The science of supersonic freefall - Red Bull Stratos

The mission, Red Bull Stratos, will take renowned athlete Felix Baumgartner to at least 120,000 feet above the earth, to the very edge of Space. From there, he will attempt a stratospheric free fall jump - the longest in the history of man - and hopefully will become the first human to break the speed of sound with his own body.

The speed of sound varies according to altitude and temperature. The Red Bull Stratos science team estimates that after only 35 seconds of freefall Baumgartner will break through the sound barrier and catch up with the speed of sound, which is likely to be about 690 miles per hour at the predicted altitude of 100,000 feet.

Known hazards at such altitudes include temperatures well below zero; an environment with too little oxygen to sustain human life; the tendency to spin uncontrollably (to the point of unconsciousness or worse); and air pressure so low that without a pressure suit blood is said to boil with life-threatening vapor bubbles. Unpredictable factors compounding those dangers include sudden changes in air pressure and resulting instability in the transonic zone (speeds approaching supersonic velocity), which in the mid-twentieth century caused aircraft to lose control or break up and resulted in the concept of a sound barrier. Of particular interest is the shock-shock interaction, a condition in which shock waves collide and create a reaction not unlike an explosions blast wave.

For more information, visit http://www.redbullstratos.com/

See our January 22, 2010 blog post about Red Bull Stratos