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Updated: Jun 20, 2026

Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
The Lucy flyby of (52246) Donaldjohanson: A bilobed asteroid with tumbling rotation
Simone Marchi1, Harold F Levison1, Keith S Noll2,3
1Solar System Science and Exploration Division, Southwest Research Institute, Boulder, CO, USA.
Abstract:
The main belt asteroid (52246) Donaldjohanson (DJ) is a likely member of the Erigone asteroid family. This implies that DJ is a fragment of a larger parent body that was destroyed in a collision about 155 million years ago. We report observations taken during a flyby of DJ by the Lucy spacecraft. We found that DJ is composed of two heavily cratered lobes, connected by a smoother neck, with overall dimensions 8.8 kilometers (km) by 4.4 km by 3.1 km. The crater density is consistent with the Erigone family's age, except for craters <0.4 km, which have been preferentially erased. DJ rotates slowly in a tumbling state, likely owing to spin-down by radiative forces. Surface spectra show iron-bearing phyllosilicates, indicating moderate aqueous evolution on the parent body.
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