The Dynamical State of the Didymos System Before and After the DART Impact
Abstract
NASA's Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the natural satellite of (65803) Didymos, on 2022 September 26, as a first successful test of kinetic impactor technology for deflecting a potentially hazardous object in space. The experiment resulted in a small change to the dynamical state of the Didymos system consistent with expectations and Level 1 mission requirements. In the pre-encounter paper Richardson (2022), predictions were put forward regarding the pre- and post-impact dynamical state of the Didymos system. Here we assess these predictions, update preliminary findings published after the impact, report on new findings related to dynamics, and provide implications for ESA's Hera mission to Didymos, scheduled for launch in 2024 with arrival in late December 2026. Pre-encounter predictions tested to date are largely in line with observations, despite the unexpected, flattened appearance of Didymos compared to the radar model and the apparent pre-impact oblate shape of Dimorphos (with implications for the origin of the system that remain under investigation). New findings include that Dimorphos likely became prolate due to the impact and may have entered a tumbling rotation state. A possible detection of a post-impact transient secular decrease in the binary orbital period suggests possible dynamical coupling with persistent ejecta. Timescales for damping of any tumbling and clearing of any debris are uncertain. The largest uncertainty in the momentum transfer enhancement factor of the DART impact remains the mass of Dimorphos, which will be resolved by the Hera mission.
Cite
@article{arxiv.2502.14990,
title = {The Dynamical State of the Didymos System Before and After the DART Impact},
author = {Derek C. Richardson and Harrison F. Agrusa and Brent Barbee and Rachel H. Cueva and Fabio Ferrari and Seth A. Jacobson and Rahil Makadia and Alex J. Meyer and Patrick Michel and Ryota Nakano and Yun Zhang and Paul Abell and Colby C. Merrill and Adriano Campo Bagatin and Olivier Barnouin and Nancy L. Chabot and Andrew F. Cheng and Steven R. Chesley and R. Terik Daly and Siegfried Eggl and Carolyn M. Ernst and Eugene G. Fahnestock and Tony L. Farnham and Oscar Fuentes-Munoz and Edoardo Gramigna and Douglas P. Hamilton and Masatoshi Hirabayashi and Martin Jutzi and Josh Lyzhoft and Riccardo Lasagni Manghi and Jay McMahon and Fernando Moreno and Naomi Murdoch and Shantanu P. Naidu and Eric E. Palmer and Paolo Panicucci and Laurent Pou and Petr Pravec and Sabina D. Raducan and Andrew S. Rivkin and Alessandro Rossi and Paul Sanchez and Daniel J. Scheeres and Peter Scheirich and Stephen R. Schwartz and Damya Souami and Gonzalo Tancredi and Paolo Tanga and Paolo Tortora and Josep M. Trigo-Rodriguez and Kleomenis Tsiganis and John Wimarsson and Marco Zannoni},
journal= {arXiv preprint arXiv:2502.14990},
year = {2025}
}
Comments
24 pages, 11 figures