IISc team's bacteria-based method may help repair cracked bricks on Moon

New Delhi: Researchers have developed a method using bacteria to repair bricks used to build structures on the Moon that can develop cracks due to the widely swinging temperatures on the lunar surface.

A team of researchers from the Indian Institute of Science (IISc), Bengaluru said future explorations of the Moon are no longer planned as "flyby" missions, instead involve setting up a permanent habitat -- for example, NASA's Artemis missions.

However, the lunar environment is extremely harsh. Temperatures can swing from 121 degrees Celsius to -133 degrees Celsius in a single day and the Moon is also constantly hit by solar winds and meteorites, they said.

Bricks exposed to such an environment can develop cracks, which can weaken the structures built using them, the team said.

In a research paper, published in the journal Frontiers in Space Technologies, the authors described that defects were artificially created in bricks, into which a slurry made of 'Sporosarcina pasteurii' bacteria, guar gum and a lunar soil-like material was poured.

The bacteria can decompose urea in the environment to convert it into carbonate and ammonia.

Calcium in the bricks can react with carbonate to form calcium carbonate -- which along with guar gum serves as "both a filler and a cementing agent", thereby repairing the cracks, the authors said.

They also found that the reinforced bricks were able to withstand temperatures ranging from 100 degrees Celsius to 175 degrees Celsius.

"Temperature changes can be much more dramatic on the lunar surface, which can, over a period of time, have a significant effect," co-author Koushik Viswanathan, associate professor at the department of mechanical engineering, IISc.

Lead author Aloke Kumar, associate professor at the department of mechanical engineering, IISc, said, "We were initially not sure if the bacteria would bind to the sintered brick. But we found that the bacteria can not only solidify the slurry but also adhere well to this other mass."

Sintering is the process of heating a compact mixture of soil-like material and a polymer called 'polyvinyl alcohol' to very high temperatures for creating much stronger bricks.

"It's one of the classical ways of making bricks. It makes bricks of very high strength, more than adequate even for regular housing," Kumar said.

However, "sintered bricks are brittle. If you have a crack and it grows, the entire structure can quickly fall apart," Viswanathan said.

The researchers had previously used the Sporosarcina pasteurii bacteria to build bricks out of material similar to lunar and Martian soil.

Currently, the team is working on a proposal to dispatch a sample of the Sporosarcina pasteurii bacteria into space as part of the Gaganyaan mission, which could help study the microbe's growth and behaviour under microgravity.