Martian air could yield methane rocket fuel with fewer unwanted byproducts

As NASA prepares to send humans to Mars as early as the 2030s, University of Mississippi researchers are working on one of the key questions: How will they get back?

Traveling millions of miles to Mars will require huge amounts of fuel. Coming back could take as much or more. Instead of hauling that much fuel across the stars, researchers are improving a technology that could allow future astronauts to make rocket fuel using resources already available on the red planet.

“You can’t bring up everything you need from Earth, because every additional kilogram adds enormous cost and complexity to launch and escape Earth’s gravity,” said Ahmed Badreldin, assistant professor of chemical engineering. “So the question becomes: How do we make the fuels and chemicals needed for space exploration from the resources already available at the destination?”

Turning Martian air into methane

In a study published in ACS Catalysis, Badreldin and Carter Racine, a doctoral mechanical engineering student at Texas A&M University, showed that future astronauts may be able to make fuel out of thin Martian air.

The atmosphere on Mars is roughly 96% carbon dioxide, one of the molecules humans exhale when they breathe. Using an engineered copper catalyst that is 100,000 times smaller than the width of a human hair, the researchers showed that carbon dioxide can be converted into methane.

“The work we’re doing is basically taking CO₂ and using electricity to convert it into carbon-containing fuels and chemicals,” Racine said. “We want to do that because right now many of these carbon-based products ultimately come from virgin fossil resources.

“If we can make them using captured CO₂ and renewable electricity, it could reduce reliance on virgin fossil carbon and help close the carbon cycle.”

Purity matters more on Mars

Other technologies can perform the same reaction, but those methods often produce multiple unwanted byproducts, Badreldin said.

“The main technical challenges for Mars applications are that you cannot assume the same extensive separation and purification infrastructure that we have on Earth,” the Ole Miss researcher said. “On Earth, you can separate (wanted and unwanted products), but on Mars, the product ultimately needs to approach propellant-grade purity.”

The copper catalysts that the researchers are developing are designed to push the reaction toward methane with high selectivity, reducing the burden on downstream purification.

Potential uses beyond spaceflight

The technology could also be beneficial on Earth, the researchers said. Methane is the primary component of natural gas and is used to make fuels and industrial chemicals.

“On Earth, there’s a lot of interest now in using methane as a feedstock for producing higher-value chemicals like alcohols,” Badreldin said. “If methane can be produced on site from CO₂, then upgraded locally, it could enable more distributed production of fuels and chemicals instead of relying only on large, centralized facilities.”

While the idea of using the technology to remove vast quantities of carbon dioxide from Earth’s atmosphere—where the greenhouse gas traps heat and contributes to planetary warming—is alluring, the technology is not there yet, Badreldin said.

“If you pull that CO₂ from the atmosphere to make methane and then burn it as a fuel source, you re-create the same CO₂,” he said. “That’s net zero. You essentially have closed the loop.

“What we are ultimately interested in is seeing whether we can move beyond simply recycling CO₂ and toward pathways that are net-negative. That means using CO₂ as a carbon source while converting it into products where the carbon is stored or used long enough that it is not immediately released back into the atmosphere.”

Aviation remains a tough target

Perfecting the process could also benefit industries that are difficult to connect to electric grids or batteries, such as air travel.

“You can’t really put a big, heavy battery on a plane because it’s not going to be able to fly very well or fly very far,” Racine said. “It’s difficult to decarbonize that industry, even though there is strong interest in doing so, because of the logistical constraints involved.

“But we could put synthetic carbon-based fuels into the same plane right now and it would fly just as well without virgin fossil fuel.”

While figuring out how to improve Earthbound carbon conversion, Badreldin’s research group also plans to test its current method with different materials to improve methane production on Mars through a grant from Mississippi NASA EPSCoR Research Infrastructure Development.

“By tuning the catalyst structure and local reaction environment, we aim to improve activity, methane selectivity and long-term stability, which is very important for this work,” Badreldin said.

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Lisa Lock

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Robert Egan

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