Neil Degrasse Tyson at Wired writes about the risk of a major asteroid collision, and what we can do to prevent it.
Currently, it looks doable to develop an early-warning and defense system that could protect the human species from impactors larger than a kilometer wide. Smaller ones, which reflect much less light and are therefore much harder to detect at great distances, carry enough energy to incinerate entire nations, but they don’t put the human species at risk of extinction.
If humans one day become extinct from a catastrophic collision, we would be the laughing stock of aliens in the galaxy, for having a large brain and a space program, yet we met the same fate as that pea-brained, space program-less dinosaurs that came before us.
I am inclined to agree. We certainly have the capacity to identify potential planet-killers and save ourselves, but we don’t exactly have a good track record of coordinated action. If we are lucky, we will have some kind of functioning asteroid mining industry in place, with indirect technological applications available to ensure that we are able to survive long enough to expand out of this fragile little basket of eggs.