An engineering experiment on the Mars rover Perseverance, dubbed MOXIE, has now successfully produced oxygen from the carbon dioxide in the Martian atmosphere, and has done so seven different times. After filtering an air sample…

…the air is then pressurized, and sent through the Solid OXide Electrolyzer (SOXE), an instrument developed and built by OxEon Energy, that electrochemically splits the carbon dioxide-rich air into oxygen ions and carbon monoxide. The oxygen ions are then isolated and recombined to form breathable, molecular oxygen, or O2, which MOXIE then measures for quantity and purity before releasing it harmlessly back into the air, along with carbon monoxide and other atmospheric gases.

Since the rover’s landing in February 2021, MOXIE engineers have started up the instrument seven times throughout the Martian year, each time taking a few hours to warm up, then another hour to make oxygen before powering back down. Each run was scheduled for a different time of day or night, and in different seasons, to see whether MOXIE could accommodate shifts in the planet’s atmospheric conditions.

During each run, the instrument produced about six grams of oxygen per hour, though a recent run produced more than 10 grams per hour, about half what a human needs to survive.

MOXIE runs only for short times, because it uses so much power the rover can’t do other work during runs. It is also only a technology test, so its operation is given a lower priority. Nonetheless, it appears that this test has successfully demonstrated that future astronauts on Mars will have a system for producing an unlimited supply of breathable oxygen. The next step would be to scale this up to produce enough oxygen to also fuel the astronaut’s return rocket.