NH037-0004
Dimorphos’ orbital perturbation induced by shape modification of Didymos after the DART impact

Wednesday, 16 December 2020
Poster
Ryota Nakano1, Masatoshi Hirabayashi1, Harrison F Agrusa2, Alex Benjamin Davis3, Alex Meyer3, Yang Yu4, Kleomenis Tsiganis5, Brent Barbee6, Joshua R Lyzhoft6, Daniel Jay Scheeres3, Alessandro Rossi7 and Derek C Richardson2, (1)Auburn University, Aerospace Engineering, Auburn, AL, United States, (2)University of Maryland College Park, College Park, MD, United States, (3)University of Colorado Boulder, Ann and H.J. Smead Department of Aerospace Engineering Sciences, Boulder, CO, United States, (4)Beihang University, Beijing, China, (5)Aristotle University of Thessaloniki, Thessaloniki, Greece, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)CNR Istituto di Fisica Applicata “Nello Carrara”, Sesto Fiorentino, Italy
Abstract:
NASA’s Double Asteroid Redirection Test (DART) spacecraft is planned to be launched in 2021. As a demonstration of an asteroid deflection method, the spacecraft will collide with the target asteroid Dimorphos, the moon of the binary system Didymos, to assess DART’s planetary defense capability. After the DART impact, fragments are expected to be ejected from Dimorphos. There is a possibility that some ejecta may reach Didymos, which is rotating with a spin period of 2.26 h, and trigger shape modification at some level. Here, by using a Finite Element Model (FEM) computation approach for Full Two-Body Problem (F2BP) simulations (Yu et al., 2019), we assess how shape modification driven orbital perturbation would occur for Dimorphos. Assuming that such shape modification is axisymmetric, we introduce a single parameter to define the deformed shape: the ratio of the shortest axis for the deformed shape to that of the original shape. We vary the shape parameter from 1.0 to 0.9 in steps of 0.02. We use the nominal initial conditions from Agrusa et al. (2020) except for the inertia dyad of Didymos, which would be different for each shape modification case. The results show that shape modification causes non-negligible effects on the orbital position of Dimorphos compared to the nominal case. For example, if the shape parameter is 0.90, the relative orbital phase of Dimorphos in the deformed case compared to the nominal case is close to 1,600 degrees after 150 days. Even for a smaller shape modification case (shape parameter = 0.98), the relative orbital phase is more than 200 degrees after 150 days. This paper introduces how Dimporphos’ orbital perturbation depends on Didymos’ shape modification. Our investigations will help assess the deflection capability of DART and characterize the geophysical conditions of the Didymos system. We finally note that our FEM code was confirmed to provide results consistent with GUBAS, a simulation package for F2BP developed by Davis and Scheeres (2020).

References

Harrison F. Agrusa et al., Icarus, vol 349 (2020): 113849.

Alex B. Davis and Daniel J. Scheeres., Icarus, vol 341 (2020): 113439.

Yang Yu et al., Celestial Mechanics and Dynamical Astronomy, vol. 131, no. 11 (2019)

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