1,4,6,- 1Institute of Space Research, DLR, Berlin, Germany
- 2NASA HQ, Washington, DC, USA
- 3Southwest Research Institute, Boulder, CO, USA
- 4The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
- 5Lockheed Martin Space, Littleton, CO, USA
- 6NASA Goddard Spaceflight Center, Greenbelt, MD, USA
On April 20, 2025, while crossing the Main Asteroid Belt, the NASA Lucy mission—en route to the Jupiter Trojan regions—encountered its second cruise target, the C-type asteroid (52246) Donaldjohanson.
During the fly-by, the L’LORRI instrument [1] acquired a series of images suitable for stereo reconstruction, covering about 40% of the asteroid’s surface. The images have a ground sampling distance ranging from 17 to 5 m/pixel and were taken at solar phase angles between 0.9° and 52°. Due to the asteroid’s slow rotation (with a spin period exceeding 10 days), no appreciable rotation was observed in the disk-resolved images.
To achieve global shape reconstruction and determine the spin state, we complemented the stereo-photogrammetric data with contour information (limb and terminator features) and lightcurve data. This lightcurve information was drawn from two sources: sequences acquired by L’LORRI during the two months preceding the approach [2]and ground-based lightcurves obtained over the past six apparitions. The ground-based observations had already revealed that Donaldjohanson is currently in a state of complex rotation.
By combining these datasets, we expect to develop a detailed digital shape model of the illuminated portion of the asteroid, along with a low-order model of its non-illuminated hemisphere. Additionally, we plan to derive the asteroid’s rotational dynamics and determine its inertia tensor—results that will be presented at the conference.
Acknowledgement: The Lucy mission is funded through the NASA Discovery program on contract No. NNM16AA08C
References: [1] Weaver, H.A., et al., Space Science Reviews, 219, 82, 2023. [2] Solanki et al., this meeting.
How to cite: Mottola, S., Preusker, F., Statler, T., Buie, M., Spencer, J., Barnouin, O., Bierhaus, E., Noll, K., Marchi, S., Levison, H., and Lucy Team, T.: Shape Reconstruction and Rotation State of Asteroid (52246) Donaldjohanson from Lucy Imaging and Ground-Based Photometry, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-1022, https://doi.org/10.5194/epsc-dps2025-1022, 2025.
