24601
27th Jun 2007, 01:03 PM
http://www.popsci.com/popsci/aviationspace/3c082d2daa463110vgnvcm1000004eecbccdrcrd.html
For sport or safety, hurtling to Earth from space without the protective shroud of a heavily engineered space vehicle seems like sheer lunacy—a hellish descent punctuated by intense heat and terminal, well . . . splatter. But believe it or not, the physics actually works out. With a heat-resistant space suit and the right kind of chutes, such a daredevil plunge should indeed be possible. And with the right people involved, it edges into the realm of the probable.
Two veterans of the space industry are working to make the idea real. While the rest of today’s space-bound private enterprises—Richard Branson’s Virgin Galactic, XCOR Aerospace, Jeff Bezos’s Blue Origin—are fixated on getting humans to space, a company called Orbital Outfitters is working on an innovative way of bringing them back, whether it’s done purely as a sport or as an emergency backup plan in case things go awry. Rick Tumlinson, a longtime civilian space booster who founded the Space Frontier Foundation and helped launch the X Prize Foundation, and Jonathan Clark, a former NASA flight surgeon who has a unique understanding of the extremes of spaceflight survival—his wife, astronaut Laurel Clark, perished in the space shuttle Columbia disaster in 2003—have begun to develop the equipment needed to return you from the heavens without a vehicle. And we do mean “you”: If you’re bold enough, Tumlinson hopes you’ll be Orbital Outfitters’s first space diver, pioneering what he calls “the most extreme sport in human history.” Even if you’d never volunteer to test their prototype, you might end up benefiting anyway, because when commercial suborbital flights become commonplace, Clark thinks the suits and chutes he and Tumlinson are developing could function as the first serviceable life jackets of the spacefaring age.
...
Together, the two plan to demonstrate a record-breaking 120,000-foot jump by 2009, and the truly unprecedented 60-mile space dive within two years—an audacious timetable. If all goes well, they’ll reach even higher. “Our ultimate goal,” Tumlinson says, “is to have individual human beings return from orbit alive.” That’s a drop from 150 miles—or more—involving increased heat and near-deadly Gs, essentially turning their divers into human meteorites.
Even that’s survivable, says NASA Jet Propulsion Laboratory engineer Robert Manning, who designs reentry systems for unmanned craft. Given the right protection—including thermal protection, oxygen, an aerodynamic heat shield and a control system—Manning says, a human being could, theoretically, fall to Earth from any height and survive. The question is whether Tumlinson and Clark can turn theory into fact, and whether anybody would be crazy enough to give their thrill ride a try.
...
Adventure-sport space dives will provide a real-world testbed to develop the technology for safety. Through repeated dives, Clark will amass data on how various suits and chutes and humans perform through the whole descent profile. “It’s what the Air Force did in the ’50s and ’60s with test pilots and parachute jumps,” Clark notes. Validate the equipment and then systematically refine it until it’s reliable enough for emergency use.
Adrenaline-junkie space divers, therefore, constitute the project’s test pilots. Even better—they will be paying Tumlinson and Clark for the privilege. Money wasn’t much of a problem for the old Air Force when testing survival gear, but in the nascent civilian space field, it’s in many ways the greatest hurdle. However much commercial operators might want their passengers outfitted with space-diver life jackets, no one has the money to pay for testing. But it may take only one disaster for the FAA to require them.
...
The 120,000-foot dive that Tumlinson and Clark propose for demonstrating their equipment is essentially the same feat as Kittinger’s, and whoever undergoes their initial tests will need no more equipment than he had: an oxygen supply to breathe, a drogue chute to prevent runaway spins, a main chute to land at survivable speeds, and a pressure suit. Exposing the human body to a near vacuum is an ugly business, something Clark can describe in gruesome detail. The same air emboli and nitrogen bubbles—“the bends”—that kill scuba divers can also kill people at high altitude. And if you go anywhere above 63,000 feet without a pressure suit, a worse fate will be yours: The water in your blood turns to gas in the low pressure. People refer to this as blood “boiling.”
