As companies work toward rocketing paying passengers into space and back on commercial spaceships, one firm plans on doing it with a twist.
Instead of riding the ship back down to Earth, passengers will jump off it, hurtling through the atmosphere at supersonic speeds until their parachute deploys and they glide safely down to their home planet.
That's the idea behind Space Diver, a company aiming to develop a spacesuit that can survive jumps from amazingly high altitudes.
Spearheading the effort is Rick Tumlinson, an entrepreneur and longtime advocate of private spaceflight. He was a founding trustee of the Ansari X Prize, which awarded $10 million for sending the first private reusable manned craft into space in 2004.
Tumlinson says the suit's initial purpose will be to outfit the ultimate extreme sport of space diving, with the eventual goal of using the suit as a kind of high-altitude life vest for spacefarers in trouble.
His other company, Orbital Outfitters, designs spacesuits for the crew and passengers of commercial spaceships. In a few months, Orbital Outfitters is set to deliver its first prototype suit to XCOR Aerospace, one of about a dozen firms hoping to start selling tickets for spaceflights within the next few years.
Those suits will be designed for protection in an emergency, complete with full pressurization and oxygen supply, but they are by no means a space-diving suit.
"In one of them, you're sitting comfortably in a vehicle," Tumlinson said. "In the other one, you are the vehicle."
Tumlinson compares the suits that his two sister companies are designing to parachutes. "A parachute is both a safety device and a sporting device," he said. "Advances at either end support the other, and that's the way we're treating this. We're going to be pushing the boundaries of extreme sport, and we're going to be pushing the boundaries of extreme safety."
Also on Tumlinson's team is Jonathan Clark, a former NASA flight surgeon who is now at Baylor Medical College's National Space Biomedical Research Institute. He has a personal interest in exploring how to return from space without a ship — his wife, astronaut Laurel Clark, died in the Columbia tragedy.
Tumlinson admits there are plenty of challenges involved in making space diving a reality. Or as Clark bluntly put it, "There are a number of different things that can kill you."
A space-diving suit must protect the wearer from extremes of temperature and pressure, provide oxygen and of course, have a very sturdy parachute. But Clark points at history to prove that it is within the realm of possibility.
The highest jump ever was made in 1960 by Air Force test pilot Joe Kittinger, who leapt from a balloon at 102,800 feet. The temperature was near 100 degrees below zero, and the pressure was low enough that his blood would have boiled without a pressure suit.
He accelerated past 600 mph before the air got thick enough to slow him to terminal velocity, which is about 120 mph. The history-making plunge took less than 14 minutes.
Tumlinson says participants will start at a low altitude and gradually work their way up. The first test jump would be from 5,000 to 10,000 feet, but it would be the first-ever dive from a rocket platform (think of Apollo missions' lunar landers). Space Diver is hoping to do that by the end of 2008.
From there, an obvious milestone would be Kittinger's record, which many have tried to break over the decades. Although technically 100,000 feet is not high enough to be considered space, the sky is black and you can see the curvature of the Earth.
The higher you go, the bigger the obstacles. If you jumped from 300,000 feet, you would speed up to 2,500 mph. Then you have to start worrying about the heat of re-entering the atmosphere, with temperatures reaching 400 degrees.
For this, Clark cites another Air Force survival story: In 1966, an SR-71 Blackbird crew had to eject at 78,800 feet going faster than Mach 3. The navigator died from a broken neck, but the pilot made it through with only minor bruises.
"He survived because his suit inflated, basically acting like a cocoon air bag," said Clark. "So what we're proposing is, if you made this suit out of thermal- and pressure-resistant material, like Kevlar or Nomex, then the pressure of the suit itself would act like a little exoskeleton, and you could survive a hypersonic re-entry."
But Clark is realistic about the risks involved. "Don't expect that this isn't going to be a real dangerous endeavor. It's going to be a challenge," he said. "We're going to make some mistakes along the way and learn some poignant lessons. But you can't just quit just because you have a problem."
So is all this really possible? Scientists say that technically, it is. Whether it will happen any time remotely soon is another matter. The biggest problem likely won't be the science behind the suit, but paying for it.
"The technology is achievable," said David Klaus, an aerospace engineering professor at the University of Colorado at Boulder who specializes in human spaceflight and spacesuits. "I think that it will be marketing and funding strategies that dictate whether this is successful."
Those sentiments are echoed by John Wozniak, an engineer at the Johns Hopkins University Applied Physics Laboratory. "If you want to put enough money and manpower behind it, I think it could be done," he said. "It's not like you have to invent impossible materials. It's just going to take a lot of engineering development, a lot of testing."
Tumlinson is hoping to acquire funding through sponsorship, and possibly by filming the project for a reality TV show. But even if that happens, it's unclear whether Space Diver is a sustainable business model.
"If you have people who are willing to surf an 80-foot tidal wave, I think you're probably going to have adventure seekers who are going to try to go for the ultimate," said Marco Caceres, a senior analyst with Teal Group, an aerospace consulting firm. "The question is, is that a big enough market to make money?"
There is also the not-so-insignificant matter of the ship that space divers would be jumping from. Tumlinson is hoping to potentially use one from XCOR or Armadillo Aerospace, which is developing a craft that can hover.
And the experts are more skeptical about using a space-diving suit for an emergency bailout from an orbiting space station or craft. That's because the speeds involved would be much greater — on the order of 15,000 mph, which translates into temperatures of thousands of degrees.
"If you're in an orbital environment, I would find it a stretch to think you could actually re-enter without a vehicle," said Klaus. But, he said, it could be possible with some kind of shield as protection from the intense heat.
"If you think about a spacesuit in a certain fashion, it's just a miniature spacecraft. It provides all the same functions," he said. "A spacesuit and a spacecraft, from a functional standpoint, are identical."