A Single Ejection Model of the DART/Dimorphos Debris Trail

TL;DR

This paper introduces a model explaining the formation of a transient double debris trail from the DART/Dimorphos collision without requiring a double ejection, by viewing a cone-shaped dust distribution from a large angle.

Contribution

The model accounts for the observed double trail as a projection effect, avoiding the need for multiple impact epochs and providing detailed particle size distribution and mass estimates.

Findings

The double trail can be explained by projection effects of a single ejection.

The particle size distribution follows a broken power-law with specific indices.

The total trail mass is approximately 1.7 to 2.2 x 10^7 kg, representing 0.4-0.6% of Dimorphos's mass.

Abstract

The collision of the NASA DART spacecraft with asteroid Dimorphos resulted in the formation of a distinctive and long-lived debris trail, formed by the action of solar radiation pressure on ejected particles. This trail briefly displayed a double appearance, which has been interpreted as the result of a double ejection. We present a model which can produce a transient double trail without the need to assume a double ejection. Our model explains the appearance of the double trail as a projection of the cone walls when viewed from a large angle to the cone axis and avoids the problem of producing dust in two epochs from a single, instantaneous impact. The particles follow a broken power-law size distribution, with differential indices q = 2.7+/-0.2 (1 um <= a <= 2 mm), 3.9+/-0.1 (2 mm < a <= 1 cm), and 4.2+/-0.2 (1 cm < a <= 20 cm). We find that the total trail mass in particles from 1 um to 20 cm in size (for an assumed density 3500 kg/m3) is ~1.7e7 kg, rising to 2.2e7 kg, when extended to boulders up to 3.5 m in radius. This corresponds to 0.4-0.6% of the mass of Dimorphos.