...
If all goes well, a jump from 120,000 feet should be relatively peaceful. As the rocket gains altitude and the atmosphere thins, the sensation of speed diminishes to nothing, and during the initial plummet, heat and G-loads are minimal. In fact, you’ll hardly know you’re moving. The drogue chute should keep you stable, you won’t break the sound barrier, and the thicker lower atmosphere will slow you to a 120mph free fall. At 3,000 feet, you can pull your main chute just like a regular skydiver. And if Clark and Tumlinson succeed, the 120,000-foot jump record won’t stand long, because theoretically, jumping from 60 miles shouldn’t be much harder. “If Carmack delivers the vehicle and we deliver working suits on the 120,000-foot jump,” Svitek says, “that’s 90 percent of what you need for the 60-mile suborbital dive.”
The missing 10 percent, though, might mean the difference between living and dying. First, without anything to push off of, there’s no way to turn around in space. Once you’ve separated from the rocket, Svitek notes, “you need to worry about orientation.” He envisions a simple cold-gas jetpack built into the suit, “almost like aerosol cans,” he says.
Then, passing into the upper atmosphere from a greater altitude and at higher speed, several dangers present themselves. This is where Clark’s knowledge comes in. Among the known dangers are heat and G-forces, which arise when air friction slows you from 2,500 mph at the top of the atmosphere to 120 mph in the thicker lower air. The Gs are a sustained but manageable 4.4. The heat is a bit trickier. Temperatures of 464°F will broil a roast, and most space suits aren’t rated to withstand that heat.
The least-understood danger comes from transonic speeds—what happens when you cross the sound barrier. Are there shock waves at such speeds that can injure a person, or send him into an unstoppable spin? No one knows because no one has ever gone that fast outside a vehicle.
...
“I don’t see anything fundamentally wrong with what they’re doing,” he says. “It’s just scary as hell.”
Wow... that's absolutely incredible.
For sport or safety, hurtling to Earth from space without the protective shroud of a heavily engineered space vehicle seems like sheer lunacy—a hellish descent punctuated by intense heat and terminal, well . . . splatter. But believe it or not, the physics actually works out. With a heat-resistant space suit and the right kind of chutes, such a daredevil plunge should indeed be possible. And with the right people involved, it edges into the realm of the probable.
Two veterans of the space industry are working to make the idea real. While the rest of today’s space-bound private enterprises—Richard Branson’s Virgin Galactic, XCOR Aerospace, Jeff Bezos’s Blue Origin—are fixated on getting humans to space, a company called Orbital Outfitters is working on an innovative way of bringing them back, whether it’s done purely as a sport or as an emergency backup plan in case things go awry. Rick Tumlinson, a longtime civilian space booster who founded the Space Frontier Foundation and helped launch the X Prize Foundation, and Jonathan Clark, a former NASA flight surgeon who has a unique understanding of the extremes of spaceflight survival—his wife, astronaut Laurel Clark, perished in the space shuttle Columbia disaster in 2003—have begun to develop the equipment needed to return you from the heavens without a vehicle. And we do mean “you”: If you’re bold enough, Tumlinson hopes you’ll be Orbital Outfitters’s first space diver, pioneering what he calls “the most extreme sport in human history.” Even if you’d never volunteer to test their prototype, you might end up benefiting anyway, because when commercial suborbital flights become commonplace, Clark thinks the suits and chutes he and Tumlinson are developing could function as the first serviceable life jackets of the spacefaring age.
...
Together, the two plan to demonstrate a record-breaking 120,000-foot jump by 2009, and the truly unprecedented 60-mile space dive within two years—an audacious timetable. If all goes well, they’ll reach even higher. “Our ultimate goal,” Tumlinson says, “is to have individual human beings return from orbit alive.” That’s a drop from 150 miles—or more—involving increased heat and near-deadly Gs, essentially turning their divers into human meteorites.
