NASA’s Perseverance rover is continuing to make history as its onboard device MOXIE creates oxygen on Mars for the first time in history.
While this week’s news from the surface of Mars may have been dominated by the spectacular first flight of a human-developed aircraft through the atmosphere, another Mars-based project — the Preserverance Rover— was preparing to fight the Ingenuity Copter for column inches.
A device aboard NASA’s six-wheeled Perseverance robot has taken carbon dioxide from the Red Planet’s atmosphere and converted it to oxygen. The impressive task was performed by an unassuming-looking Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE)¹ — a device no bigger than a conventional toaster.
The feat was accomplished on April 20 2021, Perseverance’s 60th Martian day — or Sol — on the planet's surface. Although just an initial demonstration, it could point towards the vital establishment of sustainability on the planet’s surface in the future.
“This is a critical first step at converting carbon dioxide to oxygen on Mars,” says Jim Reuter, an associate administrator for NASA’s Space Technology Mission Directorate (STMD).
MOXIE has more work to do, but the results from this technology demonstration are full of promise as we move toward our goal of one day seeing humans on Mars.”
Creating oxygen on Mars — or any other alien world — is a boon for crewed space missions, but it could also fulfill another equally vital role. Isolating and storing oxygen means that rockets could be launched from the planet's surface. This could make the Red Planet a critical stepping stone in our exploration of the solar system.
“Oxygen isn’t just the stuff we breathe,” Reuter adds. “Rocket propellant depends on oxygen, and future explorers will depend on producing propellant on Mars to make the trip home.”
A Mars Experiment with MOXIE
MOXIE sits at the front right-hand side of the Perseverance Rover. It has been referred to as a ‘mechanical tree’ due to its ability to take carbon dioxide — about 95% of Mars’ atmosphere — and convert it into oxygen.
The device — designed by researchers at the Massachusetts Institute of Technology — works by electrochemically separating the two oxygen atoms from the carbon dioxide atom, which together comprise a carbon dioxide molecule. This process requires a great deal of heat, meaning that MOXIE has to be capable of withstanding temperatures as high as 800 ⁰C.
The device was built with a range of heat-resistance materials. Some of its parts were created from a 3D-printed nickel alloy that heats and cools gases that flow past them. MOXIE also contains aerogel insulation that can hold in heat, reducing the energy it needs to consume to maintain temperature.
The outside of the car-battery-sized device is coated in a thin layer of gold which reflects infrared heat. This protects the rest of the Perseverance Rover from the intense temperatures generated by MOXIE by ensuring heat is not radiated outwards.
Though the current test was only able to produce a tiny amount of oxygen — about 5 grams, enough to sustain an astronaut for about 10 minutes — the team behind its development sees it as a system that can be scaled up.
“MOXIE is designed to make about 6 to 10 grams of oxygen per hour — just about enough for a small dog to breathe,” Asad Aboobaker, a MOXIE systems engineer at NASA’s Jet Propulsion Laboratory in Southern California, says. “A full-scale system geared to make (propellant for the flight home) would need to scale up oxygen production by about 200 times what MOXIE will create.”
The Advantages of ‘In-Situ’ Oxygen Production
With the first human — 17-year-old Alyssa Carson — set to walk on the surface of Mars in 2033, the benefits of producing oxygen on-site during manned space missions cannot be underestimated.
While astronauts living and work on the surface of Mars would not need too much oxygen — a team of four consuming about a metric ton a year according to MOXIE’s principal investigator, Michael Hecht of the Massachusetts Institute of Technology’s Haystack Observatory — launching a rocket from its surface would require a great deal more.
To burn its fuel, a rocket needs more oxygen than its own weight. So, lifting our team of four astronauts off the planet's surface would require around 7 tons of fuel and 25 tons of oxygen. Even a basic mission that concludes with a rocket launch requires hauling 25 tons of oxygen to the surface of Mars. While considerably bigger than its predecessor, a scaled-up version of MOXIE would still only weigh about a ton.
This saves crucial space on missions, ensuring that rockets are as light as possible. The MOXIE descendants should also be reusable, meaning they can be left in place for future operations.
What is Next For MOXIE?
This initial experiment was conducted to ensure that MOXIE survived the arduous seven-month journey from Earth to Mars and the touchdown on February 18 2021. Thankfully, it seems to have remained in good working order.
Over the next two years — representing one Martian year — researchers working with the instrument will conduct a further nine oxygen extraction tests. These will be carried out in three distinct waves.
Phase one will allow researchers to check MOXIE’s instruments and calibrate them. This will enable them to test the device in different conditions, at different times of the Martian day, and in the planet’s different seasons. This gauntlet of testing in varied environments will comprise stage two of the test.
The third and final stage will see what Heche describes as the team ‘pushing the envelope’ in terms of testing, trying out new operating modes, and throwing challenges at MOXIE such as comparing operations in three or more differing temperatures.
The result of this will be the development of a system that encourages sustainability for long-term manned missions.
“MOXIE isn’t just the first instrument to produce oxygen on another world,” Trudy Kortes, director of technology demonstrations within STMD concludes. “This process allows us to convert these abundant materials into useable things: propellant, breathable air, or, combined with hydrogen, water.
“It’s the first technology of its kind that will help future missions ‘live off the land,’ using elements of another world’s environment.”
References and Further Reading
¹ ‘MOXIE,’ 2020 Mission Perservance Rover, NASA, https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/
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