I know that the factors involved in actually creating a living atmosphere on an alien planet vary immensely, but how long do you think it would take to create an atmosphere on a foreign planet? I have no particular method in mind for the answer, but I was thinking of something along the terms of Dr. Kynes in the Dune series, use your own ideas though! Could it be done in 1000 years 10,000, more? Never?
Atmospheres are the natural product of the accretion of gases by a massive protoplanet or the outgassing of gases trapped or produced inside a planet. Such atmospheres, however, tend to be either inert or reducing in their chemistry.
A breathable atmosphere containing oxidizing gases is thought to be the product of life, specifically autotrophic microbes and plants that produce it by photosynthesis or a related process. However, we’re generalizing brilliantly from a sample of one in saying this, so the topic is certainly open to dispute.
I’ve seen figures ranging from 60 to 3000 years quoted for the idea of terraforming Mars and Venus, of which the most difficult component is producting a breathable atmosphere. I have no idea where in that range the probable accurate figure lies – perhaps the entire range is valid, depending on how much effort is placed into the terraforming process.
Hmmm… isn’t Mars outside the habitable zone (where liquid water can exist) and isn’t massive enough to retain water vapour anyway? Venus may be too near the sun.
Mars is probably the only planet in our system that we may be able to occupy and terraform. If you make enough atomosphere the greenhouse effect should be able to raise the temperature of the planet to a point where liquid water could exist. Although I’m no expert on the process. I’ve heard that it can be done by crashing ammonia rich asteroids into planets. The gases are released and become some type of atomsphere.
I was always under the impression that Mars was so cold was the fact that there were no oceans to retain warmth. I’m certain that Mars could become habitable if oceans were present and the atmosphere was denser but the problem would be creating a self-sustaining system. One that would persist without human intervention.
Nope. Even today with existing conditions temperatures in the summer in the “torrid zone” can get above the STP freezing point, with highs near 80 F (26-27 C). In one depressed area, IIRC Hellas, the atmospheric pressure is high enough to permit liquid water to exist (when it’s warm enough), (and ignoring the fact that it would rapidly evaporate in the near 0 humidity of the atmosphere).
Most of Mars would be relatively chilly and resemble high-elevation areas of earth in terms of air pressure after terraforming, but it would be merely a massive engineering job, not a deus ex machina act, to make it a place where one could live without supportive devices other than normal cold-weather clothing, heated buildings, etc.
Venus is another question altogether – its runaway greenhouse effect and corrosive atmosphere make it a much tougher proposition for terraforming.
I’m looking through the steam tables in my thermodynamics textbook, and from what I can tell, at “warm enough” (0.01 degrees C) the pressure only has to be 0.6113 kilopascals. Higher than that and water is liquid, lower pressure and it’s a gas.
Now, standard atmosphere on earth, which presumably would need to be the result of terraforming, is 101.325 kPa.
What I’m wondering is:
Is the ambient pressure on Mars realy only half a kilopascal? If so, to what value do we need to bring it so that we can walk around without spacesuits?
Hypothetically, if most of the atmosphere of venus were blasted away, (or at least the majority of the greenhouse gasses) where might the new temperature settle at? Could it be cool enough for human habitation on the night side at least since he planet rotates so slowly?
In the case of Mars it may require not just unfreezing what’s there, but maybe the deliberate deflection and harvesting of asteroids/comets in order to add water and gases (e.g. the nitrogen to make an earthlike environment, think those ammonia-rich asteroid/comets mentioned above) . You would probably have to also put in a large industrial infrastructure to “crack” molecular oxygen out of oxides in the rocks – If you only raise the temp/pressure of the existing CO2-based atmosphere you may be able to seed it with bacteria/algae but those would take their own sweet time to raise the ppO2 to acceptable levels. It may not be that you can ever achieve a truly self-sustaining human-friendly ecosphere.
Still, it would not be absolutely mandatory that we raise the atmospheric pressure and gas mix to 1 standard sea-level Earth atmosphere at Argyre; if a large part of Mars is the equivalent of an 3-4,000-metre ASL elevation on earth, that is still inhabitable. Though you’d be forced to gengineer your food crops to accommodate, or else have to grow them all in greenhouses. In any case, even if equal atmospheric pressure were achieved, the different gravity would result in that “native Martians” would have a tough time handling Earth conditions if they ever got to visit; if their grandparents moved in while the atmospheric pressure is at High Tibet levels, they may after some time get used to it and say that’s good enough. But that would just be the way things are: once you get within that window of basic inhabitability, it will be easier to adapt the humans than to firther adapt the environment.