Libration-induced Orbit Period Variations Following the DART Impact

Meyer, Alex J.; Gkolias, Ioannis; Gaitanas, Michalis; Agrusa, Harrison F.; Scheeres, Daniel J.; Tsiganis, Kleomenis; Pravec, Petr; Benner, Lance A. M.; Ferrari, Fabio; Michel, Patrick (2021). Libration-induced Orbit Period Variations Following the DART Impact. The planetary science journal, 2(6), p. 242. IOP Publishing 10.3847/PSJ/ac3bd1

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The Double Asteroid Redirection Test (DART) mission will be the first test of a kinetic impactor as a means of planetary defense. In late 2022, DART will collide with Dimorphos, the secondary in the Didymos binary asteroid system. The impact will cause a momentum transfer from the spacecraft to the binary asteroid, changing the orbit period of Dimorphos and forcing it to librate in its orbit. Owing to the coupled dynamics in binary asteroid systems, the orbit and libration state of Dimorphos are intertwined. Thus, as the secondary librates, it also experiences fluctuations in its orbit period. These variations in the orbit period are dependent on the magnitude of the impact perturbation, as well as the system’s state at impact and the moments of inertia of the secondary. In general, any binary asteroid system whose secondary is librating will have a nonconstant orbit period on account of the secondary’s fluctuating spin rate. The orbit period variations are typically driven by two modes: a long period and a short period, each with significant amplitudes on the order of tens of seconds to several minutes. The fluctuating orbit period offers both a challenge and an opportunity in the context of the DART mission. Orbit period oscillations will make determining the post-impact orbit period more difficult but can also provide information about the system’s libration state and the DART impact.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences > Theoretical Astrophysics and Planetary Science (TAPS)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute

UniBE Contributor:

Ferrari, Fabio


500 Science > 520 Astronomy
600 Technology > 620 Engineering




IOP Publishing




Fabio Ferrari

Date Deposited:

06 Apr 2022 14:42

Last Modified:

05 Dec 2022 16:18

Publisher DOI:





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