A lab experiment suggests oxygen and hydrogen could be extracted from buried brine on Mars. This is an interesting study as future explorers will need to produce these essential resources directly on site.
As you probably know, humans are expected to return to the Moon soon as part of the Artemis program. Unlike the Apollo program, on the other hand, NASA intends this time to register permanently on our satellite. Also, in a few years, it will be a question of establishing a permanent base there. Initially, "essential" cargo such as water, food and oxygen will be able to be transported from Earth. Nevertheless, in the long term, the transport costs will be too high. Also future explorers will have to tackle in situ resources .
With this in mind, the ESA has, for example, just awarded a contract to the British company Metalysis with the aim of developing a technology capable of extracting oxygen directly from moon dust. However, our species does not only target the Moon:Mars is also in the crosshairs of several public and private agencies.
Here again, if we ever want to establish ourselves on the red planet, it will be necessary to rely on local resources in order to hope to survive and return to Earth . Although the days of liquid water flowing on the surface are long gone, Mars still offers a few ingredients that would-be explorers could make do with.
The Mars 2020 mission, which is due to land on Mars on February 21, carries with it an instrument aimed precisely at serving this objective. The MOXIE experiment (for Mars Oxygen ISRU Experiment ) comes in a small box not much bigger than a toaster, capable of producing oxygen from atmospheric CO2 through a process called solid oxide electrolysis.
That's an interesting idea. After all, CO2 is abundant on the Red Planet. However, this is not the only possible approach. Researchers at Washington University in St. Louis (Missouri) are developing an experiment aimed at exploiting a different resource:the brine buried in the Martian soil .
From previous studies, we know that perchlorate salts (ClO4) are relatively common on Mars. These salts have a special affinity with water molecules, thus turning into brine with a very low freezing temperature. According to the data collected, there would be significant quantities of this brine under the surface of the north polar region of the planet .
To test whether we could exploit this possible resource, the researchers developed an electrolysis device offering a standard platinum-carbon cathode and a special lead-ruthenium-oxygen anode. The researchers then used it under Mars-like conditions, mixing a plausible concentration of magnesium perchlorate brine and filling the space with pure CO2. Everything was stored at -36°C . Upon power-up, brine passed through the device, separating pure oxygen on one side (anode side) and pure hydrogen on the other (cathode side).
This lab experiment would have extracted about twenty-five times more oxygen than the MOXIE unit will be able to produce. We also know that MOXIE requires about 300 watts power to operate, while this device only requires a dozen . Finally, it also produces hydrogen which could be used in a fuel cell to produce electricity . On the other hand, MOXIE works with CO2, a much more widely available and accessible resource on Mars than water.
Of course, this is just a proof of concept. A device like this will have to undergo other long-term resistance tests to ensure its performance and its robustness in the particularly hostile Martian environment. When your survival depends on such an instrument, malfunctions are not an option.
