Since mid-November, we have been nearly eight billion human beings on Earth. Because our planet is not expandable and its resources are dwindling, some believe that the salvation of our species lies in the colonization of other planets, in particular Mars. So that we can one day thrive on the red planet, Paul Smith, a civil engineer at the University of Bristol, proposes to build a forest under a dome on its surface.
The human population is expected to exceed nine billion by 2050.” If human population growth is unchecked, semi-natural areas must be sacrificed for food production and urbanization, leading to ecosystem collapse and environmentally-imposed population reduction. “, warns the scientist in theInternational Journal of Astrobiology. An alternative, he says, is to create more habitats in orbit around the Earth or on the lunar or Martian surface.
Mars is not a very welcoming planet. The average temperature is -63°C and dust storms are frequent. Not to mention that its thin atmosphere, mainly composed of CO2, is unbreathable and the absence of a magnetic field induces high levels of radiation. The latest exploration missions have however revealed that it has large reservoirs of water ice under its surface, which could be very useful if Man were to settle there permanently. It would then remain to create spaces under controlled atmosphere. This is the principle of the Martian nature reserves presented by Paul Smith.
An unusual assemblage of species for a new ecosystem
Smith suggests building “confined Earth-like ecosystems” (or CTTE), green oases on the surface of Mars as it were. Assuming containment can provide tolerable conditions, Mars offers gravity, atmosphere, enough sunlight for photosynthesis and water, while proximity to Earth allows system management, he points out. . This confined ecosystem could be large enough to accommodate a forest, a facsimile of an ancient forest more exactly.
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Concept drawing of a “forest bubble” on Mars. © P.SmithThe engineer recalls that forest environments have beneficial effects on health, both physically and psychologically (he speaks of a “psychological refuge”). This forest would also serve as a botanical garden, housing species useful to settlers for their secondary metabolites (vitamins, flavors, perfumes, medicines, colors and mood enhancers). A network of these oases is therefore, according to him, essential to consider the exploration of space by Man. ” It is easier to enter a desert, knowing that it contains an oasis “, he notes.
This environmentally controlled hemispherical enclosure would have a radius of approximately 250 meters, or a footprint of 20 hectares. It will not be a question of recreating a specific terrestrial forest biome (which would be counter-productive according to the author), but rather of gradually introducing different species, selecting those that best adapt to Martian conditions, then leaving this unusual assemblage of species is gradually forming a new ecosystem specific to Mars.
To do this, several environmental constraints will have to be taken into account, starting with radiation from solar and cosmic particles which are harmful to all living organisms. However, according to Smith, it would be relatively simple to generate an artificial magnetic field to deflect these particles. He notes, however, that certain behaviors, notably the growth and development of plants, could be compromised by the absence of the Earth’s geomagnetic field.
Ultraviolet management will be more delicate. Mars has no ozone layer and its surface is therefore exposed to high levels of UV. But these are both harmful and beneficial to organisms: Some UV is required for vitamin D synthesis and other mechanisms in animals notes the author, who adds that some pollinators use UVA rays for navigation. ” Human well-being and ecosystem functioning will therefore require modulation, not total exclusion, of Mars’ UV flux. “, he concludes.
The importance of the seasons and the lunar influence
The soil composition of these Martian nature reserves is obviously a key point. A priori, the basalt crust of Mars contains nutrients to support the growth of terrestrial plants; the essential elements (nitrogen, potassium, iron, zinc, etc.) have all been identified in Martian meteorites. But the Martian substrate also contains toxic elements, in high concentrations (iron oxides, perchlorates, hydrogen peroxide), which must be eliminated beforehand.
Another point of difficulty: to reproduce the terrestrial seasons. ” Biomes change seasonally, so CTTEs need seasons. Temporality determines critical stages of development, individual physiologies and interspecific relationships notes Smith. Mars has four seasons, which do not have the same length due to the planet’s elliptical orbit; spring in the northern hemisphere (which corresponds to autumn in the southern hemisphere) is the longest Martian season. ” The seasons also imbue characteristics essential to psychological restoration, for example, the color of autumn, the silence of winter, the flowers of spring and the foliage of summer. “, underlines the scientist.
It is not known to what extent terrestrial organisms can adapt to Martian seasons. Likewise, the effects of a completely different lunar influence than on Earth remain uncertain. As Smith reminds us, our Moon serves as a benchmark for many ecological processes — in animals, as in plants, whose growth can be influenced by the force of the tide. Conversely, Phobos and Deimos, which are much smaller, have no influence on the Martian surface.
The ability of organisms to adapt to a gravity much lower than that of Earth (on Mars, gravity is 0.38 g) also raises questions.
In summary, building a CTTE on Mars will be particularly complex, but no matter how many challenges there are, humanity faces them, according to Smith. ” From a biocentric perspective, world leaders should be concerned with the future of life in the Universe and humanity’s role in its protection and promulgation. On a planet with limited habitability, this is an important duty. Survival of life in any form is the ultimate biocentric priority “, he concludes.