Attilla is the asteroid that is heading for Earth. It has four quardants where you can go to.
Quadrant 1: is a safe zone where the Pig is placed. After the detonation, the mysterious tunnel is revealed.
Quadrant 2: is where the Alpha nuke is to be placed. You have to remove some dirt with the the Zero-G Digger first.
Quadrant 3: is where the Beta nuke is to be placed. You have to remove a boulder first, but can't use the Zero-G Digger here. You have to use the shovel to pry it loose.