(FORTUNE Magazine) – In the information economy, with the routine perils of the Machine Age mostly fading memories, it may seem as though the greatest physical danger most people face on the job is carpal tunnel syndrome. But even now there are those for whom going to work every day involves grave personal risk. They are not the racecar drivers, bridge builders, or smokejumpers, whose professions require physical daring. Rather they are "knowledge workers" for whom risk is a means to an end. The end is what gives them the courage to continue--the courage to chase the cure for a deadly new virus, or to be the first to fly a new aircraft, or to stare down the crater of an active volcano, all in the name of science. The people who do these jobs are brave, yes, but without bravura. "My wife would be furious if I got myself killed," says volcanologist Stan Williams. "But she's confident I'm trying hard to be careful. And she knows what I'm doing is important." In the pages that follow, photographer Jose Azel profiles tough-minded professionals with the courage to pursue their convictions.

PHIL NUYTTEN, 55 Founder Hard Suits

By the time Phil Nuytten was 31, his deep-sea-diving business had made him a millionaire. But Nuytten had also lost nearly half his diving buddies--many of them dying from ailments like the bends, caused by intense undersea pressures. Nuytten himself had suffered partial hearing loss. He grew determined to create a diving apparatus that would give divers the dexterity of undersea acrobats yet protect them from the weight of the ocean above. Such a suit had been imagined for 300 years, but all previous attempts had been virtually worthless below 100 feet. Nuytten, whose formal education ended at high school, and a team of engineers and metallurgists spent eight years on the problem. They invented a rotary joint that uses fluid as a bearing and is impervious to pressure. In 1986, Nuytten and his staff test-piloted the first "Newtsuit," taking it down 1,000 feet. Nuytten is now developing a lighter, cheaper version he hopes will give more people access to the seas.

STAN WILLIAMS, 44 Volcanologist Arizona State University

"Most geologists are like pathologists--they study rocks that are millions of years old," says Stan Williams, a geology professor at Arizona State University. "But volcanologists are like emergency-room doctors. The patient is in really bad trouble, and you intervene, and maybe you save some lives." The patient doesn't always cooperate. Three years ago Williams and 90 other scientists working as part of a U.N. program had gathered to study Galeras, a restless volcano in the Colombian Andes. Williams led a group to the summit. After taking samples from the crater, seven scientists relaxed, answering questions from a tourist and his two sons who had also scaled the volcano. Suddenly the peak began to tremble. "Ten seconds later everyone was dead," Williams says flatly. "Except me." It took emergency brain surgery and 16 operations to put Williams back together. But within a year he was back on active volcanos and this July returned to the summit of Galeras.

BURT RUTAN, 53 President Rutan Aircraft Factory

In the winter of 1975, a Dodge Dart could be seen racing back and forth across the Mojave Desert, a young man with long hair and muttonchop sideburns clinging to the wheel. Attached to the roof of the car was what looked like a surfboard with wings. Indeed, the driver, Burt Rutan, looked more like a surfer than an aeronautical engineer. The strange contraption was the VariEze (pronounced "very easy"), a prototype airplane with a propeller in the rear and a tail up front where the prop should be. The whole thing was held up by three spindly legs with doughnut-size wheels. The Dart was a low-budget wind-tunnel for the fiberglass-covered, plastic-foam airplane. When it came time for the VariEze's maiden flight, there was no question of who'd take the controls. "When you put four years and all your income into a dream," Rutan says, "there's absolutely no thought of not doing it yourself." At sunrise in the desert, Rutan took a breath, gunned the engine, and the VariEze was aloft. The plane proved to be a hit among airplane enthusiasts, who built it themselves, and led to other Rutan creations, including Voyager, the first aircraft to circle the globe nonstop without refueling. Next is the Boomerang, an asymmetrical craft with an engine on one wing and another in the nose. Says Rutan: "I'm going to take the first flight."

