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arXiv · 2610.35718

Post-DART impact ejecta re-accumulation on Dimorphos and implications for Hera gravity measurements

S. D. Raducan·Ö. Karatekin·M. Popescu
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Abstract

Context. The DART impact might have substantially modified the surface and near-surface structure of Dimorphos, affecting the morphology and gravity field that is to be measured by ESA's Hera mission. Aims. We investigate the post-impact redistribution of ejecta and its dependence on the assumed internal structure of Dimorphos. Methods. We performed high-resolution SPH simulations of the DART impact into two low-cohesion rubble-pile models, with and without a large central boulder. We followed the processes of ejecta re-accumulation and gravity evolution for six hours. Results. The impact ejects about 13% of Dimorphos's mass, most of which is re-accreted, producing near-global resurfacing. The ejecta blanket exceeds 8 m around the impact depression but is only a few tens of centimetres thick near the antipode, with similar large-scale deposition in both interior models. Local gravity changes reach about 10% of the pre-impact value. The central boulder affects the surface gravity only within the impact depression, where the removal of overlying material enhances its gravitational contribution. Conclusions. Hera will observe a surface and gravity field substantially modified by DART, which must be considered when interpreting measurements in terms of the internal structure of Dimorphos.

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S. D. Raducan, Ö. Karatekin, M. Popescu. 2026-10-26. Post-DART impact ejecta re-accumulation on Dimorphos and implications for Hera gravity measurements. https://doi.org/10.1051/0004-6361%2F202662657

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