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

Morphological mapping is a fundamental step in studying the pro-
cesses 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 ter-
rains 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 morpho-
logical 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.