On board the Perseverance rover, which is now flying to the Red Planet, there is a MOXIE module designed to conduct experiments on the extraction of oxygen from the Martian atmosphere. It is 96% carbon dioxide, which can be separated by electrolysis into the desired oxygen and carbon monoxide. Alas, this is far from the most economical way, so the University of Washington has already developed an alternative.
The main thing for the future Martian colonies will be relying on the planet’s local resources, so scientists are looking for anything more or less valuable there. Their attention was attracted by droplets of liquid on the legs of the Phoenix lander in 2008, which were identified as water-salt solution. There is plenty of water on Mars, but it is in the form of either ice or brine (brine), which should become the source of the coveted oxygen.
The Curiosity rover found traces of perchlorate to the south of Mars’ equator, plus NASA has a lot of images of the desert with dark streaks created by the brine that has come to the surface. Perchlorates absorb moisture very well even from the super-dry Martian atmosphere and, more importantly, keep it liquid even at -70 ℃, so they are not afraid of the night cold of this planet. American scientists have selected the optimal catalyst from lead oxide and ruthenium for perchlorate, which made it possible to reduce energy consumption for electrolysis by 25 times.
Alas, it is still difficult to say which method of obtaining oxygen will be the best in practice. The same brine on Mars cannot simply be scooped up with a bucket and poured into an electrolysis plant. However, this technology has a bonus in the form of hydrogen release, which can be used as fuel for the colonists’ machines. Experiments in this direction will be continue.