The Perturbed Full Two-body Problem: Application to Post-DART Didymos

Alex J. Meyer, Harrison F. Agrusa, Derek C. Richardson, R. Terik Daly, Oscar Fuentes-Muñoz, Masatoshi Hirabayashi, Patrick Michel, Colby C. Merrill, Ryota Nakano, Andrew F. Cheng, Brent Barbee, Olivier S. Barnouin, Steven R. Chesley, Carolyn M. Ernst, Ioannis Gkolias, Nicholas A. Moskovitz, Shantanu P. Naidu, Petr Pravec, Petr Scheirich, Cristina A. ThomasKleomenis Tsiganis, Daniel J. Scheeres

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


With the successful impact of the NASA Double Asteroid Redirection Test (DART) spacecraft in the Didymos-Dimorphos binary asteroid system, we provide an initial analysis of the post-impact perturbed binary asteroid dynamics. To compare our simulation results with observations, we introduce a set of “observable elements” calculated using only the physical separation of the binary asteroid, rather than traditional Keplerian elements. Using numerical methods that treat the fully spin-orbit-coupled dynamics, we estimate the system’s mass and the impact-induced changes in orbital velocity, semimajor axis, and eccentricity. We find that the changes to the mutual orbit depend strongly on the separation distance between Didymos and Dimorphos at the time of impact. If Dimorphos enters a tumbling state after the impact, this may be observable through changes in the system’s eccentricity and orbit period. We also find that any DART-induced reshaping of Dimorphos would generally reduce the required change in orbital velocity to achieve the measured post-impact orbit period, and will be assessed by the ESA Hera mission in 2027.

Original languageEnglish (US)
Article number141
JournalPlanetary Science Journal
Issue number8
StatePublished - Aug 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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