OK, thanks. It appears that my information must be out of date then. (I was taught about nuclear explosions being ineffective due to objects either re-coalescing (long range, rubble piles etc), or being too close to divert from earth (close range).

I was taught that the 'buckshot' effect of a bolide being destroyed via nuclear explosion would only be slightly, if at all (depending on size) preferable to the original impact, given that tracking so many fragments makes evacuation of specific cities/countries etc impossible. There's arguments involved about total kinetic energy transfer from impactor to earth, too.

(I was also taught that other options, propelling the object in a more controlled manner, are terrible in comparison to nuclear explosions, due to the age old limitations of the rocket equation. I'm sure you're familiar. )

However:
Now that we're discussing it, it might well be the case that I was being taught about interstellar objects, since the lecture grew out of a lesson about objects with an orbital eccentricity > 1.

Thanks for your post, I'll find some more recent opinions and info about solar system objects and educate myself further!
(If we have anything like the technology to propel even solar system objects I'll be super-impressed!)

Oh, the 'other thing' -

I certainly didn't mean that I disagreed that an impact could be disastrous. What I disagree with is: The idea that we have become as adept as we are at detecting asteroids and comets, out of a desire to survive.

If you read the other comments in this topic you'll see a few examples of this claim, and it's that I am challenging. (I'm really hoping this is clear now, because I'm trying really hard to state it clearly but it still seems hard to have it land. I really never said what you took me to mean, sorry.)

To clarify again: I believe that we have become as adept as we currently are because of an interest in astronomy, the general desire to understand physics, even geology and the origins of the universe etc! Not out of a desire to survive impacts.