Orbital Period Change of Dimorphos Due to the DART Kinetic Impact

分类： 天文学 >> 天文学 提交时间： 2023-02-19

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 Snodgrass

摘要： 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 minutes was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement ($\beta$) was possible. In the years prior to impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos. 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 (3$\sigma$) minutes. 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 significant amount of momentum to the asteroid beyond what the DART spacecraft carried.

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