Even that’s survivable, says NASA Jet Propulsion Laboratory engineer Robert Manning, who designs reentry systems for unmanned craft. Given the right protection—including thermal protection, oxygen, an aerodynamic heat shield and a control system—Manning says, a human being could, theoretically, fall to Earth from any height and survive. The question is whether Tumlinson and Clark can turn theory into fact, and whether anybody would be crazy enough to give their thrill ride a try.
...
Adventure-sport space dives will provide a real-world testbed to develop the technology for safety. Through repeated dives, Clark will amass data on how various suits and chutes and humans perform through the whole descent profile. “It’s what the Air Force did in the ’50s and ’60s with test pilots and parachute jumps,” Clark notes. Validate the equipment and then systematically refine it until it’s reliable enough for emergency use.
Adrenaline-junkie space divers, therefore, constitute the project’s test pilots. Even better—they will be paying Tumlinson and Clark for the privilege. Money wasn’t much of a problem for the old Air Force when testing survival gear, but in the nascent civilian space field, it’s in many ways the greatest hurdle. However much commercial operators might want their passengers outfitted with space-diver life jackets, no one has the money to pay for testing. But it may take only one disaster for the FAA to require them.
...
The 120,000-foot dive that Tumlinson and Clark propose for demonstrating their equipment is essentially the same feat as Kittinger’s, and whoever undergoes their initial tests will need no more equipment than he had: an oxygen supply to breathe, a drogue chute to prevent runaway spins, a main chute to land at survivable speeds, and a pressure suit. Exposing the human body to a near vacuum is an ugly business, something Clark can describe in gruesome detail. The same air emboli and nitrogen bubbles—“the bends”—that kill scuba divers can also kill people at high altitude. And if you go anywhere above 63,000 feet without a pressure suit, a worse fate will be yours: The water in your blood turns to gas in the low pressure. People refer to this as blood “boiling.”
...
If all goes well, a jump from 120,000 feet should be relatively peaceful. As the rocket gains altitude and the atmosphere thins, the sensation of speed diminishes to nothing, and during the initial plummet, heat and G-loads are minimal. In fact, you’ll hardly know you’re moving. The drogue chute should keep you stable, you won’t break the sound barrier, and the thicker lower atmosphere will slow you to a 120mph free fall. At 3,000 feet, you can pull your main chute just like a regular skydiver. And if Clark and Tumlinson succeed, the 120,000-foot jump record won’t stand long, because theoretically, jumping from 60 miles shouldn’t be much harder. “If Carmack delivers the vehicle and we deliver working suits on the 120,000-foot jump,” Svitek says, “that’s 90 percent of what you need for the 60-mile suborbital dive.”
The missing 10 percent, though, might mean the difference between living and dying. First, without anything to push off of, there’s no way to turn around in space. Once you’ve separated from the rocket, Svitek notes, “you need to worry about orientation.” He envisions a simple cold-gas jetpack built into the suit, “almost like aerosol cans,” he says.
Then, passing into the upper atmosphere from a greater altitude and at higher speed, several dangers present themselves. This is where Clark’s knowledge comes in. Among the known dangers are heat and G-forces, which arise when air friction slows you from 2,500 mph at the top of the atmosphere to 120 mph in the thicker lower air. The Gs are a sustained but manageable 4.4. The heat is a bit trickier. Temperatures of 464°F will broil a roast, and most space suits aren’t rated to withstand that heat.
The least-understood danger comes from transonic speeds—what happens when you cross the sound barrier. Are there shock waves at such speeds that can injure a person, or send him into an unstoppable spin? No one knows because no one has ever gone that fast outside a vehicle.
...
“I don’t see anything fundamentally wrong with what they’re doing,” he says. “It’s just scary as hell.”
Wow... that's absolutely incredible.