Without a doubt, having its own source of oxygen on Mars would solve many of the problems for future colonizers. And now, a find brings new light.
In a discovery that could one day help astronauts on Mars, scientists have found a new way to produce oxygen under Martian conditions, one that appears to be 25 times more efficient than the one to be tested by NASA's Perseverance rover.
Not that this means there is something wrong with the NASA process. "Both will be necessary," says Vijay Ramani, a chemical engineer at Washington University in St. Louis, USA.
NASA's process, to be tested in a shoebox-sized chemical plant called MOXIE ( Mars Oxygen ISRU Experiment ), uses electrical energy to split carbon dioxide into oxygen and carbon monoxide, both of which are useful: oxygen to support life and carbon. monoxide as a building block for rocket fuel for astronauts' future return trips from Mars.
Ramani's new approach starts with water and uses electricity to break it down into oxygen and hydrogen.
At its core, it's simply the old-fashioned electrolysis of water - something that generations of chemistry students have witnessed in classrooms around the world. "If you use a cell like a battery, you can pass electricity through the water and divide the water into hydrogen and oxygen," says Ramani.
It had not previously been considered for Mars because Mars is cold. "If you have pure water, it will freeze." But Martian water may not be pure, because Martian soils are known to have a lot of perchlorate.
On Earth , perchlorate is an industrial chemical that is used in explosives, fireworks, and road flares - it's not something you want in water. On Mars, however, it can act as an antifreeze, allowing water to remain liquid even at temperatures of minus 50 degrees Celsius, increasing the possibility that Mars has perchlorate brines near its surface.
Amazing efficiency
The trick to the new process, Ramani says, was trying to figure out how to electrolysis perchlorate-rich water, something that won't work in conventional electrolysis because chemicals like perchlorate poison cells and block their function.
But, his team reports in an article in PNAS magazine , this is not an insurmountable hurdle. Using cells with a mix of exotic compounds, including ruthenium, lead, and platinum, they found that they could not only tackle the problem, they could do it with surprising efficiency.
That said, Ramani believes that his team's process and the MOXIE process should be viewed as complementary, not as competitors.
MOXIE has the advantage that it can be used anywhere, since all it needs is carbon dioxide from the Martian atmosphere, which, although fine, is 95% carbon dioxide. Your computer's process requires perchlorate brine, which might not be as ubiquitous.
Furthermore, the two processes produce different products.
Ramini's produces hydrogen and oxygen. MOXIE produces oxygen and carbon, in the form of carbon monoxide. If you are looking for raw materials for more complex chemical synthesis, you need all three.
Most likely, Ramani says, the first manned missions to Mars will rely on multiple technologies to generate oxygen for breathing and make rocket fuel for the return.
At the same time, efficiency matters. The more breathable air you can get from any solar panel, the fewer solar panels you will have to carry with you, and the easier it will be to go to Mars for anything other than a quick landing and return.
The scientific research has been published in PNAS.