Future colonists of Mars should be able to turn the planet’s soil into bricks without using an oven or additional ingredients, according to US engineers.
A study, published in Scientific Reports, found that all explorers would need is to compact the soil with the equivalent of a blow from a hammer.
The engineers from the University of California San Diego, funded by Nasa, initially tried to cut down on the amount of polymers required to shape Martian soil into bricks, and accidentally discovered that none was needed.
Researchers found that to make bricks out of simulated Mars soil, without additives and without heating or baking, two steps were key: to enclose the soil in a flexible container, in this case a rubber tube, and secondly to compact the soil at a high enough pressure.
The amount of pressure needed for a small sample is roughly the equivalent of someone dropping 10lb hammer from a height of one metre, said Yu Qiao, a professor of structural engineering at UC San Diego and the study’s lead author.
The engineers believe that the iron oxide, which gives Martian soil its signature red colour, acts as a binding agent. They scanned the simulated soil’s structure and found that the tiny iron particles coat its bigger rocky basalt particles. The iron particles have clean, flat facets that easily bind to one another under pressure.
Researchers also investigated the bricks’ strengths and found that even without rebar, they are stronger than steel-reinforced concrete. They said their method may be compatible with additive manufacturing. To build up a structure, astronauts could lay down a layer of soil, compact it, then lay down an additional layer and compact that, and so on.
Proposals to use Martian soil to build habitats for manned missions on the planet are not new. However, this is the first that shows astronauts would need minimal resources to do so. Previous plans included nuclear-powered brick kilns or using complex chemistry to turn organic compounds found on Mars into binding polymers.
The research has become all the more important since the US Congress passed a bill in last month, directing Nasa to send a manned mission on Mars in 2033.