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In this Aug. 16, 1960 photo made available by the U.S. Air Force, Col. Joe Kittinger steps off a balloon-supported gondola at an altitude of 102,800 feet. In freefall for 4.5 minutes at speeds up to 614 mph and temperatures as low as -94 degrees Fahrenheit, he opened his parachute at 18,000 feet. Skydiving daredevil Felix Baumgartner is more than halfway toward his goal of setting a world record for the highest jump. A spokeswoman says Baumgartner took a practice jump Thursday, March 15, 2012 from more than 13 miles high over New Mexico. He's aiming for nearly 23 miles in the summer. The record is held by Kittinger, a retired Air Force officer. He jumped from 19.5 miles in 1960. (AP Photo/U.S. Air Force)

Skydiver aims to go supersonic

"Fearless Felix" Baumgartner has jumped 2,500 times from planes and helicopters, as well as some of the highest landmarks and skyscrapers on the planet — the Christ the Redeemer statue overlooking Rio de Janeiro, the Millau Viaduct in southern France, the 101-story Taipei 101 in Taiwan. This summer, Baumgartner hopes to hurtle toward Earth at supersonic speed from a record 23 miles up, breaking the sound barrier with only his body.