If we could just get enough people freaked about a devastating impact, it might provoke a sudden interest and massive funding for a space program. Actually, I must confess I've had those fantasies too, and a city killer squashing some valuable, but limited piece of real estate somewhere would almost certainly have that effect.

But we all know the chances of that happening within our lifetimes are very small, and it's not likely much will be devoted in the way of resources to protect us from such a remote possibility. Still, it cannot be denied, it HAS happened in the past, and it MUST happen in the future, to go into denial about this might not be a good idea.

Even if planetary defense is initiated, it will soon become like SETI, you've heard the naysayers, "We've been doing SETI fior 50 years now and nothing has turned up." The same thing will happen to planetary defense, and people who should know better will forget how totally insignificant a half-century is in the total scheme of things.

Like SETI, planetary defense is highly unlikely unless we get a near-miss that scares the hell out of everybody, or if we can somehow piggy-back some scaled-back program onto some other space activity that is profitable and has a lot of support. But I don't see much of a chance that it will spontaneously catch fire and allow us to hitch our space exploration dreams to it.