No human being has fallen farther than Joe Kittinger, but people keep trying. On Aug. 16, 1960, the U.S. Air Force test pilot floated in his 20-story-tall helium balloon to the edge of space, more than 19 miles up, higher than any man had ever gone. Clad in a space suit, he stood at the edge of his open-air gondola and said to himself: "Lord, take care of me now." Then he jumped. He quickly accelerated to 714 miles an hour -- becoming the first person to break the sound barrier without a vehicle -- before a small parachute opened...