The Story of GPS: Here We Are
There’s no question that the Global Positioning System has been and will continue to be one of the great, transformative technical achievements of the modern world. Its pervasiveness and influence are still growing by leaps and bounds. For a fascinating look at the development of GPS, its myriad uses today, and its future, you can now download Jim Carrier’s e-book, Here We Are: The History, Meaning, and Magic of GPS.
Carrier is the author of 10 books. His writing has appeared in National Geographic, the New York Times, and many other publications. He has sailed his own boat, Ranger, across the Atlantic to the Mediterranean, where the ancient Greeks established the principles on which modern navigation is based.
A short excerpt from Carrier’s book is reprinted below, with permission. The whole e-book can be ordered (for $2.99) by clicking this link:
In the Beginning, Sputnik Connected Heaven and Earth
“Listen now,” began a prescient NBC radio newscaster on Friday evening October 4, 1957, “for the sound that forevermore separates the old from the new.”
There followed the scratchy beep-beep of Sputnik. All over the world, ham operators, lab technicians, and kids and their parents rigged up receivers. On Monday, at the John Hopkin’s Applied Physics Lab in Maryland, George Weiffenbach and Bill Guier, two bespectacled junior brainiacs, set up a spectroscope, tuned in, and noticed a warble.
It took only minutes for them to recognize the warble as the Doppler effect of the satellite zooming overhead at 18,000 miles an hour. The beep’s highest frequency marked the satellite’s closest position to the lab. With scrounged gear and borrowed time on a new Univac “computer,” Weiffenbach and Guir were soon able to predict precisely the time and path of Sputnik’s 96-minute orbits.
The United States, meanwhile, scrambled to launch its own satellite. Russia’s feat had upped the ante in the Cold War. Both countries now had hydrogen bombs, and the race was on to build missiles to deliver them. Among the projects was the Polaris, to be carried by submarines. The problem was navigation. On a cloudy day in the cold North Atlantic, for example, there was no way for a sub, using a sextant, to fix its position and aim a missile.
Six months after their Sputnik experiments, Weiffenbach and Guier were summoned by the lab director, Frank McClure. He closed the door. Are you exaggerating the accuracy of your calculations? he asked. No, they said.
Well then, he wondered, couldn’t they invert the data? That is, if each orbit could be precisely plotted, using the Doppler effect, couldn’t they use the beep from a known orbit to find the position of the lab on the ground?
It was an astoundingly simple idea. Within two days, using the Doppler shift from another Russian satellite Weiffenbach and Guier “found” their location on earth to within one tenth of a mile.
Thus began space-based navigation. Johns Hopkins won a Navy contract to build Doppler-tone satellites to communicate with submarines. It was another innovation born of war, a pattern that stretched back to the Greeks. But not since John Harrison’s chronometer solved the “longitude problem,” had a single technology created such a leap. The first handmade satellites from Johns Hopkins, launched in 1959, formed the Transit system, and were the first steps toward GPS.