The Short Answer:
GPS is a system of 30+ navigation satellites circling Earth. We know where they are because they constantly send out signals. A GPS receiver in your phone listens for these signals. Once the receiver calculates its distance from four or more GPS satellites, it can figure out where you are.
Earth is surrounded by navigation satellites. Credit: NOAA.
Humans have looked to the skies to find their way since ancient times. Ancient sailors used the constellations in the night sky to figure out where they were and where they were going.
Today, all we need is a simple hand-held GPS (short for Global Positioning System) receiver to figure out exactly where we are anywhere in the world. But we still need objects high in the sky to figure out where we are and how we get to other places.
Instead of stars, we use satellites. Over 30 navigation satellites are zipping around high above Earth. These satellites can tell us exactly where we are.
What is GPS?
The Global Positioning System (GPS) is made up of satellites, ground stations, and receivers.
GPS is a system. It’s made up of three parts: satellites, ground stations, and receivers.
Satellites act like the stars in constellations—we know where they are supposed to be at any given time.
The ground stations use radar to make sure they are actually where we think they are.
A receiver, like you might find in your phone or in your parents car, is constantly listening for a signal from these satellites. The receiver figures out how far away they are from some of them.
Once the receiver calculates its distance from four or more satellites, it knows exactly where you are. Presto! From miles up in space your location on the ground can be determined with incredible precision! They can usually determine where you are within a few yards of your actual location. More high-tech receivers, though, can figure out where you are to within a few inches!
The ancient sailors of history would be flabbergasted by the speed and ease of pinpointing your location today.
GPS in everyday life
There’s a whole lot of important things GPS is used for—but perhaps nothing is more important than finding the quickest slice of pizza! Check out our fun Space Place in a Snap animation “GPS and the Quest for Pizza” to learn more about how GPS works.
article last updated June 27, 2019
FAQs
Your phone, or any device with a GPS, is programmed to know where all the satellites are at any given time. The phone uses that information—along with the amount of time the signal took to reach it—to figure out how far away the satellites are. By doing that, it computes its location.
How does GPS work in space? ›
GPS-based navigation uses one-way signals from GPS satellites to determine the spacecraft's trajectory through its on-board instruments and data processing.
How do GPS systems work for kids? ›
GPS is a system of 30+ navigation satellites circling Earth. We know where they are because they constantly send out signals. A GPS receiver in your phone listens for these signals. Once the receiver calculates its distance from four or more GPS satellites, it can figure out where you are.
How does a GPS system work? ›
HOW GPS WORKS. GPS satellites circle the Earth twice a day in a precise orbit. Each satellite transmits a unique signal and orbital parameters that allow GPS devices to decode and compute the precise location of the satellite. GPS receivers use this information and trilateration to calculate a user's exact location.
How does GPS work for dummies? ›
Your phone, or any device with a GPS, is programmed to know where all the satellites are at any given time. The phone uses that information—along with the amount of time the signal took to reach it—to figure out how far away the satellites are. By doing that, it computes its location.
Where is NASA located for kids? ›
NASA's Headquarters is in Washington, D.C. The agency has nine centers, the Jet Propulsion Laboratory and seven test and research facilities located in several states around the country.
Does GPS work on the space station? ›
ISS uses the GPS position and velocity solution as the ISS navigation state. The ISS's attitude determination filter combines the GPS receiver attitude information with ring laser gyro data available from the ISS rate gyro assembly (RGA) to produce the ISS attitude solution.
Is there a GPS in space? ›
But the system itself will work in space. The GPS constellation orbits at about 20,000km, but the signals can be used beyond that. NASA this year was able to use GPS at an altitude of 187,000km. They think it may work as far out as the moon.
How many GPS are in space? ›
Global Positioning System
| Accuracy | 30–500 cm (0.98–16 ft) |
| Constellation size |
|---|
| Nominal satellites | 24 |
| Current usable satellites | 38 (32 operational) |
| First launch | February 22, 1978 |
15 more rowsGPS satellite orbits Earth. GPS has its origins in the Sputnik era when scientists were able to track the satellite with shifts in its radio signal known as the “Doppler Effect.” The United States Navy conducted satellite navigation experiments in the mid 1960's to track US submarines carrying nuclear missiles.
What is GPS? The Global Positioning System (GPS) is a U.S.-owned utility that provides users with positioning, navigation, and timing (PNT) services. This system consists of three segments: the space segment, the control segment, and the user segment.
Can I put GPS on my kids? ›
So long as your child is under the age of 18 and you are their parent or legal guardian, you have a complete legal right to use a GPS tracking device to track their location.
What is GPS NASA? ›
National Aeronautics and Space Administration NASA What is GPS? The Global Positioning System (GPS) is a space-based radionavigation system, owned by the U.S. Government and operated by the United States Air Force (USAF).
How does GPS work indoors? ›
These devices typically work by affixing an antenna to the roof or outside of a building where GPS signal can reach it, then feeding that signal into the building via cables and transmitting it into indoor environments via one or multiple repeaters, normally fixed to a room's ceiling.
How does GPS work so fast? ›
GPS satellites have very precise clocks that tell time to within 40 nanoseconds or 40 billionths (0.000000040) of a second. There are also clocks in the GPS receivers. Radio wave signals from the satellites travel at 186,000 miles per second.
How does your GPS know where satellites are located in space? ›
The locations of the satellites are determined using tracking from ground stations. The ground stations use mechanisms such as radar, signal doppler, and laser reflectors to pinpoint the position of a satellite and to maintain an understanding of its orbital elements.
Does GPS come from space? ›
The 24 satellite system became fully operational in 1993. Today, GPS is a multi-use, space-based radionavigation system owned by the US Government and operated by the United States Air Force to meet national defense, homeland security, civil, commercial, and scientific needs.
What is the name of NASA GPS? ›
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force.
