On the red and dusty surface of Mars, nearly 100 million miles from Earth, an instrument the size of a lunchbox is proving it can reliably do the work of a small tree.
The MIT-led Mars Oxygen In-Situ Resource Utilization Experiment, or MOXIE, has been successfully making oxygen from the Red Planet’s carbon-dioxide-rich atmosphere since April 2021, about two months after it touched down on the Martian surface as part of NASA’s Perseverance rover and Mars 2020 mission.
In a study published today in the journal Science Advances, researchers report that, by the end of 2021, MOXIE was able to produce oxygen on seven experimental runs, in a variety of atmospheric conditions, including during the day and night, and through different Martian seasons. In each run, the instrument reached its target of producing six grams of oxygen per hour — about the rate of a modest tree on Earth.
Researchers envision that a scaled-up version of MOXIE could be sent to Mars 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.
“We have learned a tremendous amount that will inform future systems at a larger scale,” says Michael Hecht, principal investigator of the MOXIE mission at MIT’s Haystack Observatory.
MOXIE’s oxygen production on Mars also represents the first demonstration of “in-situ resource utilization,” which is the idea of harvesting and using a planet’s materials (in this case, carbon dioxide on Mars) to make resources (such as oxygen) that would otherwise have to be transported from Earth.
“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,” says MOXIE deputy principal investigator Jeffrey Hoffman, a professor of the practice in MIT’s Department of Aeronautics and Astronautics. “It’s historic in that sense.”
Hoffman and Hecht’s MIT co-authors include MOXIE team members Jason SooHoo, Andrew Liu, Eric Hinterman, Maya Nasr, Shravan Hariharan, Kyle Horn, and Parker Steen, along with collaborators from multiple institutions including NASA’s Jet Propulsion Laboratory, which managed MOXIE’s development, flight software, packaging, and testing prior to launch.
Seasonal air
The current version of MOXIE is small by design, in order to fit aboard the Perseverance rover, and is built to run 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 MOXIE’s 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 in February 2021, 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.
“The atmosphere of Mars is far more variable than Earth,” Hoffman notes. “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.
“The only thing we have not demonstrated is running at dawn or dusk, when the temperature is changing substantially,” Hecht says. “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.”
Ahead of the game
As MOXIE continues to churn out oxygen on Mars, engineers plan to push its capacity, and increase its production, particularly in the Martian spring, when atmospheric density and carbon dioxide levels are high.
“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,” Hecht says. “So we’ll 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. As MOXIE is just one experiment among several aboard the Perseverance rover, it cannot run continuously as a full-scale system would. Instead, the instrument must start up and shut down with each run — a thermal stress that can degrade the system 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.
“To support a human mission to Mars, we have to bring a lot of stuff from Earth, like computers, spacesuits, and habitats,” Hoffman says. “But dumb old oxygen? If you can make it there, go for it — you’re way ahead of the game.”
This research was supported, in part, by NASA.
As an enthusiast deeply immersed in the field of space exploration and planetary science, I can confidently affirm the groundbreaking significance of the Mars Oxygen In-Situ Resource Utilization Experiment, or MOXIE. The recent findings reported in the Science Advances journal provide compelling evidence of MOXIE's capabilities and its successful demonstration of converting the carbon-dioxide-rich atmosphere of Mars into breathable oxygen.
The MIT-led MOXIE mission, a vital component of NASA's Perseverance rover and Mars 2020 mission, has been operating on the Martian surface since April 2021. The instrument, roughly the size of a lunchbox, has proven its efficiency by consistently producing six grams of oxygen per hour, equivalent to the oxygen output of a modest Earthly tree. What makes this achievement truly remarkable is the instrument's ability to function under various atmospheric conditions, including different times of the day and night, as well as during different Martian seasons.
The study, led by principal investigator Michael Hecht of MIT's Haystack Observatory, reveals that MOXIE has successfully completed seven experimental runs, showcasing its reliability and adaptability. The researchers envision a scaled-up version of MOXIE that could be deployed on Mars in advance of a human mission, producing oxygen at a rate sufficient to sustain human life and even fuel rockets for the return journey to Earth.
The concept of "in-situ resource utilization" takes center stage in this achievement. MOXIE represents the first demonstration of extracting and utilizing resources from another planetary body, in this case, converting Martian carbon dioxide into oxygen. This breakthrough has profound implications for future human exploration and potential colonization of Mars.
The technical details behind MOXIE's operation involve a Solid Oxide Electrolyzer (SOXE) developed by OxEon Energy. The process begins with drawing Martian air through a filter to remove contaminants, followed by pressurization. The SOXE then electrochemically splits the carbon dioxide-rich air into oxygen ions and carbon monoxide. The isolated oxygen ions are recombined to form molecular oxygen (O2), which MOXIE measures for quantity and purity before releasing it back into the Martian atmosphere.
Despite MOXIE's current design limitations, tailored to fit aboard the Perseverance rover and operate intermittently, it has proven its capability to reliably and efficiently produce oxygen on Mars. The researchers acknowledge the challenges posed by the variability of Mars' atmosphere, with fluctuations in air density and temperature throughout the year. MOXIE's success in adapting to these conditions is a crucial step towards demonstrating its potential for continuous operation in future, larger-scale oxygen production systems.
Looking ahead, the engineers plan to enhance MOXIE's capacity and increase production, particularly during periods of high atmospheric density and carbon dioxide levels. The ongoing success of MOXIE not only represents a major milestone in space exploration but also underscores the feasibility of generating essential resources locally for sustained human presence on Mars.
