[rhino369]

If you are worried about that, why not build a biodome in the antarctic instead. Or build millions of greenhouse farms to survive impact winter.

Even if you are really into space exploration, developing a comet pusher would be infinitely more valuable.

[skorgu]

At least for the comet pusher, the tech needed to put a non-trivial number of humans on Mars has a ton of overlap with the tech needed to divert potential impacts.