Could Human Waste Feed Astronauts?

It sounds gross, but stick with us: Researchers are working on recycling astronauts' waste into food for edible stuff. Learn how (and why) in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hi brain
Stuff Lauren Vogel bomb here. A manned mission to Mars
might take around six months. Suffice it to say, when
meal times roll around, astronauts won't be dialing up delivery
pizza and root. Instead, they may be eating nutrition derived
from their own fecal matter, a concept that would save

(00:22):
on cargo, space and wait while maximizing materials already found
on the spacecraft. At Penn State University, scientists are developing
a system that leverages certain types of microbes that convert
human solid waste into protein and fat Latin foods. Researchers,
for better or Worse, have already called the result a
microbial goo that's sort of reminiscent of vegemite, a comparison

(00:44):
that seems unlikely to please vegemites corporate executives. Because it's
difficult and time consuming to grow food in space, astronauts
have to rely on items in their closed environment. The
lynch pin of the system is anaerobic digestion, which can
break down certain materials with the need for oxygen. It's
a common process for reducing municipal waste on Earth. In tests,

(01:05):
the digestion process produced methane gas. That gas turns out
to be useful in growing a microbe called Methylococcus capsulattice,
which is already used for animal feed pellets and contains
about fifty protein and thirty six percent fat content. According
to the National Academy of Sciences, humans function best when
they ingest nutrition with about fifty percent carbohydrates, twenty percent fat,

(01:27):
and ten to thirty protein, So the goose still has
a ways to go before it can count as an
ideal food source. The tests relied on substitute liquid and
solid waste instead of actual human wastes. When the real
thing is introduced, there will also be concerns about pathogens
that could cause illnesses. That's where tweaking the pH levels
and or temperatures may help. Tests showed that by increasing

(01:50):
the system's temperatures to around a hundred and fifty eight
degrees fahrenheit that's seventy degrees celsius, most germs were eliminated,
yet the nutritious microbe Thermois aquaticus survived. Alternately, they raised
the alkalinity of another batch and found that bacteria called
halo Monus deciderrata still managed to proliferate, while germs did not.
The team borrowed concepts from commercial aquarium filters that use

(02:13):
fixed film filters to neutralize fish waiste. The filters incorporate
a bacteria laden film and were adapted by researchers to
accommodate methane production. The result solid waste can be treated
in a matter of hours instead of days plus. Because
the system is self contained, it really doesn't require much
babysitting other than you know, the necessary inputs. But there's

(02:34):
also the matter of taste. Lisa Steinberg, the lead author
on the study, says that the bacteria could be mixed
with other materials and flavorings to make it more palatable.
She said in an email, it's nearly certain that there
would be plants grown in conjunction with this food stuff,
which would provide additional flavors and textures. And what about
the potential psychological issues associated with consuming a material of

(02:56):
such dreary origins, Steinberg said. Astronauts ready have to drink
their own processed urine, so they're probably accustomed to things
being done differently in space than on Earth. Some astronauts
on the International Space Station do already recycle some of
their urine. Poop, on the other hand, has a more
spectacular ending. It's blasted into space, caught an Earth's orbit,

(03:17):
and then burns up like a shooting star on reentry. Yes,
in space, poop has historically been a problem. Maybe now
poop will be part of the solution. While these still
experimental concept may not exactly fire up astronauts appetites, it
may eventually provide sustenance to space explorers who have a
limited buffet options among the stars. Today's episode was written

(03:43):
by Nathan Chandler and produced by Tristan McNeil. For more
on this and lots of other tasty topics, visit our
home planet, how stuff Works dot com.