'Brick by brick': Astronaut Shubhanshu Shukla at IISc works on Mars construction tech

New Delhi: What’s common between Indian astronomer Shubhanshu Shukla, a soil bacteria isolated from Bengaluru, gums released by Guars (cluster beans) and Mars?

Well, they all are connected to an Indian Institute of Science research that aims to perfect a technology for making bricks on the surface of the Red Planet using the Martian soil and use the same technology to make less carbon intensive bricks on the Earth.

Construction of civil structures that need bricks on Mars appears to be science-fiction now. “But some day it may happen as there is a growing trend of sending people to space,” IISc scientist Alok Kumar, who is spearheading the research initiative, told DH.

Kumar and his colleagues at the Department of Mechanical Engineering including Shukla, who is pursuing his Masters, has been working on a process known as bio-cementation to build what they call space bricks out of lunar and Martian soil simulants using a soil microbes named Sporosarcina pasteurii, guar gums - a powdery material extracted from cluster beans - and a few chemicals.

The bacterium converts urea and calcium into calcium carbonate crystals that, along with guar gum, glue the soil particles together to create brick-like materials. This process is an eco-friendly and low-cost alternative to lowering of cement used in construction.

“The idea is to do in situ resource utilisation as much as possible. We don’t have to carry anything from here. We can use those resources and make those structures, which will make it a lot easier to navigate and do sustained missions over a period of time,” said Shukla, the first Indian to enter the International Space Station.

In the current study, the authors used a more robust, native strain of the bacterium that they discovered in the soils of Bengaluru.

After establishing the bacteria’s brick-forming skills, the researchers wanted to test if the strain would survive in the Martian soil that contains a chemical named perchlorate up to one per cent. Two NASA probes – Phoenix lander and Curiosity rover – detected its presence on the planet.

The IISc team, in collaboration with Punyasloke Bhadury, a scientist at the Indian Institute of Science Education and Research, Kolkata, reported that the bacterial cells became stressed in the chemical’s presence.

But to their their surprise, they found that the presence of perchlorate made the bacteria better at gluing the soil together, but only if guar gum – essential for bacterial survival – and the catalyst nickel chloride are also present.

“When the effect of perchlorate on just the bacteria is studied in isolation, it is a stressful factor,” says Swati Dubey, currently a PhD student at the University of Florida and first author of the study, published in PLOS One. “But in the bricks, with the right ingredients in the mixture, perchlorate is helping.”

Dubey said the underlying biochemical processes might be enhancing the bacteria’s bio-cementation skills - a theory that the team would explore in future studies.

The team aims to deploy this method as an alternative, sustainable building strategy, to rely less on carbon-intensive cement-based processes – both on Earth and Mars.

“Such technologies can make future Mars landing missions smoother – by helping build better roads, launch pads, and rover landing sites. The uneven topography of the moon’s surface has caused some landers to topple over” Shukla noted.

The team is also working on a proposal to deploy the bacteria in space as part of the Gaganyaan mission, to test their growth and behaviour under microgravity.