Sunday, October 14, 2012

The tech behind Felix Baumgartner’s stratospheric skydive

Felix Baumgartner, seen from Red Bull Stratos mission control

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Sixty five years ago today, Captain Charles Yeager became the first man to travel faster than the speed of sound in his X-1 aircraft. Daredevil Felix Baumgartner just became the first man to accomplish the same feat without a plane. In an almost unimaginable stunt, the 43-year old Austrian has jumped from a specially constructed balloon at over 128,000 feet (39km) above the earth, breaking the world record for high-altitude skydives and speeds in free fall. As you would expect, Baumgartner is no stranger to extreme sports. He is an accomplished BASE jumper and, using a carbon wing, was the first to free fall across the English Channel. On this dive he broke not only the previous altitude record of 102,000 feet for a skydive, but likely the speed of sound and the record for fastest free fall during his descent.
The Red Bull Stratos team backing Baumgartner describes their feat as a “mission to the edge of space.” Years in the planning, the team has gone through many iterations of equipment and practice jumps before finally being ready to make the record-setting attempt from Roswell, New Mexico. Capsule damage during a training jump and poor wind conditions took turns delaying the effort, but today, Sunday, October 14th, 2012, Baumgartner was finally able to launch.

Getting up there

Stratos balloon being filled with Helium -- It is 55 stories high when fully inflated, and a 400+ foot sphere at altitudeEven getting high enough to make the record jump is a technical challenge. 128,000 feet (over 39,000 meters) is several times higher than the altitudes frequented by commercial jets. It even surpasses world altitude record of 123,520 feet for jet aircraft. So getting there isn’t simply a matter of hitching a ride on a plane. Baumgartner used a specially-designed balloon with a spaceship-sized capsule suspended underneath to make his ascent.
To put this altitude in perspective it is more than three times further than the seven miles James Cameron went below the surface of the ocean to reach the depths of the Mariana trench. Like Cameron’s journey, Baumgartner’s was a solitary one, packed into his one-man capsule suspended under the helium-filled Stratos balloon for his three-hour ride up.

Surviving in space

The journey up was the cushy part of the flight for Baumgartner. His 2,900-pound (1315kg) capsule is fully climate controlled. It was damaged in a hard landing during a test jump in July, which pushed the team’s schedule back to allow for repairs. Similar to Cameron’s sub, the capsule features a pressure sphere, although a six foot one made out of fiberglass and epoxy instead of the four foot version made from metal that Cameron needed. During the ascent, the sphere is pressurized to 8 psi, about the same pressure as the atmosphere at 16,000 feet above sea level.
Much like a race car cockpit, the sphere is surrounded by a cage of chromium-molybdenum (chromoly steel) tubing. An outer insulated shell of fiberglass helps protect the capsule from the -70 degree Fahrenheit (-56.7C) temperatures. An aluminum honeycomb at the bottom of the capsule protects the sphere during landing. Additional, one-time-use crush pads of cell-paper honeycomb can withstand up to 8Gs on impact.
Diagram of Stratos high-altitude record-setting mission flight plan

A lifetime of dry cleaning, all in one bag

Red Bull describes its Stratos balloon as a forty-acre dry cleaning bag. Made out of strips of plastic film which are only .0008-inches (0.02mm, 20 micron) thick, the balloon material would cover nearly 2,000,000 square feet (162,000 square meters). Polyester-fiber tape is used to reinforce the material. At launch the helium-filled balloon is 55 stories high, and very thin. As it ascends, the balloon expands, eventually holding a staggering 30,000,000 cubic feet of helium as it becomes nearly round — 334 feet high and 424 feet wide. Two trucks of helium are needed to inflate the balloon, a process taking nearly an hour. The balloon is remotely emptied, returned to earth, and hopefully recovered after a jump. I’m thinking that I wouldn’t want to be standing underneath it when it drifts down.

