MIT researcher developing technology to 'build gas stations' on Mars. How will it work?

Sending astronauts to Mars will take a huge amount of fuel. So will bringing them back safely to Earth. But it's not really practical to ferry that much fuel over a distance of 140 million miles. So Lanie McKinney, a PhD candidate in the Aerospace Plasma Group at Massachusetts Institute of Technology (MIT), is developing technology that may enable the direct generation of rocket fuel on Mars by using the carbon dioxide, which is already available in abundance in the planet's atmosphere.

McKinney's research work is based on the concept of in-situ resource utilization, or ISRU, which focuses on utilizing the resources already existing on a planet as an alternative to ferrying in supplies from Earth. Currently working under the supervision of Carmen Guerra-Garcia, the Esther and Harold E. Edgerton Associate Professor at MIT, McKinney has designed a miniature plasma reactor—referred to as a Nanosecond Repetitively Pulsed Dielectric Barrier Discharge (NRP-DBD). It uses cold plasma to split carbon dioxide into carbon monoxide and oxygen, with the oxygen being potentially useful for life support or as an oxidizer in rocket propellant. 

“If we don’t build gas stations on Mars, it will be very difficult to get humans back to Earth,” McKinney told MIT News. “We’re going to need some way to produce the propellant on site.” Although the designed plasma reactor successfully extracts oxygen from carbon dioxide, a major challenge still remains: the separation of oxygen from the mixture produced by the plasma reactor before it recombines with carbon monoxide. 

To resolve this issue, McKinney has paired the reactor with an oxygen-selective membrane that rapidly extracts oxygen in order to hinder its recombination. But the integration process is poorly understood, and McKinney and her team are unsure of how the membrane will be impacted by the highly reactive plasma environment. “We are not entirely sure what we will see,” McKinney says.

McKinney has also contributed to other projects focused on making space missions more self-reliant. As the co-leader of MIT's CERBERUZ team, she worked on NASA's LunaRecycle Challenge, which investigated ways to recycle waste into useful materials for lunar and deep-space missions. McKinney and her team designed a device that produces powder from mixed waste. Through injection molding, this powder can be reused to make 3D-printing filament and spare components. Another project saw McKinney bring together engineers and architects to find ways to protect lunar habitats from harmful radiation. The solution that the team came up with was to make cast bricks out of lunar regolith that did not need mortar or any other binder to be stacked.

As far as making rocket fuel on Mars is concerned, McKinney is not the only one working on the idea. In a study published in ACS Catalysis in April this year, Ahmed Badreldin, an assistant professor of chemical engineering at the University of Mississippi, and his team showed that astronauts could convert the carbon dioxide in Mars' atmosphere to methane using a technique known as electrochemical reduction. Methane is used by the Raptor engines on Starship, the huge, fully reusable rocket SpaceX is developing to send humans to the Red Planet.

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