MarkWhittington writes: "Fifty years ago, President John F. Kennedy stood before a joint session of Congress and proclaimed a goal of landing a man on the Moon and returning him to the Earth “before this decade is out.” Eight years later the goal was accomplished. Since then, two presidents, both named George Bush, have tried to set similar space exploration goals; both times the proposals fell victim to the vicissitudes of politics. How is it that President Kennedy’s proposal succeeded and the other two failed? Was Apollo unique for its time? Or was there another reason?"