Friday, May 22, 2020

Using Urine Productively in Space Exploration

On the Moon (or presumably, Mars), Urine can be used for landing pads, gardens, and drinking water.
https://www.wired.com/story/on-the-moon-astronaut-pee-will-be-a-hot-commodity/
"It's too expensive to ship everything from Earth, which means they'll have to get creative with the limited resources on the lunar surface. Moon dirt is a great building material and there's water in the form of ice at the south pole that can be turned into rocket fuel. But the hottest commodity of them all may very well turn out to be an astronaut's own pee.

Earlier this year, a team of European researchers demonstrated that urea, the second most common compound in human urine after water, can be mixed with moon dirt and used for construction. The resulting material is a geopolymer, which has similar properties to concrete and could potentially be used to build landing pads, habitats, and other structures on the moon.
...
On the moon, most infrastructure is likely going to be built by industrial 3D printers. Building with bricks would be way too inefficient and would limit the types of structures that could be made. But robotic 3D printers could autonomously build more complex habitats. Lunar regolith has chemical similarities to fly ash, which makes geopolymers an attractive option for building stuff on the moon. The downside is that geopolymers require a lot of water so they'll flow through the nozzle of a 3D printer.
...
Superplasticizers are materials that are used to reduce the water content of concrete and geopolymers while maintaining their flowability. On Earth, superplasticizers are typically hard-to-pronounce substances like naphthalene and polycarboxylate. But as Arnhof and her colleagues discovered, urea works just as well and could easily be sourced on the moon. Rather than filtering out contaminants in astronaut urine and recycling the waste water, the pee could be stored in a tank and harvested for urea."

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