The jump from space: how did he do it?

On the 14th of October Felix Baumgartner ascended in a balloon to over 120,000 feet. What followed was a spectacular skydive streamed live to millions around the world. The mission was to aid future development of spacesuits, protocols for high altitude/high acceleration exposure and understand the effects on the human body during supersonic acceleration and deceleration. It was also a spectacular PR stunt and could usher in a new type of marketing.

A quick summary of the mission showed Felix’s exit Altitude was 128,100 feet – the highest manned balloon flight and the highest jump altitude. He was in freefall for 4 minutes and 20 seconds and covered a distance of 119,846 feet. He was supersonic, surpassing the speed of sound by travelling at a velocity of 373meters/second.

Some controversy over the scientific value of this project has arisen, so here are some answers to a few questions about the science behind the jump.

How is his suit designed for the project?

The suit was designed to provide protection from temperatures of +100°F to -90°F. It was pressurised to 3.5 psi (the atmospheric pressure at 35000ft) to avert symptoms of decompression sickness (or “the bends”. This pressurisation also prevented ebullism, a dangerous condition where gas bubbles form in our bodily fluids. Furthermore, a “vent hose fitting” kept the suit ventilated with both warm and cool air. The warm kept Felix from becoming dangerously “cold soaked,” while the cool air helped “avert perspiration that can fog his visor.”

What is his helmet and visor equipped with?

The helmet shell was moulded from “composite materials, which help to keep its weight low (about 8 pounds), yet are strong and resistant to impact”. As visual cues were important during descent and landing, the visor was “distortion free” in the critical region of vision. Furthermore, his suit had mirrors that increased his range of vision. His visor was also equipped with a sunshade. To prevent accidental opening (which would lead to depressurisation of the suit), the visor was equipped with a mechanism requiring “two separate coordinated actions to unlock.” The helmet contained an oxygen regulator, and two high pressure oxygen cylinders provided Felix with 100 percent oxygen to breathe during the freefall. Felix was able to keep in contact with mission control through an earphone and a microphone inside the helmet.

The balloon

The balloon was 30 million cubic feet in capacity and made from strips of high-performance polyethylene (plastic) film that is only 0.0008 inches thick. Polyester-fibre reinforced load tapes are also integrated within the design to help deal with the weight burden.

Helium is used to lift the balloon because it is lighter than air. However, the density of air is thinner as you ascend. This means that eventually the balloon will stop ascending and simply float.

Felix’s capsule was attached to this balloon. After the jump the capsule detached from the balloon and parachuted back down to New Mexico.

How can he exceed the speed of sound?

For those of you curious as to how someone can surpass the speed of sound, here is a quick summary courtesy of the Red Bull Stratos team:

“Drag, or air resistance, is one of the key factors causing terminal velocity. Bailing out at a very high altitude, where the air is thin, should enable Felix to break the speed of sound before reaching more dense air that will create drag and eventually result in his terminal velocity. Still, he’ll want to streamline his body as quickly as possible to aid his acceleration.”

Thus the thin air density at high altitude led to less air resistance slowing his acceleration. This prolonged acceleration time eventually led to a greater speed.

A week on, opinions are mixed as to the benefit to the scientific community. Werner Hofmann from the University of Salzburg said, “The study of physics had nothing to learn from this experiment.”

But this quote from Felix truly sums up the spectacle: “That spin became so violent it was hard to know how to get out of it. I was able to get it under control and break the speed of sound.”

More information on Felix’s jump can be found on his sponsor’s website, at www.redbullstratos.com