Yeast, algae and urine may be astronauts’ best bet for sustenance and supplies on longer trips in space
Astronauts at the International Space Station (ISS) recently got a welcome, tasty reminder that they operate in low Earth orbit. A batch of 30 Bluebell ice cream cups were delivered on a Dragon resupply capsule, marking the end of the North American summer for people living where there are no seasons. In the future, astronauts traveling further into space, such as to Mars, won’t be able to look forward to such luxuries. Instead, there’s a good chance they’ll have to find ways to enjoy whatever their onboard yeast and algae can make out of their urine.
Recyling, not resupplying
Once a ship gets too far from Earth, astronauts won’t be able to rely on regular care packages the way they can on the ISS. Like hikers trekking deep into the woods, people making the nine-month trip to Mars will need to carry everything they might need with them when they depart. This is tough, since some items essential to nutrition, like omega-3 fatty acids, don’t have a shelf life long enough to make the trip. Growing food in space may be an option to an extent, but as tasty as space lettuce may be, growing a farm’s worth of plants won’t be efficient for a while. Instead, the answer may be to bring some very compact organisms to help do a lot of serious recycling.
Water is already heavily recycled in space, even on the conveniently located ISS. Some toilets on the station are equipped to clean astronauts urine so that potable water can be reclaimed for later use. However, other ingredients in astronaut pee may provide even more utility, such as nitrogen that can be fed to yeast. If some carbon dioxide-scrubbing algae are along for the trip, they can also be fed to the yeast, at which point astronauts will have a biological factory at their disposal to create new products. Those omega-3 fatty acids, for instance, can be created by specific strains of Yarrowia lipolytica yeast raised on algae and nitrogen, ensuring a fresh supply of nutrients for astronauts on long trips.
Beyond filling astronauts’ nutritional needs, genetically modified yeasts also promise to make raw materials, like polyesters. We normally think of polyester as a component of fabrics, but it may be usable in 3D printers to make other tools and components on demand in space. There are still a number of challenges to be overcome, such as the currently-impractical volume of yeast needed to make a small plastic tool, but the hope is that these methods will be refined in the near future.
There’s still no word on a urine-fed yeast that can make ice cream for future space travelers, but don’t despair if you really wanted some truly authentic astronaut ice cream. People are already working with yeasts to make dairy proteins without cows here on Earth, so version raised on algae and urine shouldn’t be an insurmountable problem.
Source: Space savers: astronaut urine could make supplies from nutrients to tools by Nicola Davis, The Guardian