And in the end, it is the people themselves who must rise to the occasion. Clarke points out that the "first responders" in any disaster aren't police or firefighters. They are the "people in the street," he says, who pull their fellow citizens from an earthquake-damaged building, or a crashed airliner.
So mitigating a major disaster like an asteroid collision will depend primarily on how well the people themselves are prepared. They are the ones, for example, who will have to help their fellow citizens evacuate a major metropolitan area if the asteroid is headed that way. There won't be enough cops to do the job.
But nobody can do that without adequate preparation, and the consequences of failure could be the loss of thousands of lives that could have been saved.
My guess is most people figure that scientists will come up with a plan to divert the asteroid before it hits the Earth. Some have suggested that small rockets placed on the asteroid could push it toward a different course. Others have indicated that even painting one side of the big rock could cause the solar wind to push it into a safe trajectory. Of how about a giant solar sail to pull it out of harm's way?
But that all depends on how much time we have, and whether we have the technological resources to do it.
Unfortunately, we're not anywhere close to dealing with the threat. We don't even know how to talk about it.
During the recent convention of the American Association for the Advancement of Science in Denver, one expert set off a firestorm when he suggested that government secrecy might be the best alternative.
Geoffrey Sommer of the Rand Corp., a think tank in Santa Monica, Calif., that advises the federal government on many issues, told a press conference that if a planet killer is headed our way, maybe the feds ought to just keep their mouths shut.
"If an extinction-type impact is inevitable, then ignorance for the populace is bliss," Sommer said.
His comments angered so many people that he has since decided to decline all interviews on the subject, according to a Rand spokesman.
Sommer's plight is worth noting because it reveals just how contentious this issue can be. It also shows that it will take a bold leader to move the matter forward.
Clarke, for one, isn't optimistic that's going to happen anytime soon.
"It's hard to see which politicians are going to step up to the plate," he says. "They'll be branded as crazies."
Besides, we've got lots of other things to worry about. So we'll probably just put this off until some astronomer comes up with an asteroid that really is headed our way.
But by then, it will probably be too late.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.