Space diving: The ultimate extreme sport

Anatomy of a space dive
Anatomy of a space dive

AS CAPTAIN Joe Kittinger of the US air force stood on the edge of the hatch, 31 kilometres above the Earth, he must have wondered if he was about to make a fatal mistake. On the way up, the gloved hand of his pressure suit had banged against a strut, breaking the airtight seal that would be essential for his survival on the way down.

Kittinger, a veteran of two previous record-breaking parachute jumps, didn't tell anyone. He knew that if the officers on the ground found out, they would cancel his attempt, and he didn't want that. With classic test-pilot bravado, he was determined to grit his teeth and give it a go.

Exposed to the near-vacuum of the stratosphere, around three times as high as the cruising altitude of passenger jets, his hand throbbed with fierce pain as it swelled to twice its normal size. As it turned out, the swelling saved his life: it plugged the sleeve of his pressure suit, sealing it and protecting his body from fatal decompression. Kittinger pushed away from the gondola of his balloon, and in the thin air was soon falling at almost 1000 kilometres per hour. About 5 kilometres above the ground, he opened his main parachute, and 13 minutes and 45 seconds after leaving the gondola he landed safely. Within four hours, the swelling in his hand had subsided.

The year was 1960, the project was called Excelsior, and Kittinger's risky feat set an altitude record for skydiving that is unchallenged to this day.

Not for much longer, though, if a team of space entrepreneurs and extreme sports enthusiasts have their way. They hope to begin a series of dives from the edge of space that will eclipse Kittinger's record. This time, instead of jumping from the gondola of a helium balloon they will be bailing out from the nose-cone of a rocket, one of several being developed to carry passengers into space for a few minutes of weightlessness and a spectacular view of the Earth.

It sounds like a simple daredevil stunt, but there is more to it than that. These pioneers and the safety experts and engineers backing them up will be testing and refining the pressure suits, parachutes and life-support gear that will be needed if commercial space travel is ever to become routine. This equipment could one day save the lives of space travellers faced with an emergency that prevents a normal return to Earth. In short, they will be developing the lifeboats of the space age. "There are reasons to pay serious attention," says Laurence Young, a specialist in astronautics at the Massachusetts Institute of Technology. The planned space dives, he adds, could be helpful in developing future survival systems.

Thrill-seekers

Space travel is a risky pursuit. While roughly 460 people have so far left Earth, 22 have died either in flight or during tests - about a 5 per cent fatality rate. One of those was astronaut Laurel Clark, who died during the catastrophic re-entry of the shuttle Columbia in 2003. Her husband, Jonathan Clark, a former NASA surgeon and military high-altitude parachutist, is now spending much of his time developing the equipment and techniques that may save future travellers from a similar fate. "It's almost a passion for me," says Clark, who has a day job at the Space Biomedical Research Institute at Baylor College of Medicine in Houston, Texas. "I see this as trying to develop a means to provide options for folks who are in these risky environments."

Developing space diving as a sport for thrill-seekers is the first step on this road. Extreme sport has a track record for paving the way for safety measures that later become commonplace. Generations of racing drivers, for example, have pioneered technologies that we now take for granted, including the first seat belts in cars.

Now at least half a dozen companies are spending millions of dollars developing new kinds of rockets to carry paying passengers into space (New Scientist, 8 September, p 55). Some of these companies see space diving as a source of revenue for the embryonic space-tourism industry. As space promoter Rick Tumlinson points out, people are unlikely to want more than one trip aboard a rocket ship. By contrast, extreme-sports enthusiasts - the kind of people who get hooked on adrenalin - will keep coming back for more.

This year, together with Clark and a few others, Tumlinson created the company Space Diver to develop and promote the sport. Before that, he founded Orbital Outfitters, based in Los Angeles, California, a company that aims to design, manufacture and lease spacesuits to be worn by future space enthusiasts. All told, it is an unprecedented effort to get space diving off the ground.

The team is developing what at first sight seems like a pretty wacky way to launch a diver into space. Armadillo Aerospace of Mesquite, Texas, has been developing a vertical take-off, vertical-landing spacecraft for the tourist trade, and the Space Diver team thinks the craft could offer the perfect jumping-off point for space diving. At the top of its vertical flight path, the stubby, cone-shaped rocket will coast to a standstill before falling back to Earth. The plan is to build a platform on top of the rocket on which a spacesuited passenger will be able to ride into space, in the rocket equivalent of a sporty convertible.

At the apex of the flight, the passenger would simply push away from the craft - perhaps by triggering an airbag or spring-loaded seat, or by shooting a small parachute out to one side. The crucial thing is to whisk the diver away from the spacecraft as fast as possible, so as to avoid a collision.

Then it's up to the spacesuit, life-support systems and parachute to make sure the space diver gets safely back to the ground. Clark says that the initial descent should go as fast as possible, to minimise the amount of time the diver has to contend with the frigid temperatures and near-vacuum at high altitude. After parting company with the rocket, the space diver will at first feel an eerie stillness, as Kittinger did during his jump. Above 30 kilometres, the air is so thin that there will be no sensation of movement at all, no rushing of air or feeling of pressure, and the ground below will be so far away that there will be no impression of falling.

