Nasa’s MOXIE experiment successfully makes oxygen on Mars

An MIT led experiment on Nasa’s Mars rover has proven it’s possible, in principle, to make oxygen and rocket fuel from the Martian air

A small but important Nasa experiment on Mars has demonstrated it’s possible to manufacture oxygen on the Red Planet using resources found on the Red Planet.

The Mars Oxygen In Situ Resource Utilization Experiment, or Moxie, has produced oxygen from the carbon dioxide in the Martian atmosphere seven times since landing on Mars in 2021. Moxie produced around six grams of oxygen per hour, the same rate as a small tree on Earth, and not bad for a lunchbox-sized device, according to findings published on Wednesday in a new paper in the journal Science Advances.

“This is the first demonstration of actually using resources on the surface of another planetary body, and transforming them chemically into something that would be useful for a human mission,” Massachusetts Institute of Technology professor of aeronautics and astronautics and principal investigator for Moxie Jeffery Hoffman said in a statement. “It’s historic in that sense.”

The ability to extract important resources from extraterrestrial environments is an area of ongoing research at Nasa and other space agencies since every gram of material that can be produced on site is a gram that doesn’t have to be launched from Earth at the start of the mission. Nasa and the European Space Agency have plans to test similar technologies on the Moon.

MIT began developing Moxie in 2014, and the experiment rode to Mars along with Nasa’s Perseverance rover in 2020, landing on Jezero Crater in February 2021. In the intervening months, Moxie has turned on seven times, during different atmosphere conditions, to demonstrate that it can pull carbon dioxide from the air and convert it to oxygen.

“The atmosphere of Mars is far more variable than Earth,” Dr Hoffman said. “The density of the air can vary by a factor of two through the year, and the temperature can vary by 100 degrees. One objective is to show we can run in all seasons.”

Moxie works by sucking in Martian air, filtering it, and then using electrolysis to split carbon dioxide into oxygen and carbon monoxide; it’s nearly the same electrochemical process used to produce oxygen and hydrogen from water in a fuel cell. Moxie then purifies and combines the singular oxygen atoms to produce O2, breathable oxygen.

Moxie releases the oxygen and carbon monoxide back into the Martian atmosphere, but a scaled-up version of Moxie on a future Mars mission would pump that oxygen into some sort of storage tank for future use. That could be providing breathable O2 for astronauts, or even more importantly, liquid oxygen for the manufacture of rocket fuels.

Assuming that a mission to Mars would include an ascent vehicle to allow astronauts on the surface to return to Mars orbit and eventually home to Earth, and that such a vehicle would use liquid oxygen and liquid methane as propellant, it would be exceedingly expensive to launch such a vehicle from Earth.

“While all [Mars Ascent Vehicle] propellant could be brought from Earth to the surface of Mars, 12 to 13 tons are required in low Earth orbit for every ton landed on Mars using current technology,” Dr Hoffman and his colleagues write in the new paper. “Thus, ~500 tons would need to be launched to Earth orbit to transport the required MAV propellant from Earth for every Mars mission.”

While Moxie is a small and singular experiment, it demonstrates that manufacture of oxygen, and possibly rocket fuel, is possible on Mars. If that process can be scaled up, it’s just one less thing the planners of a future Mars mission, already complicated enough, will need to worry about.

“To support a human mission to Mars, we have to bring a lot of stuff from Earth, like computers, spacesuits, and habitats,” Dr Hoffman said. “But dumb old oxygen? If you can make it there, go for it — you’re way ahead of the game.”