WASHINGTON -- Fifty years ago this week, America was shaken out of technological complacency by a beeping 180-pound aluminum ball orbiting overhead. Sputnik was a shock because we had always assumed that Russia was nothing but a big, lumbering and all-brawn bear. He could wear down the Nazis and produce mountains of steel but had none of our savvy or sophistication. Then one day we wake up and he beats us into space, placing overhead the first satellite to orbit the Earth since God placed the moon where it could give us lovely sailing tides.

At the time, all thoughts were about the Soviets overwhelming us technologically. But the panic turned out to be unwarranted. Sputnik was not subtle science. The Soviets were making up for their inability to miniaturize nuclear warheads -- something that does require sophistication -- by developing massive rockets. And they had managed to develop one just massive enough to hurl a ball into Earth orbit.

We had no idea how lucky we were with Sputnik. The subsequent panic turned out to be an enormous boon. The fear of falling behind the Communists induced the federal government to pour a river of money into science and math education. The result was a generation of scientists who gave us not only Apollo and the moon, but the sinews of the information age -- for example, ARPA that created ARPANET that became the Internet -- that have assured American technological dominance to this day.

There was another lucky outcome of Sputnik. Two years earlier, President Eisenhower had proposed "Open Skies" under which the U.S. and Russia would permit spy-plane overflights so each would know the other's military capabilities. The idea was to reduce mutual uncertainty and strengthen deterrence. Soviet leader Nikita Khrushchev rejected the idea out of hand.

The advent of the orbiting satellite circumvented the objection. By 1960, we had launched our first working spy satellite. But our greatest luck was the fact that the Soviets got to space first. Sputnik orbiting over the United States -- and Eisenhower never protesting a violation of U.S. sovereignty -- established forever the principle that orbital space is not national territory but is as free and open as the high seas. Had we beaten the Russians into orbit -- and we were only a few months behind -- Khrushchev might very well have protested our presence over sovereign Soviet territory and reserved the right to one day (the technology was still years away) shoot us down.

Sputnik and the space age it launched had one other curious, wholly unexpected effect. Before Sputnik, while still dreaming about outer space in science fiction, we always assumed that one step would create the hunger for the next -- ever outward from Earth orbit to the moon to Mars and beyond.

Not so. It took only 12 years to go from Sputnik to the moon, on which we jumped about for a brief interlude and then, amazingly, abandoned.

There are technological, budgetary and political reasons to explain this. But the most profound is psychological. It's cold out there. "In the Shadow of the Moon" is a magnificent new documentary of the remembrances of some of those very few human beings who have actually gone to the moon. They talk, as you'd expect, about the wonder and beauty and grandeur of the place. But some also recall the coldness of that desolation. One astronaut tells how on the moon's surface he was seized with the realization that he and his crewmate were utterly alone (BEG ITAL)on an entire world(END ITAL).

On Earth, you can be wandering a forbidding desert but always with the hope that there might be something human over the horizon. On the moon there is nothing but dust and rock, forever. And then -- just about all the astronauts talk about this -- you look up and see this beautiful blue marble, warm and fragile, hanging in the black lunar sky. And you long for home.

The astronauts brought back that image in the famous photo, "Earthrise" -- and, with it, that feeling of longing. That iconic image did not just help spur the environmental movement. With surpassing irony, it created at the very dawn of the space age a longing not for space, but for home.

This is perhaps to be expected for a 200,000-year-old race of beings leaving its crib for the first time. We will, however, outgrow that fear. It was 115 years from Columbus to the Jamestown colony. It will take about that same span of time for a new generation -- ours is too bound to Earth -- to go out and not look back.