EPSC Abstracts
Vol. 18, EPSC-DPS2025-140, 2025, updated on 09 Jul 2025
https://doi.org/10.5194/epsc-dps2025-140
EPSC-DPS Joint Meeting 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Interior and gravity characterization of the C-type asteroid (52246) Donaldjohanson seen by NASA’s Lucy flyby
Masatoshi Hirabayashi1, Stefano Mottola2, Edward Bierhaus3, Daniel Britt4, Harrison Agrusa5, Olivier Barnouin6, Jennifer Scully7, Jessica Sunshine8, Simone Marchi9, Keith Noll10, John Spencer9, Harold Levison9, and Lucy Team
Masatoshi Hirabayashi et al.
  • 1Georgia Institute of Technology, Atlanta, GA, U.S.A. (thirabayashi@gatech.edu)
  • 2Institute of Space Research, DLR, Berlin, Germany
  • 3Lockheed Martin Space, Littleton, CO, U.S.A.
  • 4University of Central Florida, Orlando, FL, U.S.A.
  • 5Université Côte d'Azur, Observatoire de la Côte d’Azur, Nice, France
  • 6Johns Hopkins University Applied Physics Laboratory, Laurel, MD, U.S.A.
  • 7Jet Propulsion Laboratory California Institute of Technology, Pasadena, CA, U.S.A.
  • 8University of Maryland, College Park, MD, U.S.A.
  • 9Southwest Research Institute, Boulder, CO, U.S.A.
  • 10NASA/Goddard Space Flight Center, Greenbelt, MD, U.S.A.

NASA’s Lucy [1] successfully flew by the C-type asteroid (52246) Donaldjohanson [2] on April 20, 2025 [3]. The asteroid exhibited unique topographic and geological features [4-6]. While the imaged area was limited to the illuminated hemisphere at the time of the flyby, L’LORRI [7] and TTCAM [8] images reveal the asteroid’s elongated and contact binary shape [4, 9]. The asteroid has a highly elongated shape, about 8 km long, with a greater than 2:1 axis ratio [4].

We apply a mission-developed shape model [9] to investigate Donaldjohanson’s surface gravity field and structural properties. Due to its complex shape, escape speeds are low and vary along the body. The slow rotation does not contribute significantly to surface acceleration. We expect the interior to be dominated by compression, but the asteroid’s irregular topography makes the stress field complex. Given its slow spin period, our analysis is expected to be almost independent of the rotational effect.

The presentation will discuss Donaldjohanson’s structural and gravitational environment and the implications for its formation and evolution scenarios.

The Lucy mission is funded through the NASA Discovery program on contract No. NNM16AA08C. This study is also supported under the NASA Lucy PSP program.

 

[1] Levison et al. (2025), PSJ, 2:171, doi:10.3847/PSJ/abf840.

[2] Marchi et al. (2025), PSJ, 6:59, doi:10.3847/PSJ/adb4f4.

[3] Levison et al. (2025), this conference.

[4] Bierhaus et al. (2025), this conference.

[5] Scully et al. (2025), this conference.

[6] Nichols-Fleming et al. (2025), this conference.

[7] Weaver et al. (2023) SSR 219, doi:10.1007/s11214-023-01028-z.

[8] Bell et al. (2023) SSR 219, doi:10.1007/s11214-023-01030-5.

[9] Mottola et al. (2025), this conference.

How to cite: Hirabayashi, M., Mottola, S., Bierhaus, E., Britt, D., Agrusa, H., Barnouin, O., Scully, J., Sunshine, J., Marchi, S., Noll, K., Spencer, J., Levison, H., and Team, L.: Interior and gravity characterization of the C-type asteroid (52246) Donaldjohanson seen by NASA’s Lucy flyby, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-140, https://doi.org/10.5194/epsc-dps2025-140, 2025.