Without a doubt our planet will be hit again many times in...

Without a doubt our planet will be hit again many times in the future, unless we can prevent it from happening. We're not sure yet what the best way to do this is, but in order to figure that out, we've really got to better understand what comets and asteroids are made of and how they're put together. So, in a sense, Deep Impact is our latest attempt to get to know our potential enemies.