The Process

Lunar Environment

BENGALURU: This won’t be just another brick in the wall. In what holds potential of aiding construction of future settlements on Moon, a team of Indian Institute of Science (IISc) and Isro researchers has developed “space bricks” using Lunar Soil Simulant (LSS).The team led by Aloke Kumar , an assistant professor from the mechanical engineering department at IISc, took up the research on manufacturing bricks using LSS given that prospects of in situ resource utilisation — using local resources available on Moon — have gained favour for proposed habitat projects on Moon planned by different agencies around the world.They used LSS developed by Isro for the purpose. And, as reported first by TOI in February 2018, Isro has mastered the process of creating LSS whose properties match 99.6% with the samples brought back from Moon by the Apollo missions.Also, a futuristic project of building ‘Igloos’ on Moon is already underway in Isro, but it is yet to be officially budgeted. The space agency has more than 60 tonnes of LSS lying with it.“The name (space brick) itself conveys an idea of settlements outside Earth. We started working on this about two-and-a-half years ago, trying to answer one question: Can we make bricks out of lunar soil? We began working on the process, and today, we’ve manufactured bricks in our lab,” Kumar told TOI.Kumar said they used “bacterial growth induced biocementation technology” to manufacture bricks. They wanted to organically grow bricks and therefore chose bacteria and tried a process called “microbial induced calcite precipitation”, wherein, in the right conditions, the bacteria can precipitate calcium carbonate.Now, here’s what all this means in layman’s terms: Bacteria are very versatile and certain species are capable of bio-mineralisation — process by which living organisms produce minerals to harden or stiffen existing tissues — which was done to make this brick.So, the team used one specific bacteria (Sporosarcina pasteurii), which was introduced into LSS, which then hardened. “In perfect condition, the LSS, which is a powder, slowly turns into a brick after 15-20 days of introducing the bacteria,” Kumar explained.However, the first set of bricks lacked strength and could be broken with bare hands. “We then used guar gum, a naturally occurring polymer, as an additive. The results were fantastic and the brick exhibited an approximate 10-fold increase in strength,” Kumar said.Guar gum, extracted from guar beans has thickening and stabilizing properties useful in food, feed, and industrial applications.On whether, this bacteria can function in the same manner in the lunar environment, Kumar said: “All organisms change their behaviour in varying conditions. Therefore, in order to further test the promise of this technology in extra-terrestrial conditions, it is essential to carry out tests in low-gravity conditions.”Towards this end, the team has proposed designs for payloads that can be tested in microgravity conditions. “Our results and proposed designs have a strong potential for utility in creating human habitations,” Kumar said, adding that in the next phase, they will simulate microgravity conditions in their lab and eventually hope to test the same in space.Other than Aloke, the IISc team includes Rashmi Dixit K Viswanathan , while the Isro team comprises Arjun Dey, Anuj Nandi, I Venugopal (who heads the lunar habitation project), N Sridhara and A Rajendra. While the team from IISc developed the technology at its lab on campus, the Isro team helped them.