Terraformation
The terraformation initially resulting from the Science-fiction becomes a science studying the transformation of the natural environment of a Planet, a the Moon or another body, in order to meet the conditions there allowing a Vie of the terrestrial type, thus hoping to make it livable by the Man.
The official term in French is écogenèse .
The paramount action to arrive there is the modification or the creation of a atmosphere of composition close to that of the Ground, essential component with the development of the life. One also speaks about planetary engineering if the objective is not to make resemble the planet in question the Earth.
It should be noted that each candidate with the terraformation present of the conditions which are clean for him, making the process specific for each one of them. The principal undertaken studies relate to planet nearest to ours: Mars. Others relate to Venus, Europe (satellite of Jupiter) and Titan (satellite of Saturn), but the conditions seem much more difficult to modify.
Fiction with science
See also: Terraformation in fiction
Gradually, the scientists were interested in the terraformation, to start with American Carl Sagan who proposed terraformer Venus in 1961, using algae injected into its atmosphere. The Venusian environment is however rather infernal, with a temperature about 460°C and a pressure 90 times higher than that on Earth. These conditions are related to the presence of Carbon dioxide (CO2) and of steam, two gases with Greenhouse effect.
The algae were to generate Dioxygène by Photosynthèse and of the mineral Carbone while breaking up. The fall of the rate in CO2 then involved the cooling and the condensation of the steam. Unfortunately, carbon tends to reform of CO2 under strong temperature… and the objective thus does not seem atteignable.
Following this first development, the terraformation gradually was essential like a real possibility and today the terraformation of Mars is a subject seriously under consideration by many scientists.
March
The images evoked by Mars are those of a red planet, dries, rocky… without life. However, one distinguishes there sometimes from the valleys of eroded appearance and research in situ seems to indicate the presence of old rivers and old seas. However if water, essential component with the life such as we know it, ran over Mars, where is it today and can one make it re-appear? In fact the main questions animate the debates around the terraformation of planet. The objective is thus to give again at Mars this environment which it seems to have lost and to add the necessary one for the Man to it.
Inventory of fixtures
March has several common points with the Earth. Its number of revolutions, the slope of sound Orbit or the aspect of its surface shows the possibility for landscapes modelled by seasons close to those which the Earth knows. The ground (Regolith) Martian is composed of many Oxyde S (
CO2
Moreover, this atmosphere is made up to 96% of CO2, for only 0.13% of O2, and does not offer protection against the cosmic rays or the Ultraviolet S, destructors for the living beings. It is thought that formerly, the atmosphere was much denser, always made up in major part of CO2, which made it possible liquid water to run out. It is supposed that this disappeared CO2 and this water are contained in the polar icecaps and the ground. The first stage of the terraformation thus consists in increasing the average temperature of planet to release them. One does not know well the interactions between the various tanks of CO2 (regolith, cap, atmosphere), but a sufficient quantity to raise the pressure up to 300 or 600 mbar must be present.
The temperature and the greenhouse effect
The increase in the temperature of Mars is the crucial point of the terraformation of planet. To arrive there, it is a question of increasing the Greenhouse effect to give an impulse to the process, which develops then itself. An initial impulse of 4°C could prove to be sufficient, according to the studies of Robert Zubrin, president of the Mars Society. The process would be then rather long, unless doing everything oneself.
The first solution is the use of giant mirrors in orbit of 100 km ray for 200.000 tons. These mirrors must reflect the sunlight towards the south pole in order to dissolve the cap and to release CO2 which it has. The construction of such mirrors is not alleviating, but the Russian project Znamya of 1999 showed an employable type of technology, even if they were only “small” mirrors 25 m in diameter. CO2 being a gas with greenhouse effect, the solar energy retained by the atmosphere would be more important and the temperature would rise. With regard to the regolith, the release would require certainly more energy and would be longer. If the heating caused using the cast iron of the cap is not sufficient, then it would be necessary to be able another.
To dissolve the cap, one can also try to reduce his coefficient of Albédo. Currently of 0.77, to go down it to 0.73 could allow to vaporize the cap in 100 years. To arrive there, the evoked solution consists in blackening the cap by depositing there dust, coal powder… The winds Martians, enough violent ones, pose a serious problem then. Moreover, the problem of the regolith remains whole.
Other gases are more effective than CO2 with regard to the greenhouse effect, like the Chlorofluorocarbone S (CFC). An idea would be to build factories of production of CFC on the surface of Mars, as in Aliens . It is thought that CFC are at the origin of the warming of the Earth and thus, why not use the same technique for Mars? These factories would require nevertheless teams including/understanding a few thousands of residents Martians. Zubrin thinks that in 50 years, the atmosphere could be sufficiently thick to stop the harmful radiations and to make it possible men to move without diving-suit, but with oxygen masks.
Another method is the use of Astéroïde S containing of powerful gases with greenhouse effect like the Ammoniac. Such asteroids are probably present towards the outside of the Solar system where it is easier to modify their orbit to make them meet Mars. The lifespan of ammonia in the atmosphere is reduced, like that of CFC, it would then be necessary to resort to a rather destroying regular bombardment, or to use bacteria recycling the Azote photolysis out of ammonia.
These distinct methods, lists nonexhaustive, can also be combined in order to improve the results.
