In the “The Martian,” astronaut Mark Watney uses a slightly...smelly source of fertilizer
to grow food on Mars, mixing Martian dirt with feces to create soil for his potatoes.
But the idea of using human by-products on a deep-space exploration mission isn’t so
far-fetched.
In fact, it’s probably essential if we want to make the months-long trip to the red planet
for realsies.
Human waste is inevitable, but rather than thinking of our bathroom leavings as a dead
end, space researchers see them as an appealing resource.
Astronauts on the International Space Station already drink their own urine.
Ever since 2009, filtration systems on the station have been able to convert water from
sweat, showers, and yes, pee into drinking water.
In a multi-step process, the water is carefully filtered by vacuum distillation.
Then it’s treated with iodine to kill any bacteria and comes out squeaky clean.
It does in the US-built part of the station, anyway.
The Russian-built water reclamation system doesn’t use urine.
Which means whenever the astronauts get a chance, they haul bags of pee from the Russian
side and feed it into the American reclamation system.
No point in letting that water go to waste.
Water isn’t the only thing in urine.
It’s packed with carbon and nitrogen, locked up in a molecule called urea.
It’s a good bet that if a molecule has carbon and nitrogen in it, then there’s a microorganism
that can eat it.
Which is how researchers from Clemson University plan to convert astronauts’ urine into plastics
and nutrients using some mighty microbes.
Specifically, yeast.
Yeast are super great.
They give us beer, bread, and in the future, maybe brain food.
This little superhero is called Yarrowia lipolytica.
To grow it in space, astronauts would feed it algae grown from the recycled carbon in
their breath.
But it would also need nitrogen.
Fortunately, it thinks pee is delicious.
With all that tasty good stuff from breath and pee, this space yeast could become a living
recycling plant.
That’s because they are carbon master craftsmen.
They’re great at making oils and fats, stringing carbon together in long chains to produce
a huge variety of energy-packed products.
A little genetic tampering by humans can shape what products they make, and how much of them.
One thing the researchers want the yeast to make is omega-3 fatty acids.
You may have heard of these as the healthy fats abundant in fish.
They’re needed for proper brain function and may improve heart health.
Inconveniently, our bodies can’t make omega-3s.
We have to get them in our diet.
And as supplements, omega-3s have too short of a shelf life to last through your joyride
to Mars.
So these yeast are being engineered to become supplement powerhouses, producing omega-3s
that astronauts can harvest from some of the growing yeasties and eat.
Which means the yeast will be making plenty of brain food so our astronauts can continue
scienceing.
But that’s not all the researchers want to harness this handy little yeast for.
Future space missions will rely on 3D printers to make tools and other things that astronauts
will need on the fly.
That 3D printer still needs plastic to make things from, though.
Enter our hero yeast once more.
The fats and oils this yeast produces are made mostly of carbon and hydrogen.
But those same organic raw materials are also what you need to make plastic.
The yeast can actually be genetically engineered to spit out PHAs, which are a kind of polyester
-- the same kind of plastic fiber that pops up in your clothes.
Which means this space-faring, pee-swilling yeast could make not just nutritional supplements,
but raw material for plastic tools that astronauts can use.
Just don’t think too hard about where that wrench came from.
The yeast makes plastic as a way of storing food for itself to eat later.
Yum, plastic.
I love soda bottles, don’t you?
That means it can be hard to get the PHAs out of the yeast, which is holding on to its
precious food supply.
There could be a way to engineer the yeast to feed right into the printer, but the researchers
aren’t sure yet, and they might end up using a more traditional extraction method.
Basically, space researchers are thinking hard about how to recycle everything astronauts
touch--again and again and again--on an atomic level.
The yeast is just one way to tackle some of these problems, and we’ll probably need
lots of creative engineering to get astronauts to Mars in one piece--and eventually, to bring
Matt Damon home.
Again.
Seriously, why do we always have to keep saving that dude!?
Could you swallow supplements knowing they were grown from last week’s pee?
Let us know in the comments, and give the thumbs up and subscribe buttons some love
while you’re there.
And hey, thanks for watching!