Austrian skydiver and extreme athlete Felix Baumgartner hopes to take the leap of his life tomorrow, attempting 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 doesn't, a tragic fall could be live-streamed on the internet for the world to see.
The 43-year-old former military parachutist is scheduled to jump from a balloon-hoisted capsule 37km near Roswell on Tuesday morning (about 2am on Wednesday, NZT). He wants to break the record set in 1960 by Joe Kittinger, who jumped from an open gondola at an altitude of 31km. Kittinger's speed of 988kmh 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 24km high in March and 28.97km 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. Those solutions are something NASA is watching closely. The space agency is interested in the potential for escape systems on future rocket ships.
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. 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.
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 won't say how much the project, called Stratos for stratosphere, is costing.
The organisers say there are some 30 video and still cameras to record the jump, including five attached to Baumgartner's pressure suit, along with cameras from the capsule, on the ground and a helicopter.
A live internet stream of the event is being promoted at http://www.redbullstratos.com/live , from all cameras except those on Baumgartner's body. But organisers said there will be a 20-second delay in their broadcast of footage in case of a tragic accident.
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 Monday jump to Tuesday.
Baumgartner's team remained optimistic about getting the mission off the ground.
"From what we are looking at so far, we are on schedule (for Tuesday)," meteorologist Don Day said at a media briefing Sunday.
Weather permitting, Baumgartner will be lifted into the stratosphere around 7am 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 that will protect him from temperatures as low as minus 70 and a lack of oxygen.
He hopes to reach a speed of 1110 kph to break the sound barrier.
Baumgartner, who has made more than 2500 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.
Baumgartner faces a slew of dangers during his record attempt. Here is a look at some of the risks:
* Colliding shock waves, triggered by a human body moving faster than the speed of sound, could hit with the force of an explosion, though the risk of this is much less likely in the stratosphere where the air is extremely thin.
* The low-pressure environment could cause Baumgartner to go into a flat spin. If a spin lasts for too long, he could lose consciousness and injure his eyes, brain and cardiovascular system.
* Exposure to vacuum, even for a short period of time, could cause Baumgartner's blood literally to boil. The condition, known as ebullism, causes fluids in the body to turn to gas.
* Gas seeping into the body due to a relatively rapid exposure to low pressure can cause decompression sickness, or "the bends."
* As pressure decreases, trapped gas in the body can cause ear blockages, dizziness and acute tooth, sinus and gastrointestinal pain. When decompression is sudden, lungs can over-inflate and collapse. A gas bubble in an artery could stop blood flow.
* Extremely cold temperatures pose a threat to Baumgartner and his equipment. Excessive heat from the sun is also a risk.
* Ultraviolet radiation is more than 100,000 times as strong at 120,000 feet, where Baumgartner plans to begin his jump, as it is at ground level, but Baumgartner should have a very short exposure time.
* Wind shear could make Baumgartner nauseous and could destroy his balloon.
* A breach in Baumgartner's protective spacesuit or the accidental deployment of a parachute are considered the biggest safety concerns.
- AP and Reuters