Indian scientists have developed what they claim is a sustainable process for making brick-like structures on the Moon. The Microbial Induced Calcite Precipitation process would use bacteria to create a solid structure from lunar soil. The bricks, they suggest, could be used to assemble habitation structures on the lunar surface.

To create the brick, scientists with the Indian Institute of Science and Indian Space Research Organization mixed the Sporosarcina pasteurii bacteria, which produces calcium carbonate crystals, with a simulant of lunar soil. Next, reports Tech Explorist, they added urea and calcium along with gum extracted from guar beans. After a few days of incubation the resulting material was found to possess significant strength and machinability.

The material can be fabricated into any freeform shape using a lathe. “This is advantageous because this completely circumvents the need for specialized molds – a common problem when trying to make various shapes by casting,” says Koushik Viswanathan, assistant professor in the Department of Mechanical Engineering. “This capability could also be exploited to make intricate interlocking structures for construction on the moon without additional fastening mechanisms.”

The next step in the development process is to make larger bricks with a more automated production process, and to test them under varied loading conditions like impacts and moonquakes.

Geoff Brooks, a chemical engineer with Australia’s Swinburne University, has been giving considerable thought to the challenges of building structures under the extreme conditions of the Moon. Temperatures swing from -180° C to 120° as the Moon alternates between intense light and deep darkness. The surface is bombarded by solar and cosmic rays. Glass-like dust particles get everywhere. Even the chemical behavior of materials changes.

“If you think about the way bricks are made, a bit like pottery, imagine trying to make pottery on the moon, where the perfect vacuum changes the way materials heat up and the shape that they take,” Brooks tells Create, an Australian engineering publication. “These are the kinds of experiments we’re now building, to test not only how the materials will react on the moon but how we can work with those conditions to create a structure.”

Humans will need structures to shelter them from cosmic rays and moon dust. “We will need buildings with thick walls to protect space travelers,” he says. “However, on the moon we have only the rocks on the ground and the sun to work with. Everything else is difficult and expensive to get there.”

Other research priorities include finding ways to manage abrasive dust, and recycling space junk. 

Brooks heads a team of approximately 15 academics and PhD students encompassing disciplines such as mechanical engineering, mechatronics, product design, and physics.

European researchers have found that the urea in human urine can be used as a “plasticizer” to combine with lunar regolith to make building materials.

The cost of transporting building materials to the Moon is so expensive — roughly $10,000 per pound — that scientists are looking for ways to utilize materials readily available on the Moon. Dutch, Norwegian, Spanish and Italian researchers theorized that urea could be incorporated into concrete to soften the initial mixture and make it more liable before it hardens, reports Phys.org.

“To make geopolymer concrete that will be used on the moon, the idea is to use what is already there: regolith (loose material from the moon’s surface) and the water from the ice present in some areas,” explains one of the authors, Ramón Pamies, a professor at the Polytechnic University of Cartagena (Murcia). “But moreover, 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 urine are water and urea, a molecule that allows the hydrogen bonds to be broken and, therefore, reduces the viscosities of many aqueous mixtures.”

Using material similar to regolith mixed with urea, researchers have manufactured concrete cylinders using a 3-D printer. The urea mixture supported heavy weights and remained almost stable in shape. Resistance was tested at a temperature of 80°C, and was found to increase even after eight freeze-thaw cycles like those on the Moon.

Next step: figuring out how to extract the urea from the urine.