Perseverance and its MOXIE oxygen-production instrument. NASA/JPL-Caltech; MOXIE’s production was measured inside the instrument. Source.
On April 20, 2021, MOXIE demonstrated oxygen production from the Martian atmosphere for the first time.
The instrument travelled aboard Perseverance, which landed on Mars in February 2021. Inside MOXIE’s compact, gold-coloured housing, an electrochemical process separated oxygen from carbon dioxide drawn from the surrounding atmosphere. The achievement was controlled production inside a device, not the first existence of oxygen anywhere on Mars.
Mars' thin atmosphere is 95% composed of carbon-dioxide.
In the first experiment, MOXIE produced a total of about 5.4 grams of oxygen during an hour of operation In later testing it reached 12 grams per hour, providing a measured result beyond the first successful run.
Astronauts, on average, require over 800 grams of oxygen per-day.
What this experiment shows is that oxygen can be created on Mars and that this could help maintain life on the planet. It also means that oxygen can be produced for use as a rocket oxidizer, meaning that astronauts wouldn't have to carry so much oxygen on their initial journey.
MOXIE's principal investigator, Michael Hecht, told reporters:
"To burn its fuel, a rocket must have many times more oxygen by weight. To get four astronauts off the Martian surface on a future mission would require 15,000 pounds of rocket fuel and 55,000 pounds of oxygen. The astronauts who spend a year on the surface will maybe use [2,200 pounds] between them to breathe."
Jeffrey Hoffman, a Professor of the practice in the MIT Department of Aeronautics and Astronautics, added:
One day before MOXIE’s first oxygen run, on April 19, 2021, the Ingenuity helicopter delivered by Perseverance completed the first powered, controlled flight on another planet. The brief first flight demonstrated powered flight in the thin Martian atmosphere. It opened a path toward further tests of robotic aerial exploration, while MOXIE explored a different use of the same atmosphere: processing it into a useful resource.
The Perseverance rover was sent to Mars in order to carry out experiments such as this and search for possible signs of ancient microbial life in rocks recording Mars’s distant past.
[h/t: Daily Mail]
From the first grams to a completed experiment
MOXIE—the Mars Oxygen In-Situ Resource Utilization Experiment—first produced oxygen on Mars in April 2021. By the end of its work in 2023, it had completed 16 runs and generated a total of 122 grams of oxygen.
At its most productive, it reached 12 grams per hour, with purity of 98 percent or better. NASA’s final mission report describes the results and the range of Martian conditions under which the instrument was operated.
Those quantities are deliberately modest. MOXIE was a technology demonstration, not a life-support plant already supplying astronauts.
How the chemistry works
The instrument takes in Martian air, compresses and heats it, and uses an electrochemical process to separate oxygen from carbon dioxide. The oxygen produced during the test was measured and then released; MOXIE did not fill a storage tank for a future crew.
The broader idea is in-situ resource utilization: making something useful from material available at the destination rather than launching all of it from Earth.
Why rockets are central to the story
People need oxygen to breathe, but a Mars ascent rocket would also require a substantial supply of oxidizer. Producing that oxygen on Mars could reduce the amount of material that must be transported there.
A practical system would need to be much larger and operate reliably over long periods. It would also need the associated power, processing and storage equipment. Demonstrating oxygen production is one important step, not proof that every part of that future system is ready.
What the result does not mean
MOXIE did not make the Martian atmosphere breathable or begin terraforming the planet. It processed a small flow of local gas inside an engineered device.
Scale is central to interpreting the result. The final total of 122 grams was produced across sixteen separate runs, not continuously over two years. Likewise, the peak rate of 12 grams per hour describes a demonstrated operating rate, not a guarantee of uninterrupted production. The next engineering challenge is to sustain output and handle the oxygen after it has been made, including the cooling and storage required for a larger system.
Two experiments, two different futures
Perseverance also delivered Ingenuity, the helicopter that demonstrated powered flight on Mars. One experiment explored using the atmosphere as a resource; the other tested flying through it.
To see the landscape around these experiments, explore Perseverance’s early panoramic views. The photographs provide the setting, while MOXIE’s measurements show an achievement that a landscape image alone could never reveal.
Biology creates another set of questions for experiments beyond Earth. The cotton-germination experiment carried by Chang’e 4 is a useful example of why a carefully defined milestone should remain distinct from a complete life-support system.
Additional source and image references: Perseverance rover hardware beside the compact gold-colored MOXIE instrument
Research and documentation: NASA: Perseverance extracts its first oxygen on Mars · MIT: MOXIE’s first oxygen production
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