Felix Baumgartner prepares for 23-mile skyfall

Felix Baumgartner pictured in flight over Dover on July 31, 2003 (Getty Images)

Skydiver Felix Baumgartner is preparing to take the leap of his life aiming for the highest, fastest free fall in history.

If he survives, the man dubbed "Fearless Felix" could be the first skydiver to break the sound barrier. If he does not, his failure could be live-streamed on the internet for the world to see.

Rigged with cameras, the 43-year-old former military parachutist is scheduled to jump from a balloon-hoisted capsule 23 miles up near Roswell, New Mexico tomorrow. He wants to break the record set in 1960 by Joe Kittinger, who jumped from an open gondola at an altitude of 19.5 miles. Kittinger's speed of 614 mph was just shy of breaking the sound barrier at that height.

Baumgartner, who has been preparing for the jump for five years, has made two practice runs from the Roswell area, from 15 miles in March and 18 miles in July.

And while he and his team of experts recognise the worst-case scenarios - including "boiling" blood and exploding lungs - they have confidence in their built-in solutions.

Baumgartner's top medical man is Dr Jonathan Clark, a former NASA flight surgeon whose wife, astronaut Laurel Clark, died in the space shuttle Columbia accident in 2003. Dr Clark is dedicated to improving astronauts' chances of survival in a high-altitude disaster.

The No. 1 fear is a breach of Baumgartner's suit, which could cause potentially lethal bubbles to form in his bodily fluids, a condition known as boiling blood. There are also risks he could spin out of control, causing other problems.

This death-defying venture is being sponsored by energy drink maker, Red Bull, which has funded other extreme athletic events. The project's team of experts has a plan for almost every contingency. The spacesuit and capsule were tested in the early skydiving practice runs. The company will not say how much the project, called Stratos for stratosphere, is costing.

But whether Baumgartner can make what he vows will be his final jump depends on the weather. A cold front that brought winds to the area this weekend prompted the team to move the planned jump a day forward.

Baumgartner's team remained optimistic about getting the mission off the ground.

"From what we are looking at so far, we are on schedule," meteorologist Don Day said.

Weather permitting, Baumgartner will be lifted into the stratosphere around 1400 BST by a helium balloon that will stretch 55 stories high. Once he reaches his target altitude, he will open the hatch of his capsule and make a gentle, bunny-style jump. Any contact with the capsule on his exit could break open the pressurised suit.

He hopes to reach a speed of 690 mph to break the sound barrier.

Baumgartner, who has made more than 2,500 jumps from planes, helicopters, landmarks and skyscrapers over the past 25 years, promises this jump will be his last.

He says he plans to settle down with his girlfriend and fly helicopters on mountain rescue and firefighting missions in the US and Austria.

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AP