Abiotic Methane Formation by Electrochemical Reactions under Simulated Martian Dust Conditions

Abstract Reports of Martian methane (CH4) remain controversial, with some in situ detections but stringent upper limits from the Trace Gas Orbiter (TGO). While CH4 is often considered to be a potential sign of biological or geological activity, the origin and variability of reported Martian CH4 remain unresolved. Dust activity, a fundamental feature of the Martian climate, brings together atmospheric carbon dioxide (CO2), water preserved in hydrous surface minerals, and strong electrochemical effects associated with electrostatic discharge (ESD), thereby creating favorable conditions for the generation of CH4. Here, we show that low-pressure CO2 discharge in the presence of hydrated minerals can produce detectable CH4 under controlled laboratory conditions, supporting a potential abiotic CH4 formation pathway associated with dust activity. The CH4 response is strongly mineral-dependent and is generally enhanced by greater availability of accessible mineral-associated water, while externally supplied water alone is insufficient to induce CH4 formation in all mineral systems. These findings reveal a plausible coupling among atmospheric CO2, mineral-associated water, and dust electrochemistry that provides an additional near-surface abiotic pathway for the formation of Martian CH4.