Mary Roach - Packing for Mars

But the Columbia astronauts faced crueler threats than windblast and thermal burns. “We had some very unusual injury patterns that were not explainable by anything that we are accustomed to,” Clark said. By “we,” he meant flight surgeons: people accustomed to brains spun off their stems and limbs snapped by windblast.

“We know how people break apart,” Clark continued. “They break on joint lines.” Like chicken. Like anyone with bones. “But this wasn’t like that. It was like they were severed, but it wasn’t from some structure cutting them up.” He spoke in a flat, quiet manner that reminded me of Agent Mulder from The X-Files . “And it couldn’t have been a blast injury, because you have to have an atmosphere to propagate a blast.”

I was looking at the Columbia patch. The seven crew members’ last names were stitched around the perimeter: MCCOOL RAMON ANDERSON HUSBAND BROWN CLARK CHAWLA. Clark. Something clicked in my head. When I had first arrived on Devon Island, I’d heard that the spouse of one of the Columbia astronauts would be here. Laurel Clark was Jon Clark’s wife, I now realized. I didn’t know whether to say something, or what that something would or should be. The moment passed, and Clark kept talking.

The atmosphere at 40 miles up is too thin for blast waves, but not for shock waves. The investigation team concluded, mostly through a process of elimination, that that’s what killed the Columbia astronauts. Clark explained that in breakups at speeds greater than Mach 5—five times the speed of sound, or about 3,400 miles per hour—an obscure shock-wave phenomenon called shock-shock interaction comes into play. When a reentering spacecraft breaks apart, hundreds of pieces—none with the carefully planned aerodynamics of the intact craft—are flying at hypersonic speeds, creating a chaotic web of shock waves. Clark likened them to the bow waves behind a water-skier’s boat. At the nodes of these shock waves—the places where they intersect—the forces add together with savage, otherworldly intensity.

“It basically fragmented them,” Clark said. “But not everyone. It was very location-specific. We had things that were recovered completely intact.” He said one of the searchers who combed the Columbia’s 400-mile debris path in Texas found a tonometer, a device that measures intraocular pressure. “It worked.”

The wind outside the medical tent had picked up. The turbine made a tortured sound. It was a strange evening. We sat side by side, staring at the slides on Clark’s laptop, him narrating and me listening. Occasionally I’d interrupt with a question, but not the ones on my mind. I wanted to ask him how he had coped with learning the details of his wife’s death. I wondered why he had chosen to join the investigation. It seemed insensitive to ask. I imagine he got involved for the same reason he’s involved in the Red Bull Stratos Mission. He wants to learn everything he can about the things that happen to human bodies when the vehicle in which they are traveling breaks apart at high altitudes and crazy speeds. He wants to apply what he learns to design technologies that can be put in place to protect those bodies, to keep astronauts and space tourists alive, to keep families intact.

It is an extremely complicated challenge. Any spacecraft escape system works for a limited range of altitude and speed. Ejection seats, for instance, will work for the first eight to ten seconds of launch, before Q force—as the interplay of air density and speed-generated wind force is known—builds to a lethal level. An ejection system needs to quickly blast the astronauts far enough away from the craft to keep them from smashing into its appendages or getting caught in the fireball of a catastrophic explosion. The most recent Space Shuttle escape system employed a long pole that crew members would hook onto to slide out away from the craft and clear its wing. Retired aerospace engineer and space historian Terry Sunday points out that this would only work well if the shuttle were flying in stable, straight-and-level flight. “And in that case,” says Sunday, “why would you want to leave it?”

To survive the extreme speed and heat of reentry is yet more problematic. The Russian space agency has tested prototypes of an inflatable crew escape pod called a ballute (an amalgam of balloon and parachute ). Heat shielding on the broad forward face of the pod protects the terrified occupant, and the large surface area creates the drag needed to slow the pod to a speed where a multistage parachute system could, if all goes well, lower it safely to Earth. It has never flown all the way from space to the ground. Alternatively, a parachute system could lower an entire capsule or crew cabin to the ground. (Current plans call for NASA’s new Orion capsule to be used initially as an ISS escape pod.) The chute would be heavy and costly to launch—and in the case of the Space Shuttle, the process of separating the crew compartment from the rest of the craft presented serious technical challenges. Also, the parachute would need its own heat shielding to keep it from melting during reentry, and this would make deployment trickier.

What about airplane passengers? Is there a way to bail out safely from a jet that’s about to crash? Why, other than the weight and expense, don’t airlines outfit every seat with a portable oxygen supply and a seat-back parachute? Many reasons. Time for a short primer on windblast and hypoxia.

AT THE HALFWAY POINT of the Beaufort Wind Force Scale, air is traveling 25 to 31 miles per hour. “Umbrella use becomes difficult,” states the Beaufort, a tad overdramatically. The scale tops out at 73 to 190 miles per hour—hurricane-force wind. That is all the blow nature can muster. Where the Beaufort leaves off is where windblast studies begin. Windblast isn’t weather. The air isn’t rushing into you; you are rushing into it—having bailed out or ejected from an imperiled craft.

At the speed of a typical private plane—135 to 180 miles per hour—the effects of windblast are mainly cosmetic. The cheeks are pressed flat against the skull, bestowing a taut, over-face-lifted appearance. I know this both from hideous photographs of me in the SkyVenture wind tunnel and from a 1949 Aviation Medicine paper on the effects of high-velocity windblast. In the latter, a man identified as J.L., handsome at 0 miles per hour, appears in a 275-miles-per-hour windblast with his lips blown agape, gums in full view like an agitated, braying camel.

At 350 miles per hour, the cartilage of the nose deforms and the skin of the face starts to flutter. “The waves begin at the corners of the mouth…and progress across the face at the rate of about 300 per second to the ear, where they break, causing the ear to wave.” Umbrella use is out of the question. At faster speeds this Q force causes deformations that can, as the Aviation Medicine paper gingerly phrases it, “exceed the strength of tissue.”

Cruising speed for a transcontinental passenger jet is between 500 and 600 miles per hour. Do not bail out. “Fatality,” to quote Dan Fulgham, “is pretty much indicated.” A windblast of 250 miles per hour will blow an oxygen mask off your face. At 400 miles per hour, windblast will remove a helmet—as it did to Bill Weaver’s SR-71 copilot. His visor was blown open and acted like a sail, snapping his head back against the neck ring of his suit and breaking his neck. At 500 miles per hour, “ram air” blasts down your windpipe with enough force to rupture various elements of your pulmonary system. An unnamed test pilot mentioned in a paper by John Paul Stapp ejected at more than 600 miles per hour. The windblast pried open his epiglottis and inflated his stomach like a pool toy. (This worked to his advantage, as he had ejected over water. “The estimated three liters of air in the stomach substituted as flotation gear, which he was in no condition to inflate,” wrote Stapp.)