Skydiver’s 36km jump bids to break sound barrier
If he survives, the man dubbed “Fearless Felix” could be the first skydiver to break the sound barrier. If he does not, his failure could be live-streamed on the internet for all to see.
Rigged with cameras, the 43-year-old former military parachutist is scheduled to jump from a balloon-hoisted capsule 37km up near Roswell, New Mexico, today. He wants to break the record set in 1960 by Joe Kittinger, who jumped from an open gondola at an altitude of 19.5 miles (31km). Kittinger’s speed of 614mph (about 988km/h) was just shy of breaking the sound barrier at that height.
Baumgartner, who has been preparing for the jump for five years, has made two practice runs from the Roswell area, from 15 miles in March and 18 in July.
And while he and his team of experts recognise the worst-case scenarios — including “boiling” blood and exploding lungs — they have confidence in their built-in solutions.
His top medical man is Dr Jonathan Clark, an ex-Nasa flight surgeon whose wife, astronaut Laurel Clark, died in the space shuttle Columbia accident in 2003. Dr Clark is dedicated to improving astronauts’ chances of survival in a high-altitude disaster.
The main fear is a breach of Baumgartner’s suit, which could cause potentially lethal bubbles to form in his bodily fluids, known as boiling blood. There are also risks he could spin out of control.
The project’s team of experts has a plan for almost every contingency. The spacesuit and capsule were tested in the early skydiving practice runs. It is not known how much the project — called Stratos for stratosphere and sponsored by energy drink Red Bull — is costing.
Whether Baumgartner can make what he vows will be his final jump depends on the weather. A cold front that brought winds to the area this weekend prompted the team to move the planned jump a day forward.
Baumgartner’s team remained optimistic about getting the mission off the ground. “From what we are looking at so far, we are on schedule,” meteorologist Don Day said.
Weather permitting, Baumgartner will be lifted into the stratosphere at about 2pm Irish time by a helium balloon that will stretch 55 stories high.
Once he reaches his target altitude, he will open the hatch of his capsule and make a gentle, bunny-style jump. Any contact with the capsule on his exit could break open the pressurised suit. He hopes to reach a speed of 690mph to break the sound barrier.
Baumgartner, who has made 2,500 jumps from planes, helicopters, landmarks, and skyscrapers, 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 US and Austria.
A helium-filled balloon will lift Baumgartner, sitting inside a custom-built capsule, to an altitude of 36,576m. At that altitude, the upper limits of the stratosphere, the atmosphere is a mere inkling of its sea-level self, exerting a pressure less than 0.5% of its value near the ground. Even if gradually acclimated, humans cannot survive long above 7,900m without an oxygen tank, so a much higher Baumgartner will require extra oxygen.
When he exits his capsule and plunges into the void, he’ll accelerate for about 30 seconds before hitting peak speed, said Michael Weissman, a physicist at the University of Illinois.
Weissman estimates that Baumgartner’s speed will max out just above the sea-level speed of sound, which is about 1,225km/h.
Baumgartner stops accelerating because of collisions with air molecules. Called a “drag force”, air resistance opposes a falling body’s downward motion, counteracting the downward force of gravity by pushing the body upward. The faster the body falls, the greater the air resistance so, at a certain velocity, called terminal velocity, the drag force becomes equal and opposite to the gravitational force. With the forces balanced, the body stops accelerating, once external forces remain constant.
At that point, Baumgartner enters safer territory: The fall turns into an ordinary skydive. But what will happen to his body before that point, as he plunges through the stratosphere at the speed of sound?
For one thing, according to physicist Louis Bloomfield of the University of Virginia, a shock wave, also known as a sonic boom, will envelop his body. “He’ll be colliding with the gas so fast that it can’t flow out of his way because it effectively doesn’t know that he’s coming,” said Bloomfield.
Those high-speed collisions with air will create a huge amount of heat.
“When he’s near the maximum speed, almost all the gravitational potential energy he loses [from] falling gets converted to heat,” said Weissman. If he and his suit together weigh about 110kg, he’ll produce about 300kw of heat when falling at sonic speeds.
“If that heat was simply dumped into the skydiver, he’d heat almost 1C per second, which would be rapidly fatal,” he said. “Of course, most of that heat goes into the atmosphere.”
Assuming Baumgartner’s suit holds up, he should survive the fall. But Weissman said the very act of making that assumption suggests this stunt is dangerous.
If Baumgartner is worried, he’s not showing it. “I feel like a tiger in a cage waiting to get out,” he said.
