In the spring of 1959, NASA introduced Americans to a new kind of hero -- the astronaut. But deep in the New Mexico desert, far from the Project Mercury spotlight, the Air Force was also preparing to launch a man towards the heavens. With a fraction of NASA's budget and none of its renown, Project Excelsior was about to send Captain Joseph Kittinger 100,000 feet above earth, propelled there not by rocket, but by balloon. Though largely forgotten, this group of explorers would be the first to venture into the frozen vacuum on the edge of our world, testing the very limits of human physiology and human ingenuity in this deadly realm.