FUTURE colonists on Mars could use plasma technology to make their own oxygen.
The atmosphere on Mars is 96 per cent carbon dioxide, says Vasco Guerra at the University of Lisbon in Portugal. This can be split to extract breathable oxygen and carbon monoxide, a fuel that could give us a “gas station on the Red Planet”, he says. He and his team calculate that creating a carbon dioxide plasma — a mush of ions made by passing an electric current through a gas — could split carbon dioxide from oxygen more easily on Mars than on Earth (Plasma Sources Science and Technology, DOI: 10.1088/1361-6595).
The lower atmospheric pressure on Mars would allow us to create plasmas without the vacuum pumps or compressors necessary on Earth. Also, the temperature of around -60°C is just right to let the plasma more easily break one of the chemical bonds that keeps carbon and oxygen tightly bound, while preventing the carbon dioxide from re-forming.
For now, this is largely theoretical. Guerra’s team are working with a very small prototype that operates using 150 to 200 Watts for 4 hours per 25-hour Mars day. But Guerra says that a further version scaled up by a factor of 100 could produce 8 to 16 kilograms of oxygen daily. “The International Space Station currently consumes oxygen in the range of 2 to 5 kilograms per day, so this would be enough to support a small settlement,” says Guerra. Because the system wouldn’t require heat or additional pressure, it could be less cumbersome than other proposals, such as MOXIE, a system that splits carbon dioxide using electrolysis. This would need temperatures of 800°C and compressors.
“The plasma system could produce enough oxygen to support a small settlement”
MOXIE’s creators say their system is more advanced than the plasma one. “They’ve left out how the carbon dioxide is collected and how the oxygen is separated from the other gases,” says Michael Hecht, a member of the MOXIE initiative. “The devil is in the detail,” he says.
This article appeared in print under the headline “Making fuel and oxygen on Mars using plasma”
Article amended on 27 October 2017
We corrected the oxygen production of the proposed prototype.