The final act came, like a surreal desert mirage, in a place as forbidding and alien as the valleys of the moon.

Fitting, that. The United States successfully brought two men back from the void of space today. The country also placed about 500,000 people, gawkers and groupies, soldiers and scientists, on alien soil -- a feat that many believe is the ultimate point of all this toying in the far beyond.

Never had the Mojave Desert, a barren plain with more ghost towns than real towns, seen anything like this -- an invasion of at least half a million people clambering through the goyote grass of dry river beds, trampling brittle mesquite, for the five-minute finale of the Columbia.

The trumpets of a double sonic boom -- a thunderous crack crack -- signaled first that astronauts John W. Young and Robert L. Crippen were back; then a short contrail streaking the azure sky 50,000 feet high as the Columbia swept east toward Death Valley, and finally the lumbering space craft, dropping like a stone toward a flawless landing on a white, dry lake.

Groupies and generals alike, their hopes and goals different, their glistening eyes the same, watched in almost spellbound silence as the black-and-white spaceship landed. That scene was surreal, too, the mind-bending mirages of the desert creating water in the lake, the way a desert auto driver sees unreal mirrors on the highway ahead.

For a moment it was like the splashdowns of old, then the dust scudded up behind the Columbia. Jerry Brown cheered, generals cheered, Trekkies cheered and Young and Crippen relaxed under the full weight of earth air again.

Young returned from a trip that was, in terms of distance and drama, like a drive to work after a European vacation. His last space adventure had taken him to the Plains of Descartes on the moon, 250,000 miles farther than the voyage of the Columbia. But that only told part of the story.

John F. Kennedy, in telling Americans that the nation was going to the moon, quoted Confucius about a trip of a thousand miles beginning with a single step. In terms of the technology involved in the voyage of the Columbia, Young and Crippen had taken far more than that single step -- or even Neil Armstrong's giant leap for mankind.

One crucial moment today told the story most graphically. As the Columbia jockeyed precisely for the life-and-death positioning of its deorbit burn, only the most sophisticated computers could have handled such complexity.

Young spoke of the 38 thrusters aboard "that racial," the Columbia, all pointing in different directions, all firing simultaneously. "The human being could never remember how to point 38 thrusters . . . couldn't do it," the test pilot conceded.

He then went on with man's natural defense against the encroachment of all these mechanical brains: "But it's just a fast adding machine, that's all it is."

Meanwhile, back on the planet that no longer holds mankind to its bosom, back where Mother Earth's apron strings are becoming untied, the technological explosion that permitted this is not quite so flawless.

If the averages held up, 70 Americans were killed by the simple and brute technology of handguns in the 54 hours, 20 minutes and 52 seconds of Columbia's voyage.

The United States and the Soviet United continued to train their nuclear warheads on each other in the same old Mexican standoff of mutual assured distruction, trusting a super-technology that occasionally has 40-millisecond misunderstandings.

Still, there is not telling where we go from here -- whether the technology of the Columbia will allow us to escape, as the spaced-out Trekkies believe, before the technology of The Bomb gets us; whether the serenity of the space-high view of the blue planet will somehow, make all the petty, tribal feuding below seem so irrelevant that it stops.

Or whether the cost -- minuscule as it is compared to the cost of the tribal feuding -- brings the adventure to an end.

Nothing about all this is more sadly revealing of the threat the space explorers feel to their budget, than the way they justify this to the megeneration, the hedonists demanding instant gratification: Teflon frying pans and better Coke bottles.

The National Aeronautics and Space Administration has produced a glossy, 147-page book called "Spinoff 1980" to tell us of the down-to-earth benefits of 20 years in space. On page 125 a bikini-clad bond lies seductively on an adapted blanket of thermal radiation insulation. It allows her to get a better sun tan faster.

Evens California's Gov. Brown who often is ridiculed for his futuristic view of the wonderment, felt required today to stand on the edge of the dry Mojave Desert lake in front of the Columbia and say that it meant more jobs for Californians, that it was "good business."

The Trekkies may be closer to right. What gets lost in the talk of greasless frying pans and faster skin-frying is the essence of man and the ultimate justification for spending the kind of wealth that Queen Isabella took a chance on.

Out here, in this desert where Columbia's boom-boom has been heard a thousand times before from men in aircraft edging the frontiers outward, from men who risked and occasionally lost their lives pushing further into the future, it is easier to grasp.

They are sometimes a wacky crew of adventurers, a flamboyant, earthy, hard-drinking, hard-playing elite corps.

Men first broke the sound barrier here, first took winged craft to the edges of space from this same dry lake bed.Back during the second world war, America's first propellerless aircraft flew from here.

Those early crazies loved to take the first experimental jets out for joy rides, buzzing stunned private pilots getting their first look at a flying machine without a propeller. The most storied legend of those days in 1942 is about the early jet jockey who donned a gorilla's mask as he swept up on an unsuspecting Piper pilot.

He got into hot water for that one, but he justified it straight-forwardly and successfully: If someone told you he saw a gorilla flying an airplane without a propeller, would you believe anything he said?

Thirty years ago, when Young was in college, the Georgia Institute of Technology didn't even offer classes in computer technology. If he had told his classmates that one day he would smuggle a corned-beef sandwich into space, that another day he would return from the black void using five computers to coordinate 38 engines firing in different directions, would anyone have believed him? Would anyone have said, sure, but what I really need is a faster sun tan?