Hundreds of thousands of years ago, the earliest humans began looking to the position of the sun to help guide them home from their daily hunting and gathering missions. About 5,000 years ago, early sailors in the Mediterranean and the South Pacific figured out that they could use the positions of the stars and their arc across the sky to avoid getting lost on the open seas at night.

But today, modern people can simply look to their phones and receive exact real time navigation information delivered instantly by an interconnected system of 24 satellites to anyone, anytime, anywhere, doing anything –– whether commanding a nuclear submarine in the North Atlantic, on the road trying to find the next highway exit with a gas station, or just stumbling home from a strange bar at the end of a Friday night. Such is the miracle of the Global Positioning System.

William Guier, Frank T. McClure and George Weiffenback
William Guier, Frank T. McClure and George Weiffenback, instrumental scientists in developing GPS.

The innovations that eventually produced the modern GPS began during The Space Race of the 1950s and 60s. In 1957, shortly after the Soviet Union launched the first artificial satellite, Sputnik 1, two physicists at Johns Hopkins University’s Applied Physics Laboratory quickly realized that by monitoring the frequencies of the radio waves sent back to Earth by Sputnik, and then using the relationship of wave frequencies to distance (also known as the Doppler Effect), they could accurately locate the satellite’s position in orbit. Over the next few years, they then flipped their work from users locating satellites to satellites locating a user, which led to the first crude satellite geopositioning systems in the 1960s.

Gladys West - Adsum
Gladys West working at the Dahlgren Division in Virginia

But in order to create a fully encompassing and highly precise satellite navigation system, the challenges went far beyond simply measuring the frequencies of radio waves. Such a system required an interconnected network of satellites that could provide coverage over the entire Earth, as well as advanced mathematical algorithms that could account for the imperfect shape of the earth as well as the differing effects of gravity on radio waves in space. The project to create this fully complete satellite navigation system began in 1973, led by three physicists and the mathematician Gladys West, whose work on mathematically modeling the shape and gravitational forces of the Earth was particularly groundbreaking. After two decades of work, the modern GPS system and its network of 24 satellites finally became fully operational in 1995.

Satellite Bird Cage
GPS needs three satellites to find your location, but with more satellites comes more accuracy.

When GPS first opened to widespread civilian use in 2000, early GPS devices were accurate to within 5 meters and used primarily as guides for traditional navigation, often alongside standard maps and compasses. However, as the technology has improved, many GPS devices today are accurate to within 30 centimeters, a level of precision that allows for things like self-driving cars and the devices that many athletes now wear to track their movements during matches and training. As such advances continue and GPS becomes more woven into daily life in even more ways, human beings soon––if not already––may be able to avoid entirely the experience of ever being lost again. On the other hand, sometimes there’s nothing better.