On September 26, 2022, NASA's Double Asteroid Redirection Test (DART) mission successfully impacted Dimorphos, the natural satellite of the binary near-Earth asteroid (65803) Didymos. Numerical simulations of the impact provide a means to explore target surface material properties and structures, consistent with the observed momentum deflection efficiency, ejecta cone geometry, and ejected mass. Our simulation, which best matches observations, indicates that Dimorphos is weak, with a cohesive strength of less than a few pascals (Pa), similar to asteroids (162173) Ryugu and (101955) Bennu. We find that a bulk density of Dimorphos, rhoB, lower than 2400 kg/m3, and a low volume fraction of boulders (<40 vol%) on the surface and in the shallow subsurface, are consistent with measured data from the DART experiment. These findings suggest Dimorphos is a rubble pile that might have formed through rotational mass shedding and re-accumulation from Didymos. Our simulations indicate that the DART impact caused global deformation and resurfacing of Dimorphos. ESA's upcoming Hera mission may find a re-shaped asteroid, rather than a well-defined crater.
@article{arxiv.2403.00667,
title = {Physical properties of asteroid Dimorphos as derived from the DART impact},
author = {S. D. Raducan and M. Jutzi and A. F. Cheng and Y. Zhang and O. Barnouin and G. S. Collins and R. T. Daly and T. M. Davison and C. M. Ernst and T. L. Farnham and F. Ferrari and M. Hirabayashi and K. M. Kumamoto and P. Michel and N. Murdoch and R. Nakano and M. Pajola and A. Rossi and H. F. Agrusa and B. W. Barbee and M. Bruck Syal and N. L. Chabot and E. Dotto and E. G. Fahnestock and P. H. Hasselmann and I. Herreros and S. Ivanovski and J. -Y. Li and A. Lucchetti and R. Luther and J. Ormö and M. Owen and P. Pravec and A. S. Rivkin and C. Q. Robin and P. Sánchez and F. Tusberti and K. Wünnemann and A. Zinzi and E. Mazzotta Epifani and C. Manzoni and B. H. May},
journal= {arXiv preprint arXiv:2403.00667},
year = {2024}
}