Gradually, as the air gets denser, pressure against the diver's body will increase, building up to a massive deceleration. One problem still being worked out is how to prevent divers from going into a spin, which could leave them unconscious, as it did on some of the early high-altitude balloon jumps. This could by done by equipping the suit with stabilising fins or cold-gas attitude-control jets, or deploying a drogue chute. A simple adjustment of the diver's posture might even do the trick, as it does for regular skydivers. The team is still debating whether a head-first posture or the classic horizontal spreadeagled position is likely to work best. Once within a kilometre or two of the ground, the main parachute will deploy automatically and the diver will float gently to Earth.

In a tribute to the record-breaking 1960 venture, the rocket used for the first space dives will be called Excelsior 2. "It's in honour of Joe Kittinger," Tumlinson says. The original Excelsior programme took place before anyone had ridden a rocket into space, and testing the ability of humans to survive in space was one of its primary motivations. "We're picking up where Kittinger left off. He was all about safety," he adds. "This is not a stunt for stunt's sake."

What's more, Armadillo's craft will be commanded from the ground, so after the diver has ejected it will return to Earth uncrewed. "Since there is no driver, there is 50 per cent less risk to human life," Tumlinson points out.

By early next year, Space Diver aims to begin low-altitude tests. First, the team will drop dummies from the rocket to make sure the ejection system works as planned. Next, tests will begin with people, who will make the first-ever jumps from a rocket, starting at a modest altitude of about 3 kilometres. These early tests will be the crucial proof of concept. "We need to show that we can leave the vehicle safely," Tumlinson says. "Everything else has already been done in the 60s."

Or maybe not quite everything. Spacesuit design has come a long way since then and so have parachutes. The group will work with engineers from NASA's Jet Propulsion Laboratory in Pasadena, California, drawing on the lab's experience in developing parachutes for Mars landers, which are the closest thing so far to chutes designed to work in the thin atmosphere space divers will encounter. If the sport becomes popular, it will, in turn, build up a substantial body of experience that could help the designers of future Mars missions.

The spacesuits are already under development. Suits being made for low-altitude tourist space flights will serve the same function as the orange pressure suits that shuttle astronauts have worn since the 1986 Challenger disaster. These are designed to protect the wearer in case of a loss of pressurisation in the cabin or if the crew are forced to eject. Later versions, designed for space diving, will be more like those that shuttle astronauts wear for space walks, which will allow more freedom of movement as well as providing life support on the way down.

In the vacuum of space or the near-vacuum of high altitude, a person's blood literally boils, so maintaining pressurisation is vital. Temperature control also poses particularly tough problems in a space dive. As air friction builds up, the outside of the suit could heat up considerably. Then, as the diver slows, the frigid air of the upper atmosphere will cool it to around -40 C.

A temperature-control system that uses liquid circulating through the suit will be needed to keep the diver comfortable through both phases. Ultimately, Clark hopes to develop systems that will protect people from just about anything that could go wrong in space. "I'm trying to take the whole mission profile and look at all the different what-ifs," he says. "We'll take a crew-survival approach and go through every phase of it."

Space lifeboats

If everything works as planned, paying customers might be able to start diving from space as early as 2009, Tumlinson says. By then the team hopes to break Kittinger's record with a jump from 37 kilometres, and from there the plan is to build up to 91 kilometres, which would be the first jump from space.

Ultimately, Tumlinson aims to develop systems that would allow astronauts to bail out of orbiting craft and return safely to Earth. The International Space Station, for example, orbits at an altitude of between 320 and 350 kilometres, but the altitude itself is not the problem: any system that could return people from the edge of space should also work for stationary jumps from higher altitudes. The real challenge is dissipating the energy released on re-entry into the atmosphere as the diver slows from an orbital velocity of tens of thousands of kilometres an hour.

Various concepts have been discussed over the years, including small inflatable "lifeboats" that astronauts could climb into for the return to Earth. "The big issue is to distribute the heat loading over a wide enough area so that the heat could be dissipated even by something inflatable," Tumlinson says. Another requirement is that, as with the shuttlecock shape of Burt Rutan's SpaceShipOne, the craft automatically orients itself to the airstream. "No action would be required by the passenger, even if you have an unconscious person," says Tumlinson. "It could be a kind of orbital ambulance."

Tumlinson looks forward to a time when all inhabited space structures, from the International Space Station to Bigelow Aerospace's planned commercial space stations and any others that may come along, will be equipped with enough lifeboats to accommodate everyone on board. Such developments might begin by 2012, he says.

In the meantime, the focus is on developing the space diving systems. "It will be an interesting challenge," Tumlinson says. "But it's going to be fun." Nobody is saying yet who will make the experimental jumps, though the first high-altitude runs will most likely be carried out by members of the team who designed the systems.

Would Clark like to be the first one? "Oh yeah," he insists. "I've done high-altitude parachuting. I'm willing to put myself at that risk as well. I don't know if I'll do the high-high jumps, but I'll certainly be involved in the early tests." To most of us it might seem foolhardy, but Kittinger would understand.

From issue 2626 of New Scientist magazine, 18 October 2007, page 46-49