Earth's Quasi-satellite Kamo'oalewa's Possible Origin as Lunar Ejecta

The most recently discovered quasi-satellite (QS) of the Earth is the near-Earth asteroid Kamo'oalewa (469219), which is exceptional amongst the sparse population of Earth's co-orbitals due to its long-term residence in its current QS state, as well as the long-term persistence of its horseshoe (HS) transitions revealed by numerical simulations. Kamo'oalewa's close proximity to Earth, as well as its unknown dynamical original and physical properties, make this body a scientifically compelling candidate for a future space mission (Venigalla et al. 2017; Jin et al. 2020).

Considering its very Earth-like orbit and its L-type reflectance spectrum, we explore the hypothesis suggested by Sharkey et al. (2021) that it might have originated in the Earth-Moon system as a debris-fragment from a meteroidal impact with the lunar surface. We carry out numerical simulations, using the open source REBOUND N-body software package, of test particles ejected from the Moon's surface at different locations and with a range of ejection velocities exceeding the lunar escape velocity. We find that most of these ejecta evolve into heliocentric orbits, but a small minority of these ejecta evolve into co-orbital states compatible with Kamo'olewa's dynamical behavior.