After the winds subsided Baumgartner, wearing a pressurized spacesuit, climbed into the specially made capsule designed to carry him into the stratosphere. But the gusts then picked up again.

If the launch had proceeded, it would have taken about 2.5 to 3 hours for the 55-story tall balloon to reach 120,000 feet.

Baumgartner’s goal is to break the record of 102,800 feet for the highest-altitude freefall, a milestone set in 1960 by U.S. Air Force Colonel Joe Kittinger.

As he falls from 120,000 feet Baumgartner would also break the sound barrier. With virtually no air to resist his fall, he was expected to reach the speed of sound, which is 690 mph at that altitude, after about 35 seconds of freefall.

He would stay supersonic for nearly a minute and should freefall for a total of 5 minutes and 35 seconds.

When Baumgartner jumps from the capsule, the position of his body will be crucial, since there is no air for him to move around in. If he falls in a way that puts him into a rapid spin, Baumgartner could pass out and risk damaging his eyes, brain and cardiovascular system.

Baumgartner’s safety gear includes his custom spacesuit that will protect him from low pressure and the extreme cold. Temperatures are expected to be as low as about minus 70 degrees Fahrenheit (minus 57 degrees Celsius.)

The near-vacuum puts him at risk of ebullism, a potentially lethal condition in which fluids in the body turn to gas and the blood literally boils. Severe lung damage could occur within minutes.

Helicopters equipped with newly developed instruments to treat lung damage would be standing by during Baumgartner’s skydive.

(Additional reporting by Jane Sutton in Miami; Editing by Tom Brown and Doina Chiacu)