The one fact in Deep Impact that we can all agree on is that we should not allow the Earth to get hit by a large meteor. Depending on its size, it could potentially destroy anything from a city to the entire planet. And nations it doesn’t destroy outright would still have to deal with big atmospheric and weather problems caused by dust and debris. General badness all around.
Where common sense and the film divide is just how best to dodge an oncoming meteor. I wrote a while back on the idea of painting one side of the asteroid black while beaming heat onto it, causing the asteroid to shift course. It’s a neat idea, but not nearly as neat as the gravity tractor, not just because this approach is more elegant, but because there’s a British company called EADS Astrium that announced last week that they could actually build one if it were needed.
The idea for the tug first proposed by NASA scientists Edward Lu and Stanley Love in a paper in Nature in 2005. The pair realized that sure, we could change an asteroid’s course by docking a rocket onto the asteroid and pushing it, but landing on an asteroid is really hard: The asteroid is an extremely fast-moving target, and often it rotates asymmetrically around its axis, meaning that a lumpy part of the asteroid could smash a relatively teeny rocket in its rotational path. But, the scientists argued, the spaceship could hover 200 meters or more above the asteroid and use their mutual gravitational attraction to form a “towline” between the two. Then ship could use its own propulsion to slowly pull the asteroid to another course. It would have to push very gently to avoid breaking the bond and flying away, but over the course of 15 to 20 years, the asteroid could be persuaded to miss our planet.