Splitting molecules to make air
NASA is paving the way for human life on Mars and needs to prove that oxygen can be produced locally, up on the Red Planet! The experiment they performed in April 2021 used a special device called MOXIE (Mars Oxygen In-Situ Resource Utilization Experiment), part of the equipment of Perseverance, a rover sent to Mars to explore one of its craters.
This device can convert CO2, which makes up 96% of Mars's atmosphere, into breathable oxygen. Plants have been doing exactly that for 470 million years through photosynthesis: by converting CO2 into O2, they have been keeping CO2 levels around 0.035% in the Earth’s atmosphere. This chemical reduction is the exact opposite of the oxidation that occurs in our lungs when we breathe.
The Mars 2020 Perseverance Rover and Moxie Credit: NASA/JPL-Caltech.
MOXIE is a solid oxide electrolyzer cell, co-developed by the Massachusetts Institute of Technology (MIT) and the NASA/Caltech Jet Propulsion Laboratory, among others. It uses the same reduction reaction as the one occurring when a car’s exhaust gases are treated by a catalyst, turning NOx into harmless nitrogen, which makes up 79% of Earth’s atmosphere.
Similarly, the catalytic process applied by MOXIE splits the CO2 molecules into CO and O atoms that recombine into O2, gaseous oxygen. The electrolyser needs to work at a high temperature, around 800°C, so its ceramic components become reactive and conductive and can remain stable for a long time. These ceramics are based on a combination of oxides of rare earths that can stand the high temperatures and be used as an electrolyte forming a dense layer in the electrolyser.
Ready for the space technology race
Solvay, a key actor in the chemistry of rare earth compounds, is well positioned to enter the race for these emerging space technologies, as the solid oxide electrolyser cell (SOEC) or fuel cell (SOFC) often use Yttria-stabilized Zirconia or Cerium Gadolinium oxides as electrolytes. The latter is also part of our “Green Hydrogen platform" technology offer.
“The technologies for electrolysers or fuel cells are emergent and could be a transition to Green Hydrogen, targeting stationary fuel cell or heavy duty equipment like boats, trucks, etc.,” says Camille Jourde, Business Development Manager of Rare Earths Specialties for Special Chem. From hydrogen as fuel on Earth, to producing air for the first humans on Mars, it’s one giant leap we’re ready to make.
