An artist's rendering of the Mars Ice Home concept.

Crews living on Mars (artist’s impression) could survive on oxygen extracted from the salty water that permeates some of the planet’s soils. Credit: NASA/Clouds AO/SEArch

Chemistry

How salt water on Mars could give astronauts a breather

Water locked away in Martian sediments could be split into the gases needed by humans and their machines.

A device that uses electricity to decompose water could be used to transform brines on Mars into a supply of hydrogen fuel and life-supporting oxygen.

The red planet’s atmosphere is rich in carbon dioxide but contains just 0.14% oxygen. To support a human on Mars, NASA plans to generate oxygen by ripping it from CO2, creating carbon monoxide and oxygen.

As an alternative strategy, Vijay Ramani and his colleagues at Washington University in St. Louis, Missouri, built an electrolyser, a device that splits liquid water into its constituent gases, hydrogen and oxygen. Most Martian water is frozen, but some areas of the planet have high concentrations of magnesium salts, which help water to remain liquid at low temperatures. The researchers’ electrolyser has one electrode made of a lead- and ruthenium-based compound, which promotes oxygen gas generation at the electrode even under salty conditions.

The team tested the electrolyser on a concentrated solution of magnesium salts in a CO2-rich atmosphere at –36ºC, simulating Martian conditions. Compared with NASA’s approach, the electrolyser has the potential to produce 25 times the volume of oxygen using the same amount of power.