Now this is fascinating. As always, truth is much stranger than fiction. I was listening to an excellent podcast called "Nova Science Now" which was my original source for the news of the impending strike from a big rock in the year 2036, which has a high probablility of hitting us right in the middle of the Pacific ocean. The first question that comes to mind is, "So what is Nasa doing about it?" and the answer is nothing. Then the next question is "Well can't we just send some nukes and blow it up?" and the answer according to Nova is no. The nuke would likely just rearrange things, and there would be no way to be CERTAIN that the job is done, and the public needs certainty. So that's when the scientist being interviewed offered up his idea. And it was an idea that just shocked me with its simplicity.

As you all know, all large bodies attract each other due to gravity. It's the weakest force in the universe, but it's what holds us to this planet, and what holds the moon to Earth, and us and the rest of the planets to the Sun.

The idea is this: Send a small craft into space to rendezvous with the rock. Then instead of making tricky maneuvers and landing, and setting up a rocket to propel it away from us, you simply park it nearby in space, and stop it from falling. That's right, stop it from falling... onto the rock. With just a small amount of propellant, the craft can sit in a stationary orbit, stopping itself from falling onto the rock, and this action will pull the asteroid in the direction of the craft. Without touching it. It would have the same effect as if we shot a grappling hook down to it and started pulling. They call this a "gravitational tractor"

Who the hell could have thought of something so simple? The guy says we only have to change its VELOCITY by a few ten thousandths of a kilometer per hour over many years of tugging and it will miss.

Thank God for big brains. That rocks.