A Toxic Element In The Planet's Soil Could Be Used To Build Them

It will never be possible for us to send construction materials to Mars in order to establish colonies there: to place 1 kg of payload there we must launch around 12 kg of fuel and structures into low Earth orbit, which brings us to an average amount close to 20,000 euros/kg. That’s stratospheric, but remember, by the time NASA sent the Perseverance rover in 2020, the launch cost alone was about $243 million. If prices have fallen since then, it is thanks to the arrival of SpaceX’s reusable launchers.

In any case, there is consensus on the fact that, in order to establish a lasting human presence there, it will be necessary to use the resources on site: this is the concept of the ISRU (In Situ Resource Utilization), essential for the actors who will participate in this conquest. The use of biomineralizing bacteria, for example, or transforming Martian regolith, loaded with perchlorates (a highly flammable toxic cocktail) made of concrete resistant to the infernal conditions of the Red Planet. An idea that comes to us from the Indian Institute of Science (Bangalore, India), which has just published a study on January 29 in the journal PLOS One detailing this proposal.

Objective Mars: toxicity is strength

The researchers behind this study set their sights on an earthly bacteria called Spore load of pasteuria. It is its metabolism that interested them, since it naturally produces urea which, by reacting with calcium, generates calcium carbonate crystals. By mixing these crystals with guar gum (a thickening agent), the researchers managed to agglomerate false regolith (artificial dust reproducing Martian dust) to form solid bricks.

Even if Spore load of pasteuria is sensitive to the toxicity of perchlorates; when in contact with these substances, it secretes a particularly sticky protein extracellular matrix. Using an electron microscope, the team observed that this organic substance fills the interstitial voids between the regolith grains and the calcium crystals (the “phenomenon of “ biocimentation “). It also forms micro-ponts Who facilitate the precipitation of calcium carbonate in a much more dense and homogeneous manner.

This biochemical network not only blocks pores, but also delivers nutrients to stressed bacteria, allowing them to continue to mineralize the soil despite ambient toxicity.

The rest of the program for the Indian Institute of Science team will consist of place these organic bricks in chambers simulating Martian conditions. The objective is to verify whether biocementation and secretion of the protective matrix by Spore load of pasteuria can withstand an atmospheric pressure ten times lower than that of Earth and an air composed of 95% carbon dioxide.

If the bacteria survives and continues its work as a worker, future colonists could inject into the soil of Mars nutrient solutions to solidify the foundations of habitats in the planet’s substrate. Of course, all this still remains in the domain of theory, and we are very far from master this process on a large scale. Let’s imagine that the mineralization, once there, takes months to start, the construction of a base would take years. Suffice to say that the first manned missions will not have the luxury of waiting that long and many other factors will need to be taken into account. How do you feed the stumps enough urea to get them to work? Would the structures made of these biobricks really ensure their waterproofing role against radiation and temperature variations? Isn’t it too big a risk to take to imagine contaminating the Martian soil as soon as you arrive on it? Brief, we could unravel dozens of questions without ever having the answer ; this is the other side of the coin of experimental research. A great theoretical feat who is now awaiting his baptism of fire (and perchlorate)!