With the successful impact of the NASA 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.
@article{arxiv.2307.16777,
title = {The Perturbed Full Two-Body Problem: Application to Post-DART Didymos},
author = {Alex J. Meyer and Harrison F. Agrusa and Derek C. Richardson and R. Terik Daly and Oscar Fuentes-Muñoz and Masatoshi Hirabayashi and Patrick Michel and Colby C. Merrill and Ryota Nakano and Andrew F. Cheng and Brent Barbee and Olivier S. Barnouin and Steven R. Chesley and Carolyn M. Ernst and Ioannis Gkolias and Nicholas A. Moskovitz and Shantanu P. Naidu and Petr Pravec and Petr Scheirich and Cristina A. Thomas and Kleomenis Tsiganis and Daniel J. Scheeres},
journal= {arXiv preprint arXiv:2307.16777},
year = {2023}
}