Actually, it's 1000 years to get to the point where trees and such like can grow, with humans using air breathers like aqualungs, and another few millennia, perhaps 100,000 years before humans can breath the air. Those are the estimates of the Mars society for the 1000 years and Chris McKay for the 100,000 years. On the Earth it took hundreds of millions of years.
But as well as that, Mars is no second Earth. It is further away from the sun, colder, less atmosphere etc etc. Move Earth out there and it would turn into a frozen planet. So they assume mirrors in space to warm it up and factories generating greenhouse gases - and - it needs high technology for the foreseeable future to keep it going. Mars may well have life already - and at any rate just adding life to a planet doesn't terraform it automatically.
And also it is temporary - at some point it would eventually unterraform, the only question is how long, because with its lighter gravity it can't hold onto the gases indefinitely.
The Mars trilogy has the process massively speeded up. It's science fiction and shouldn't be taken as science prediction. After all how many science fiction stories of say 20 years ago or 50 years ago accurately predicted the C21? They are great for stimulating the imagination - but are a product of their time, and the science fiction writers can't actually see the future, just imagine it very vividly for others to enjoy. Sometimes they get things right with astonishing perceptiveness, sometimes they get things wrong in surprising ways - and the thing is - we can't tell in advance which of those it is.
So - far better to think in terms of enclosed habitats rather than terraforming a planet. And for those, the biointensive farming system lets you grow enough food for one person on 4,000 square feet of ground (about 372 square meters), so about 64 feet by 64 feet, or about 19 meters by 19 meters: Page on growbiointensive.org
That's assuming a vegan diet which is the diet that needs least ground area per person. (Can be supplemented e.g. by B12 which can be provided by growing bacteria).
For six people, say, you'd need 157 feet by 157 feet, or about 48 meters by 48 meters for a vegan diet.
In space then we would use aerponics most likely to reduce mass - where you grow plants with their roots in moist air Aeroponics. I think that might well be able to reduce the area needed per person even further but don't know if anyone has done the calculation.
You also have to generate all your own oxygen, in space this can be done with green algae most efficiently. You need a few square meters of green algae per person - which can also be stacked in trays. The Russians did experiments like this, but it has never flown in space. Because you can stack the green algae, I don't think this would add significantly to the total growing area needed for your habitat. But it does need to be tested in space.
Then - the Russians in BIOS-3 using aquaponics for some of the crops and very rapid growing successions of crops like beet, dwarf wheat etc were able to reduce the growing area required to a tiny 13 square meters per person to supply most of their food and all their oxygen. See also Why doesn't NASA have plants inside space stations for oxygen, since they get sunlight 24/7? (I'll add this at the end as a link).
The whole thing seems feasible - but you don't need to terraform Mars to do it - and myself, I think it's best thought of as a system for orbital colonies rather than surface colonies - because as soon as you have humans on the surface of Mars, you have made an irreversible decision there to introduce Earth life to Mars - at least that is if there are habitats for life on the surface of Mars as is seeming increasingly possible.
I don't think we are ready to make that decision when we don't yet know if there is native life on Mars - or indeed had a chance to study the planet in its native state without introduced life. Or for that matter without a clear future strategy - why we are introducing life there - and what are the best lifeforms to introduce if we do. For instance, we might want to "Marsform" Mars - to encourage the native life, if it has native life - that is Chris McKay's idea.
Or we might want to terraform it eventually once we know a lot more about Mars and life - but if so - if we use the process of ecopoesis - then for several centuries you'd have nothing growing there except ponds of green algae. And you might need to be careful about introducing other lifeforms, e.g. aerobes or detritovores. If you can have a planet with only green algae, nothing else, who knows, maybe you can speed up the formation of an oxygen rich atmosphere. I think myself that terraforming is a project for a stable civilization - it's like having a child - you are committed to the whole process of bringing up that child. In the same way if you start the process of terraforming a planet - you are committed to that process for the next several millennia. So - I think only a stable long lived technological civilization can do that successfully. If we lose our technological capabilities - then Mars, far from being a way to avoid that issue - because it is so much more dependent on technology than the Earth - would be the first to be lost. As we lose our technological capability, anyone on Mars would want to get back to Earth as the only place humans can survive in our solar system without technology.
If we land humans there without forethought about whether to introduce life to Mars, and why we do it, and what lifeforms to introduce - then we are introducing lifeforms that co-exist with humans in human habitats to evolve and spread over a planet that may have no life on it or its own native life - without any planning or design. Personally I don't think that is wise. Not at least until we understand more about Mars and about life.
But we can make enclosed habitats in space - increasingly larger ones - and have those projects finished within a few decades instead of a few millennia - and for much less cost also - I think that's the way to go right now rather than attempt terraforming anywhere outside of Earth.
So - first step there is to start creating habitats in space that are closed system, able to generate all their own oxygen and food. So far nobody has attempted this. We've only had a few small scale biological experiments on board the space station. I think surely feasible, but there may be many teething problems, glitches to work out in space, and it may take quite a few years, or depending how easy it is to do, perhaps decades to sort those all out before we are ready to create bigger self sustaining habitats or to send them to other planets (orbiting them for instance) or elsewhere in the solar system.
The closest we have on Earth is Biosphere II. But it is too big to send into space - and also - it had problems - main one was to do with the type of concrete used to make the habitat, which nobody expected to be an issue. So - who knows what issues will turn up with closed system habitats in space.
See also Trouble With Terraforming Mars
And Why doesn't NASA have plants inside space stations for oxygen, since they get sunlight 24/7?
