It always struck me as kind of crazy that anybody talks about building colonies on Mars, the moon, Venus, or anywhere off-world. I like sci-fi as much as the next guy, but the fact of the matter is that we already have a planet with suitable gravity, and breathable air.
We're not even close to using up all of the available space on this planet. Why would we build on Mars when we have Antarctica? Why build on Venus when we have giant empty deserts in Nevada?
On Earth, a cracked window doesn't mean that everybody will suffocate or be pulled apart by a vacuum. Plus, it comes with plenty of raw materials and suitable gravity.
No matter how bad Earth gets pollution-wise, I just can't see off-world colonies as realistic until we use up the land we already have.
leak in your bio-dome doesn't