Skydiver cancels try at supersonic jump

His medical director is Dr. Jonathan Clark, a NASA space shuttle crew surgeon who lost his wife, Laurel Clark, in the 2003 Columbia accident. No one knows what happens to a body when it breaks the sound barrier, Clark said.

"That is really the scientific essence of this mission," said Clark, who is dedicated to improving astronauts' chances of survival in a high-altitude disaster.

Clark told reporters Monday he expects Baumgartner's pressurized spacesuit to protect him from the shock waves of breaking the sound barrier. If all goes well and he survives the jump, NASA could certify a new generation of spacesuits for protecting astronauts and provide an escape option from spacecraft at 120,000 feet, he said.

Currently, spacesuits are certified to protect astronauts to 100,000 feet, the level former Air Force Capt. Joe Kittinger reached in his 1960 free-fall record from 19.5 miles. Kittinger's speed of 614 mph was just shy of breaking the sound barrier at that altitude.

Follow Jeri Clausing at http://twitter.com/jericlausing.