Deep space missions come with challenges, not the least of which is limited storage space. But scientists are finding ways to reduce the amount of supplies and costly shipments astronauts need on missions, partly by making use of what's already on hand — including human waste.
"If you had the means to manufacture medicines and food and nutraceuticals and tools, you wouldn't have to plan ahead. You could make what you need as you need it," Mark Blenner of Clemson University told CBC News.
Blenner's research, in partnership with NASA, has found ways to combine a specific type of yeast with human urine and turn it into a plastic that could be fed into a 3D printer to make objects like tools. The urine-yeast combo was also used to create omega-3 fatty acids, which are sold as nutritional supplements and contribute to heart, eye and brain health.
The research was presented Tuesday during the national meeting and exposition of the American Chemical Society in Washington, D.C.
While the ability to create a material and objects while in space is part of the research, Blenner is especially excited about the possibility of being able to make vitamins or medicine while in space.
Fresh vitamins, drugs
"There are a lot of vitamins and also medicines that degrade just over time. As we have a three-plus year space mission, the quality of critical nutrients will start to decline to the point they're no longer there," he explained. "It's difficult to send new supplies that are going to retain their quality, so you have to find a way to make them on site."
In the early phases of the research, Blenner discovered the yeast used in the research, Yarrowia lipolytica, liked to eat pure urea, a substance found in urine.
When the research switched to working with human urine, which also contains other things besides urea, researchers found the yeast had the ability to "tolerate the other stuff that's in urine," he said. The yeast grew even better in the human urine than in pure urea.
In order to grow, yeast needs not just nitrogen, but also carbon, which is something there is a lot of in space, Blenner said.
It could possibly be gathered as carbon dioxide from astronauts' breathing, he said.
The final piece of the puzzle was to combine the yeast and carbon, which required what Blenner called the "middle man" in the form of photosynthetic cyanobacteria. The fast-growing microbes turn sunlight and carbon dioxide into sugars. The yeast then uses the sugars and human urine to produce plastics and fatty acids.
Developing plastics and omega-3 fatty acids from astronaut waste shows the possibility of what can be made in space from things that are already there, Blenner said.
However, he doesn't expect astronauts to be able to produce everything they may need on a long mission from their own waste. Some supplies will need to be shipped up and others may be made using other chemical processes.
"We don't view this as the holy grail of how we're going to enable space travel," Blenner said, "but it's certainly an interesting part of the equation."