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When it comes to water and Mars, there is good news and not so good news. The good news: there is water on Mars! The not so good news?
There is water on Mars.
The red planet is very cold; the non-frozen water is almost certainly full of salt from the Martian soil, which lowers its freezing temperature.
You can’t drink salt water, and the usual method of using electricity (electrolysis) to break it down into oxygen (for breathing) and hydrogen (for fuel) requires salt removal – a cumbersome and costly endeavor in a harsh and dangerous environment.
If oxygen and hydrogen could be extracted directly from the salt water, however, the brine electrolysis process would be much less complicated and less expensive.
Engineers from the McKelvey School of Engineering at Washington University in St. Louis have developed a system that does just that. Their research was published today in the Proceedings of the National Academy of Sciences (PNAS).
The research team, led by Vijay Ramani, Roma B. and Raymond H. Wittcoff Distinguished University Professor in the Department of Energy, Environmental Engineering, and Chemicals, did not simply validate its brine electrolysis system under typical terrestrial conditions; the system was tested in a simulated Martian atmosphere at -33 ⁰F (-36 ⁰C).
“Our Martian brine electrolyser fundamentally changes the logistical calculation of missions to Mars and beyond,” Ramani said. “This technology is equally useful on Earth, where it opens up the oceans as a valuable source of oxygen and fuel.”
In the summer of 2008, NASA’s Phoenix Mars Lander “touched and tasted” the Martian water, the vapors of the melted ice carved by the lander. Since then, the European Space Agency’s Mars Express has discovered several underground water ponds that remain liquid thanks to the presence of magnesium perchlorate – salt.
To live – even temporarily – on Mars, not to mention returning to Earth, astronauts will have to produce some of the necessary goods, including water and fuel, on the Red Planet. NASA’s Perseverance rover is en route to Mars now, carrying instruments that will use high-temperature electrolysis. However, the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) will only produce oxygen, from carbon dioxide in the air.
“Our Martian brine electrolyser radically changes the logistical calculation of missions to Mars and beyond.”
Vijay Ramani
The system developed in Ramani’s laboratory can produce 25 times more oxygen than MOXIE using the same amount of energy. It also produces hydrogen, which could be used to power the astronauts’ journey home.
“Our new brine electrolyzer incorporates a lead rutenate pyrochlore anode developed by our team along with a platinum-on-carbon cathode,” said Ramani. “These carefully designed components, coupled with the optimal use of traditional electrochemical engineering principles, have produced this high performance.”
The thoughtful design and unique anode allow the system to operate without the need to heat or purify the water source.
“Paradoxically, the perchlorate dissolved in water, the so-called impurities, actually helps in an environment like that of Mars,” said Shrihari Sankarasubramanian, a research scientist with the Ramani group and first joint author of the paper.
“They prevent the water from freezing,” he said, “and also improve the performance of the electrolyser system by lowering the electrical resistance.”
Typically, water electrolyzers use highly purified deionized water, which adds to the cost of the system. A system that can operate with “suboptimal” or salt water, such as the technology demonstrated by Ramani’s team, can significantly increase the economic value proposition of water electrolysers everywhere, even right here on planet Earth.
“Having demonstrated these electrolyzers in challenging Martian conditions, we intend to deploy them under much milder conditions on Earth to use brackish or salt water to produce hydrogen and oxygen, for example, through seawater electrolysis,” said Pralay Gayen. , a postdoctoral research associate in Ramani’s group and also first joint author of this study.
Such applications could be useful in the defense realm, creating oxygen on demand in submarines, for example. It could also provide oxygen as researchers explore unexplored environments closer to home, deep in the sea.
The underlying technologies that enable the brine electrolyzer system are patented through the Office of Technology Management and are available for license from the university.
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