WASHINGTON, D.C. — The Air Force celebrated 20th anniversary of the Global Positioning System during a ceremony at the Smithsonian’s National Air and Space Museum in Washington D.C., July 17.

GPS was originally invented to aid the military with operations and intelligences. It’s a constellation of orbiting satellites that provides global coverage of navigation to military and civilians worldwide.

“There are 39 satellites up there right now,” said Maj. Benjamin Calhoon, the chief of the Positioning, Navigation and Timing Branch within the Space Operations Division of Headquarters Air Force. “To provide global coverage, only 24 satellites (are) needed.”

At minimum, the system consists of 24 satellites orbiting in space in six regions. In each region there are four satellites that move semisynchronous. The system provides location, velocity and precise time by using this formula for accurate location: distance = rate x time.

“In a preliminary U.S. economic benefits study, results show GPS contributes $68.7 billion annually,” Calhoon said.

Nowadays, anyone with a GPS receiver can use it to navigate from one place to another instead of just the military. On a daily basis, it benefits runners with smartwatches, self-driving cars, payment transactions, stock trade, power grids and tracking shoes to help those with Alzheimer’s disease.

“Our nation has 16 critical infrastructures; there is not a single component that is not touched by GPS in some way, some naturally more than others,” Calhoon said. “GPS does it all, it’s amazing.”