Getting to Mars could rely on astronauts making tools and food from their own urine

Besides the vast distances, and the fact you’ll most certainly die if you step outside without a suit, one of the most significant hurdles in getting to Mars is taking enough food and tools with us.

Astronauts can’t take spare parts and nutrients into space because every extra ounce adds to the cost of fuel needed to escape Earth’s gravity. They do, however, create a vast amount of waste – and this could be key to achieving our mission objectives.

“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,” explains researcher Dr Mark A Blenner from Clemson University. “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 on Earth, they’ll be reluctant to throw waste molecules away. Astronauts already drink recycled urine and sweat. In particular, the International Space Station can recycle about 93% of the liquids it receives. The filtration systems were installed in 2009 and the station converts water from sweat showers by carefully filtering it using vacuum distillation treated with iodine to kill any bacteria. It takes around eight days to recycle and is said to be purer than some water on Earth. 

Blenner 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, continues Blenner. They’ll need to be made en route, 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 that use nitrogen and carbon to grow. Blenner’s team discovered that the yeast can obtain nitrogen from urea in untreated urine. Meanwhile, the yeast obtains carbon from CO2, which could come from astronauts’ exhaled breath, or from the Martian atmosphere. To use the CO2, however, the yeast require a middleman to “fix” the carbon into a form they can “eat” and, to do this, they rely on algae provided by the researchers.

One of the yeast strains studied produces Omega-3 fatty acids. Another strain has been engineered to produce monomers and link them to make polyester polymers. Those polymers could be used in a 3D printer to generate new tools. Blenner’s team is continuing to engineer this yeast strain to produce a variety of monomers that can be turned into different types of polyesters.

The researchers are presenting their results at the 254th National Meeting & Exposition of the American Chemical Society. The project is one of eight being funded by NASA with a view to travelling into deep space under its Space Technology Research Grants. Each proposal falls under the Early Career Faculty scheme and comes with approximately $200,000 in funding per year, up to three years. 

Image: American Chemical Society