Asteroid (469219) 2016 HO3, the smallest and closest Earth quasi-satellite

TL;DR

This paper identifies asteroid 2016 HO3 as a long-term quasi-satellite of Earth, highlighting its dynamical behavior, potential as a study target, and the influence of planetary resonances on its orbit.

Contribution

It reports the discovery of 2016 HO3 as a quasi-satellite of Earth and analyzes its long-term orbital stability and dynamical behavior using full N-body simulations.

Findings

2016 HO3 is a quasi-satellite of Earth for nearly 100 years, with a potential to remain a long-term companion.

It is the closest known Earth quasi-satellite, making it accessible for future in situ studies.

Orbital stability is influenced by secular resonances and the mass of Jupiter.

Abstract

A number of Earth co-orbital asteroids experience repeated transitions between the quasi-satellite and horseshoe dynamical states. Asteroids 2001 GO2, 2002 AA29, 2003 YN107 and 2015 SO2 are well-documented cases of such a dynamical behaviour. These transitions depend on the gravitational influence of other planets, owing to the overlapping of a multiplicity of secular resonances. Here, we show that the recently discovered asteroid (469219) 2016 HO3 is a quasi-satellite of our planet -the fifth one, joining the ranks of (164207) 2004 GU9, (277810) 2006 FV35, 2013 LX28 and 2014 OL339. This new Earth co-orbital also switches repeatedly between the quasi-satellite and horseshoe configurations. Its current quasi-satellite episode started nearly 100 yr ago and it will end in about 300 yr from now. The orbital solution currently available for this object is very robust and our full N-body calculations show that it may be a long-term companion (time-scale of Myr) to our planet. Among the known Earth quasi-satellites, it is the closest to our planet and as such, a potentially accessible target for future in situ study. Due to its presumably lengthy dynamical relationship with the Earth and given the fact that at present and for many decades this transient object remains well positioned with respect to our planet, the results of spectroscopic studies of this small body, 26-115 m, may be particularly useful to improve our understanding of the origins -local or captured- of Earth's co-orbital asteroid population. The non-negligible effect of the uncertainty in the value of the mass of Jupiter on the stability of this type of co-orbitals is also briefly explored.