On the red dusty surface of Mars, nearly 100 million miles from Earth, an instrument the size of a lunchbox is proving it can reliably do the job of a small tree.
Since April 2021, about two months after touching down on the surface of Mars as part of NASA, the MIT-led Mars Oxygen In Situ Resource Utilization Experiment (MOXIE) has successfully harvested carbon dioxide-rich resources from the Red Planet. Oxygen is produced in the atmosphere. Perseverance rover and the Mars 2020 mission.
In a study published today in the journal scientific progress, The researchers report that by the end of 2021, MOXIE was able to produce oxygen in seven experimental runs on Mars in a variety of atmospheric conditions, including day and night, and in different seasons on Mars. In each run, the instrument hit its goal of producing 6 grams of oxygen per hour—roughly the rate of an average tree on Earth.
The researchers envision that a scaled-up version of MOXIE could be sent to Mars ahead of a human mission, producing oxygen continuously at the rate of hundreds of trees. At this capability, the system should produce enough oxygen to sustain humans once they arrive, and to fuel rockets for astronauts to return to Earth.
The stable output of MOXIE so far is a promising first step towards this goal.
“We’ve learned a lot that will inform future systems on a larger scale,” said 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”, the harvesting and use of terrestrial materials (in this case carbon dioxide on Mars) to create resources (such as oxygen) that would otherwise have to be Shipped from Earth.
“This is the first time actually using resources from the surface of another planetary body and chemically converting them into something useful for human missions,” said Jeffrey Hoffman, MIT professor of practice and associate principal investigator at MOXIE. astronautics. “In that sense, it’s historic.”
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, as well as collaborators from multiple institutions, including managing the NASA Jet Propulsion Experiment developed by MOXIE room, flight software, packaging and pre-launch testing.
The current version of MOXIE is small in design to accommodate the Perseverance rover, and is designed for short runs, turning on and off on each run, depending on the rover’s exploration plan and mission responsibilities. By contrast, a full-scale oxygen plant would include larger units that ideally operate continuously.
Although MOXIE’s current design makes the necessary compromises, the instrument has shown that it can reliably and efficiently convert the Martian atmosphere into pure oxygen. It first draws Martian air through a filter to remove contaminants. The air is then pressurized and the carbon dioxide-rich air is electrochemically broken down into oxygen ions and carbon monoxide through an instrument developed and manufactured by OxEon Energy, the Solid Oxide Electrolyzer (SOXE).
The oxygen ions are then separated and recombined to form breathable molecular oxygen or O2then MOXIE measures quantity and purity, which are then released back into the air harmlessly with carbon monoxide and other atmospheric gases.
Since the rover landed in February 2021, MOXIE engineers have activated the instrument seven times throughout the Martian year, each time taking several hours to warm up, then another hour to make oxygen before powering down. Each run was scheduled for a different time of day or night, as well as a different season, to see if MOXIE could adapt to changes in Earth’s atmospheric conditions.
“Mars’ atmosphere is much more variable than Earth’s,” Hoffman noted. “The density of the air can change twice in a year and the temperature can change by 100 degrees. One goal is to show that we can operate in all seasons.”
So far, MOXIE has shown that it can produce oxygen at almost any time of day and year on Mars.
“The only thing we haven’t shown is running at dawn or dusk, when temperatures are changing dramatically,” Hecht said. “We do have a trump card that will allow us to do this, and once we test it in the lab, we can hit that final milestone showing that we’re really ready to run.”
before the game
As MOXIE continues to churn out oxygen on Mars, engineers plan to ramp up its capacity and increase its output, especially during Martian spring, when the atmosphere is dense and carbon dioxide high.
“The next run will be at the highest density of the year, and we just want to make as much oxygen as possible,” Hecht said. “So we’ll set everything as high as possible and let it run for as long as possible.”
They will also monitor the system for signs of wear. Since MOXIE is just one of several experiments on the Perseverance rover, it cannot operate continuously like a complete system. Instead, instruments must be turned on and off for each run—a thermal stress that degrades system performance over time.
If MOXIE runs successfully with repeated opening and closing, this shows that a complete system designed to run continuously can run for thousands of hours.
“To support human missions to Mars, we have to bring a lot of things from Earth, like computers, space suits and habitats,” Hoffman said. “But stupid old oxygen? If you can do it, go for it – you’re way ahead.”
This research was supported in part by NASA.