An international team of researchers has developed a new way of producing oxygen on the Red Planet using gases from the local atmosphere and cold plasma. The technology could play a crucial role in the development of human life support systems by generating plenty of oxygen for breathing, making rocket fuel, fertilizers and building materials while minimising the weight of equipment.
Space mission programmes aimed at scientific exploration and possible colonisation of the Moon and Mars are constantly expanding and setting ever more ambitious goals. One major landmark is NASA's Artemis III mission, which will place people on the surface of the Moon in 2024 for the first time in 50 years. Among its long-term goals is the sustained presence of humans on Earth's satellite (or its orbit) and the use of the skills and knowledge gained for the next step, sending humans to Mars.
So-called in situ resource use (collecting and recycling the resources found, for example, on Mars and using them to support human life) is crucial to making these plans a reality. After all, it would be far easier, cheaper and safer for space settlements to develop technology to obtain the same oxygen from the atmosphere or regolith (soil) of the Red Planet than to bring it from Earth. Yet oxygen is needed not only for breathing by astronauts, but also, for example, as a component of rocket fuel.
An international team of scientists from Portugal, France, the USA and the Netherlands has proposed a new approach to producing oxygen on Mars. Their technology is based on generating non-thermal (cold) plasma and using conductive membranes to separate the gas mixture. A detailed description of the development, as well as test results of the first prototypes, are outlined in an article published in the Journal of Applied Physics.
Cold plasma is a highly reactive gaseous medium, usually created and maintained by electrical discharges. In it, free high-energy electrons and relatively cold non-ionized gas molecules coexist - unlike ordinary plasmas (such as those made of stars) which are made up of electrons and positively and negatively charged ions. This type of plasma is called cold or non-thermal because it is obtained at temperatures close to room temperature instead of a few thousand degrees, typical of normal (thermal or hot) plasma.
The idea of the authors of the new work is that with the help of these free electrons from cold plasma and without heating to get out of carbon dioxide, which in the atmosphere of Mars is more than 95 percent oxygen. Then, using special conductive membranes, filter the oxygen from the resulting gas mixture and apply it to breathing, making rocket fuel, fertilizers and building materials.
According to the researchers, the strengths of the developed plasma technology are that it is compact, scalable, reliable, versatile and does not require expensive materials. What's more, unlike other methods of producing oxygen, the method is perfectly adapted to be powered by intermittent energy sources (such as solar panels) and can operate at Martian low pressure, as it is ideal for igniting the plasma. This sets the new technology apart from the solid oxide electrolysis used in the MOXIE instrument on the Perseverance rover, which is already being tested on Mars.