On this sandy, desolate point of land, where alligators cruise through vine-tangled bayous while America's super technology probes the heavens, the spaceship Columbia glimmers eerily in the early-morning light and awaits two men.

In the past, on uncertain first flights into the unknown like this one, the spacecraft would have been waiting for the more expendable cargo of chimpanzees or computers.

But not this time. In the pre-dawn hours Friday, John W. Young and Robert L. Crippen are to climb aboard the flying gas tank of the Columbia. They will sit atop 3.7 million pounds of fuel -- enough, in the unlikely event of an explosion, to sear the bleak landscape for a mile in all directions.

Then, in effect, someone will light the match that will launch America into a new space era.

The astronauts are jet jockeys, test pilots trained to use barrel rolls and power dives to push new flying machinery to its limits. They see themselves as rugged individualists made, as Tom Wolfe wrote, of The Right Stuff. To follow chimps or silicon-stuffed sensors is, well, demeaning.

They joke about the risks, the way men made of The Right Stuff think they should.

One Apollo astronaut's answer to the danger question is legend: "How would you feel," he bantered, "if you were sitting atop 50,000 parts, all of which were built by the lowest bidder?"

Young, the drawing, unexpressive commander of Columbia, gives it the same macho nonchalance.

"NASA always makes it right," Young said a month ago, pausing for effect before adding: "Eventually."

There is no eventually on this flight. The decision to fly the first shuttle with men was made almost seven years ago during a mix of budget crunches and a growing confidence that the unknowns in space had been narrowed to acceptable limits.

The astronauts and their space-agency bosses are painfully aware of the money problems, especially at a time when only the "truly needy" are winning the battle for federal bucks. It's cheaper to fly with men, reducing the number of test flights and reducing the number of exotic machines.

"It's the right way to go," Young said. "It would cost a tremendous amount of money and slip the program many, many months to go unmanned on the first flight, and it really wouldn't be as safe."

Back in the early days, of course, the unknowns were much greater. It wasn't known whether man could live in space, whether he could survive reentry, how he would react to weightlessness.

There never was any question about the danger in such an alien environment, where all those 50,000 low-bid parts have to interact perfectly, but the deadly problems seem to come up at random, and not just on maiden flights.

America lost its only astronauts in a flash fire in their capsule during a ground test here. The most life-threatening experience in space came on the third flight to the moon, and, having men aboard may have saved it after a liquid oxygen tank blew up inside the spacecraft.

On the 54-hour flight of the Columbia, Young and Crippen will have little to do with the flying of the craft. But it is possible that men could save the Columbia where computers couldn't.

In orbit, for example, the Columbia's huge cargo doors will be open to help cool the ship. On reentry, when the searing friction of Earth's atmosphere raises temperatures as high as 2,750 degrees Fahrenheit, the doors have to be closed. If the computers fail then, one of the astronauts could leave the ship for a space walk in an attempt to jimmy the doors shut.

Space agency officials also contend that, while risk is inherent in putting men into space, the Columbia has been tested more thoroughly than any machine America has launched yet: almost 4,000 separate ground tests and 9,000 computer analyses that say the mission will succeed.

The shuttle has been test-flown high above the Mojave, and pilots have taken it in for its ticklish high-speed desert landing. The boosters and engines have been ignited and they worked.

Still, it is all so revolutionary and so psychologically important to the future of man's reach for the heavens that no one here is taking success for granted.

Crippen, who never has been in space, was asked recently if Young, who is going out for the fifth time, ever reassured him about the safety.

"Uh, no," the rookie astronaut fumbled.

"Actually, he reassures me," cut in Young, the veteran, and everyone laughed.