Will Astronauts Produce Food from Human Waste?

Astronauts could soon be eating food produced from their own waste, according to a new study from researchers at Pennsylvania State University. This idea could provide significant benefits to the colonization of space, as humans begin to colonize the solar system and points beyond.

Microbial reactors would break down both solid and liquid waste, while hindering the growth of pathogens, which could make space travelers ill. The food produced by this method would be a gelatinous, edible substance.

“We envisioned and tested the concept of simultaneously treating astronauts’ waste with microbes while producing a biomass that is edible either directly or indirectly depending on safety concerns. 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,'” explained Christopher House, geosciences professor at Penn State.

Space Toilet
A space toilet at Gagarin Cosmonauts Training Center. Could this be the beginning of space food? Photo by Christopher Michel. CC from Wikimedia.

Carrying food from Earth on long-duration space missions would add mass to the spacecraft and launch vehicle, increasing the cost of such a journey. Growing food in space would require vast expenditures of water and energy – two valuable resources on a long trip through space.

Researchers utilized artificial human waste to test their ideas, allowing microbes to digest the waste material through anaerobic digestion. Nutrients were removed from the process and placed into a microbial reactor in order to produce the edible gel. This process produced methane, which was utilized to grow Methylococcus capsulatus, a microbe commonly used for animal feed. The sample was composed of 52 percent protein and 36 percent fat. In an attempt to destroy pathogens, the research team also grew Halomonas desiderata bacteria in an alkaline environment, and Thermus aquaticus at temperatures that kill most other microbes.

Roughly half the raw material in the experiment was converted into other forms by the microbes within 13 hours. This is significantly faster than current methods of eliminating waste products. Researchers utilized a fixed-film filter, like those in aquariums, to convert materials in the waste into fatty acids.

The production of methane could lead to explosions aboard spacecraft, which has resulted in a lack of studies demonstrating how human waste could be converted to food. However, this volatile gas is commonly created on the International Space Station (ISS) as air is recycled.

Astronauts will not be recycling their waste into food right away, however, as this experiment only tested parts of what would need to be a complete system.

Analysis of the study was published in the journal Life Sciences in Space Research.

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