April 21, 2021 PUBLICATION 21-044
Technicians at NASA’s Jet Propulsion Laboratory lower the MOXIE (Mars Oxygen In-Situ Resource Utilization Experiment) instrument into the belly of the Perseverance Rover. Credits: NASA / JPL-Caltech
The growing “first” list for Perseverance, NASA’s newest six-wheeled robot on the surface of Mars, includes converting part of the red planet’s thin, carbon dioxide-rich atmosphere into oxygen. A toaster-sized experimental instrument on board Perseverance, called the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE), did this job. The test took place on April 20, the 60th Mars day, or Sol, since the mission landed on February 18.
While the technology demonstration is just beginning, it could pave the way for science fiction to become a scientific fact – isolating and storing oxygen on Mars to propel rockets that could lift astronauts from the planet’s surface. Such devices could one day also provide breathable air to the astronauts themselves. MOXIE is an exploration technology study – as is the Mars Environmental Dynamics Analyzer (MEDA) weather station – and is sponsored by NASA’s Directorate for Space Technology Mission (STMD) and the Directorate for Human Exploration and Operations Mission.
“This is a critical first step in converting carbon dioxide to oxygen on Mars,” said Jim Reuter, associate administrator for STMD. “MOXIE still has a lot to do, but the results of this technology demonstration look promising as we get closer to our goal of one day seeing humans on Mars. Oxygen isn’t just the stuff we breathe. Rocket fuel depends on oxygen, and future explorers will rely on producing fuel on Mars to make the journey home. “
For rockets or astronauts, oxygen is key, said MOXIE’s lead researcher Michael Hecht of the Massachusetts Institute of Technology’s Haystack Observatory.
After a 2 hour warm-up period, MOXIE began producing oxygen at a rate of 6 grams per hour. The value was reduced twice during the run (called “current sweeps”) to assess the status of the instrument. After one hour of operation, the total oxygen produced was about 5.4 grams, which is enough to keep an astronaut healthy for about 10 minutes of normal activity. Credits: MIT Haystack Observatory
In order to burn its fuel, a missile needs to have more oxygen by weight. Removing four astronauts from the surface of Mars for a future mission would require approximately 7 tons of rocket fuel and 25 tons of oxygen. In contrast, astronauts who live and work on Mars would need much less oxygen to breathe. “The astronauts who spend a year on the surface may consume a ton between them,” said Hecht.
Transporting 25 tons of oxygen from Earth to Mars would be an arduous task. Transporting a 1 ton oxygen converter – a larger, more powerful descendant of MOXIE that could produce those 25 tons – would be far more economical and practical.
The Martian atmosphere consists of 96% carbon dioxide. MOXIE separates oxygen atoms from carbon dioxide molecules, which are made up of one carbon atom and two oxygen atoms. A waste product, carbon monoxide, is released into the Martian atmosphere.
The conversion process requires a lot of heat to reach a temperature of around 800 degrees Celsius. To make this possible, the MOXIE unit is made of heat-resistant materials. These include 3D-printed parts made of nickel alloys that heat and cool the gases flowing through, as well as a lightweight airgel that holds the heat. A thin gold coating on the outside of MOXIE reflects infrared heat, preventing it from radiating outwards and potentially damaging other parts of Perseverance.
During this first operation, MOXIE’s oxygen production was quite modest – about 5 grams, which is about 10 minutes of breathable oxygen for an astronaut. MOXIE is designed to generate up to 10 grams of oxygen per hour.
This technology demonstration was designed to ensure the instrument survived launch from Earth, a nearly seven-month journey through space, and landing with Perseverance on February 18, Martian year (nearly two years on Earth).
These oxygen production runs will be in three phases. In the first phase the function of the instrument is checked and characterized, while in the second phase the instrument is operated under different atmospheric conditions such as different times of the day and seasons. In the third phase, Hecht said: “We will go beyond the scope” – try out new operating modes or “introduce new folds, e.g. a run in which we compare operations at three or more different temperatures”.
Illustration of the MOXIE instrument showing the elements in the instrument. Credits: NASA / JPL
“MOXIE is not just the first instrument to produce oxygen on another world,” said Trudy Kortes, director of technology demonstrations at STMD. It is the first of its kind technology that will help future missions “live on land” by using elements of another world’s environment, also known as in situ resource use.
“It’s about taking regolith, the substance found on the ground, into a processing facility and making a large structure out of it, or taking carbon dioxide – most of the atmosphere – and converting it to oxygen,” she said. “This process enables us to convert these abundant materials into usable things: propellants, breathable air or, in combination with hydrogen, water.”
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A key objective of Perseverance’s mission to Mars is astrobiology, including finding signs of ancient microbial life. The rover will characterize the geology and past climate of the planet, pave the way for human exploration of the red planet, and be the first mission to collect and cache Martian rocks and regolith (broken rock and dust).
Subsequent NASA missions, in collaboration with ESA (European Space Agency), would send spaceships to Mars to collect these sealed samples from the surface and bring them back to Earth for in-depth analysis.
The Mars 2020 Perseverance mission is part of NASA’s Moon-to-Mars exploration approach, which includes Artemis missions to the moon in preparation for human exploration of the red planet.
NASA’s Jet Propulsion Laboratory in Southern California, managed for NASA by Caltech of Pasadena, California, built and manages the operations of the Perseverance rover.
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