On the dusty red 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. Yes in April 2021, NASA already reported that it had managed to manufacture oxygen on Marsnow confirms that it has been able to do so in different atmospheric conditions.
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The discovery, an important step in the possibilities of a still distant colonization of Mars, has been published today in the magazine Science. Since February 2021, the so-called “In Situ Oxygen Resource Utilization Experiment on Mars” (Moxie, in its English acronym) had been successfully making oxygen from the planet’s carbon dioxide-rich atmosphere when it landed on the Martian surface as part of NASA’s Perseverance robotic rover mission.
The researchers of Massachusetts Institute of Technology (MIT, in its English acronym), the body responsible for Moxie, reported in a press release that, by the end of 2021, that the device was able to produce oxygen in seven experimental rounds in different atmospheric conditions, including during the day and night, and through different Martian seasons. In each of the tests, the instrument met its goal of producing six grams of oxygen per hour, about the rate of a small tree on Earth.
The researchers envision that an enlarged version of Moxie could be sent to Mars as a preliminary to a human mission. The goal would be to continuously produce oxygen at the rate of several hundred trees. With that capacity, the system would generate enough oxygen to support humans once they arrived, and especially to fuel a rocket that would return astronauts to Earth.
For now, Moxie’s steady production is a “promising” first step toward that goal. “We’ve learned a lot that will form the basis for future larger-scale systems,” says Michael Hecht, principal investigator for the mission at MIT’s Haystack Observatory.
Moxie’s production of oxygen 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 chemically transforming them into something that would be useful for a human mission,” says Moxie Associate Principal Investigator Jeffrey Hoffman, professor of this practice in the Department of Aeronautics and Astronautics from MIT. “It’s historic in that sense.”
The current version of Moxie is small by design, to fit aboard ‘Perseverance’, and is built to run for short periods, starting up and shutting down with each stroke, depending on the vehicle’s exploration schedule and mission demands. . In contrast, a large-scale oxygen factory would include larger units that, ideally, would run continuously.
How does it work
Moxie first sucks in the Martian air through a filter that cleans it of contaminants. The air is then pressurized and sent through a developed instrument that electrochemically splits carbon dioxide-rich air into oxygen and carbon monoxide ions.
The oxygen ions are then isolated and recombined to form breathable molecular oxygen, or O2, the quantity and purity of which is measured in the Moxie before it is safely returned to the environment, along with carbon monoxide and other atmospheric gases.
Since the Perseverance rover’s landing in February 2021, engineers have powered up the instrument seven times throughout the Martian year, each time taking a few hours to warm up and then another hour to make oxygen before shutting down again. Each run was scheduled for a different time of day or night, and in different seasons, to see if it could adapt to changes in the planet’s atmospheric conditions.
“The atmosphere of Mars is much more variable than that of Earth,” says Hoffman. “Air density can vary by a factor of two throughout the year, and temperature can vary by 100 degrees. One of the goals is to show that we can work 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 haven’t shown is that it works at dawn or dusk, when the temperature changes substantially,” says Hecht. “We’ve got an ace up our sleeve that will allow us to do that, and once we test it in the lab, we’ll be able to hit that last milestone to show that we really can get it up and running at any time.”
a trick won
As Moxie continues to produce oxygen on Mars, engineers plan to expand its capacity and increase production, especially in the Martian spring, when atmospheric density and carbon dioxide levels are high. They will also monitor the system for signs of wear.
If MOXIE can function successfully despite being repeatedly turned on and off, this would suggest that a full-scale system, designed to run continuously, could do so for thousands of hours. “To maintain a human mission on Mars we have to bring many things from Earth – such as computers, space suits and habitats –; but if you can make plain old oxygen there, you already have a lot of cattle,” says Hoffman.