High Dive

Shoot Up

Although his company's focus is on descent, Tumlinson can't test his suits or entice paying customers without a vehicle to carry them high enough. He's looking past balloons, which involve an hours-long ascent. (For one thing, he plans to sell a reality-show program to a television network to help fund the venture, and rocket launches are much more exciting than using balloons.) Tumlinson has approached both XCOR and Armadillo Aerospace, another company attempting to create its own manned space-launch system. These young, upstart space-tourist efforts tend to miss the timetables they set for themselves by grand margins, so Tumlinson is casting a wide net.

His longest-standing relationship is with entrepreneur John Carmack, the Texas-based creator of the Doom and Quake videogames who created Armadillo in 2001 to develop a rocket that could carry passengers into suborbital space. Carmack's proposed single-stage system is a simple platform resting on top of two stacked modules, each containing four spherical fuel tanks powered by four engines. Far denser than a balloon, Carmack's rocket–a smaller version of which has so far ascended to only 164 feet–can fly in less-than-ideal weather. That stability, combined with the slow acceleration of his liquid-oxygen and ethanol-powered engine, creates another compelling element of the space-dive experience: an open-air trip to altitude, strapped into the chair with the great outdoors washing over you at 250 miles an hour in the lower atmosphere. "It's like being in a Formula One racecar without a windshield," Carmack says with a smile.

Fall Down

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