Our planet's recent close call with one asteroid direct visit from another has definitely made it seem important to consider how to avoid the pesky things in the future. One solution is to direct the Sun's power into pulverising lasers, but another option just involves covering incoming rocks with spray paint.
The plan, as described by Dave Hyland, professor of physics and astronomy and faculty member in the aerospace engineering department at Texas A&M goes a little something like this: When you see a dangerous space-rock headed this way, you send a special space ship out to meet it and blast it with a coating of space-spray paint. The new coat of paint would then affect the asteroid's reflectiveness, allowing the Sun's energy to catch it just right and send it off a collision course.
If we were to pull this off, there'd be a few obstacles to over come. First, you couldn't use standard Earth-paint. It couldn't be oil or water-based; it'd probably have to be a dry powder, attracted to the rock with static electricity. Second, you'd have to get to the asteroid early, so that a barrage of photons would have enough time to push it away. Still, it could be a cheap solution, and NASA has approached Hyland about testing it. It probably won't be ready for Apophis' close call in 2029/2036, but it could be a viable strategy eventually. Now someone reach out to Banksy, and see what he thinks. [PhysOrg]