The global surface roughness of 433 Eros from the NEAR laser rangefinder

We performed the first global surface roughness assessment of the asteroid 433 Eros at baselines (horizontal distances) of 4–200 m. We measured surface roughness using the root-mean-square (RMS) deviation over a variety of baselines after first detrending the height to remove long-wavelength slope effects. The global surface roughness of Eros is found to be self-affine at all baselines investigated. The surface roughness is statistically correlated with crater density at baselines of 100–200 m and boulders at a baseline of 5 m. No global spatial statistical correlation was found for baselines of 4–200 and mapped tectonic lineaments, ponds, slope, or geopotential elevation. The surface roughness of the crater Shoemaker (Charlois Regio) is controlled by the interplay of a high boulder density producing higher surface roughness values at small baselines and low crater density lowering surface roughness values at long baselines. We estimated the mobile regolith thickness (regolith that moves around and infills topography) to be 0.2–6.2 m from the difference in the surface roughness values at the baseline of 4 m. Furthermore, we find that the change in RMS deviation as a function of baseline compares favorably with the moon, and differs significantly from existing results for rubble-pile asteroid Itokawa.