Human settlements on Mars are one step closer after scientists created ‘space bricks’.
These could be created on the Red Planet by mixing astronauts’ urine with the dusty Martian soil.
The bricks are made by mixing dust with urea, the main compound in urine, and bacteria as well guar gum and nickel chloride.
The slurry can be poured into moulds of any shape and over a few days the bacteria convert the urea into calcium carbonate crystals.
These crystals, as well as biopolymers which are secreted by the bacteria, act as cement that holds the soil particles together.
The new bricks, which were developed by researchers from the Indian Institute of Science, are less porous than others which researchers have tried to use to make Martian bricks.
Bacteria seep deep into the bricks’ pore spaces and use their proteins to bind particles together, making them less porous and creating stronger bricks.
The new method can make complex shapes of brick, unlike a method the team had used to try and make bricks from the moon’s soil, which ended up producing bricks that could only be cylindrical.
To begin with, the bacteria did not grow at all because soil on Mars is rich in iron, which is toxic for many organisms.
Nickel chloride was the key ingredient that unlocked the process and made the soil hospitable for bacteria.
The group now plan to investigate how Mars’ atmosphere and low gravity will affect the strength of space bricks.
The Martian atmosphere is 100 times thinner than the Earth’s and is made from 95 per cent carbon dioxide, which could significantly stunt bacterial growth.
To try and test what would happen to the bricks in practice, the team have made a Martian Atmosphere Simulator device that reproduces the atmospheric conditions of the red planet in a lab.
The team has also developed a lab-on-a-chip device that aims to measure bacterial activity in micro-gravity conditions.
With help from the Indian Space Research Organisation, the team plan to send such devices into space, so that they can study the effect of low gravity on the bacterial growth.
Dr Aloke Kumar, a senior author of the study said: ‘I’m so excited that many researchers across the world are thinking about colonising other planets.
‘It may not happen quickly, but people are actively working on it.
‘This biological approach, coupled with a scalable casting method, towards manufacturing of bricks presents a promising and highly sustainable potential route for in situ utilization of structural elements on extra-terrestrial habitats.’
The findings were published in the journal PLoS One.
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