Researchers have demonstrated in a lab setting that oxygen and hydrogen can be efficiently extracted from subsurface brine on Mars, offering a vital resource for future explorers who must produce these essentials on-site.
As part of NASA's Artemis program, humans are set to return to the Moon with plans for a permanent presence, unlike the Apollo era. Initially, critical supplies like water, food, and oxygen can be shipped from Earth. However, long-term sustainability demands in-situ resource utilization (ISRU) to cut exorbitant transport costs.
The European Space Agency (ESA) recently contracted UK-based Metalysis to develop technology for extracting oxygen directly from lunar regolith. Yet, Mars remains a prime target for public and private space agencies.
Establishing a foothold on the Red Planet will require relying on local resources to sustain life and enable return missions. While surface liquid water is a relic of Mars' past, subsurface reserves offer promising alternatives.
The Mars 2020 Perseverance rover's MOXIE instrument (Mars Oxygen ISRU Experiment)—a compact, toaster-sized device—produces oxygen from atmospheric CO2 via solid oxide electrolysis, tapping into the planet's abundant CO2 supply.
Building on this, experts at Washington University in St. Louis are pioneering a method to harness brine embedded in Martian soil.
Prior missions confirmed perchlorate salts (ClO4)—common on Mars—form brines with low freezing points when binding water molecules. Data indicate substantial deposits beneath Mars' north polar region.
The team engineered an electrolysis setup with a platinum-carbon cathode and lead-ruthenium-oxygen anode. Under simulated Martian conditions—a mix of magnesium perchlorate brine in pure CO2 at -36°C—the device split the brine, yielding pure oxygen at the anode and pure hydrogen at the cathode.
This proof-of-concept produced about 25 times more oxygen than MOXIE, using just a dozen watts versus MOXIE's 300 watts. Bonus: the hydrogen can power fuel cells for electricity. That said, CO2 remains more accessible than water-based brine. Further tests are essential to validate long-term durability in Mars' harsh environment, where reliability is non-negotiable for survival.
