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Can urine whiz rockets to Mars?

Kenny Allen / NASA file

A Delta 2 Heavy rocket rises from Cape Canaveral Air Force Station in Florida in September, carrying the twin GRAIL spacecraft toward the moon. Scientists say bacteria could turn urine into rocket fuel for future trips beyond Earth orbit.

The idea of using urine to whiz rockets to the moon and beyond is once again leaking into the realm of possibility. 

That's because scientists have begun to crack the code of how bacteria that live without the aid of oxygen convert ammonium — a key chemical in urine — into hydrazine, which is a type of rocket fuel.

"It is a complex of three proteins" that do the trick, Mike Jetten, a microbiologist at Radboud University Nijmegen in the Netherlands, explained to me in an email today.

The urine-to-fuel concept first gained traction in the 1990s when scientists discovered the microbe, called anammox for anaerobic ammonium oxidation, that does this, but the idea stalled out when scientists realized only small quantities of the fuel are produced.

"Now that we understand how hydrazine is made we can try to improve the catalyst," Jetten said. "And we produce millions of tons of ammonium in wastewater every year," he added, suggesting that therein is enough of the material to manufacture rocket fuel. 

For now, the microbe is used in wastewater treatment facilities, and the findings reported Sunday in the journal Nature have more realistic and earthly applications there, said Jetten. "The better we know the process, the better we can optimize and design new wastewater treatment systems," he said.

The team is also investigating "a new concept in which waste is converted into methane," Jetten added.

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John Roach is a contributing writer for msnbc.com.