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Of the seven science instruments proposed for the next U.S. Mars rover, scheduled for a 2020 launch date, MOXIE test the engineering to produce and store oxygen, pulled from the Martian atmosphere.
Developed in partnership with NASA’s Jet Propulsion Laboratory, it’s based on the fact that the Martian atmosphere, though extremely thin, is composed of 96 percent carbon dioxide, which means its a vast potential source of oxygen for future explorers and settlers. Essentially, MOXIE is a fuel cell in reverse. Instead of generating electricity by using oxygen to burn a fuel, it uses a process called solid oxide electrolysis , where electricity is employed to split carbon dioxide into oxygen and carbon monoxide.
This process would see Martian air pumped into the unit through a dust filter and pressurized before being passed into a fuel cell. At high temperatures, some ceramic oxides act as oxygen ion conductors. In the fuel cell, a thin, non-porous disc of this ceramic separates two porous electrodes. One electrode acts as the cathode and the other as the anode. Carbon dioxide passes through the cathode and when it comes into contact with the ceramic, the interaction of electricity and the ceramic causes the carbon dioxide to split into oxygen and carbon monoxide. The oxygen and the carbon monoxide are then separated and the oxygen stored.
What makes this unusual is that NASA has actually dedicated one science instrument to engineering research, not pure science. The agency does not do this much anymore, but such research is essential if the U.S. is going to someday send humans to other planets.