How to Defend Earth from Asteroids

Phil Plait offers an interesting Ted talk on asteroids and how to defend the earth from them.   Keeping them from destroying the planet is essential for sustainable development.   He talked about NASA hitting a comet to alter the path of the object.  A similar strategy can be done to prevent it from getting it into the keyhole that will allow it crash into the earth.

                                              http://www.ted.com/talks/phil_plait_how_to_defend_earth_from_asteroids.html