Orbital period change of Dimorphos due to the DART kinetic impact

Cristina A. Thomas*, Shantanu P. Naidu, Peter Scheirich, Nicholas A. Moskovitz, Petr Pravec, Steven R. Chesley, Andrew S. Rivkin, David J. Osip, Tim A. Lister, Lance A.M. Benner, Marina Brozović, Carlos Contreras, Nidia Morrell, Agata Rożek, Peter Kušnirák, Kamil Hornoch, Declan Mages, Patrick A. Taylor, Andrew D. Seymour, Colin SnodgrassUffe G. Jørgensen, Martin Dominik, Brian Skiff, Tom Polakis, Matthew M. Knight, Tony L. Farnham, Jon D. Giorgini, Brian Rush, Julie Bellerose, Pedro Salas, William P. Armentrout, Galen Watts, Michael W. Busch, Joseph Chatelain, Edward Gomez, Sarah Greenstreet, Liz Phillips, Mariangela Bonavita, Martin J. Burgdorf, Elahe Khalouei, Penélope Longa-Peña, Markus Rabus, Sedighe Sajadian, Nancy L. Chabot, Andrew F. Cheng, William H. Ryan, Eileen V. Ryan, Carrie E. Holt, Harrison F. Agrusa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision1, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement (β) was possible2,3. In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos4–6. Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be −33.0 ± 1.0 (3σ) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.

Original languageEnglish
Pages (from-to)448-451
Number of pages4
Issue number7957
Early online date1 Mar 2023
Publication statusPublished - 20 Apr 2023


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