Influence of Martian environmental variables on methane partial pressure estimation

Methane is considered a potential biosignature gas. The Mars Science Laboratory (MSL) Curiosity rover has observed seasonal variations in atmospheric methane within Gale Crater, suggesting possible microbial activity. The origin of this methane could be either biological or abiotic or a combination of the two. Different physical mechanisms, involving distinct environmental variables, produce varying concentrations of methane. By analyzing the influence of various environmental variables on methane partial pressures and comparing differences between physical models and empirical measurements, we can better discern methane production mechanisms. This study investigates factors affecting methane cycling. We find that temperature and pressure strongly correlate with Martian atmospheric methane, while Ultraviolet (UV) radiation at the atmospheric boundary and surface UV radiation exhibit weaker correlations. Using Fuller’s method, we successfully reproduce the seasonal methane cycle in Gale Crater. Several potential physical models suggest that gas diffusion driven by variations in pressure and temperature within the shallow subsurface regolith may represent a primary mechanism determining methane concentrations observed in Gale Crater. However, errors in the pressure-dominated model cannot be neglected. As Curiosity enters its uphill exploration phase, we suggest that atmospheric pressure will play a significant role in predicting the methane concentrations that it will detect.