A man on ledge, 23 miles up and no fear

They've dubbed it the "mission to the edge of space".

The pedants will no doubt point out that Felix Baumgartner's attempt to make the highest ever skydive from 120,000ft (36.5km) is nowhere near space; and of course, they'd be right - the so-called Karman line is judged to be at about 100km (328,000ft). But this kind of misses the point.

At the altitude the Austrian daredevil intends to leap out of his capsule, the air pressure is less than 2% of what it is at sea level. He'll be jumping into a near vacuum. He's all but in space.

It's been a long road for Baumgartner. He first discussed with his sponsors Red Bull the idea of breaking Col Joe Kittinger's 52-year-old parachute mark back in 2005.

Since then, he's had to battle technical and budgetary challenges to make it happen, calling on the expertise of a top-notch team - Kittinger included - to pull him through.

The 43-year-old now needs not so much as a fair wind but next to zero wind to launch his "monster balloon" and capsule. He should realise his dream in the coming days.

"It's enormously difficult to launch a balloon this big," team meteorologist Don Day told me.

"When it comes down to launching Felix, it'll all be about wind speed and wind direction. We need calm to 3mph, from the ground up to about 250m. If it's any more than that, our launch crane cannot keep up. But right now, Tuesday's looking good."

Baumgartner will try to break four records here in Roswell, New Mexico:

Highest ever parachute jump. On 16 August 1960, the US Air Force pilot Kittinger jumped from 102,800ft (31.3km). Baumgartner will use a helium balloon with 10 times the volume to get another 18,000ft (5.5km) higher into the sky. The polyethylene envelope is an extraordinary thing. It will be 55 storeys high on lift-off, and as wide as a football field when fully inflated in the stratosphere; but the membrane itself will be just 20 microns thick. Think of the plastic bag in which you collect your dry cleaning.

BBC News