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arXiv · 2502.14990

The Dynamical State of the Didymos System Before and After the DART Impact

Derek C. Richardson·Harrison F. Agrusa·Brent Barbee·Rachel H. Cueva·Fabio Ferrari·Seth A. Jacobson·Rahil Makadia·Alex J. Meyer·Patrick Michel·Ryota Nakano·Yun Zhang·Paul Abell·Colby C. Merrill·Adriano Campo Bagatin·Olivier Barnouin·Nancy L. Chabot·Andrew F. Cheng·Steven R. Chesley·R. Terik Daly·Siegfried Eggl·Carolyn M. Ernst·Eugene G. Fahnestock·Tony L. Farnham·Oscar Fuentes-Munoz·Edoardo Gramigna·Douglas P. Hamilton·Masatoshi Hirabayashi·Martin Jutzi·Josh Lyzhoft·Riccardo Lasagni Manghi·Jay McMahon·Fernando Moreno·Naomi Murdoch·Shantanu P. Naidu·Eric E. Palmer·Paolo Panicucci·Laurent Pou·Petr Pravec·Sabina D. Raducan·Andrew S. Rivkin·Alessandro Rossi·Paul Sanchez·Daniel J. Scheeres·Peter Scheirich·Stephen R. Schwartz·Damya Souami·Gonzalo Tancredi·Paolo Tanga·Paolo Tortora·Josep M. Trigo-Rodriguez·Kleomenis Tsiganis·John Wimarsson·Marco Zannoni
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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.

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Derek C. Richardson, Harrison F. Agrusa, Brent Barbee, Rachel H. Cueva, Fabio Ferrari, Seth A. Jacobson, Rahil Makadia, Alex J. Meyer, Patrick Michel, Ryota Nakano, Yun Zhang, Paul Abell, Colby C. Merrill, Adriano Campo Bagatin, Olivier Barnouin, Nancy L. Chabot, Andrew F. Cheng, Steven R. Chesley, R. Terik Daly, Siegfried Eggl, Carolyn M. Ernst, Eugene G. Fahnestock, Tony L. Farnham, Oscar Fuentes-Munoz, Edoardo Gramigna, Douglas P. Hamilton, Masatoshi Hirabayashi, Martin Jutzi, Josh Lyzhoft, Riccardo Lasagni Manghi, Jay McMahon, Fernando Moreno, Naomi Murdoch, Shantanu P. Naidu, Eric E. Palmer, Paolo Panicucci, Laurent Pou, Petr Pravec, Sabina D. Raducan, Andrew S. Rivkin, Alessandro Rossi, Paul Sanchez, Daniel J. Scheeres, Peter Scheirich, Stephen R. Schwartz, Damya Souami, Gonzalo Tancredi, Paolo Tanga, Paolo Tortora, Josep M. Trigo-Rodriguez, Kleomenis Tsiganis, John Wimarsson, Marco Zannoni. 2025-02-20. The Dynamical State of the Didymos System Before and After the DART Impact. https://doi.org/10.3847/psj%2Fad62f5

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