Interpretation of the Disk-Integrated Lightcurve of the Dinkinesh System as Observed by Lucy

Abstract

The Lucy mission, launched in October 2021, will encounter the first of its primary targets, the Trojan asteroids, in August 2027. A flyby of main-belt asteroid (MBA) Donaldjohanson in April 2025 had always been planned as a rehearsal and system test for the Trojan encounters [1]. However in early 2023 the project decided to spend a small amount of fuel to enable an additional close (430 km) flyby of MBA (152830) Dinkinesh on November 1st 2023, providing a valuable opportunity for an earlier rehearsal. Ground-based data showed Dinkinesh to be a typical small (~1 km diameter) S-type inner main-belt asteroid [2,3], and it was chosen only for its accessibility to the spacecraft. However, Lucy data has revealed it to be an exceptionally interesting science target, in particular due to the discovery of its satellite, now named Selam.