In the 1950s, the U.S. Air Force dropped crash-test dummies from planes to try out parachute designs at Holloman Air Force base in New Mexico. Locals thought the bodies were aliens jumping out of UFOs. The Air Force was happy to allow Russian spies to think New Mexicans were nutty rather than reveal its new military technology. Graham Murdoch
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Before famed skydiver Felix Baumgartner can jump out of his balloon at 120,000 feet, his ground crew will have to clear it with the Federal Aviation Administration. “Felix will be coming in like a missile,” says Jon Clark, the medical director of the Red Bull Stratos mission. “We don’t want him to be confused with one.”

The Highest Dive

In the 1950s, the U.S. Air Force dropped crash-test dummies from planes to try out parachute designs at Holloman Air Force base in New Mexico. Locals thought the bodies were aliens jumping out of UFOs. The Air Force was happy to allow Russian spies to think New Mexicans were nutty rather than reveal its new military technology.

Joe Kittinger, a U.S. Air Force test pilot, set the highest jump record, at 102,800 feet, in 1960, and in doing so helped develop parachutes and pressurized flight suits worn by fighter pilots and astronauts. Baumgartner wants to make a similar contribution. A sensor-filled chest pack will measure his heart rate and oxygen intake to reveal how his body reacts to supersonic speeds—this could prove useful to astronauts and space tourists needing to make a hasty exit from orbit. His custom-made pressurized jump suit will also influence the next generation of high-altitude protective gear.

The biggest danger is something called the shock-shock interaction, which can occur when shock waves created by cracking the sound barrier intersect and intensify. Clark speculates that the phenomenon could have caused the unexplained shearing forces that injured the crew in the Columbia space shuttle disaster. They were traveling faster than Mach 5. Baumgartner will top out at Mach 1, so the threat to him is hard to predict. He could be injured, or even die. “We think Felix will be fine,” Clark says, “but quite honestly it’s a huge unknown.”

Kittinger, who is advising the team, notes that even if Baumgartner passes through the sound barrier unscathed, he still has 100,000 feet to fall. His suit could breach or he could go into a deadly spin. Clark considers this and sighs, “It ain’t over till it’s over.”

That Last Step Is a Doozy

1. Jump From the Capsule
Once Baumgartner reaches 120,000 feet, he will depressurize the capsule, carefully shuffle to the door, and even more carefully dive out. A wrong move could damage his helmet or pressurized jump suit—a potentially fatal mistake.

2. Pass Through the Sound Barrier…
Within 30 seconds, Baumgartner will accelerate to about 690 mph—fast enough to break the sound barrier at 100,000 feet. To survive the shock waves he creates, he will need to assume a bullet-like body position, which will be difficult in the pressurized suit.

3. …and Back Again
He will travel faster than the speed of sound for only a few seconds before he hits denser air that will slow him down. Scientists are particularly interested in how his body will handle the transition between supersonic and subsonic speeds.

4. Free Fall
He’ll spend roughly the next five minutes free-falling, slowing to a terminal speed of 120 mph. Turbulence or an erratic hand gesture could upset his aerodynamics, sending him into a 120-rpm spin that could knock him out. If he spins at 100 rpm for more than 10 seconds, a special parachute, called a drogue, will deploy to slow the spin.

5. Pull the Cord
At about 5,000 feet, he will deploy his main chute or, if he’s unable to, it will activate automatically. Depending on how the wind pushed his balloon during its ascent, he could land as far as 150 miles away from the launch site.

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