Space walking at the speed of sound

Baumgartner’s suit is essentially a highly-ruggedized spacesuit. Eight pounds of composite materials provide him with a 3 psi environment for his entire trip down, and protects him from the extreme temperatures he’ll experience. He doesn’t need to try to breathe 3 psi air, as the suit provides him with pure oxygen.
Baumgartner space suit diagramA main and reserve chute are of course essential equipment for Baumgartner. They are only designed to be deployed up to about 172 mph (277 kph), so Baumgartner needs to slow down, by entering the thicker atmosphere closer to earth after about five minutes of free fall, before safely pulling his rip cord. There is a fail-safe which could have deployed the main shoot if he had been moving at more than 115 feet (35 meters) per second at 2,000 feet (610 meters) or less altitude. Fifteen more minutes of floating down on his parachute got Baumgartner safely on the ground.
Baumgartner has almost certainly also set a world record for speed, as well as height. During the jump his team measured his top speed at nearly 730 mph, well above the speed of sound and the previous record. His chest pack includes an instrument package that will be used by officials to verify whether he did indeed break the sound barrier during his free fall. If the team’s calculations are correct Baumgartner broke through the speed of sound — approximately 690 meters per second — within a minute after jumping. Lower-altitude jumps are limited in speed by the drag of the atmosphere, but at over 100,000 feet the air is thin enough to allow much greater speeds.
Amazingly the team kept visual contact with Baumgartner during the jump and was able to transmit live video of the event. For most of the jump, except for a period when he was tumbling, Baumgartner could also be heard speaking with the team, including relaying that his leg was swelling up during the free fall. The only one of the records Baumgartner set out to shatter that didn’t fall was time in free fall. He pulled his rip cord and successfully deployed his main chute about four minutes and 22 seconds after jumping, instead of the over six minutes he had hoped for — probably because his free fall speeds were higher than expected.

Spinning, and not in a good way

We’ve all seen video of airplanes going into a tailspin. Diving from altitude carries the same risk, except magnified because a human body can spin much faster than a plane. The resulting force is enough to cause unconsciousness and potentially a “redout” leading to brain injury. The Red Bull team equipped Baumgartner’s rig with a special drogue chute that could have deployed to stabilize him if a suit-mounted G meter registered over 3.5 Gs for more than six seconds. The closest Baumgartner got to this type of problem was tumbling mid-way through his free fall, which he quickly corrected.

Covering the jump: Beyond Google Glass

Baumgartner's chest pack with electronics and cameraGoogle might have made waves broadcasting a low-altitude jump with Google Glass cameras and special antennas, but this jump required a much more extreme set of cameras and communication technology. The capsule itself featured nine HD cameras and three 4K cameras, along with three more high-resolution digital still cameras. Because of the altitude, critical electronics components are housed in a pressurized “keg” that contains two miles of wires.
Four of the twelve capsule cameras are rated for space and life outside the capsule, while eight of them live in nitrogen-filled housings on the exterior, and three are in the interior. All the cameras are remotely controlled from the ground, and filled three microwave channels with video during the flight. Baumgartner’s suit also had three HD video cameras, one on each thigh and one on his chest.
None of this was enough to get the jump broadcast live. A unique ground system, nicknamed JLAIR for Joint Long-range Aerospace Imaging and Relay, had to be developed to track the capsule and Baumgartner during the flight and dive. Using several massive telescopes and high-powered zoom lenses mounted on a four-ton motorized pedestal the JLAIR kept the broadcast antennas focused on target.

A link to the past

In an unlikely parallel to Cameron’s deep-sea dive, Baumgartner also broke a record that is over fifty years old. In 1960, then Air Force Captain Joe Kittinger sky dived from 102,800 feet, also over New Mexico. Like Don Walsh’s dive to the Challenger Deep of the Mariana trench in the Trieste in 1960, it was done at a time before much of the technology in use today was invented. Kittinger is a consultant to the Red Bull Stratos project, just as Walsh was to Cameron’s effort. Kittinger’s jump was chronicled on film, and has been turned into a YouTube video with a rock sound track. Look for the guy checking the free fall time with a stopwatch:
It’s hard to imagine the feeling of jumping out of a space capsule 22 miles above the earth and simply falling for over four minutes as space turns into sky. Fortunately for Baumgartner he was able to keep his wits together, control his body position, and successfully pull his rip cord to make a great landing — steering his parachute to an open area and walking as he landed. After this, the most awesome of his many feats, he plans to settle down with his family and merely fly helicopter rescue flights for adventure.

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