Now, we can construct structures on Moon from urine.
A new study suggests that urea, second abundant in urine after water, could be useful for making concrete for lunar structures.
“I was thinking, what’s available on the moon? If you add humans, then what do you have available?” says Anna-Lena Kjøniksen, a Norwegian University chemist.
Anna-Lena Kjøniksen, who made cement from urea and faux lunar soil, says, “”We have not yet investigated how the urea would be extracted from the urine, as we are assessing whether this would really be necessary, because perhaps its other components could also be used to form the geopolymer concrete. And adds, “The actual water in the urine could be used for the mixture, together with that which can be obtained on the Moon, or a combination of both.”
To reside in other planets or moon, astronauts need to pack light since carrying shipping materials from Earth is expensive. Less than a kilogram sent into the orbit around the Earth costs around $10,000.
On Earth, to reduce the need for the amount of water in the cement, we use a chemical called superplasticizer. It makes the mixture flexible enough to print 3D structures. Most superplasticizers are organic compounds but are also not available on the Moon.
Then came the idea of urea. Anna-Lena Kjøniksen has previously used urea to make plastic mixtures less viscous. Urea reduces friction and lets the molecules slid past each other easily by breaking the Hydrogen bonds between the molecules. So, this chemist gave it a try.
The main ingredients of Kjøniksen cement are silica and aluminium oxide powder (faux lunar dust). The key chemical component of this ingredient possesses properties similar to fly ash, the main component of common cement mixtures, only with larger and more crystalline grains. The team mixed the powder with urea, supplied from a chemical supplying company, along with some water. The obtained substance proved the use of urea to be as worthy as that of superplasticizers used in Earth.
The mixture obtained has a lightweight and can withstand high temperatures. It can form stable structures, reported by the team of Journal of Cleaner Production.
Kjøniksen plans to test the cement in a vacuum chamber with high temperature, mimicking the Moon’s atmosphere.