Water
The more pleasant temperature and the denser atmosphere do not make planet wetter. To reactivate the Cycle of water, necessary to the development of the life, one can resort to certain evoked principles précédemment.
The southern cap must contain an significant amount released at the time of its cast iron for example. The ground contains some probably also in the form of Permafrost or Pergélisol. Then, it should be vaporized, using the mirrors which one concentrates the light on a restricted zone, or directly starting from a core of Comet, frozen, which would be crushed on the surface. These methods remain preferable with the use of thermonuclear bombs, which would return the planet radioactive.
If water is spread on the surface of planet, an immense ocean (Oceanus Borealis) will cover the northern hemisphere with planet and the craters of the southern hemisphere will form practically circular big lakes.
The écopoïèse and oxygenates it
A sufficiently dense atmosphere, water in abundance, here is a paradise for some Bacterium S primitives of the Earth. This phase of use of bacteria is called the écopoïèse. Indeed, certain champions of survival support the absence of oxygen in the air and could thus proliferate under the conditions created over Mars. nourishing of CO2 for the Photosynthesis, these bacteria would gradually introduce oxygen into the air Martian, opening the way with higher plants when the partial pressure reaches 1mbar. The Man will have to wait then approximately 900 years to demolish himself of his oxygen mask and to breathe of the air with a partial pressure out of oxygen of 120mbar, vital minimum. The rate of CO2 should be also reduced by the inert gas addition, as nitrogen, where one speaks again of the asteroids…
The genetics could have a role in these operations in order to create plants carrying out the possible Photosynthèse most effective, to accelerate the phenomenon. Sometimes some propose to jump the bacterial phase by directly burning the ground using the mirrors to break up its oxides. It is also thought that the contact between water and oxides releases directly from oxygen what would facilitate work.
Here are how certain scientists intend to create a second livable planet in our solar system. However the process is long, insufficient current technologies, without speaking about the many unknown factors which persist.
Limits
Even if necessary technologies are not inevitably so out of reach (thermonuclear fusion, to move asteroids and to reduce the time of the voyages, or construction in orbit are already under development for example.) and even if the Man always knew to create the tools for which it required, such a company is not topicality. It will initially be necessary to consider autonomous bases covered, by maintaining a small ecosystem there, which will pose already many problems.
Moreover, if the life is already present at the surface of planet, the importation of land living beings would be likely to make disappear Martian biology. In order to avoid the loss of important information, that they relate to of the living beings or even only geology, it seems that it will initially be necessary to explore Mars without transforming it, to withdraw all the scientific informations from them.
Gravity over Mars is weak and was even insufficient to retain its atmosphere. Thus if it redensifie, nothing is ensured that it is not exhausted again. This process would proceed however over very a long period.
Another contrary disadvantage with the establishment of the Man over Mars is the absence of Magnetic field and the enormous difficulty of restoring one of them. On Earth, the Magnétosphère is generated by the activity of the heart of planet and prevents the energy particles of the Solar wind from striking its surface. The thickening of the atmosphere would improve a little protection, but it would be necessary nevertheless to avoid the exposures prolonged to the free air.
Being given the duration necessary to the terraformation of Mars, none among us will see it completely and if it takes place indeed a day, it will be made certainly manner very different from that presented here. Knowledge in planetology and planetary engineering remain indeed still very compartmental.
Some even plan to rather adapt the Man to other environments than to adapt the environment. Indeed, the Nanotechnologie S could make it possible to make so that oxygen is not essential any more for example. Others announce that the colonization of space will be rather made by space stations that by the terraformation of various planets.
An important controversy remains as for the utility of such a company. To preserve the humanity of a terrestrial cataclysm, thirst for knowledge, to propagate the life, the intelligence…
Venus
To decrease the temperature
Two tracks are explored to decrease the temperature on the surface of Venus:
- to decrease the solar radiation, either by making shade, or by increasing the Albedo.
- to decrease the Greenhouse effect.
To decrease the atmospheric pressure
To expel gas out of planet seems very difficult. The best solution seems to be to transform gas into solid compound or liquid. Either while sending dust of Magnesium or of Calcium (that one could take on Mercure, which would lead to the carbonate formation, or by injecting hydrogen which would lead to the production of Graphite and of water via the Réaction of Bosch. Another solution would be to introduce living organisms, like bacteria extrêmophiles, but if the temperature on the ground remains the same one, the organic matter would become again immediately of carbonic gas.
Floating cities in the clouds
An original idea to allow a fast Venus colonization, proposed by Geoffrey A. Landis, is to make float immense gas bags with approximately 50km of altitude, the condition of taking care that the known as bags resist the current rains of sulphuric acid at this altitude, where the atmospheric pressure and the temperature are close to the terrestrial conditions. One could build cities inside the bags, which would float on the dense atmosphere of Venus as of the Montgolfière S whose cockpit would be inside the balloon. The gas inside would be a respirable mixture.
Such cities could be like a head of bridge from where to ensure the heavy interventions for a complete Venus terraformation.
Other possible modifications
The Venus rotation is very slow, with the result that one day Venusian lasts almost a year. To accelerate rotation would require too much energy, but a system of mirrors in rotation could make it possible to produce successions of days and nights more usual for the land ones.
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