The Lucy flyby of (52246) Donaldjohanson: A bilobed asteroid with tumbling rotation

Michael E. Brown, W. M. Grundy, J. R. Spencer, S. A. Stern, M. W. Buie, Richard P. Binzel, C. B. Olkin, H. A. Weaver, O. S. Barnouin, Carly Howett, Tod R. Lauer, J. W. Parker, Silvia Protopapa, Dennis C. Reuter, S. J. Robbins, A. Verbiscer, Michael A. Vincent, M. Pätzold, Joshua P. Emery, J. F. Bell, P. R. Christensen, V. E. Hamilton, W. F. Bottke, S. Marchi, Amy Simon, Keith Noll, Neil Dello Russo, E. B. Bierhaus, Brian A. Keeney, Harold F. Levison, David Vokrouhlický, Harrison Agrusa, Masatoshi Hirabayashi, Fiona Nichols‐Fleming, J. Geeraert, Eric Sahr, Rich Burns, D. Poland, S. Mottola, Frank Preusker, J. E. C. Scully, E. S. Costello, Coralie D. Adam, J. M. Sunshine, Julien Salmon, Thomas S. Statler, Brian H. May, Daniel Britt, H. H. Kaplan, Katherine Kretke, John Andrews, Kevin Berry, Emma Birath, Russell Carpenter, Mark Effertz, Kristen Francis, Sheila Gray, Katie Hegedus, David Kaufmann, Thomas Kennedy, Jim McAdams, Matthew Montanaro, Jon Pineau, Ishita Solanki, Dale Stanbridge, Brian Sutter

2026-06-18

SCID: 54.1/cksgh6h6

Abstract (AI)

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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DOI

10.1126/science.aec0503

Publication Date

2026-06-18

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Authors

Michael E. Brown

W. M. Grundy

J. R. Spencer

S. A. Stern

M. W. Buie

Richard P. Binzel

C. B. Olkin

H. A. Weaver

O. S. Barnouin

Carly Howett

Tod R. Lauer

J. W. Parker

Silvia Protopapa

Dennis C. Reuter

S. J. Robbins

A. Verbiscer

Michael A. Vincent

M. Pätzold

Joshua P. Emery

J. F. Bell

P. R. Christensen

V. E. Hamilton

W. F. Bottke

S. Marchi

Amy Simon

Keith Noll

Neil Dello Russo

E. B. Bierhaus

Brian A. Keeney

Harold F. Levison

David Vokrouhlický

Harrison Agrusa

Masatoshi Hirabayashi

Fiona Nichols‐Fleming

J. Geeraert

Eric Sahr

Rich Burns

D. Poland

S. Mottola

Frank Preusker

J. E. C. Scully

E. S. Costello

Coralie D. Adam

J. M. Sunshine

Julien Salmon

Thomas S. Statler

Brian H. May

Daniel Britt

H. H. Kaplan

Katherine Kretke

John Andrews

Kevin Berry

Emma Birath

Russell Carpenter

Mark Effertz

Kristen Francis

Sheila Gray

Katie Hegedus

David Kaufmann

Thomas Kennedy

Jim McAdams

Matthew Montanaro

Jon Pineau

Ishita Solanki

Dale Stanbridge

Brian Sutter

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