Project Manhigh took humans to the threshold of space using balloons. In the 1950s, a small band of Air Force doctors were on the cutting edge of the United States' space research programs. Working at the Aeromedical Field Laboratory at Holloman Air Force Base in southern New Mexico, they used balloons to carry laboratory animals followed by human pilots above 99% of the atmosphere. Drawing upon flight reports and technical data, this book documents Project Manhigh and the high altitude flights that preceded it. The Manhigh flights were, in many ways, prototypes for future space missions. On each of the three flights, the Air Force placed a lone pilot in a sealed capsule nineteen miles above the ground. At such extreme altitudes, the pilots were well within the functional equivalent of outer space and needed the sealed capsule to survive. Manhigh existed prior to the creation of NASA and helped pave the way for human space exploration.