One of the challenges we face when thinking about developing off-Earth settlements is what resources we could use to build our habitats – after all, we can't efficiently ship loads of concrete or bricks to the Moon or Mars. The ideal solution would be to harness as many in-situ materials as possible. Recently we've seen several innovative strategies, from mixing lunar dust with a biopolymer to extracting metals from Martian soil.
We recently saw researchers at the University of California, San Diego detail a way to bake bricks from Martian soil without heat. Now scientists at the European Space Agency (ESA), who have been investigating methods for building settlements on the Moon for several years now, have built on an earlier 3D printing process using lunar materials mixed with a binding salt to develop a new way to 3D print bricks using nothing more than moondust and concentrated sunlight.
To test the new process the researchers used a simulated moondust composed of terrestrial volcanic materials and cooked it in a solar furnace. Using 147 curved mirrors, the solar furnace focused sunlight into a high-temperature beam that could melt the simulated moondust into a solid.
"This was done on a 3D printer table, to bake successive 0.1 mm layers of moondust at 1,000° C (1,832° F)," explains Advenit Makaya, a materials engineer working on the project for ESA. "We can complete a 20 x 10 x 3 cm (7.9 x 3.9 x 1.2 in) brick for building in around five hours."
As a proof of concept, the tests seem to indicate this is a very feasible method of lunar construction, with the resulting bricks reportedly being as strong as gypsum, but there are still more tests needed to understand how transferable the process is to off-Earth conditions. A follow-up project dubbed RegoLight is set to explore the potential for these construction processes to be applied to lunar environments.
"Our demonstration took place in standard atmospheric conditions, but RegoLight will probe the printing of bricks in representative lunar conditions: a vacuum and high-temperature extremes," says Advent.
Looking at more earthly uses, the simplicity of the technology could offer new ways to construct emergency housing in situations where transporting building resources may be costly or time-consuming.
"3D printing of civil structures using solar power and in-situ resources could support rapid construction of post-disaster emergency shelters, removing long, costly and often inefficient supply chains," explains Tommaso Ghidini, head of the ESA's Materials and Processes division.
You can take a look at the process in the ESA video below.