Of blood and dust. Incredible space construction ideas
Lunar settlement projects are already being developed. Next in line is Mars. But delivering anything there is expensive and technically difficult. Therefore, scientists are considering various options for the production of food, fuel, energy and building materials from local raw materials, including the waste products of the colonists.
Relying on local materials
Mars does not have a dense atmosphere and magnetic field. The early settlers will need a secure shelter to protect themselves from cosmic radiation, solar radiation and micrometeorites. In addition, sandstorms rage on Mars and wind speeds can exceed one hundred kilometers per hour. The only material from which something can be built is loose surface rocks, Martian regolith.
You also need a stabilizer, a binder that gives strength to the material. At the same time, raw materials must be plastic – this is the requirement of additive technology.
As a stabilizer, one usually considers either inorganic cement, which can be obtained from the water contained in the Martian ice, as well as carbon dioxide and nitrogen in the atmosphere of the Red Planet, or biosynthetic polymers such as spider silk or albumin protein found in the blood of cattle.
Mixed in blood
Biological binders (tree resins, collagen from hooves, casein from cheese, animal blood) have been widely used to make glue for thousands of years. Petroleum-based synthetic adhesives are – by historical standards – a very recent invention.
Animal blood was often added to mortars in the Middle Ages. In the 19th century, by mixing sawdust with bull’s blood, bois durci, a hardened tree, was obtained in France. When heated to 150-200 degrees Celsius under pressure, excess moisture was removed from the mixture. In this case, albumin molecules were combined into oligomeric chains and permeated the entire mass, giving it extraordinary strength. Tempered wood was used to make small interior items, furniture decor elements, picture frames. For one kilogram of such “wood” only about 130 milliliters of blood was required. In fact, it was the first biocomposite material.
At the beginning of the 20th century, the American company Haskell Manufacturing produced haskelite – plywood glued with a hydrophobic glue based on bovine albumin. It was used to make aircraft hulls, boats, floating bridges, as well as elements of building structures.
More than once, there have been ideas to use the blood drained in slaughterhouses, which is usually thrown away or burned, in the production of building blocks, for which patents were granted. But all such inventions remained unclaimed – “bloody” bricks are too expensive. Another thing is Mars, over which the hand of the market is not in control.
Astronaut blood concrete
It is clear that there are no plans to bring cows to the Red Planet. For now, anyway. So, instead of bovine, you will have to use human albumin. By mixing loose material, like the lunar or Martian regolith, with this protein from human blood, British scientists have obtained a biocomposite that is not inferior to concrete. They named it AstroCrete.
Created two options – for the Moon and Mars, with an albumin concentration of 15 and 37.5 percent, respectively. The compressive strength is from 19.5 to 25 megapascals, as in ordinary concrete, and if urea is added, then up to 39.7.
Albumin is the most abundant protein in human blood. In its plasma – 40-45 grams per liter, replenished at a rate of 12-25 grams per day. According to calculations, a liter of blood is enough for 300 grams of composite concrete. If each astronaut donates blood twice a week, this will give about 2.5 kilograms of composite per month. In 72 weeks, you can build a room for another colonist.
This technology does not require bioreactors and equipment for the production of synthetic polymers, therefore, the consumption of energy, water and time is lower. It is important that production does not depend on supplies from Earth. Provided that other life support systems are working normally, the colony will be able to independently expand living space or restore the destroyed one.
Spicy dietary supplement
Albumin’s binding properties arise when blood proteins are unfolded. They bond together to form flat structures known as beta sheets, which hold the particles in the material. But for this they must be denatured. Urea, another AstroCrete ingredient, works best for this.
On average, a person produces from one to two liters of urine per day, which is 20-35 grams of urea. It is separated in the life support system when receiving clean water. This is a valuable raw material. They can, for example, fertilize plants. But, according to scientists, atmospheric Martian nitrogen is perfect for this, and it is better to put urea on “bloody” concrete.
Spiders are next
Spider silk has been considered as an alternative to human albumin. The basis of the web is the same protein from which the silkworm weaves cocoons – fibroin. Its adhesion properties are not worse than that of albumin, and the molecules are alsoform strong networks due to hydrogen bonds.
Spiders have been sent into space more than once. A recent experiment – two different-sex individuals of the species Trichonephila clavipes were observed on the ISS for two months – showed that they weave webs in zero gravity without any problems.
However, the spider option is more difficult. They need separate rooms – spacious enough not to interfere with each other. They need to be looked after, fed with fly larvae. Also, unlike silkworms, spiders are more difficult to breed. Everything goes to the fact that it will be necessary to create synthetic analogues of spider silk based on recombinant proteins.
In a Martian settlement, raw materials can theoretically be synthesized in a bioreactor, and so that it does not stand idle, it can also make biofuels, chemicals, pharmaceuticals, food, and process human waste products. But so far there are no such universal attitudes and, apparently, the first settlers will have to rely mainly on their own forces and local resources.