Zhurong Rover Reveals Salt Weathering-Driven Surface Modification by Transient Brine Activity on Mars

Surface coatings and weathering textures on Martian rocks offer critical insights into recent surface-atmosphere interactions, transient water activity, and the potential for habitable microenvironments. As part of China’s Tianwen-1 mission, the Zhurong rover landed in southern Utopia Planitia (25.1°N, 109.9°E). This study investigates the spectral and morphological properties of surface rocks observed along Zhurong’s traverse, with the aim of constraining the formation mechanisms responsible for observed features. Although in situ reflectance spectra exhibit limited compositional diversity, Zhurong identified distinctive surface textures, including shallow surface-confined pits, exfoliated flakes, and thin coatings. These features point to the role of salt weathering processes during post modification under present day Martian conditions. We propose a multi-stage alteration model involving aeolian dust deposition and electrostatic aggregation, followed by hydration-driven processes such as salt deliquescence, brine formation, and cementation. Environmental conditions derived from the Mars Climate Database support the possibility of transient relative humidity peaks sufficient for salt activation and brine cycling. Comparative observations from Jezero crater reinforce the broader relevance of these mechanisms across Mars. These features not only reflect ongoing surface alteration processes but also represent promising targets for biosignature preservation and astrobiological investigation.