At our current level of scientific understanding, there is really no place to go. And if there were, how should we deal with the biological forms that are already there? What if their cells attack ours? Or vice versa?

IMO, unless we can crack light travel (won't be easy,) there is no hope of getting an expedition to a terra type planet. Maybe some robots, in a few thousand years.

I can't say our time won't run out before we solve the problems.

--imm

Mars, the asteroids and the orbiting space colonies proposed by Gerard K. O'Neill. The image below is from the Space Studies Institute slide show.

I don't see moving large populations onto nearby planetary objects, unless they are terraformed. That's a problem.

Maybe free orbiting space colonies could be developed, and problems of biodiversity, raw materials, and zero gravity are dealt with, but how far would you want to be from a space suit?

--imm

Build a self-propelled asteroid out of the Earth and/or Moon and equip it with advanced navigation systems and with room for growth. Sail through space forever.

I also think strictly speaking that isn't required. We "could" hole up in asteroids, in stations/ships in space, and some moons including ours in a money is no object scenario and over time seed Mars and even return to Earth in it's usable lifespan for quite a while. All mostly within the reach of existing and emerging technology and the rest not far from reach.

An asteroid hit doesn't mean leaving the solar system but it might mean leaving during a rough patch and eventually completely but such is likely hundreds of millions of years off and more likely billions before abandoning the system will be required. I suspect we will either already have long produced a few different answers for long distance travel before the need even actually arises should our star act anywhere near as expected.
However, in such time frames our world will be on schedule for a substantial number of consequential hits and several mass extinction level contacts.

The further we are from being all in one basket the greater the long term viability of our species be it from one village to one continent to one world to one solar system to one quadrant to one galaxy and beyond that. The quicker the better because of expansion but it doesn't need to be in one bite. Mars and beyond greatly increases our odds.

might be cheaper than the cost of sending substantial numbers of humans to other planets or moons that could sustain life.



I'm 100% in favor of humans developing space colonies and living on other planets, just so I make myself clear. But I think that if the purpose is because of some future asteroid strike, such an event could still be defended against.

There are probably space aliens all over the place. To us they look like dust.

Maybe the reason they don't talk to us is we're boring.

Carl Sagan himself stayed alive until he didn't. There was nothing practical or impractical about it. It just was. That's what people do. They live until they die.

Likewise, a species exists and then it doesn't. At the rate we're killing off other species it's probably only fair humans become extinct too.

Personally I think it would be romantic if we created space-faring artificial intelligences well adapted to the harsh environments of space. They would be our "intellectual children." Perhaps they might remember us when we are gone. But this has nothing to do with either practicality or staying alive.

I don't expect I'll ever go into space myself since I don't even like getting on airplanes. Nevertheless, it is very interesting to me that people have gone into space and can share their personal perspectives. I don't begrudge taxes spent on space exploration, but my support is 100% "exploratory and romantic zeal." We ought to be spending a lot more on romantic projects like space exploration and a lot less on war.



Tracy Caldwell Dyson in the Cupola module of the International Space Station.