Researchers are developing a way to convert astronaut urine and exhaled carbon dioxide into plastics to make tools in space.
The idea of using human waste in space isn’t new: Astronauts aboard the International Space Station already drink water converted from their sweat, showers and pee.
The newly developed system relies on specific strains of yeast, that use urea in urine and carbon dioxide from astronauts’ exhaled breath, to produce polyester polymers that can be used in a 3-D printer to make new plastic parts, while other strains can even produce essential omega-3 fatty acid nutrients for the astronauts.
The research could enable long-duration space trips and make a trip to Mars possible in future.
The idea of using human waste in space isn’t new: Astronauts aboard the International Space Station already drink water converted from their sweat, showers and pee.
A The study results will be presented today at the 254th National Meeting and Exposition of the American Chemical Society (ACS), the world’s largest scientific society.
According to the leader of Dr Mark Blenner, the leader of the study and a researcher at Clemson University in South Carolina, astronauts can’t take many spare parts into space because every extra ounce adds to the cost of fuel needed to escape Earth’s gravity.
‘If astronauts are going to make journeys that span several years, we’ll need to find a way to reuse and recycle everything they bring with them,’ said Dr Blenner.
‘Atom economy will become really important.’
According to Dr Blenner, the solution lies in part with astronauts who will constantly generate waster from breathing, eating and using materials.
However, instead of throwing away these waster materials like on Earth, Dr Blenner and his team are working on how to re-purpose the molecules from this waste and convert them into products the astronauts need, such as polyesters and nutrients.
HOW IT WORKS
Dr Mark Blenner, a researcher at Clemson University, led a study involving converting waste products, such as urine, into useful compounds such as polyester molecules to manufacture plastic parts in space, and even essential omega-3 fatty acid nutrients for the astronauts.
Dr Blenner’s system includes a variety of strains of yeast from a species called Yarrowia lipolytica.
Dr Blenner’s system includes a variety of strains of yeast from a species called Yarrowia lipolytica (pictured), which require nitrogen and carbon to grow
These yeast strains require nitrogen and carbon to grow, and Dr Blenner’s team found that the yeast can obtain their nitrogen from urea in untreated urine.
The yeast obtain their carbon from carbon dioxide, either from astronauts’ exhaled breath, or from the Martian atmosphere.
However, to use the CO2, the yeasts requires a middleman to ‘fix’ the carbon into a form they can ingest.
To do this, the yeast relies on photosynthetic cyanobacteria or algae provided by the researchers.
For example, some essential nutrients such as omega-3 fatty acids, have a shelf life of just a couple of years, says Dr Blenner.
So if astronauts were to undertake a long-duration space mission, omega-3 fatty acids would have to be made en route, beginning a few years after launch, or at the destination.
‘Having a biological system that astronauts can awaken from a dormant state to start producing what they need, when they need it, is the motivation for our project,’ says Dr Blenner.
Dr Blenner’s system includes a variety of strains of yeast from a species called Yarrowia lipolytica.
These yeast strains require nitrogen and carbon to grow, and Dr Blenner’s team found that the yeast can obtain their nitrogen from urea in untreated urine.
The yeast obtain their carbon from carbon dioxide, either from astronauts’ exhaled breath, or from the Martian atmosphere.
However, to use the CO2, the yeasts requires a middleman to ‘fix’ the carbon into a form they can ingest.
To do this, the yeast relies on photosynthetic cyanobacteria or algae provided by the researchers.
One of the strains the researchers developed can produce omega-3 fatty acids, a nutrient that the body cannot make itself and which contributes to heart, eye and brain health.
Another strain that the team made can produce monomers – a molecule that can be bonded to other identical molecules – and link them to make polyester polymers, which is the same kind of plastic fiber found in certain clothes.
The system relies on specific strains of yeast that use urea in urine and carbon dioxide from astronauts’ exhaled breath to produce polyester polymers and even omega-3 fatty acid nutrients. The research could enable long space trips such as a trip to Mars. Pictured is the ISS
These polymers could be used in a 3-D printer to generate new plastic parts.
Dr Blenner’s team is continuing to develop this yeast strain to produce a range of different monomers that can be linked to produce different types of polyesters with a range of properties.
For now, the engineered yeast strains can only produce small amounts of polyesters or nutrients, but the researchers are working on increasing output.
The researchers are also looking into applications on Earth, for example in fish farming and human nutrition.
For example, fish raised via aquaculture need to be given omega-3 fatty acid supplements which could be produced by one of the yeast strains.
Other researcher groups are also exploiting yeast but in a different way.
The newly developed system relies on specific strains of yeast, that use urea in urine and carbon dioxide from astronauts’ exhaled breath, to produce polyester polymers that can be used in a 3-D printer to make new plastic parts aboard the International Space Station
For example, a research team with chemical firm DuPont is already using yeast to make omega-3 fatty acids for aquaculture, but its yeast feed on refined sugar instead of water products.
In addition, two other teams are engineering yeast to male polyesters, but unlike Dr Blenner’s team, they aren’t engineering the organisms to optimize the type of polyester produced.
Regardless of the approach, these researchers are all adding to the body of knowledge about the Yarrowia lipolytica yeast species, which has been studied much less than, for example, the yeasts used in beer production.
‘We’re learning that Y. lipolytica is quite a bit different than other yeast in their genetics and biochemical nature,’ Dr Blenner says.
‘Every new organism has some amount of quirkiness that you have to focus on and understand better.’
The idea of using human waste in space isn’t new: Astronauts aboard the International Space Station already drink water converted from their sweat, showers and pee