Mars’ underground brine could be a good source of oxygen

If humans are ever going to visit Mars, they may well need to make some crucial resources while they are there in order to survive long enough to explore and restock for the long return journey. Although the days of flowing surface water are long gone, the red planet is not entirely without the raw ingredients to make this work.

The Mars 2020 mission that launched in July is carrying an experiment with exactly this goal in mind. MOXIE—the Mars Oxygen In-Situ Resource Utilization Experiment—is a box not much bigger than a toaster that produces oxygen from atmospheric CO₂. While a much larger version would be required to make liquid-oxygen fuel for a rocket, MOXIE is sized to produce about the amount of oxygen an active person needs to breathe.

A new study led by Pralay Gayen at Washington University in St. Louis, Missouri, tests a device that could tap a different resource—perchlorate brine believed to exist in the Martian ground at some locations. The device can split the water in that brine, producing pure oxygen and hydrogen.