October 15, 2012

On Sunday, October 14, the Austrian daredevil Felix Baumgartner became the first human to skydive at supersonic speeds. Baumgartner, a former paratrooper, leapt from a helium balloon more than 24 miles (39 kilometers) above Earth’s surface. As he plunged through the upper atmosphere, he reached a speed of 833.9 miles (1,342 kilometers) per hour–nearly 25 percent faster than the speed at which sound travels through air. He fell for four minutes and 20 seconds. Baumgartner also broke the skydiving altitude record. The dive took place on the 65th anniversary of the first supersonic airplane flight, by American test pilot Chuck Yeager.

The dangers of Baumgartner’s dive went far beyond those faced by run-of-the-mill skydivers. The huge helium balloon brought Baumgartner to the edge of outer space, where there is barely any air. With such little air pressure, the boiling point of water becomes lower than normal human body temperature. Baumgartner had to wear a pressurized suit to keep his body fluids from boiling away. His suit also shielded him from cold, radiation, and the effects of dangerous shock waves that occur when an object breaks the speed of sound.

Baumgartner plunged from his balloon at an altitude of about 24 miles (39 kilometers), in the layer of the atmosphere called the stratosphere. (World Book Illustration)

The pressure suit had disadvantages, however. Baumgartner, encased in the 100-pound (45-kilogram) suit for for more than two hours of ascent, had to overcome intense claustrophobia. During both the ascent and the fall, the suit’s visor fogged up, blinding Baumgartner. In addition, the bulky suit made it more difficult for Baumgartner to sense whether he was spinning. If a person spins too fast during freefall, blood is whipped outward from the center of the body, much like the way liquid in a salad spinner is flung to the edge of the bowl. The effects can easily be fatal. Baumgartner did begin spinning about 90 seconds into his fall, but the experienced skydiver was able to stop his rotation.

Baumgartner’s skydive was streamed live over the Internet. Millions watched him leap from the balloon and plunge towards the blue orb of Earth below. The stunt, financed by the energy drink company Red Bull, was the culmination of five years of work involving 300 people. Scientists hope to use data from Baumgartner’s suit to construct better protection for astronauts and pilots. Baumgartner, for his part, said he was now “retired from the daredevil business.”

Additional World Book articles:

• Air
• Airplane (Supersonic airplanes)
• Parachute
• Sonic boom
• Aviation (1947) (a Back in Time article)