One of the more mundane, but critical, challenges when it comes to building future space habitats, such as moon bases, is the prohibitive cost of transporting materials from Earth. The cost of transporting just 0.45 kilos (that’s roughly equal to about five blueberry muffins) from Earth is around $10,000. The Holy Grail, therefore, would be to discover a way of recycling materials in space into building blocks that could be used for construction.
A team of European researchers believes it may have found exactly that — and it involves a distinctly DIY-sounding combination of astronaut urine and moon dust; both of which would be in ready supply on any future moon mission.
In tests, the researchers from Norway, Spain, the Netherlands, and Italy, in cooperation with the European Space Agency (ESA), tested the concoction as a potential 3D printing material. In experiments carried out at Norway’s Østfold University College, they found that their printed samples are capable of supporting heavy weights, maintaining their structure, and even surviving repeated freeze-thaw cycles.
Shima Pilehvar
“[In our work] we are utilizing lunar regolith, a.k.a. moon dust, in combination with sodium hydroxide and water, to make geopolymer concrete,” Professor Anna-Lena Kjøniksen, one of the researchers on the project, told Digital Trends. “Geopolymer concrete is a concrete that [does] not utilize ordinary cement. It is desirable to use this on the moon since it is horrendously expensive to bring anything up from Earth. Since water is in limited supply on the moon, we need to add something to reduce the amount of water we need to gain good flow-properties for 3D-printing building structures.”
Chemicals aren’t, of course, in any more ready supply in space than anything astronauts would usually bring from Earth. However, urine can provide an abundant source of one particular chemical, called urea, which is useful for breaking hydrogen bonds. Breaking hydrogen bonds in the moon dust concrete reduces its viscosity, making it softer and more pliable before it hardens. This, in turn, makes the resulting material one which could be more easily 3D-printed as a structure, the same way researchers have explored 3D-printing entire buildings on Earth.
“The next step is to test if we can use this for 3D-printing in a vacuum,” Kjøniksen said. “In addition, we are going to test the concrete’s ability to stop irradiation, which there is much more of on the moon than on Earth … If we manage to develop a geopolymer concrete that can be 3D-printed in a vacuum and still give the desired mechanical and radiation shielding properties, we hope they will test it in space in the future.”