Astronaut poop could spawn ‘microbial goo’ to eat on deep-space voyages, scientists say

Deep-space voyages create a whole world of logistical nightmares for astronauts to sort through — and that’s before even embarking on missions to Mars and beyond.

Two of those challenges are especially thorny, though: How do you stock enough food on board to last months or years? And where do you store months or years worth of human waste?

Scientists at Pennsylvania State University say they have solved both of those problems at once. But if you’re squeamish, you might not like the researchers’ inventive solution: Take human waste from astronauts, and use microbes to transform it into biomass that astronauts can eat.

“Anaerobic digestion is something we use frequently on Earth for treating waste,” Christopher House, a professor of geosciences at Penn State, said in a statement. “What was novel about our work was taking the nutrients out of that stream and intentionally putting them into a microbial reactor to grow food.”

Solving the food and waste problems simultaneously would be a major achievement, researchers said. That’s especially true given how much fuel would be spent carrying heavy food stores into space, and how much room would be eaten up with hydroponic or other traditional food-growing operations.

“That’s why this might have potential for future space flight,” House said. “It’s faster than growing tomatoes or potatoes.”

But how exactly did the researchers prove it?

First, researchers got their hands on the same kind of artificial liquid and solid waste that waste management tests use. Then they made an enclosed cylinder — four feet long, but just four inches in diameter — and filled it with the fake waste and some microbes to break the waste down.

That anaerobic digestion process breaking down the waste (similar to what happens in our stomachs) created methane, researchers said. And that methane could be put to use growing yet another microbe: Methylococcus capsulatus, which is already being used as animal feed, the Financial Times reports.

“It’s a little strange, but the concept would be a little bit like Marmite or Vegemite where you’re eating a smear of ‘microbial goo,’ ” House said.

The microbe produced in that process is about 50 percent protein and 35 percent fat, making it appropriate for human food consumption, researchers said.

But even for creating pig and fish food, the process of turning methane into something edible has only recently taken off on a commercial scale, the Financial Times reports.

Ideally, proponents of the animal feed said, the process could be a closed loop in which methane from animal waste could be turned right back into animal food — just as the Penn State researchers demonstrated was possible for astronauts.

The process, however, isn’t an easy one on a large level.

“It is a difficult reaction to control,” Henrik Busch-Larsen, chief executive of Unibio, a company working on a methane-generated animal feed, told the newspaper. “You need to get as much methane gas as possible into the liquid that the bacteria are in.”

And at least here on Earth, it will be a while until people are munching on Methylococcus capsulatus protein bars.

“You would have to modify the process,” Busch-Larsen told the Financial Times. “It is not for tomorrow.”

The team at Penn State also studied growing microbes in high heat and high alkaline environments, researcher said, which would hopefully kill waste-related pathogens that could cause safety concerns. And even in those environments, researchers said they were able to produce thriving edible bacteria.

Though the system isn’t ready for prime time, the study did show that it’s feasible, House said, with each part of the process “quite robust and fast.”

Their NASA-funded research was published in the journal Life Sciences in Space Research in November.

This story was originally published January 26, 2018 at 5:15 PM with the headline "Astronaut poop could spawn ‘microbial goo’ to eat on deep-space voyages, scientists say."