Baumgartner will first ascend to an altitude of 120,000 feet (36,000 meters) in a six-foot diameter (1.8 meters) pressurized capsule suspended from a high-altitude balloon.
Once at the correct altitude, Baumgartner steps from the capsule and begins to fall. Within about 40 seconds he accelerates enough to break the sound barrier, which has never been done by a free-fall skydiver.
In 1960, United States Air Force Col. Joseph Kittinger made a similar jump from the lower altitude of 102,800 feet (31,000 meters). [8 Craziest Skydives of All Time]
General Electric proposed in the 1960s that an astronaut stranded in Earth orbit might survive a fiery return through the atmosphere with nothing but a space suit and a personal heat shield shell packed with foam insulation. Both NASA and the U.S. Air Force declined to test the technology.