JAMES NACHTWEY, 48 Photojournalist

Robert Capa, the famous combat photographer, said that if a picture wasn't good enough, the photographer wasn't close enough. James Nachtwey embodies that credo. "Many times I have been as close as you can get--where people around me are getting killed," he says. "But it has to be. I want the visual perspective to be as though you were there, sharing the same space--the same emotions--as the subject." In 1981, a few years after college, Nachtwey went to Belfast to cover street fighting, without an assignment. His photographs wound up in Newsweek. He hasn't stopped since, covering conflicts ranging from Nicaragua to Lebanon, Afghanistan, Bosnia, and Chechnya. In the process he has won many awards, taken shrapnel under one eye, and seen colleagues killed. But he keeps at it, for Time now. "When someone's pictures are published in the mass media, they're seen by the people who make the decisions," he says. "They realize there's a groundswell of outrage building, and something's got to be done."

MARK C. LEE, 44 Astronaut NASA

Mark C. Lee remembers seeing Alan Shepard's Mercury space launch in 1961 from the one-room school he attended in rural Wisconsin. "Some of those kids had rarely seen a TV picture before," he says. Now an astronaut who's logged nine million miles around the Earth in three space shuttle flights and spent seven hours floating outside the shuttle, he lives with a danger that's otherworldly. "Most of the time it's like a dream," he says. "You and the shuttle are going 17,000 miles an hour, and you look at the shuttle, and it looks almost like a picture painted against the blackness. And then you look down at the Earth between your feet, and you realize that you're going around the world." The idea that the 1986 Challenger disaster could be repeated isn't far from his mind. "There are a hundred different things that could happen," Lee says. But he'll go up again, helping to work on the Hubble Telescope.

MERLIN D. TUTTLE, 55 Founder Bat Conservation International

Merlin D. Tuttle has been fascinated by bats since childhood, when he saw thousands of them streaming from caves near his home in Tennessee. He wrote his doctoral thesis on the migratory habits of gray bats. In 1982 he founded Bat Conservation International to protect endangered bat species. Few thought that bats had a chance of winning the PR battle, but soon articles explaining that bats ate harmful insects without hurting man began appearing nationwide, from National Geographic to the New Yorker. Tuttle next took his crusade abroad, where he set about photographing hundreds of bat species in their natural environments. These environments have other creatures: cannibal tribes in the Venezuelan jungles, gun-toting truckers who shot at Tuttle in Peru, and one very ornery cobra in Thailand. Yet more proof that bats are among the least dangerous creatures that hang around in caves.

PETER JAHRLING, 50 Virologist U.S. Army Medical Research Institute of Infectious Diseases

Most people would shrink from taking blood from rats, snakes, or humans infected with a lethal virus. But when Peter Jahrling did just that as a medical student at Cornell University, which was field-testing a vaccine against Venezuelan encephalitis, he found he liked being on the raw edge of an active epidemic. "We had whole populations in harm's way," he says. "If we could figure out where the virus was heading--and get ahead of it--we could save some lives." Later he became the sole researcher studying a killer West African virus named Lassa--he had lassa vanity plates--and eventually found a treatment. His renown was such that when monkeys began dying at a quarantine facility in Reston, Virginia, he was asked to diagnose tissue samples. In a story chronicled in the best-seller The Hot Zone, he and colleagues feared as the work progressed that the monkeys had the deadly virus Ebola Zaire, which could spread to man, causing a health catastrophe in the U.S. The Ebola virus is legendary for the grisly way it takes its victims. In the end, Jahrling's team was able to reassure the world: The monkey-killing virus was not a man killer after all but a new strain dubbed Ebola Reston.

SCOTT YENZER, 40 Founder Haverfield Corp.

In 1983, Scott Yenzer had a helicopter flying service, patrolling power lines in Florida. He also had a crazy idea: If a bird could land on a power line without blowing up, why couldn't he? At the time, power companies had to either shut off the current or dispatch workers in insulated cherry pickers to repair big transmission lines. If repairs could be made from a helicopter, inaccessible lines would be easy to maintain. But could you pack 500,000 volts into a chopper without blowing up the gas tanks? Without frying the aircraft's electrical system? Or the pilot? One morning Yenzer flew out to a big line. He braced himself as the chopper approached the wire. Ppffsszzt. An arc of electricity leaped from Yenzer's helmet microphone into his lip. Another struck his leg. Another bit into his ear. But the chopper had not exploded. "I thought, If this is as bad as it gets, it's okay," he says. "I can work it out." Yenzer has since evolved methods of maintaining power lines safely from the air and does so for more than 100 utilities.

REPORTER ASSOCIATE Eryn Brown