By the time the radar signal caught their eye it was too late to do anything. Planes traveling faster than sound were already inside the defense zone of the city. Private First Class Jerry Conlon glanced from the radar screen to the other five members of his Atomic Gun Post team on the outer perimeter of the city. The look in their eyes was one of dazed alarm. Automatically he joined them in zipping shut radiation suits, and then they went for the gun controls, knowing it was too late. A flash o