Macro-scale roughness reveals the complex history of asteroids Didymos and Dimorphos

TL;DR

This study introduces rapid topographic roughness analysis methods to classify asteroid terrains, revealing their complex histories and surface processes on Didymos and Dimorphos, the targets of NASA's DART mission.

Contribution

The paper presents novel, efficient techniques for terrain detection and characterization from topographic data, applicable to asteroid surface studies and beyond.

Findings

Didymos exhibits high surface heterogeneity and recent resurfacing signs.

Dimorphos is rougher, likely due to formation and interaction history.

Methods reliably identify morphological units at multiple scales.

Abstract

Morphological mapping is a fundamental step in studying the processes that shaped an asteroid surface. Yet, it is challenging and often requires multiple independent assessments by trained experts. Here, we present fast methods to detect and characterize meaningful terrains from the topographic roughness: entropy of information, and local mean surface orientation. We apply our techniques to Didymos and Dimorphos, the target asteroids of NASA's DART mission: first attempt to deflect an asteroid. Our methods reliably identify morphological units at multiple scales. The comparative study reveals various terrain types, signatures of processes that transformed Didymos and Dimorphos. Didymos shows the most heterogeneity and morphology that indicate recent resurfacing events. Dimorphos is comparatively rougher than Didymos, which may result from the formation process of the binary pair and past interaction between the two bodies. Our methods can be readily applied to other bodies and data sets.