Again the missiles came down on the midnight to dawn quadrant. Again the heavens twinkled with interceptions and detonations, and the horizon exploded great puffs of light while the ground shook. But this time there was a ghastly variation, for a brilliant nova burst overhead, flooding the nightside of the planet with garish light. A swarm of fission heads had struck Mars's tiny satellite, Phobos, instantly vaporizing it into a sunlet.