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

Abstract

A number of Earth co-orbital asteroids experience repeated transitions\nbetween the quasi-satellite and horseshoe dynamical states. Asteroids 2001 GO2,\n2002 AA29, 2003 YN107 and 2015 SO2 are well-documented cases of such a\ndynamical behaviour. These transitions depend on the gravitational influence of\nother planets, owing to the overlapping of a multiplicity of secular\nresonances. Here, we show that the recently discovered asteroid (469219) 2016\nHO3 is a quasi-satellite of our planet -the fifth one, joining the ranks of\n(164207) 2004 GU9, (277810) 2006 FV35, 2013 LX28 and 2014 OL339. This new Earth\nco-orbital also switches repeatedly between the quasi-satellite and horseshoe\nconfigurations. Its current quasi-satellite episode started nearly 100 yr ago\nand it will end in about 300 yr from now. The orbital solution currently\navailable for this object is very robust and our full N-body calculations show\nthat it may be a long-term companion (time-scale of Myr) to our planet. Among\nthe known Earth quasi-satellites, it is the closest to our planet and as such,\na potentially accessible target for future in situ study. Due to its presumably\nlengthy dynamical relationship with the Earth and given the fact that at\npresent and for many decades this transient object remains well positioned with\nrespect to our planet, the results of spectroscopic studies of this small body,\n26-115 m, may be particularly useful to improve our understanding of the\norigins -local or captured- of Earth's co-orbital asteroid population. The\nnon-negligible effect of the uncertainty in the value of the mass of Jupiter on\nthe stability of this type of co-orbitals is also briefly explored.\n