Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

TL;DR

This study documents the evolution of asteroid ejecta over five weeks following the DART spacecraft impact, revealing brightness changes, secondary material release, and morphological evolution through a comprehensive observational campaign.

Contribution

It provides the first detailed, multi-facility observational analysis of ejecta evolution over five weeks after a planned asteroid impact.

Findings

Brightness initially increased by ~1.4 magnitudes

Dimming rates of 0.11-0.12 mag/day in the first week

Return to pre-impact brightness after approximately 24-25 days

Abstract

The impact of the DART spacecraft into Dimorphos, moon of the asteroid Didymos, changed Dimorphos' orbit substantially, largely from the ejection of material. We present results from twelve Earth-based facilities involved in a world-wide campaign to monitor the brightness and morphology of the ejecta in the first 35 days after impact. After an initial brightening of ~1.4 magnitudes, we find consistent dimming rates of 0.11-0.12 magnitudes/day in the first week, and 0.08-0.09 magnitudes/day over the entire study period. The system returned to its pre-impact brightness 24.3-25.3 days after impact through the primary ejecta tail remained. The dimming paused briefly eight days after impact, near in time to the appearance of the second tail. This was likely due to a secondary release of material after re-impact of a boulder released in the initial impact, through movement of the primary ejecta through the aperture likely played a role.