Time-series variations of recurring slope lineae on Mars compatible with contemporary water activity from bedrock aquifer melting

Determining the current presence of liquid water on Mars has important hydrological, geological, and astrobiological implications. Recurring slope lineae (RSL), as features presently developing on Mars, have been suggested to result from transient flows of liquid water or dry particles. This study presents a time-series analysis of RSL in Palikir and Raga craters on Mars, using datasets collected during Mars years (MY) 32 to 36. Our results unveil a significant increase in RSL after the global dust event in MY 34 compared to other years and its dependence on surface temperatures on sun-facing slopes. Further investigation into the relationship between RSL and bedrock outcrops suggests a plausible scenario for RSL formation based on the melting of bedrock aquifers. A landslide observed close to the RSL-rich region may have been formed by the slope’s destabilization due to groundwater influx, which could indicate a water-related origin for the RSL. This outcome is further supported by spectral evidence of the presence of hydrated salts in RSL during the summer and their absence in autumn. Our results provide a possible scenario for RSL formation and support the hypothesis that RSL may be related to contemporary water activity on Mars.