how would you spot all or most of killer asteroids on the way to earth and develop a system to avoid it?

How about this system? US Patent 6,452,538 B1 At least it will spot them. Unfortunately, we don't have many telescopes scanning the sky for NEO/NEAs, and the ones we have only work at night ;)

I'm not a strong believer in destroying monolithic asteroids (nukes just don't do the job), but deflecting them will work if we have the lead time. Not weeks, but at least months and preferably years.

As for the partial breakup comment, the reductio is clear: breaking up a large NEO is preferable to getting hit by the original, even if all the pieces still come in. Proof? A 100 ft diameter rock (about 75,000 tons) that explodes will release the energy of a small nuclear device, but something like that amount comes in as dust every year and we never even notice it.

If the US government is putting nuclear missiles in Earth orbit, claiming they are an asteroid defense system, then you would be very gullible to believe that this is the real reason for the deployment. When was the last time one of our government's "big pronouncements" turned out to be the truth? Carter? Kennedy?

actually they are already making a system for this!! but this system that we have can only stop asteroids or comets that are a few months way from hitting earth there is no way they can stop it if it is only a week away trust my answer i took astronomy this year oh and alsothey dont stop the puny asteroids that turn out to be dust or a small rock when it hits the ground.

We have telescopes trained on all sectors of space, so if one approaches, we can see it. Any anti-asteroid system would probably incorporate a nuclear weapon. We've got rockets that can send the weapon out to meet it. You either want to powderize the asteroid, or deflect it. What you *don't* want to do is bust it up into chunks, because then you might have more problems.

GO JACKSON LOL

nah, if we do it it'll involve some seriously funkay deep space radar and telescope systems and missle or laser defenses, depending on where our technologies are at that point.

It won't happen until we get smacked by a smaller one. Its human nature to procrastinate.