Rocket Fuel from Human Waste

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

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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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