3D Radiative Transfer Simulations for Characterization of the Optically Thick DART Ejecta Plume

Abstract

The Hyperion package is a three‐dimensional Monte‐Carlo radiative transfer approach to modeling dust ejecta. Because it has proven to be a powerful tool for simulating optically thick environments with complicated structure, we are applying the routines to observations of the Double Asteroid Redirection Test (DART) impact on asteroid Dimorphos. Our analysis focuses on the LICIACube LUKE red‐filter image acquired 175 s after impact, when the near‐surface plume remained dense and not strongly structured. The model incorporates the updated Dimorphos shape model, spacecraft and solar geometry derived, and size‐dependent scattering properties of realistic dust particles. We adopt an axisymmetric conical ejecta geometry and iteratively adjust the particle size distribution (PSD) and vertical number density profile to reproduce observed brightness profiles extracted from the LUKE image. We find that a power‐law PSD with slope and a number density peak located at approximately 120 m above the surface best reproduces the brightness contrast between the illuminated surface, the bright ejecta plume, and the adjacent dark band produced by shadowing within the optically thick material. The resulting best‐fit model implies a total ejecta mass of kg within 500 m of the impact site.