The Pentagon: It has been revealed that a secret U.S. project in the 1950's called for detonating an atom bomb on the moon as a demonstration of the nation's Cold War might. The project was never carried out. But the planning included calculations by astronomer Carl Sagan - then a young graduate student. Officials believed that viewing the nuclear flash from Earth might have intimidated the Soviets and boosted Americans' confidence. A missile was to carry a small nuclear device and launched toward the moon, where it would be detonated upon impact. Officials apparently abandoned the idea because of the danger to people on Earth in case of a failure.