The Global Surface Roughness of 25143 Itokawa

TL;DR

This study presents the first detailed global surface roughness maps of asteroid 25143 Itokawa at scales of 8-32 meters, revealing distinct geologic processes compared to other asteroids like Eros.

Contribution

It provides novel high-resolution surface roughness maps of Itokawa and compares its geologic processes with Eros, highlighting differences in surface evolution.

Findings

Itokawa's surface roughness is shaped by down-slope activity and material redistribution.

Eros's surface roughness is influenced by recent large impact craters.

Spatial variations in roughness may affect YORP rotational dynamics.

Abstract

Surface roughness is an important metric in understanding how the geologic history of an asteroid affects its small-scale topography and it provides an additional means to quantitatively compare one asteroid with another. In this study, we report the first detailed global surface roughness maps of 25143 Itokawa at horizontal scales from 8--32~m. Comparison of the spatial distribution of the surface roughness of Itokawa with 433 Eros, the other asteroid for which this kind of analysis has been possible, indicates that the two asteroids are dominated by different geologic processes. On Itokawa, the surface roughness reflects the results of down-slope activity that moves fine grained material into geopotential lows and leaves large blocks in geopotential highs. On 433 Eros, the surface roughness is controlled by geologically-recent large impact craters. In addition, large longitudinal spatial variations of surface roughness could impact the role of YORP on Itokawa.