This afternoon extreme athlete and skydiver Felix Baumgartner will attempt a 23-mile free fall into the southern New Mexico desert.

The 43-year-old hopes to become the first person to break the sound barrier outside of an airplane. The former military parachutist from Austria planned to take off in a 55-story, ultra-thin helium balloon that would take him into the stratosphere.

Baumgartner will make a nearly three-hour ascent to 120,000 feet, then take a bunny-style hop from a pressurized capsule into a near-vacuum where there is barely any oxygen to begin what is expected to be the fastest, farthest free fall from the highest-ever manned balloon.

Scientist are hoping that his stratosphere jump would help provide valuable information for next-generation spacesuits and techniques that could help astronauts survive accidents.

Potential risk of the jump would be any contact with the capsule on the exit that can potentially make a tear in his pressurized suit. The rip could expose him to a lack of oxygen and temperatures below as low as 70 degrees below zero, and could cause lethal bubbles to form with in bodily fluids, a condition known as "boiling blood."

Baumgartner, who has made more than 2,500 jumps from planes, helicopters, landmarks and skyscrapers, has been preparing for this leap for five years.

After 25 years of skydiving, Baumgartner promises this jump will be his last.

He says he plans to settle down with his girlfriend and fly helicopters on mountain rescue and firefighting missions in the U.S. and Austria.

The venture is being sponsored by energy drink maker, Red Bull, and the company won't say how much the project is costing.

Watch Baumgartner's "Stratos Jump" live stream, click here.

Below is a simulation of what the jump should look like: