Falling.(skydiving)

Somewhere around sixty-three thousand feet above the earth, our body fluids begin to boil. They do this not because the temperature is so high but because the atmosphere is so thin. Water, kept liquid by air pressure on earth, turns to gas as the pressure drops, bubbling noticeably on the tip of the tongue. Physiologists call this altitude Armstrong's Line, after the Army Air Corps doctor who defined it, in the nineteen-thirties, and it may be the greatest barrier to our survival in space. But there are plenty of others.

Above ten thousand feet, pilots without air tanks begin to suffer hypoxia: their brains get so little oxygen that they start to speak gibberish and make foolish errors. At forty thousand feet, temperatures can drop below negative sixty-five degrees Fahrenheit. At fifty thousand feet, any gases trapped in the body expand to more than eight times their volume at sea level, swelling intestines, rupturing lung tissue, and distending the abdomen until it hinders breathing. In 1959, when a Marine lieutenant colonel named William Rankin bailed out of his fighter jet at fifty thousand feet, he barely survived the fall, bleeding from every orifice. Had he stayed at that altitude without an oxygen mask, he would have blacked out within ten seconds and suffered brain damage within minutes.

Michel Fournier has fallen from thirty-nine thousand feet--he holds the French record for high-altitude skydiving--but he longs to go much higher. His record jump was just a warmup, he says, for what he calls le Grand Saut, the Great Leap: the highest, longest, and fastest jump ever attempted. Later this summer, weather and equipment permitting, Fournier will don a pressure suit, climb into a space capsule attached to a vast helium balloon, and rise twenty-five miles above the plains of Saskatchewan--more than twice the height of Armstrong's Line. Then he'll jump out.

"The dream is to come back from space on foot," Fournier told me one afternoon this spring. We were standing on a ridge overlooking his house in the village of Bendejun, in the hill country north of Nice. In the middle distance, the medieval fortified town of Coaraze stood watch over olive groves, goat trails, and gnarled forests of laurel and pine. Above us, the sky was pale blue and cloudless, and seemed to hold no menace. "Isn't it marvellous?" Fournier said, throwing his arms wide. "What Olympian calm! C'est le paradis terrestre!" He turned to me and grinned. "I could have landed in a worse spot," he said.

Fournier is a retired colonel in the French Army. He has made more than eight thousand jumps in his career, but he looks less like a paratrooper, these days, than like un petit fonctionnaire: big ears and bulbous nose, square jaw and silvery hair. As he talks, he hunches his shoulders, flutters his hands, blows out his cheeks, and bobs his head--the full arsenal of Gallic mannerisms. One moment, he'll cry out in high delight--"Hoo-hoo!"--eyebrows peaked like accents circonflexes. Then, suddenly, his lips clamp shut and his eyes glint, like a toad that has swallowed a dragonfly. "This is a world of brutes, of war," he told me. "Look at what is happening in Darfur, in Iraq. Oh la la. But I love life. I like good things--les belles femmes, la bonne bouffe." Skydiving, he said, should bring "nothing but pleasure and happiness." Even if it may kill you.

The gravel path we were on served as Fournier's exercise track. Every morning before dawn, he hiked there from the village below, along a switchback trail through the thorny garigue. Lavender, rosemary, and purple anemone lined the way, releasing their scent as the sun grew hot. In the spring, the mountainside was carpeted in yellow mimosa blossoms--"a magnificent odor," Fournier said, "but not so good for people with allergies." The full circuit ran five or six miles, with stops along the way for yoga, calisthenics, and pistol marksmanship in a nearby quarry. "It concentrates the mind," he said.

Fournier had turned sixty-three that May. His eyes were still good, after a round of laser surgery in 2002, but his eight thousand leaps from unpressurized planes had taken a toll on his hearing. Shirtless, his torso had the burled, knobby look of an old chestnut tree, the skin just starting to loosen over the bunched muscles beneath. I asked him if he wasn't too old to be an astronaut. "Why?" he said, frowning, as if the idea had never occurred to him. "John Glenn was seventy-seven when he went into space." He clenched his fist and shook it in the air. "La bete est solide!" he said. The beast is robust!