Carbon dioxide is already being converted into oxygen on Mars thanks to an invention undergoing testing that could lead to the colonization of the red planet.
Day and night across the seasons, a lunchbox-sized instrument generates breathable gas from Mars’s thin atmosphere. In several experimental runs, it reached its target of producing six grams per hour–about the rate of an average tree on Earth.
The study was published in the peer-reviewed multidisciplinary open-access scientific journal Science Advances on August 31. It is titled: Mars Oxygen ISRU Experiment (MOXIE)—Preparing for human Mars exploration and authored by a group of scientists, led by Professor Jeffrey Hoffman of the Massachusetts Institute of Technology.
The breakthrough opens the door to establishing farms on a world 100 million miles away–mirroring the plot of the Hollywood blockbuster The Martian. Local production will boost future missions. They are also essential for future human settlements. Pioneers would be able to cultivate crops–just like Matt Damon’s stranded character Mark Watney.
The MIT-led Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) has been successfully making oxygen from the CO2-rich atmosphere since February 2021.
Deputy principal investigator Professor Jeffrey Hoffman said: “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. It’s historic in that sense.”
MOXIE touched down as part of NASA’s Perseverance rover mission. It was able to produce oxygen in a variety of atmospheric conditions.
It opens the door to sending a scaled-up version ahead of a human mission to continuously produce oxygen–at the rate of several hundred trees. At that capacity, the system should generate enough oxygen to both sustain humans once they arrive, and fuel a rocket for returning astronauts back to Earth. So far, MOXIE’s steady output is a promising first step toward that goal.
Principal investigator Dr. Michael Hecht said: “We have learned a tremendous amount that will inform future systems at a larger scale.”
Harvesting and using a planet’s materials, such as CO2, to make oxygen or other resources that would otherwise have to be transported is known as “in-situ resource utilization.” The prototype is small by design, in order to fit aboard Perseverance, and is built for short periods, starting up and shutting down with each run, depending on the rover’s exploration schedule and mission responsibilities.
In contrast, a full-scale oxygen factory would include larger units that would ideally run continuously. Despite the necessary compromises in the current design, the instrument has shown it can reliably and efficiently convert Mars’ atmosphere into pure oxygen.
It does so by first drawing the Martian air in through a filter that cleans it of contaminants. The air is then pressurized, and sent through the Solid Oxide Electrolyzer (SOXE), an instrument developed and built by OxEon Energy, that electrochemically splits the carbon dioxide-rich air into oxygen ions and carbon monoxide.
The oxygen ions are then isolated and recombined to form breathable, molecular oxygen, or O2, which MOXIE then measures for quantity and purity before releasing it harmlessly back into the air, along with carbon monoxide and other atmospheric gases.
Since the rover’s landing, MOXIE engineers have started up the instrument seven times throughout the Martian year, each time taking a few hours to warm up, then another hour to make oxygen before powering back down. Each run was scheduled for a different time of day or night, and in different seasons, to see whether MOXIE could accommodate shifts in the planet’s atmospheric conditions.
Prof. Hoffman said: “The atmosphere of Mars is far more variable than Earth. 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.”
So far, MOXIE has shown that it can make oxygen at almost any time of the Martian day and year. Dr. Hecht said: “The only thing we have not demonstrated is running at dawn or dusk, when the temperature is changing substantially. We do have an ace up our sleeve that will let us do that, and once we test that in the lab, we can reach that last milestone to show we can really run any time.”
As MOXIE continues to churn out oxygen, engineers plan to push its capacity, and increase production, particularly in the Martian spring, when atmospheric density and carbon dioxide levels are high.
Dr. Hecht said: “The next run coming up will be during the highest density of the year, and we just want to make as much oxygen as we can. So we will set everything as high as we dare, and let it run as long as we can.”
They will also monitor the system for signs of wear and tear. MOXIE is just one experiment among several aboard Perseverance. It cannot run continuously as a full-scale system would. Instead, it must start up and shut down with each run–a thermal stress that can degrade the instrument over time.
If MOXIE can operate successfully despite repeatedly turning on and off, this would suggest that a full-scale system, designed to run continuously, could do so for thousands of hours. Prof. Hoffman said: “To support a human mission to Mars, we have to bring a lot of stuff from Earth, like computers, spacesuits, and habitats. But dumb old oxygen? If you can make it there, go for it–you are way ahead of the game.”
The study was part funded by NASA. Last week Portuguese scientists came up with a plasma-based method to convert carbon dioxide into oxygen. Generating products on Mars by harnessing and processing local resources will be vital. Transporting them is simply not an option.
Oxygen is key to creating a breathable environment. It is also the starting point for farms on Mars–opening the door to “resource independence” from Earth. NASA and Elon Musk’s SpaceX are committed to sending people to our neighboring world in the near future. But the logistical challenges are huge.
Delivering food is too costly – and impractical. Producing it locally is imperative. In the film, Watney fertilizes Martian soil with his feces. He slices potatoes and plants the cuttings–growing enough food to last hundreds of days.
Produced in association with SWNS.
