Thought you all would like to read this...
To give credit where credit is due, I found it here...
http://www.wired.com/news/technology/0,72646-0.html?tw=rss.index

Feb. 14, 1989: GPS Enters Orbit

By Tony Long| Also by this reporter
02:00 AM Feb, 14, 2007

1989: The first of 24 satellites that will comprise 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 map-making, 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 is made available 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.

(Source: Peter H. Dana, The Geographer's Craft Project; Wikipedia)

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Sincerely,
Matthew A. Shapiro
Multi-Systems, Inc
http://msisolutions.com/