Hey guys when they finally sent the Askgard rocket and it missed Superman had already hit it and the remaining rock was 3 miles across(just verified this on the DVD). They don't say what the payload of the devise was so we don't really have enough information to speculate as to if it would have been successful if it had it. So it might have had a chance at making the remaining rock a bunch of rubble. That would have lessed the harm to earth substantially.
