For many years, it has become apparent that one of the most significant issues that human-crewed missions to Mars are going to face is the reliable provisioning of oxygen and fuel.
Now, scientists have just figured out how to make a water electrolyzer able to produce pure oxygen under Mars-like conditions. The new system operates at a far lower input power than NASA’s existing carbon dioxide electrolyzer and would be well-suited to water reservoirs beneath the Martian surface.
Why Make Oxygen on Mars?
Oxygen is essential to human life on Mars, not only for breathing but also as an oxidizer, either in a rocket engine or in a spacecraft as a life support system. The atmosphere of Mars is 96% carbon dioxide with almost no oxygen, so either oxygen must be manufactured in a place or it needs to be carried from a place.
NASA’s 2020 flight to Mars took the Mars Oxygen In-Situ Resource Utilization Experiment- MOXIE, which splits atmospheric CO2 into oxygen and carbon monoxide. However, such a process requires high temperatures for the reaction and gives CO as the byproduct.
Finding and Harnessing Martian Brine Water
Evidence for liquid water on Mars in the form of brine beneath the surface came from NASA’s Phoenix lander and several Mars orbiters. Note, for instance, that these brine pools are liquid at temperatures down to −60°C due to high perchlorate concentrations.
Classical water electrolysis requires an aqueous electrolyte, where salt concentrations have to be deficient to make specific ion conductivity. But Martian brines are full of salts, and the extreme cold of that planet may affect the kinetics of electrodes.
Emulating Martian Conditions for Electrolysis
Pyrochlores are generally fast ionic conductors with the formula A2B2O7. To that end, the researchers constructed an electrolyzer of the glassy-carbon-supported anode with Pb2Ru2O7−δ, Pt catalysts supported by carbon at the cathode, and a commercial anion-exchange membrane separator filled with regolithic brine in the form of a 2.8 molar solution of magnesium perchlorate that was saturated with CO2.
The temperature in the rig was kept close to the Martian surface temperature of −36°C by a bath of dry ice in an ethylene. It was found that this design generated purified oxygen and hydrogen gas that see an energy efficiency projected up to thirty percent.
MOXIE produces approximately 10 to 20 grams of oxygen per hour, roughly a third of the quantity required by a resting human. What’s even worse, the scientists discovered that this brine electrolyzer would be optimized for the Martian environment or conditions, far smaller in size, lighter weight, and over 25 times superior in oxygen yield when similar power is provided compared with MOXIE.
Making Way for Manned Missions on Mars
This new type of water electrolyzer is an essential breakthrough in maintaining manned missions on Mars. The fact that Martian brine is utilized allows for the effective production of hydrogen fuel and oxygen. This would immensely restrict the weight that future missions would be required to transport from Earth, thus making them more self-sufficient.