Quote from source:
Are you ready for some free fall?

Austrian daredevil Felix Baumgartner officially announced that sometime this year, he intends to jump from a balloon at a height of nearly 23 miles, breaking the 50-year-old world record for the highest parachute jump held by retired U.S. Air Force pilot Joe Kittinger. Kittinger is the Stratos mission’s capcom (short for capsule communicator), which means that he will be the voice in Baumgartner’s helmet. Kittinger’s advice to his successor: “Have fun, enjoy it, and tell us all about it when you get down” [Scientific American].

Baumgartner is a BASE jumper who once flew a glider across the English Channel, but he and his team say they have loftier goals than simply a world record and a huge adrenaline rush. If he makes the jump, Baumgartner could be the first person to break the sound barrier without the benefit of an aircraft, and his crazy stunt could provide valuable data on how that affects the body. Just as Kittinger did, Baumgartner will go up in a balloon, though his pressure suit, capsule and monitoring equipment will be much more advanced [Reuters]. Baumgartner says that a successful test would also benefit future spaceflight, showing that if astronauts had a problem as their craft entered the stratosphere, it theoretically would be possible for them to bail out and safely reach the ground.