I just read this story on CNN about how the Near Earth Object Observation Program has made substantial progress in cataloguing all the asteroids that may hit earth. It's interesting to think of this from the perspective of the Gaia Hypothesis. The earth has essentially developed foresight and self defense. She has grown human beings that in order to defend themselves must defend her. She can now with her human-built technology and through her human eyes (that she grew with her own proteins and fats) perceive a distant threat and respond to it. She has somehow managed to grow a self-defense system that may keep her from being destroyed by random piece of space rock.