Photograph by Luke Aikins, Redbull Photofiles

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Sky diver Felix Baumgartner free-falls toward New Mexico during test dive.

Photograph by Luke Aikins, Redbull Photofiles

Watch Supersonic Skydive Live: Video of Felix Baumgartner's Jump

Austrian sky diver to attempt record-breaking free fall.

The countdown has begun. Sky diver Felix Baumgartner is set to step out of a pressurized capsule and free-fall 23 miles (37 kilometers) from the edge of space to the New Mexico desert.

Watch live video coverage here, then tune in to the National Geographic Channel documentary Space Dive in November (date TBD).

Seven years in the making, the so-called Red Bull Stratos Mission to the Edge of Space is expected to break records as the highest, fastest, and longest-duration skydive.

Baumgartner's team estimates the Austrian sky diver and helicopter pilot will reach Mach 1.2—roughly 690 miles (1,110 kilometers) an hour—and free-fall for five and a half minutes before opening a parachute at 5,000 feet (1,524) to float him to the ground.

Originally scheduled for Monday but postponed due to projected high winds, the feat would make him the first human to break the sound barrier without the propulsion, or protection, of a vehicle.

The current free fall record is held by Joseph Kittinger, a retired U.S. Air Force colonel and current Red Bull Stratos team member, who fell 19.5 miles (31.3 kilometers) on August 16, 1960. (See classic pictures of Kittinger's skydive.)

Kittinger, after years of refusing to help see his record broken, is now enthusiastically behind Baumgartner. "I felt that he was dedicated, that he was sincere. He's a trained athlete, he's an aviator." They have a special bond.

"I'll be the only one that knows exactly how Felix feels at that moment when he jumps from the step, 'cause I've done it," Kittinger says in Space Dive, a National Geographic Channel documentary to air in November.

Baumgartner agrees: "[Joe] knows how lonely you are at that altitude." In fact, Baumgartner will not allow any voice other than Kittinger's in his helmet, so that's how the scientific and medical team on the ground will communicate with him. "It feels like, if Joe's there, nothing can go wrong."

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