be discovered among near-Earth asteroids. Dynamical pathways taken by lunar ejecta are complex and worthy of deeper investigation. For more details, please see our preprint here:

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