[ad_1]
If humans visit Mars, they may need to create some crucial resources while they’re there in order to survive long enough to explore and refuel for the long return journey. Although the days of surface water flow are long gone, the red planet is not entirely without the raw ingredients to make it work.
The Mars 2020 mission, launched in July, is conducting an experiment with exactly this goal in mind. MOXIE, the in situ oxygen resource utilization experiment on Mars, is a box not much larger than a roaster that produces oxygen from atmospheric CO2.2. While a much larger version would be required to produce liquid oxygen for a rocket, MOXIE is sized to produce roughly the amount of oxygen an active person needs to breathe.
A new study by Pralay Gayen of Washington University in St. Louis, Missouri, tests a device that can harness a different resource: perchlorate brine believed to exist in Martian soil in some places. The device can split the water in that brine, producing pure oxygen and hydrogen.
Perchlorate (ClO4), we found, are common on Mars. These salts have an affinity for water molecules and can accumulate water vapor over time, turning into a brine with a very low freezing temperature. There is evidence of considerable amounts of what this brine might be beneath the surface of the northern polar region of Mars, and smaller amounts have been invoked as a possible explanation for the striated activity that sometimes appears on the Martian slopes.
To see if we could harness this resource, the researchers built an electrolysis device that they ran under conditions similar to those on Mars. It uses a standard platinum-carbon cathode and a special lead-ruthenium-oxygen anode that researchers have previously developed. They mixed a plausible concentration of magnesium perchlorate brine and filled the headspace in that container with pure CO.2 for an atmosphere similar to that of Mars. The whole was kept at -36 ° C (-33 ° F). When turned on, the brine flows through the device, splitting into pure oxygen gaseous captured on the anode side and pure hydrogen gas on the cathode side.
The device performed quite well, producing around 25 times more oxygen than its MOXIE counterpart. MOXIE requires approximately 300 watts of power to operate and this device corresponds to oxygen output at approximately 12 watts. Furthermore, it also produces hydrogen which could be used in a fuel cell to generate electricity. And it would be smaller and lighter than MOXIE, the researchers say. Ultimately, this all just proves that MOXIE is working with a lower quality, but more widely accessible resource in atmospheric CO.2 instead of water.
A device like this should go through long-term stress testing, of course, to ensure that performance doesn’t degrade over time and is generally robust. The membrane separating the cathode and the sides of the anode has been carefully operated to prevent CO2 to get dirty, for example. If your survival depends on a device you brought to Mars, failures are not an option.
PNAS, 2020. DOI: 10.1073 / pnas.2008613117 (About DOI).
Source link
