Topographic Roughness of Asteroid 4 Vesta: Implications for Geological Evolution and Surface Processes

As the second-largest body in the asteroid belt and the only known intact differentiated protoplanet， Vesta provides a unique natural laboratory for understanding the early stages of planetary formation and the evolution of the Solar System. This study provides new constraints on the geological evolution of Asteroid 4 Vesta through a comprehensive analysis of its topographic roughness. Utilizing high-resolution DTM data from the Dawn spacecraft， we calculate gravity-corrected slopes， RMS height， and the Hurst exponent to map surface texture at critical scales.Our results reveal a pronounced hemispheric dichotomy， with the southern hemisphere exhibiting significantly higher roughness and steeper slopes compared to the smoother northern terrain. The Hurst exponent values (～0.9) indicate strong topographic self-similarity， analogous to the lunar highlands， suggesting impact bombardment as the dominant process shaping Vesta’s surface. Furthermore， we identify a global slope asymmetry in crater walls， with pole-facing slopes systematically steeper than equator-facing ones， a pattern attributed to Vesta’s large-scale topographic tilt induced by its rapid rotation and significant oblateness. These findings quantitatively link surface roughness to specific geological units and evolutionary stages， providing new constraints on the roles of impacts， tectonics， and global shape in shaping the surface of a differentiated asteroid.