Rocket Fuel from Human Waste

Human waste could generate both methane fuel and water for future space missions to Mars or beyond

2 min read
Illustration: Getty Images

Getting rid of human waste has been a problem for NASA since the earliest days of space exploration. That’s why the U.S. space agency is funding researchers to figure out how to transform such waste into rocket fuel for future space missions.

The human waste of astronauts and cosmonauts aboard the International Space Station has usually been dumped with other trash in space capsules that burn up in the Earth’s atmosphere, according to But engineers in Florida have developed a anaerobic digester process that can turn such organic waste into biogasa mix of methane and carbon dioxide. Additional processing can also create water and oxygen.

“The idea was to see whether we could make enough fuel to launch rockets and not carry all the fuel and its weight from Earth for the return journey,” said Pratap Pullammanappallil, an associate professor of agricultural and biological engineering at the University of Florida in Gainesville, in a press release. “Methane can be used to fuel the rockets. Enough methane can be produced to come back from the moon.”

Such research originated from NASA’s now-defunct Constellation program intended to send astronauts back to the moon. NASA supplied scientists with a waste package that included chemically-produced human waste, simulated food waste, towels, wash cloths, clothing and packaging materials—the estimated waste from a human mission to the moon.

Pullammanappallil and his then-graduate student Abhishek Dhoble figured out how to extract 290 liters of methane per crew per day from the waste. Their digestion process could also potentially generate 200 gallons of non-potable water from the waste each year.

Such a process could also potentially prove useful on Earth if it’s efficient enough. Methane fuel could help heat buildings, generate electricity or act as fuel for vehicles. The University of Florida has also tested a version of the digester that could be used by farmers.

It’s not clear whether such digesters will be ready for deployment on space missions anytime soon. But it doesn’t hurt for NASA and other space agencies to consider potential solutions in advance before sending human astronauts on deep-space missions to visit asteroids or Mars.

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Top Tech 2022: A Special Report

Preview two dozen exciting technical developments that are in the pipeline for the coming year

1 min read
Photo of the lower part of a rocket in an engineering bay.

NASA’s Space Launch System will carry Orion to the moon.

Frank Michaux/NASA

At the start of each year, IEEE Spectrum attempts to predict the future. It can be tricky, but we do our best, filling the January issue with a couple of dozen reports, short and long, about developments the editors expect to make news in the coming year.

This isn’t hard to do when the project has been in the works for a long time and is progressing on schedule—the coming first flight of NASA’s Space Launch System, for example. For other stories, we must go farther out on a limb. A case in point: the description of a hardware wallet for Bitcoin that the company formerly known as Square (which recently changed its name to Block) is developing but won’t officially comment on. One thing we can predict with confidence, though, is that Spectrum readers, familiar with the vicissitudes of technical development work, will understand if some of these projects don’t, in fact, pan out. That’s still okay.

Engineering, like life, is as much about the journey as the destination.

See all stories from our Top Tech 2022 Special Report

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