The Perseverance rover exploring the surface of Mars has created breathable air on the red planet. An experimental device on the NASA rover split carbon dioxide molecules down to their component parts, creating enough breathable oxygen for a person for about 10 minutes. This was also enough oxygen to make small amounts of rocket fuel.
The device that was able to do this is called MOXIE, which stands for Mars Oxygen In-Situ Resource Utilization Experiment. Carbon dioxide, or CO2, is the primary gas in the atmosphere on Mars. MOXIE breaks the chemical bonds in CO2, which releases oxygen.
The device works like “an electrical tree,” says Michael Hecht, MOXIE’s principal investigator at the Massachusetts Institute of Technology in Cambridge. This means that it breathes in CO2 and breathes out oxygen.
“When we burn anything, gas in the car or a log in the fireplace, most of what we’re burning is oxygen,” Hecht says. On Earth, we take all that oxygen for granted. “We don’t think about it.” But on Mars, oxygen is largely bound up in CO2.
MOXIE arrived on Mars with the Perseverance rover this past February 18. Two months later, MOXIE warmed to about 800° Celsius (1,472° Fahrenheit). It then ran long enough to produce five grams of oxygen. That is only enough for one person to breathe for about 10 minutes. But the main reason to make oxygen on Mars isn’t for breathing, according to Hecht. It’s to make fuel for the return trip to Earth.
Future astronauts will have to either bring oxygen with them or make it on Mars. A rocket powerful enough to lift a few astronauts off the surface of Mars would need about 25 metric tons (27.5 U.S. tons) of oxygen. That’s too much to bring on the trip.
MOXIE is a prototype for the system astronauts could one day use to make rocket fuel. When running at full power, MOXIE can make about 10 grams of oxygen per hour. Powered by Perseverance, it will run for about one Martian day at a time. Hecht notes that a scaled-up version, however, could run nonstop for the 26 months before astronauts arrive.
MOXIE can’t run full time now because it would use too much of Perseverance’s power. The rover has other instruments to run while on its science mission, which is to search for signs of past life on Mars. MOXIE will get a chance to run at least nine more times over the next Martian year (about two Earth years).
The success of this system could set the stage for a permanent research station on Mars. “That’s not something I expect to see in my lifetime,” Hecht admits. Still, he says, “MOXIE brings it closer by a decade.”