Roughness Distribution in the Equatorial Region of Mercury

Kurzfassung

Topographic roughness is a useful tool for studying surface evolution on rocky planets. Roughness on Mercury has been investigated using data from the Mercury Laser Altimeter (MLA) onboard Space ENvironment, Geochemistry, and Ranging (MESSENGER) mission [1]. MLA has successfully mapped roughness on Mercury at baselines down to sub-km scales [2, 3, 4, 5], though its observation is limited to the north-polar region because of the eccentric orbit of MESSENGER and the limited ranging distance of MLA. One way to complement the lack of roughness data in the equatorial region is to use image-based digital elevation models (DEMs). The MESSENGER Global DEM MSGR_DEM_USG_SC_I_V02 [6] has been used to quantify roughness on a global scale [7]. However, a previous study reported that this DEM does not resolve topography at km scale because of interpolation and over-smoothing during the DEM production [7]. Therefore, roughness map at km-scale baselines is still missing for the region below 45°N latitude on Mercury. In this study, we present a new roughness map in the equatorial region of Mercury based on the latest global DEM (version 20240927) produced as described in Preusker et al. [8]. Comparison between the DEM and images has shown that the effective resolution of this DEM is approximately 5 km [8, 9]. Investigating roughness with this DEM, we present anomalous features in roughness at the kilometric scale and discuss the correlation between roughness distribution and other geologic features.