And on my Science20 blog Could Astronauts Get All Their Oxygen From Algae Or Plants? And Their Food Also?
But as well as that, Mars is no second Earth. It is further away from the sun, colder, less atmosphere etc etc. Move Earth out there and it would turn into a frozen planet. So they assume mirrors in space to warm it up and factories generating greenhouse gases - and - it needs high technology for the foreseeable future to keep it going. Mars may well have life already - and at any rate just adding life to a planet doesn't terraform it automatically.
And also it is temporary - at some point it would eventually unterraform, the only question is how long, because with its lighter gravity it can't hold onto the gases indefinitely.
The Mars trilogy has the process massively speeded up. It's science fiction and shouldn't be taken as science prediction. After all how many science fiction stories of say 20 years ago or 50 years ago accurately predicted the C21? They are great for stimulating the imagination - but are a product of their time, and the science fiction writers can't actually see the future, just imagine it very vividly for others to enjoy. Sometimes they get things right with astonishing perceptiveness, sometimes they get things wrong in surprising ways - and the thing is - we can't tell in advance which of those it is.
So - far better to think in terms of enclosed habitats rather than terraforming a planet. And for those, the biointensive farming system lets you grow enough food for one person on 4,000 square feet of ground (about 372 square meters), so about 64 feet by 64 feet, or about 19 meters by 19 meters: Page on growbiointensive.org
That's assuming a vegan diet which is the diet that needs least ground area per person. (Can be supplemented e.g. by B12 which can be provided by growing bacteria).
For six people, say, you'd need 157 feet by 157 feet, or about 48 meters by 48 meters for a vegan diet.
In space then we would use aerponics most likely to reduce mass - where you grow plants with their roots in moist air Aeroponics. I think that might well be able to reduce the area needed per person even further but don't know if anyone has done the calculation.
You also have to generate all your own oxygen, in space this can be done with green algae most efficiently. You need a few square meters of green algae per person - which can also be stacked in trays. The Russians did experiments like this, but it has never flown in space. Because you can stack the green algae, I don't think this would add significantly to the total growing area needed for your habitat. But it does need to be tested in space.
Then - the Russians in BIOS-3 using aquaponics for some of the crops and very rapid growing successions of crops like beet, dwarf wheat etc were able to reduce the growing area required to a tiny 13 square meters per person to supply most of their food and all their oxygen. See also Why doesn't NASA have plants inside space stations for oxygen, since they get sunlight 24/7? (I'll add this at the end as a link).
The whole thing seems feasible - but you don't need to terraform Mars to do it - and myself, I think it's best thought of as a system for orbital colonies rather than surface colonies - because as soon as you have humans on the surface of Mars, you have made an irreversible decision there to introduce Earth life to Mars - at least that is if there are habitats for life on the surface of Mars as is seeming increasingly possible.
I don't think we are ready to make that decision when we don't yet know if there is native life on Mars - or indeed had a chance to study the planet in its native state without introduced life. Or for that matter without a clear future strategy - why we are introducing life there - and what are the best lifeforms to introduce if we do. For instance, we might want to "Marsform" Mars - to encourage the native life, if it has native life - that is Chris McKay's idea.
Or we might want to terraform it eventually once we know a lot more about Mars and life - but if so - if we use the process of ecopoesis - then for several centuries you'd have nothing growing there except ponds of green algae. And you might need to be careful about introducing other lifeforms, e.g. aerobes or detritovores. If you can have a planet with only green algae, nothing else, who knows, maybe you can speed up the formation of an oxygen rich atmosphere. I think myself that terraforming is a project for a stable civilization - it's like having a child - you are committed to the whole process of bringing up that child. In the same way if you start the process of terraforming a planet - you are committed to that process for the next several millennia. So - I think only a stable long lived technological civilization can do that successfully. If we lose our technological capabilities - then Mars, far from being a way to avoid that issue - because it is so much more dependent on technology than the Earth - would be the first to be lost. As we lose our technological capability, anyone on Mars would want to get back to Earth as the only place humans can survive in our solar system without technology.
If we land humans there without forethought about whether to introduce life to Mars, and why we do it, and what lifeforms to introduce - then we are introducing lifeforms that co-exist with humans in human habitats to evolve and spread over a planet that may have no life on it or its own native life - without any planning or design. Personally I don't think that is wise. Not at least until we understand more about Mars and about life.
But we can make enclosed habitats in space - increasingly larger ones - and have those projects finished within a few decades instead of a few millennia - and for much less cost also - I think that's the way to go right now rather than attempt terraforming anywhere outside of Earth.
So - first step there is to start creating habitats in space that are closed system, able to generate all their own oxygen and food. So far nobody has attempted this. We've only had a few small scale biological experiments on board the space station. I think surely feasible, but there may be many teething problems, glitches to work out in space, and it may take quite a few years, or depending how easy it is to do, perhaps decades to sort those all out before we are ready to create bigger self sustaining habitats or to send them to other planets (orbiting them for instance) or elsewhere in the solar system.
The closest we have on Earth is Biosphere II. But it is too big to send into space - and also - it had problems - main one was to do with the type of concrete used to make the habitat, which nobody expected to be an issue. So - who knows what issues will turn up with closed system habitats in space.
See also Trouble With Terraforming Mars
And Why doesn't NASA have plants inside space stations for oxygen, since they get sunlight 24/7?
And on my Science20 blog Could Astronauts Get All Their Oxygen From Algae Or Plants? And Their Food Also?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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