Recycling Human Waste For 3D Printing Materials in Space
The researchers are presenting their results today at the 254th National Meeting & Exposition of the American Chemical Society (ACS).
Astronauts can't take a lot of 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," Mark A. Blenner, Ph.D., says. "Atom economy will become really important."
The solution lies in part with the astronauts themselves, who will constantly generate waste from breathing, eating and using materials. Unlike their friends on Earth, Blenner says, these spacefarers won't want to throw any waste molecules away. So he and his team are studying how to repurpose these molecules and convert them into products the astronauts need, such as polyesters and nutrients.
Some essential nutrients, such as omega-3 fatty acids, have a shelf life of just a couple of years, says Blenner, who is at Clemson University. They'll need 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," he says.
Blenner's biological system includes a variety of strains of the yeast Yarrowia lipolytica. These organisms require both nitrogen and carbon to grow. Blenner's team discovered that the yeast can obtain their nitrogen from urea in untreated urine. Meanwhile, the yeast obtain their carbon from CO2, which could come from astronauts' exhaled breath, or from the Martian atmosphere. But to use CO2, the yeast require a middleman to "fix" the carbon into a form they can ingest. For this purpose, the yeast rely on photosynthetic cyanobacteria or algae provided by the researchers.
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