Could astronauts on Mars make their own fuel for the trip home?

"The zinc is fundamentally a great catalyst," says Houlin Xin. "It has time, selectivity, and portability—a big plus for space travel." (Credit: Nicolas Lobos/Pexels)

Researchers may have come up with a solution to one of the most pressing challenges of a Mars voyage: How do we get enough fuel for the flight back to Earth?

Houlin Xin, an assistant professor in physics and astronomy at the University of California, Irvine, and his team have discovered a more efficient way of creating methane-based rocket fuel theoretically on the surface of Mars, which can make the return trip all the more feasible.

The new discovery comes in the form of a single-atom zinc catalyst that will synthesize the current two-step process into a single-step reaction using a more compact and portable device.

“The zinc is fundamentally a great catalyst,” Xin says. “It has time, selectivity and portability—a big plus for space travel.”

Illustration of astronauts and structures on Mars
This concept depicts astronauts and human habitats on Mars. NASA’s Mars 2020 rover will carry a number of technologies that could make Mars safer and easier to explore for humans. (Credit: NASA)

The process of creating methane-based fuel has been theorized before, initially from Elon Musk and Space X. It utilized a solar infrastructure to generate electricity, resulting in the electrolysis of carbon dioxide, which, when mixed with water from the ice found on Mars, produces methane.

Known as the Sabatier process, astronauts on the International Space Station use it to produce breathable oxygen from water. One of the main issues with the Sabatier process is that it is a two-stage procedure requiring large faculties to operate efficiently.

The method Xin and his team developed will use anatomically dispersed zinc to act as a synthetic enzyme, catalyzing the carbon dioxide and initializing the process. This will require much less space and can efficiently produce methane using materials and under conditions similar to those found on the surface of Mars.

“The process we developed bypasses the water-to-hydrogen process, and instead efficiently converts CO2 into methane with high selectivity,” Xin says.

Currently, Lockheed and Boeing rockets use liquid hydrogen as fuel. While it is cheap and effective, this fuel source has its drawbacks. Liquid hydrogen leaves carbon residue in the engine of the rocket, which requires cleaning after each launch; something that would be impossible on Mars.

Space X and Elon Musk developed and are currently testing a methane fuel-based engine, known as the Space X Raptor. Raptor will power Space X’s next generation of spacecraft named Starship and Super Heavy. At this time, neither have made it into orbit, and only one has consistently taken flight.

Despite the breakthrough, Xin’s process is far from implementation. Currently the team only have a “proof of concept,” meaning that while they have tested and proven it in a lab, they have yet to test it real world—or planet—conditions.

“Lots of engineering and research is needed before this can be fully implemented,” Xin says. “But the results are very promising.”

The research appears in the Journal of the American Chemical Society.

Source: Ian Anzlowar for UC Irvine