The following essay is adapted from the introduction to Space: 50 Years and Counting, now available in leading bookstores and newsdealers or directly from Sky Publishing.

Fifty years after it officially began on October 4, 1957, we still often refer to the era we live in as the Space Age. Our extraterrestrial explorations have planted a set of mileposts in our memories — from those first brief forays into weightlessness to permanently occupied space stations, from spindly probes snapping a few pictures while whizzing past a distant planet to rovers probing every nook and cranny and telescopes peering into the deepest vastness. It’s no surprise that venturing beyond our home planet is considered by many to be the defining achievement of our era, a symbolic pinnacle of human civilization.

But for the United States, at least, the Space Age began not with glory but with worldwide humiliation.

In mid-1955 President Dwight Eisenhower declared that the nation would place a scientific satellite into orbit during the International Geophysical Year, a worldwide 18-month stretch of cooperative research. The IGY kicked off with much fanfare on July 1, 1957, with the US envisioning a satellite launch later that year. But before the planned Vanguard satellite ever met its rocket, on October 4th a persistent beeping from orbit revealed that the Soviet Union had orbited the world’s first satellite, Sputnik 1, and in doing so had won the first leg of what would become a race to space.

Sputnik wasn’t much of a satellite, but it was a beefy 184-pound beach ball compared to Vanguard’s 3-pound grapefruit. Amateur skygazers, mobilized worldwide to track the first satellites, watched it pass overhead through their telescopes. And its simple beeping signal, powerful enough to be picked up by amateur radio operators around the world, left no doubt that the achievement was real.

Just a month later, on November 3rd, the USSR awed the world again by launching the first space traveler, a small mongrel dog named Laika, aboard Sputnik 2.

The US effort swung into overdrive. After a spectacular Vanguard launch failure, televised live that December, Washington officials gave the nod to a parallel satellite program headed by Wernher von Braun, and Explorer 1 rocketed into orbit successfully on January 31, 1958. It was followed on March 17th by Vanguard 1 — which, as just the fourth satellite ever launched from Earth, remains in orbit today. Later that year, Congress created a new agency, the National Aeronautics and Space Administration (NASA), to lead the fledgling US space effort.

Today we take so much of what followed Sputnik 1 into space for granted. We think little of the fact that a phone call from here to the next town might bounce off a satellite 22,400 miles overhead, that a few keystrokes can instantly summon an online satellite view of anywhere on Earth, that space has become the ultimate platform for observing our universe, or that we can send little remote-controlled vehicles to probe odd-looking rocks on a planet 100 million miles away.

And nowadays even the promise of inexpensive, routine flights into space is back again, but in a new guise: an armada of entrepreneurs who think that the open market can deliver what decades of government bureaucracy could not. Eager customers have already snapped up $200,000 tickets for half-hour flights to the fringes of space, while space hotels and even privately-funded Moon bases are taking shape on computerized drawing boards.

This first half century of space exploration was just the bumpy beginning of what may be an endless, gradual expansion — just our first walks around the block after leaving the cradle of Earth. The decades ahead will no doubt bring us face to face with marvels we can’t yet imagine, as we explore our near and distant environs more deeply.

But there will always remain something special in our collective human memory about the first halting steps made into the cosmos that surrounds us. Even the language we use, in dozens of words and phrases, now draw from the A-OK’s, the nominals, and the major malfunctions of the space program.

As we strive to understand the universe we live in, all systems are go, and the countdown has just begun.