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Feb. 14, 1989: GPS Enters Orbit « adafruit industries blog
The first of 24 satellites that will make up the global positioning system is put into orbit.
GPS revolutionized navigation, both at sea and on land, by providing position reports with unprecedented, pinpoint accuracy. Each satellite is placed in a specific orbit at a specific altitude to ensure that four or five satellites are always within range from any point on the planet. A GPS receiver picks up signals from the satellites and trilaterates the data to fix the position.
This satellite system is so valuable — besides navigation, GPS has applications in mapmaking, land-surveying and the accurate telling of time — that even though it was developed and is maintained by the U.S. Department of Defense, it’s been available since 1993 without charge to anyone, anywhere on Earth.
Although GPS has eliminated the need for determining a ship’s position by shooting the sun or stars, no sailor worthy of the name would put to sea, even now, without the ability to use a sextant. Electronic navigation devices fail, and even GPS isn’t immune to the odd glitch, and the open ocean is a lonely place to be if you don’t know where you are.