3D Reconstruction of DART Ejecta at Dimorphos Reveals an Anisotropic, Filamentary Structure

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Abstract We present a 3D reconstruction of the ejecta plume generated by the DART impact on Dimorphos based on LUKE images acquired by LICIACube. Using adaptive histogram equalization and geometric coregistration from multiple vantage points, we identified and tracked extended ejecta features and reconstructed their 3D spatial distribution with a voxel-based method. The reconstructed ejecta field shows strong anisotropy. An azimuth-matched comparison with the published elliptical cone highlights coherent, direction-dependent departures from a simple conic surface, despite broad agreement on the global cone orientation. This quantifies nonaxisymmetric structures that cone models cannot capture. We derived lower limits to ejecta velocities ranging from 20 to 50 m s −1 , consistent with numerical simulations of hypervelocity impacts into weak, porous targets. Compared to laboratory experiments, these values correspond to few-meter launch depths, suggesting a significant role of near-surface boulders in the ejecta distribution. Complementing this ejecta filament analysis, we studied 105 isolated comoving diffuse ejecta features, tracked up to 7 km from the impact site. These features followed highly tangential (85 ∘ –92 ∘ from the impact direction) trajectories relative to Dimorphos’s surface. Their velocity distribution peaks around 50 m s −1 , indicating that crater excavation persisted throughout the imaging sequence. Our results challenge and refine previous cone-based ejecta distribution models, offering new insights into the complex nature of impact-induced ejecta and improving constraints relevant for planetary defense strategies. Given these new insights, we urge the designers of future planetary defense missions to take into consideration anisotropic ejecta models for more realistic estimates of the imparted momentum via a kinetic impactor technique.

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