Morpheus, I agree that it is the small ones, but we haven't even spotted all the big near earth objects yet. We could probably stop it if we had enough time, and I am pretty sure we would try if we were certain it would hit. I think that we need to map out our close surroundings as much as we can, as quickly as possible.

Here is an article on an interesting project regarding defense against asteroids:

http://www.space.com/businesstechnology/te...tug_031015.html