SRocks and pace You collide with the atmosphere of the earth all the time. The vast majority is smaller than any harm, but the risk of a larger asteroid (or guilty) gives an unprepared city that is eaten by space agencies all over the world seriously. The first goal of potential planet defender is to discover: finding all things that are able to expose such damage and confirm that they are not in a collision with the Earth. The other goal is to test the techniques that can destroy any large asteroids that rush to the planet or more, more reasonably, are keen on them.
