For what? Big rocks falling out of the sky is not exactly something you can prepare for. You would have no idea where they would hit or how.
As long as we are stuck on planet earth and not spread out this is the kind of thing that we are vulnerable to. Maybe we dodged the bullet this time, but there will always be a next time.
I say we should nuke Iran on that day and blame the comet...
And The Time After That...........