Ass-troplastic! Printing parts from p.. er... human waste

Boffins flushed with success as new uses found for cosmic cack

Space Shuttle toilet (pic: Smithsonian)

Researchers reckon some smart bacteria and a 3D printer could solve the twin challenges of transporting materials on a journey to Mars and dealing with all the solid waste generated by space-faring humans.

The team from the University of Calgary have devised a process (PDF) called ‘Astroplastic’, which produces polyhydroxybutyrate (PHB) from solid lumps of human excreta. PHB, a bioplastic, can then be used to print useful items for astronauts.

NASA has form with 3D printing in space and has shown that tools such as a ratchet wrench can be produced in a matter of hours.

A 3D printer needs material to work with, and the research points the way to a future where astronauts will be able to quite literally do it themselves.

The Astroplastic process took genetically modified Escherichia coli (E. coli) to make PHB granules and designed fermentation and extraction processes to create a continuous PHB production system, suitable for use by a 3D printer aboard a spacecraft.

The (rear) end to end process sees astronaut feces collected from a vacuum toilet and left to ferment for three days to increase the amount of volatile fatty acids (VFAs) that E. coli will chow down on to produce the PHB. Centrifugation and filtration is used to extract liquid containing VFAs from solids.

The delightful brew is then dropped into another fermenter along with the modified E. coli and the resulting PHB extracted.

The final product can be used in a Selective Laser Sintering (SLS) 3D printer, thankfully with no further tinkering.

The team also sought input from Canadian astros Robert Thirsk and Bowie-botherer Chris Hadfield, who pointed out that anything that goes into space needs to be easily repaired by crew members. Hadfield, for one, has had personal experience of the facilities failing onboard the ISS.

To underline the real-world nature of their work, the team painstakingly calculated that the mass of the equipment would come in at 900 kg, considerably less than the 5,000 kg of plumbing needed on the ISS to transform reclaimed water into something free of the distressing tang of urine.

Boffins have already proposed using human waste as radiation shielding on a mission to Mars, and Matt Damon memorably grew potatoes out of the stuff in the movie The Martian.

With this new research, it seems there is no end to the possibilities afforded by poo. ®

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