(CNN) -- The first seven U.S. astronauts were hailed as heroes two years before any of them had ventured beyond Earth's comforting blue atmosphere.

Introduced to the public on April 9, 1959, the "Mercury seven" were considered so important to the U.S. Cold War effort that when John Glenn returned from his historic flight, President John F. Kennedy ordered NASA not to send him aloft again.

The fear was that an untimely accident might deprive the country of a symbol of American know-how, courage and might, and perhaps demoralize other Cold Warriors.

"It's interesting how at odds we were then with the Soviet Union," recalls Patty Carpenter, wife of Scott Carpenter.

The seven Mercury astronauts -- Carpenter, Cooper, Glenn, Grissom, Schirra, Shepard and Slayton -- were chosen from an original pool of 508 military men that was winnowed to 18 finalists.

The final seven were selected on the basis of endurance tests, rigorous physicals and extensive psychiatric studies, and after they were subjected to hellish vibration, acceleration, heat and noise tests to ensure that they could, indeed, handle space flight.

Their images were buffed to a high luster by Tom Wolfe in his book "The Right Stuff" -- and by the film that followed -- which depicted them as bright, brave and spirited men who were not above a little gratuitous mischief.

Alan Shepard recalled in an interview with the Houston Chronicle a few years ago that the astronauts used to race their cars on the runway at Cape Canaveral, and that one night the others made some mechanical adjustments to his Corvette so they could beat him.

Now in their 70s, the Mercury seven are four. Virgil "Gus" Grissom died in the fire that swept through an Apollo capsule on the launch pad at the Kennedy Space Center in 1967, and Donald "Deke" Slayton died five years ago of complications from a brain tumor. Alan Shepard died July 21, 1998 at a community hospital in California. He was 74.

The others moved on from NASA to other endeavors and only Gordon Cooper, at 71 the youngest, claims not to be retired or partially so.

What is most notable is that almost 40 years after they were brought together through a highly competitive and unsentimental process, the four see each other two or three times a year and are touchingly fond of each other.

	Five of the orginal Mercury seven pose in front of a Mercury capsule mock-up on May 5, 1986 at a formal dinner honoring Shepard's May 5, 1961 flight. From left: Carpenter, Cooper, Shepard, Slayton, and Schirra.

"We're kind of like a bunch of brothers," says Cooper. "We're quite close."

"Right on," says Carpenter. "I always thought of us as 'All for one, one for all,' like the Three Musketeers. There's an abiding camaraderie that pleases everybody. It's the life of the group."

Wally Schirra, too, mentions the camaraderie, but hastens to add that there was -- and still is -- "always that sibling rivalry."

Sibling, of course, implies family. And while the competitive fires still burn, it is a familiar and friendly burn. It is the currency, the medium, by which these men of the John Wayne generation communicate. They may not ever say so, but there is a feeling that they are bound not just by respect, accomplishment and history, but also by deep affection.

"They're all very competitive," says Patty Carpenter, "but I've never heard any of them say anything bad about another."

While Glenn readied himself this summer for the return to space he never gave up on, Schirra went on a fishing trip to Alaska, Cooper made plans to market a new cargo plane to Third World countries and Carpenter worked on his third novel.

Collectively, they jog, walk, hike, sail, play tennis, ski, ride horses, fly anything they can get their hands on and play golf. They know, however, that they are facing their mortality, and no matter how heroic their efforts, it is the one Corvette they cannot cheat.

"We're all facing the Grim Reaper," says Carpenter, explaining at once their anxiety and their vigor. "It's like John Denver put it in one of his songs -- 'Live, live without care.'"