Methane and oxygen from energy‐efficient, low temperature in situ resource utilization enables missions to Mars.

The United States National Aeronautics and Space Administration's (NASA's) mandate is a human mission to Mars in the 2030s and sustained exploration of Mars requires in situ resource utilization (ISRU). Exploiting the Martian water cycle (alongside perchlorate salts that depress water's freezing point to <213 K) and the available 95 vol.% atmospheric CO2, we detail an ultra‐low temperature (255 K) CO2–H2O electrolyzer to produce methane fuel and life‐supporting oxygen on Mars. Our polarization model fit experimental Martian brine electrolyzer performance and predicted CO2 electrolysis occurring at comparatively lower potentials (vs. water electrolysis) on Mars. A hypothetical 10‐cell, 100 cm2 electrode‐area‐per‐cell electrolyzer produced 0.45 g W−1 day−1 of CH4 and 3.55 g W−1 day−1 of O2 at 2 V/cell and 50% electrolyzer faradaic efficiency versus a best‐case production of 2.5 g W−1 day−1 of O2 by the Mars Oxygen in situ Resource Utilization Experiment (MOXIE) from NASA's Mars 2020 mission (MOXIE produces no fuel). Material performance requirements are presented to advance this technology as an energy‐efficient complement to MOXIE. [ABSTRACT FROM AUTHOR]