How many years away are we from being able to colonize another planet?
We are not close to being able to colonize another planet. Mars is the best candidate in our solar system, and it is so hostile that we would still be better off on Earth even after an all out nuclear war. The atmosphere contains almost no oxygen and is so thin that you can’t survive without a space suit. It isn’t enough to have an oxygen mask, you need a full pressure suit like you do on th Moon. There is no ozone layer so the surface is bathed in ultraviolet light. There is no planet wide magnetic field, so radiation from the solar wind constantly bombards the surface. The chemistry of the soil is caustic and would kill any plants we planted there, even in a pressurized dome. People who say we could move there if Earth becomes polluted have no idea how difficult that would be. No amount of pollution, not even 1,000 Chernobyl accidents, could ever make Earth as bad a place to live as Mars is now. So we need a planet more Earth like. It will not be found in this solar system, so we need interstellar travel. That will not happen for a very long time, if it ever happens at all.