Global Positioning System (GPS)

In 1973, the Defense Department combined its competing satellite navigation systems.

The new joint program under the Air Force was called the NAVSTAR Global Positioning System, or GPS. It introduced synchronized time from space, provided by onboard atomic clocks. The system was intended for a range of military applications, including locating ships and targeting weapons. GPS designers envisioned that civilians would use the system as well.

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GPS Constellation

GPS satellites are positioned in precise, circular orbits 18,000 kilometers (11,000 miles) above the Earth. They orbit once every 12 hours.

Credit: National Air and Space Museum, Smithsonian Institution.

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U.S. Naval Observatory Alternate Master Clock

The U.S. Naval Observatory Alternate Master Clock at Schriever Air Force Base.

Credit: U.S. Air Force

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System Maintenance

The successful operation of a satellite navigation system requires around-the-clock monitoring of the satellites’ health and the periodic replacement of older satellites.

Credit: U.S. Air Force

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How Does GPS Work?

From maintaining infrastructure, transporting goods, delivering services, or just meeting friends, people often use technology just as sophisticated as that used by pilots and soldiers. How does it work?