"I'm coming home," Felix Baumgartner radioed Sunday just before stepping off his 24-mile-high (39-kilometer-high) balloon capsule and into the history books.

He wasted no time getting there: In the process of logging the highest ever jump, Baumgartner reached unprecedented speeds of 833.9 miles (1,342 kilometers) an hour while free-falling in a pressurized suit, according to preliminary data.

Though he appeared no worse for the wear during a post-jump press conference, Baumgartner had, officials announced, broken the sound barrier during the free fall, reaching Mach 1.24. Asked what it was like to go supersonic, he said, "It's hard to describe, because I didn't feel it. You know, when you're in that pressure suit, you don't feel anything. It's like being in a cast."

"Be sure to duck your head real low as you go out the door," warned retired U.S. Air Force pilot Joseph Kittinger, who set the previous height record in 1960—19.5 miles (31.3 kilometers)—and was the only Red Bull Stratos team member with a direct radio link to Baumgartner. (See classic pictures of Kittinger's skydive.)

Soon after, Baumgartner dived from beneath history's largest helium balloon—55 stories tall and as wide as a football field.

After a 4-minute, 22-second free fall—not the longest duration on record, as he'd hoped (that record-breaking speed may have had something to do with it)—the Austrian sky diver opened his parachute at about 5,000 feet (1,524 meters).

"Couldn't have done it any better myself," Kittinger said over the radio, and to the millions who watched the live Internet feed of Baumgartner's skydive.

Baumgartner safely touched down at 2:17 p.m. ET after roughly ten minutes total in the air—the picture perfect desert landing punctuated by an apparently elated Baumgartner falling to his knees before being whisked away by a recovery helicopter.

Stratos Skydive Rife with Risks

Baumgartner faced mortal dangers at every turn: Should his pressurized suit have torn, for starters, the lack of atmospheric pressure at extreme altitudes could have caused his blood to boil. (See "Supersonic Skydive's Five Biggest Risks: Boiling Blood, Deadly Spins, and Worse.")

And if his body had gone into a so-called flat spin—rotating perhaps hundreds of times a minute—he could have suffered extreme eye and brain injury.

At supersonic speeds, Baumgartner confronted dangers wholly unknown to science.

"We try to anticipate as much as we can about supersonic speed," Red Bull Stratos Medical Director Jon Clark said last week. "But we really don't know, because nobody has done this before."

Baumgartner Joins High-Flying Pantheon

Despite the dangers, Baumgartner remained optimistic before the skydive.

In an interview with Red Bull, he commented: "I have the best team behind me. For me, I have been preparing ever since I started BASE jumping. I have been working towards this goal since I was a little kid when I started looking up to people like Joe Kittinger. And with him on my team, I know I am surrounded by the best in the field."

Fittingly, Baumgartner accomplished his feat on the 65th anniversary of Chuck Yeager's record-breaking supersonic flight—a milestone not lost on the Austrian pilot.

"In 65 years it goes to show there are still challenges to overcome, and you should never lose sight of trying to achieve them," he said. "I would be proud to be a part of that group of explorers."