A numerical survey of transient co-orbitals of the terrestrial planets

We have investigated numerically the evolution of near-Earth asteroids (3753) Cruithne, (3362) Khufu, 1989 VA, (10563) 1993 WD, and 1994 TF2 that enter the coorbital regions of the Earth or Venus. We show that the coorbital libration modes identified in F. Namouni (1999, Icarus 137, 293-314) and F. Namouni et al. (1999, Phys. Rev. Lett. 83, 2506-2509) are strong enough to survive tens of thousands of years under planetary perturbations in the Solar System. We give a detailed analysis of the nature of libration modes as functions of the argument of perihelion. The effects of close approaches with the coorbiting planet as well as neighboring planets are characterized. Based on these results, we argue for a steady-state flux of objects temporarily captured in coorbital configurations with the planets. (C) 2000 Academic Press.