(CBS News) Austrian skydiver Felix Baumgartner has jumped more than 2,500 times from planes and skyscrapers.
Now, he's training for his biggest leap yet: a 120,000-foot jump to break a 52-year old record.
Wednesday, Baumgartner made a second successful test jump - from more than 96,000 feet.
Baumgartner strapped into a capsule and rose by helium balloon more than 18 miles above Roswell, N.M. and jumped. Ninety-six thousand feet is three times higher than jetliners cruise.
He spent four minutes in freefall, reaching a top speed was 536 mph, and landed safely in the desert.
Since 1998, the 43-year-old base jumper-turned-skydiver has made a series of improbable jumps -- like one in Rio de Janeiro off the statue of the Redeemer, and a 2007 plunge from the 91st floor of the Taipei 101 tower in Taiwan, the world's tallest building at the time.
In the Mojave Desert north of Los Angeles, Baumgartner has trained for his greatest leap of faith. One so high, it's out of this world: a freefall dive from 120,000 feet. That's 23 miles above the Earth.
"I think I'm born to fly," Baumgartner says. "You never run out of tall buildings (to jump from), but it's the same thing over and over again ... because how many highest buildings in the world are you gonna do? So I had to find something else."
One-hundred-twenty-thousand feet is roughly the altitude from which the space shuttle got rid of its booster rockets. From there, someone could easily see the curvature of the Earth, and the blackness of space.
It's a hostile environment. The air's so thin, so cold, it's a near vacuum.
Baumgartner's equipment, especially his pressurized suit, is his lifeline.
Asked whether the mental aspect is more difficult than the physical one, Baumgartner replied, "I think it's a little bit of both.
"I also had a hard time spending a lot of hours in the suit because, as soon as you lock the visor, you're in your own little world. You can only hear yourself breathing. It's hard to breathe. And I couldn't stay in that suit for a long time. ... I needed help from a psychiatrist to get over those feelings, those claustrophobic feelings."
In March, Baumgartner test-jumped from 71,000 feet. That's 13-and-a-half miles up.
With each higher jump - 96,000 feet Wednesday, 120,000 feet sometime next month -- the danger rises with the altitude.
An instrument panel built into his suit tracks his vital signs -- his heart and respiratory rates -- monitored by his Red Bull Stratus team of scientists on the ground.
"Everybody thinks about the big things," Baumgartner points out, "but those little details, they could kill you."
In desert practice jumps, Baumgartner needs to perfect his falling technique. Fall wrong, and his body could get out of control. Aerodynamic forces could spin his body like a top, up to 240 rotations per minute. And his only hope of landing alive at that point would be a special stabilizing chute.
"Every time when you do something, it is a test," Baumgartner notes. "You have to pass that test to reach the next level."
There is very little margin for error.
But, says Baumgartner, "Everything is based on the technique that we have developed the last couple years and my skills ... because, at the very end of the day, if anything goes wrong, I have to pay for it."
In 1960, Air Force Capt. Joe Kittinger rose in an open-air gondola and jumped from 102,000 feet -- 19 miles high -- still the highest, fastest and longest skydive on record.
Baumgartner wants to top that record, with help from his training partner and mentor -- Kittinger, now 83.
"The fundamentals are the same. The threat's the same," Kittinger says.
The equipment in 1960 was like "driving a Model T Ford (compared to a) 2020 Ferrari," Kittinger observes. "The danger is still there. It hasn't changed a bit. ... And Felix will be going through the same thing, except he's going to be four miles higher."
So high, Baumgartner could be in freefall for five-and-a-half minutes. He'll feel temperatures, including wind chill, of minus 148 degrees.
His top speed could reach 690 mph -- and he'd become the first human in freefall to break Mach 1, the speed of sound.
"I love the challenge," Baumgartner says. "That's the reason I became a skydiver, and as soon as I was a skydiver, I was looking for a challenge. ... And based on all these results, we should be ready for the big one."
This is not just a crazy publicity stunt. NASA is following Baumgartner's efforts carefully, and wirh each jump, Baumgartner is trying to advance the science of survival in high altitude.
To see Mark Strassmann's report, click on the video in the player above.