How bacteria could help build and maintain cities on the moon

Bacteria may help repair lunar bricks using regolith for lunar cities.

: Scientists are exploring the use of bacteria, specifically Sporosarcina pasteurii, to help construct and repair lunar cities by utilizing local resources like lunar regolith. The bacteria convert urea and calcium into calcium carbonate, binding regolith particles to make bricks. Testing showed bacterial slurry restored 28-54% of bricks' strength, though concerns remain about bacterial behavior in extraterrestrial conditions. An upcoming Indian space mission, Gaganyaan, may investigate these possibilities further.

The innovative use of bacteria in lunar construction offers a promising frontier in space exploration. Researchers, particularly from the Indian Institute of Science (IISc), have been experimenting with making bricks using lunar regolith simulants combined with the bacterium Sporosarcina pasteurii. This bacterium converts waste products like urea into calcium carbonate, a binder when mixed with guar gum, which is extracted from guar beans. This material enables the binding of lunar regolith particles to form bricks, aiming for cost-efficiency by using resources available on the moon rather than launching heavy materials from Earth.

Koushik Viswanathan, from the IISc's Department of Mechanical Engineering, highlights the challenge of moon's extreme conditions on the bricks. Sintered bricks, while strong, face significant thermal stress due to the lunar temperature range of 250°F (121°C) to -208°F (-133°C). Lunar bricks must also endure impacts from micrometeorites and cosmic rays, where cracking and structural fatigue pose a substantial risk to any lunar outpost's integrity.

The IISc team developed a method using bacterial slurry as a sealant to fill the cracks and holes in bricks. Initial tests applied this slurry to damaged sintered bricks, finding that it restored a significant degree of compressive strength, though not to the original levels. Aloke Kumar, also from the IISc, remarks on this approach's efficacy while acknowledging uncertainties about bacterial behavior in space conditions, such as changes in carbonate production.

To further explore bacteria's viability in extraterrestrial environments, the IISc proposes an experiment to test Sporosarcina pasteurii in space as part of India’s Gaganyaan mission. This crewed space mission, set to launch as early as 2026, aims to expand our understanding of microbial life in space. If successful, it would be the first experiment of its kind, potentially revolutionizing how structures are built and maintained on other celestial bodies.

These efforts mark a significant advancement in sustainable lunar exploration and the potential for establishing lunar bases by leveraging native materials and innovative biological methods. As researchers continue to explore these possibilities, the dream of building and maintaining lunar cities moves closer to becoming a reality.

Sources: IISc, Gaganyaan mission, Frontiers in Space Technologies.

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