Orbital period change of Dimorphos due to the DART kinetic impact
Morrell, Nidia; Cheng, Andrew F.; Dominik, Martin; Agrusa, Harrison F.; Farnham, Tony L.; Naidu, Shantanu P.; Chabot, Nancy L.; Rivkin, Andrew S.; Bonavita, Mariangela; Khalouei, Elahe; Snodgrass, Colin; Sajadian, Sedighe; Knight, Matthew M.; Thomas, Cristina A.; Chesley, Steven R.; Holt, Carrie E.; Rabus, Markus; Chatelain, Joseph; Contreras, Carlos; Longa-Peña, Penélope; Ryan, William H.; Benner, Lance A. M.; Busch, Michael W.; Giorgini, Jon D.; Moskovitz, Nicholas A.; Ryan, Eileen V.; Skiff, Brian; Osip, David J.; Brozović, Marina; Pravec, Petr; Hornoch, Kamil; Kušnirák, Peter; Gomez, Edward; Greenstreet, Sarah; Lister, Tim A.; Scheirich, Peter; Bellerose, Julie; Rush, Brian; Taylor, Patrick A.; RoŻek, Agata; Mages, Declan; Seymour, Andrew D.; Jørgensen, Uffe G.; Polakis, Tom; Salas, Pedro; Armentrout, William P.; Watts, Galen; Phillips, Liz; Burgdorf, Martin J.
United States, Czech Republic, Chile, United Kingdom, Denmark, Germany, South Korea, Iran
Abstract
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.