Mars rover’s MOXIE oxygen generator takes a step closer to supporting human life on the Red Planet


Located aboard the Mars Perseverance rover, MOXIE successfully manufactures oxygen from the red planet’s carbon dioxide-rich atmosphere since his arrival in February 2021.

The new report, published in the journal Scientists progressreveals how MOXIE (Mars Oxygen In-Situ Resource Utilization Experiment), which is about the size of a car battery, makes oxygen like a tree, by inhaling carbon dioxide from the Martian atmosphere and exhaling oxygen.

According to the study, MOXIE has proven it can produce oxygen across seven experimental runs by the end of 2021 – under a range of atmospheric conditions – during day and night, and during different Martian seasons. Indeed, MOXIE achieved its oxygen production target, with a rate of 6g of oxygen per hour – about the same rate as a tree on Earth.

It is hoped that a larger-scale version of MOXIE could operate on Mars in the future, before a human mission, to produce oxygen at a rate equivalent to several hundred trees. This in turn would generate enough oxygen to sustain visiting astronauts and power a rocket back to Earth.

“We learned a huge amount that will inform future larger-scale systems,” said Michael Hechtprincipal investigator of the MOXIE mission at the Haystack Observatory at the Massachusetts Institute of Technology.

MOXIE in the clean room at NASA’s Jet Propulsion Laboratory, Pasadena, California. © NASA/JPL-Caltech

MOXIE’s oxygen production on Mars also represents the first demonstration of “in situ resource utilization”, which involves the harvesting and use of a planet’s raw materials. In this case, it’s carbon dioxide on Mars – to make resources (like oxygen) that would otherwise have to be transported from Earth (where our oxygen level is 21%).

To put this into context, carbon dioxide makes up about 96% of the gas in the Martian atmosphere, compared to 0.13% of oxygen.

“This is the first demonstration of actually taking resources from the surface of another planetary body and chemically transforming them into something that would be useful for a human mission,” said Jeffrey Hoffman, deputy principal investigator. by MOXIE. “It’s historic in that sense.”

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Due to the need to fit aboard the Perseverance rover, the current version of MOXIE is understandably small. It is designed to run for short periods of time, starting and stopping each time it runs.

A full-scale oxygen plant on the Red Planet would require much larger units which should ideally operate continuously.

To convert the Martian atmosphere into pure oxygen, MOXIE draws air through a filter that cleans it of contaminants. Then the air is compressed and heated to 800°C and sent through a solid oxide electrolyser (SOXE), an instrument that electrochemically splits carbon dioxide-rich air into oxygen and carbon monoxide ions.

These oxygen ions are then isolated and recombined to form breathable oxygen, the quantity and purity of which MOXIE measures. The oxygen is then released into the air, along with carbon monoxide and other atmospheric gases, primarily argon and nitrogen.

So far, MOXIE has proven that it can make oxygen at almost any time of the Martian day and year, but there is still one test condition that researchers want to study.

“The one thing we haven’t demonstrated is running at dawn or dusk when the temperature changes dramatically,” Hecht said. “We have an ace up our sleeve that will allow us to do that, and once we’ve tested it in the lab, we can reach that final milestone to show that we can really race anytime.”

Looking ahead, the researchers plan to push MOXIE’s capacity and increase its production in the Martian spring when atmospheric density and CO2 levels are high. They will also monitor the instrument for signs of wear.

If MOXIE can operate successfully, despite repeated switching on and off, this would lay the foundation for a full-scale system. This should be designed to run continuously and should run for thousands of hours to support a future human mission.

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

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