Yes it is viable. We could probably build self supporting space colonies close to Earth in the near future - even back in the 1970s we had the technology to build a "Stanford Torus".
We would surely make many mistakes and would need to build many experimental habitats before we get successful large scale colonies. But - is no real reason why it's impossible. We have
If we develop nuclear fusion - able to create "mini suns" then it would be easy to build similar habitats right out to the Oort cloud.
Then because the Oort clouds of nearby stars mingle, then we would be well on the way to colonizing the entire galaxy.
With exponential growth - even slow colonization would take maybe tens or hundreds of millions of years at most - not billions of years.
Terraforming planets is completely unnecessary for this - as there is enough material available for making space colonies in the asteroid belt for hundreds of times the entire surface of all terraformable planets in our solar system - probably the same for other star systems - and what's more - the space habitats are more pleasant places to live, more controllable environment etc.
I think a future space faring civilization might well no longer have our focus on planetary surfaces as the best places to live in space.
The big question though is, should we do this?
Problem is - that if we have self replicating machines by then - as we surely will - then any of the trillions of inhabitants of the galaxy have the power to completely reshape the galaxy - and some perhaps will do just that. Maybe something stupid like make it into paperclips. Maybe something that they see as sensible and worthwhile - but other humans and other ETs do not agree that it is beneficial or it gets out of control - especially when they find their home worlds and solar systems getting transformed by this, to them, "alien tech" self replicating machines - which might well have the ability to take planets apart by then. Or seeding our worlds with XNA that destroys DNA - or whatever it is that someone somewhere in the galaxy decides, for their own obscure reasons - is a good thing to do - or does by mistake.
So - I'm not sure that sensible ETs - or ourselves - will choose to colonize the galaxy at all - and if so would need to have many highly reliable safeguards in place. Exploration without colonization doesn't have this issue - but colonizing does need thought and care.
Galactic colonization seems reckless in the extreme - a major risk to our galaxy - unless we can devise safeguards of some kind - both technological and political or social - to keep it safe.
We also have to be peaceful at the early stages of space colonization because these habitats - at high internal pressures of tons per square meter (for close to Earth normal breathable atmospheres) - and surrounded by vacuum in all directions - are extremely vulnerable to the kilometers per second speeds of interplanetary spacecraft.
They are fragile almost as soap bubbles compared to the huge velocities of interplanetary spacecraft and cargo, For these to survive in space - then we need an end to war, terrorism, guerrilla warfare and all similar forms of violent solutions to our problems (at least in space) - or else - we will destroy all our space colonies probably soon after they are constructed, within a decade or two, century at most.
So either way - is a future hard to imagine at the present. Many things would need to change first. Developing the technology to get living humans to another star is perhaps a thousandth or a millionth part of what would need to be done.
Developing safeguards to do this in a way that protects the galaxy and ourselves long term from dangers of self replicators and such like technology - and shorter term from our own violent tendencies to destroy fragile space habitats - would be far harder (unless some other earlier ET has already done it, of course).
See also my answer to If some day we develop spaceships with wormhole technology, how many years it would take to colonize the entire galaxy?
We would surely make many mistakes and would need to build many experimental habitats before we get successful large scale colonies. But - is no real reason why it's impossible. We have
- Biosphere II - though it was not a success, it came close to success and the problem was a reaction with the concrete they hadn't predicted - not a flaw in the design itself
- Soviet experiments using algae - found it's actually quite easy to provide enough oxygen for humans to breath from trays of algae in a spaceship - this is on the ground - for some reason they never followed it up in space
If we develop nuclear fusion - able to create "mini suns" then it would be easy to build similar habitats right out to the Oort cloud.
Then because the Oort clouds of nearby stars mingle, then we would be well on the way to colonizing the entire galaxy.
With exponential growth - even slow colonization would take maybe tens or hundreds of millions of years at most - not billions of years.
Terraforming planets is completely unnecessary for this - as there is enough material available for making space colonies in the asteroid belt for hundreds of times the entire surface of all terraformable planets in our solar system - probably the same for other star systems - and what's more - the space habitats are more pleasant places to live, more controllable environment etc.
I think a future space faring civilization might well no longer have our focus on planetary surfaces as the best places to live in space.
The big question though is, should we do this?
Problem is - that if we have self replicating machines by then - as we surely will - then any of the trillions of inhabitants of the galaxy have the power to completely reshape the galaxy - and some perhaps will do just that. Maybe something stupid like make it into paperclips. Maybe something that they see as sensible and worthwhile - but other humans and other ETs do not agree that it is beneficial or it gets out of control - especially when they find their home worlds and solar systems getting transformed by this, to them, "alien tech" self replicating machines - which might well have the ability to take planets apart by then. Or seeding our worlds with XNA that destroys DNA - or whatever it is that someone somewhere in the galaxy decides, for their own obscure reasons - is a good thing to do - or does by mistake.
So - I'm not sure that sensible ETs - or ourselves - will choose to colonize the galaxy at all - and if so would need to have many highly reliable safeguards in place. Exploration without colonization doesn't have this issue - but colonizing does need thought and care.
Galactic colonization seems reckless in the extreme - a major risk to our galaxy - unless we can devise safeguards of some kind - both technological and political or social - to keep it safe.
We also have to be peaceful at the early stages of space colonization because these habitats - at high internal pressures of tons per square meter (for close to Earth normal breathable atmospheres) - and surrounded by vacuum in all directions - are extremely vulnerable to the kilometers per second speeds of interplanetary spacecraft.
They are fragile almost as soap bubbles compared to the huge velocities of interplanetary spacecraft and cargo, For these to survive in space - then we need an end to war, terrorism, guerrilla warfare and all similar forms of violent solutions to our problems (at least in space) - or else - we will destroy all our space colonies probably soon after they are constructed, within a decade or two, century at most.
So either way - is a future hard to imagine at the present. Many things would need to change first. Developing the technology to get living humans to another star is perhaps a thousandth or a millionth part of what would need to be done.
Developing safeguards to do this in a way that protects the galaxy and ourselves long term from dangers of self replicators and such like technology - and shorter term from our own violent tendencies to destroy fragile space habitats - would be far harder (unless some other earlier ET has already done it, of course).
See also my answer to If some day we develop spaceships with wormhole technology, how many years it would take to colonize the entire galaxy?
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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