Perseverance reliably produces oxygen from Martian CO2

The Perseverance rover takes a look back at Jezero Crater. / NASA/JPL-Caltech

Science | Mars

The success of a NASA rover experiment is a key step for the future human conquest of the red planet

The first humans on Mars will have to make their own air and, to that end, one of the seven instruments on the Perseverance rover has been working for more than a year on the red planet like a small tree. It produces oxygen from the carbon dioxide that makes up 96% of the neighboring world's atmosphere. And it does so day and night, and in all seasons, according to a study published in the journal 'Science Advances'. “This is the first demonstration of using resources on the surface of another planet and chemically transforming them into something that would be useful for a human mission. It's historic in that sense," says Jeffrey Hoffman of the Massachusetts Institute of Technology (MIT) and deputy principal investigator for the Martian In Situ Oxygen Resource Utilization Experiment (MOXIE).

Developed by MIT, MOXIE is a key instrument in NASA's Human Exploration Program for its ability to produce breathable oxygen that can also be used as fuel for spacecraft. The first humans on the red planet will have similar, but large, equipment that will extract the oxygen necessary for their survival from the poisonous atmosphere. NASA estimates that a one-ton version of MOXIE could generate the 25 metric tons of oxygen needed for astronauts to breathe during their stay and to fuel them for return.

MOXIE is the size of a toaster. It's what NASA calls a demonstration technology, a prototype instrument for future missions. In the same category comes the Ingenuity mini-helicopter, which has already completed 30 flights during which it has remained in the air for a total of more than 55 minutes. Both landed on the neighboring world on February 18, 2021 in the Perseverance rover, whose objectives are to search for traces of ancient microbial life, collect rock samples that will be brought to Earth in a few years and establish the bases of manned missions.

like a little tree

Until the end of last year, MOXIE generated oxygen in seven cycles of several hours. Depending on the tasks Perseverance had to do, the operating periods were scheduled to run at different times of the day and in different seasons. In all cases, it produced 6 grams of oxygen per hour, the equivalent of a small tree. The first thing the device does is filter the air to clean it of contaminants, then it electrochemically separates carbon dioxide (CO2) into oxygen ions and carbon monoxide (CO), and finally recombines the oxygen ions into breathable oxygen (O2). ).

Moxie before being introduced to the off-roader in March 2019. /


“The only thing we haven't shown is that it works at dawn or dusk, when the temperature changes substantially. We have an ace up our sleeve that will allow us to do that, and once we test it in the lab, we can hit that last milestone to show that we really can make it work at any time," says Michael Hecht, MOXIE Principal Investigator at the observatory. Haystack at MIT.

Since air density and temperature vary widely on Mars, it is imperative that such a device generate oxygen in all scenarios. MIT engineers want to expand MOXIE's capacity and increase its oxygen production, especially in the Martian spring, when atmospheric density and carbon dioxide levels are highest. “We want to produce as much oxygen as we can. So we'll put it as high as we dare and let it run as long as we can," says Hecht.

Before the first humans set foot on Mars, habitats, jeeps, laboratories and other devices will arrive on the planet that astronauts will already find there. Among them, at least one large piece of equipment that continuously produces the oxygen generated on Earth by several hundred trees. “To support a human mission to Mars, we have to bring a lot of things from Earth: computers, spacesuits and habitats. But silly old oxygen? If you can do it there, do it: we're way ahead of that," says Hoffman.

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