Austrian Felix Baumgartner accomplished three things this weekend no other human has ever done. On Sunday, the 43-year-old pilot and parachutist leapt off a platform dangling from a balloon 128,000 feet above the earth becoming the record-holder for highest manned balloon flight (128,097 feet), longest total freefall distance (119,846 feet) and the fastest speed a person has ever travelled without the aid of a vehicle (833.9 miles per hour).
It was one of the most extraordinary things I have ever witnessed.
And it generated some great questions, which, in honour of Baumgartner's death-defying act, are answered here.
Could Baumgartner have floated into outer space?
No. Engineers estimated the helium balloon used in the feat could float to approximately 130,000 feet before the pressure inside the balloon would equalize with the air pressure outside the balloon. If the balloon were able somehow to continue beyond this equilibrium point, the helium would continue to expand in the thinner and thinner air of the upper atmosphere until the balloon burst.
The other main thing to consider here is that although Red Bull, the sponsor of the event, touted it as the "jump from the edge of space," that may have been a bit sensationalist.
The Earth's atmosphere is technically 10,000 kilometres thick. Effectively, though, it only extends to approximately 85 to 100 kilometres before the density becomes so low as to be a virtual vacuum. By international convention "space" begins somewhat arbitrarily at 100 kilometres at which point human travellers are considered astronauts.
As impressive as Baumgartner's accomplishment was at just over 37 kilometres, he had a long way to go before reaching outer space.
Finally, there is gravity and atmospheric drag. Even if, by some physics-defying miracle the balloon had kept going and burst, Baumgartner and his capsule would have been brought back to the ground. Even the International Space Station, which orbits at 350 to 400 kilometres above the planet, requires regular altitude boosts to maintain its orbit.
Wouldn't breaking the sound barrier rupture Baumgartner's eardrums?
No. It helps here to understand what creates a sonic boom. A travelling object creates pressure waves that travel at the speed of sound. As the object accelerates, these waves become more compressed in front of the object causing the later ones to collide with earlier ones. When the object reaches and exceeds the speed of sound the waves merge into a single shock wave that creates the characteristic boom because of the sudden drop in pressure caused by the object moving out of the pressure zone.
Not only would Baumgartner's sonic boom not have harmed him, he wouldn't even have been able hear it because he was moving faster than it was. Even if somehow, he could have heard it, it's highly unlikely it would have ruptured his eardrums. Typical sonic booms created by large aircraft generate approximately 140 decibels, below the threshold for damage. A small object such as a person would likely not generate nearly that level of sound.
Why wouldn't Baumgartner burn up in the atmosphere?
As discussed above, Baumgartner never came close to leaving the atmosphere. And he had an initial speed of basically zero when he jumped. Objects such as meteors burn up when they hit the atmosphere because they are travelling at enormous speed to begin with.
There are a dozen major meteor showers every year. Their arrival speeds range from 23 to 71 kilometres per second. At these speeds the air is instantaneously heated to as much as 1,650C. Even at his highest speed of 833 mph, Baumgartner was always safe from generating enough heat to harm him.
