[peterwoo]

The odds of a medium sized impact in the next few thousand years are very small. Still, an advanced asteroid defense capability should be prepared, since even the small-ish bolides that we expect to hit with greater frequency should be eliminated. This should reduce the risk from catastrophic impactors even further.

Settlement of e.g. Mars will never be needed in the time frames we should be thinking about. If asteroid defense is developed, then for thousands of years that will not be a concern at all. And if in 2,000 years they need a settlement on Mars, the people in 1,800 years can prioritize doing it.

In other words I don't see it as a priority. Material conditions on Earth are not great, and we are threatened by catastrophes in the atmosphere, oceans, and tectonic plates. Earth and its cities are infinitely more responsive to our efforts and investment than Mars or elsewhere. There is so much that we can do here in this century, while settling another planetary body in this century seems basically impossible.

[wst_]

People would not go to Mars because they need to. They will go because they want to. We always were an exploring types.

I may not happen within this century, maybe even not this millennium. But I believe it will happen. And for the time being it would be great adventure just to try and make the Mars more friendly.

[AstralStorm]

I like the base rate fallacy committed there. In recent history, there have been at least 5 sizable asteroid impacts, each of which would evaporate a big city. Just lucky those didn't hit any. In longer term, two of those triggered mass extinctions.

[PeterisP]

If a "evaporate a big city" or "kill all humans on Earth" asteroid strikes, the existence of a Mars colony doesn't help my personal survival or well-being in any way whatsoever unless I'm there.

And if I'm there, odds are that it made my personal survival chances worse, since they're mostly determined by the many "normal" causes of death and being a pioneer in a world not really suited for humans is likely to be worse than Earth.

You could make an argument that it's not wise to put all your eggs in one basket, and it has some merit in this discussion, but when all I have is one egg, the only thing I can do is to pick the safest basket I have - and for now it's Earth.

[peterwoo]

Can you elaborate? I do say that we should develop the asteroid defense capability, to eliminate those smaller more frequent impacts and others. My terminology was not standard or precise and I apologize for that. I mean by "small" those which are akin to an atom bomb or a hydrogen bomb explosion, and "medium" those which would cause catastrophe over a large region but not global annihilation.