Skydiver Felix Baumgartner has made some craaaaazy jumps over the years, including BASE jumping from Petronas Towers and the Taipei 101 skyscraper. Impressive, but nothing compared to his plan to skydive from 23 miles above the Earth next week.

The Austrian adventurer will ascend to 120,000 feet in a pressurized capsule and, wearing only a spacesuit and a parachute, jump. As he plummets earthward in what will be the highest skydive ever, Baumgartner will become the first person to break the sound barrier in freefall.

Crazy? Perhaps. But ‘Fearless Felix’ already has made two practice jumps, from 13 miles and 18 miles, that went perfectly. Well, almost perfectly.

Baumgartner’s capsule was damaged during a hard landing after his leap from 97,145 feet in July, necessitating a complete overhaul. It was completed last week, and with everything up to par, Red Bull Stratos technical director Art Thompson has declared all systems go. The launch window opens Oct. 8.

“I feel like a tiger in a cage waiting to get out,” the 43-year-old former military parachutist, a veteran of more than 2,500 jumps, said in a statement.

Baumgartner hopes to break the unofficial record Joe Kittinger, a retired Air Force colonel from Florida, set in 1960 when he jumped from 102,800 feet. He expects to free fall for at least five minutes (another record) and exceed the speed of sound, around 700 mph at that altitude. His jump comes 65 years after Chuck Yeager became the first person to break the speed of sound.

During his test jump in July, Baumgartner’s descent from 18 miles up took 10 minutes and 36 seconds, and he reached 536 mph during a freefall that lasted 3 minutes and 48 seconds.

Baumgartner will be carried aloft in a 2,899-pound capsule suspended beneath a 55-story helium balloon. The capsule looks like something you’d see atop a Saturn rocket, and the Red Bull Stratos team has spent years honing its design and construction. The 8-foot-diameter capsule features a 6-foot diameter pressure vessel that will protect Baumgartner from the cold air (as low as -70 Farenheit) and thin oxygen he’ll experience ascending to the edge of the stratosphere.

Everything worked as planned during two earlier jumps, but the capsule landed on a rocky patch after July’s test flight, damaging its outer shell and framework. Ten days of testing confirmed that the capsule’s pressure sphere and electronics remained intact, but the Stratos team decided to replace some components of the life support system. The capsule was thoroughly shaken down in an altitude chamber at Brooks Air Force Base in San Antonio, Texas, then sent back to Roswell, New Mexico, where Baumgartner will lift off on Monday.

There are more than bragging rights at stake here. The Red Bull team insists there is some scientific merit to the jump.

“Red Bull Stratos is an opportunity to gather information that could contribute to the development of life-saving measures for astronauts and pilots — and maybe for the space tourists of tomorrow,” Baumgartner said. “Proving that a human can break the speed of sound in the stratosphere and return to earth would be a step toward creating near-space bailout procedures that currently don’t exist.”

The flight plan has Baumgartner reaching the speed of sound at around 100,000 feet roughly 30 seconds after jumping into a near-vacuum. His speed will slow as the atmosphere grows denser, and after freefalling for about five minutes he will deploy his parachute. He expects the entire jump to take 15 to 20 minutes. This being the era of 24/7 news and always-on social media, the entire thing will be broadcast live via the internet.

Of all the things that could go wrong — including a life-threatening breach of his suit or a flat spin during his dive — Baumgartner says the biggest challenge will be positioning himself for the fall to Earth once he’s stepped into the void.

“I have to get myself into a stable position before I reach the speed of sound,” he said. “With all my experience in the air that shouldn’t be too much of an issue, but in order to stabilize my body I need wind resistance. The problem is that for around 30 seconds I will have no air cushion whatsoever, meaning that I won’t be able to control the way my body spins.”

What’s most interesting, though, is Red Bull claims Baumgartner’s heart rate will be highest as he’s reaching his peak altitude, not when he’s falling to Earth. In the moments before he opens the capsule door, he will follow a detailed technical procedure that includes more than 40 steps. “That is the moment when you realize that you are completely dependent upon technology, in a place where there really is nobody around to help you,” he said.

Once he opens the capsule door, the rest is just, well, falling.

“Directly before the jump my heart rate will drop, because that is the time when I am in control of most things going on,” he said. “Just before I set off I will know that I am heading home.”