Urine luck: astronaut pee shown to shrink the cost of Moon bases

Both Nasa and the China National Space Administration have plans to build bases on our nearest celestial neighbour to aid in space exploration and to use as a possible jumping-off point for a trip to Mars.

The current cost of transporting just 0.45kg into space is around $10,000 (£7,665), making the prospect of any sort of permanent Moon base an expensive proposition.

Scientists have been trying to find ways to lower this cost by reusing or repurposing as much space-bound material as possible.

A team of researchers from Norway, Spain, the Netherlands and Italy, in cooperation with the European Space Agency (ESA), have found that the urea in urine can be used as a plasticiser in the construction of concrete structures.

Plasticisers are used as an additive that can be incorporated into concrete to soften the initial mixture and make it more pliable before it hardens. The concrete itself could be made from rock matter found on the Moon.

“To make the geopolymer concrete that will be used on the Moon, the idea is to use what is there: regolith (loose material from the moon’s surface) and the water from the ice present in some areas,” said Professor Ramón Pamies at the Polytechnic University of Cartagena.

“With this study we have seen that a waste product, such as the urine of the personnel who occupy the moon bases, could also be used. The two main components of this body fluid are water and urea, a molecule that allows the hydrogen bonds to be broken and, therefore, reduces the viscosities of many aqueous mixtures.”

Using a material developed by ESA, which is similar to Moon regolith, together with urea and various plasticisers, the team used a 3D printer to manufacture various ‘mud’ cylinders and compared the results. 

The samples carrying urea were able to support heavy weights and remain almost stable in shape.

Once heated to 80°C, their resistance was also tested and even increased after eight freeze-thaw cycles like those on the Moon.

“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,” said researcher Anna-Lena Kjøniksen.

“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.”

The scientists stress the need for further testing to find the best building material for the Moon bases, where it can be mass-produced using 3D printers.

Last year, the UK Space Agency said it was bidding to provide key communications services between the Lunar Orbital Platform Gateway, which is a proposed space station orbiting the Moon, and scientists back on Earth.