Blast That Comet!

NASA and its political defenders spend much of their time trying to justify highly risky human space efforts on the grounds that exploration for exploration's sake is somehow hard-wired into our DNA. But the coolest stuff the agency is doing involves simply trying to find creative ways to answer nagging questions about the universe, whether or not such efforts involve astronauts. The latest case in point is yesterday's launch of the Deep Impact spacecraft. On Independence Day, the craft will rendezvous with comet Tempel 1, blast it hard enough to produce a crater somewhere between the size of a house and a football stadium, take pictures of the whole event and find out just what comets are made of. Expect much fanfare--as much as there is for, say, a Mars landing (and much more than a shuttle launch). Why? Because this project is utterly captivating, and because it is likely to generate highly important data.