On an October Friday in 1957, Americans discovered that while they had been busy making weekend plans, their country had become the tortoise to the Soviet Union hare. Soviet scientists that day shot into orbit the first artificial Earth satellite, a beeping metallic ball not quite two feet in diameter that circled the globe every hour and a half at 18,000 miles per hour. It was called Sputnik, “traveling companion” in Russian.

Shock, dismay and fear were dominant emotions then for Americans. How, they asked, could they have fallen so appallingly behind their Cold War enemy in this new field of combat, the space race? Their political leaders felt a sense of urgency. Nine months after Sputnik, the National Aeronautics and Space Administration came into being, followed soon by the human spaceflight program known as Project Mercury. Four years later, in 1962, the young president, John F. Kennedy, boldly pledged that before the decade was out, the United States would send men to the moon.

And it did. The tortoise persevered and surpassed the hare, its dominance affirmed on July 20, 1969, when Apollo 11 astronauts set foot on the lunar surface. It was a moment of American exultation and global fascination, viewed on television by more than half a billion people — one-seventh of the planet’s population.

But it proved to be just that: a moment. There were some doubts among Americans, even before Apollo 11 but certainly after, about the wisdom of reaching for the stars while troubles swelled on Earth. By that July in 1969, American opposition to the Vietnam War was reaching a critical mass, riots scarred one United States city after another, and traditional values seemed under assault on multiple fronts.