Global Positioning Satellite (GPS) is not actually 1 satellite but the name of the technology created by a constellation of 24 satellites. The Department of Defense (DOD) owns and operates this system and makes it available for civilian use. Sputnik 1, the first artificial satellite that was launched by the Soviet Union in 1957, emitted radio transmissions which were monitored by 2 American physicists. They soon realized that they could use these radio transmissions to pinpoint the location of the satellite along its orbit. By 1973, DOD officially started the “GPS Project” to meet its needs for accurate navigation.

The civilian use of this system was first authorized by President Ronald Reagan in 1983, as a response to the Korean Airlines (KAL) plane crash.  A KAL civilian aircraft had mistakenly strayed into Soviet air space and was shot down killing 269 people. The presidential directive guaranteed that the navigational information would be available at no charge to commercial users.

Succeeding generations of technology have increased the precision of GPS. The satellites have more sophisticated electronics and the computers that analyze the signals have become faster and more accurate. GPS location features are now part of a wide range of devices from boats to cell phones to automobiles and are so user friendly that even “Siri” and “Alexa” can communicate with them.

All GPS devices depend upon the signals of at least 4 satellite signals that beam along an unobstructed line of sight.  Obstacles like mountains and buildings block the relatively weak GPS signals, so outdoor wilderness excursions can take you places where your phone or watch don’t work. The use of a compass and advance planning of the route you will take are still necessary for the ambitious outdoor adventurer.  

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