A Pre-flyby View on the Origin of Asteroid Donaldjohanson, a Target of the NASA Lucy Mission

Abstract

The NASA Lucy mission is scheduled to fly by the main-belt asteroid (52246) Donaldjohanson on 2025 April 20. Donaldjohanson (DJ hereafter) is a member of the primitive (C-type class) Erigone collisional asteroid family located in the inner main belt in proximity of the source regions of asteroids (101955) Bennu and (162173) Ryugu, visited respectively by the OSIRIS-REx and Hayabusa2 missions. In this paper we provide an updated model for the Erigone family age and discuss DJ evolution resulting from nongravitational forces (namely Yarkovsky and Yarkovsky–O’Keefe–Radzievski–Paddack (YORP)), as well as its collisional evolution. We conclude that the best-fit family age is 155 Myr and that, on such timescales, both Yarkovsky and YORP effects may have affected the orbit and spin properties of DJ. Furthermore, we discuss how the NASA Lucy mission could provide independent insights on such processes, namely by constraining DJ shape, surface geology, and cratering history.

Keywords

• Main belt asteroids