• The first GPS satellite was launched in 1978.
• The current system is composed of second generation GPS satellites, called Block II.
• The first Block II satellite was launched in 1989.
• The Defense Department declared GPS fully operational in 1995.
• When the system was first introduced, miscalculations were programmed into GPS transmissions to limit the accuracy of non-military GPS receivers. This operation was cancelled in May 2000.
• There are 24 GPS satellites in orbit at this moment.
• The 24 satellites cost an estimated $12 billion to build and launch.
• Each satellite weighs about 1,735 lb (787 kg).
• The satellites are in orbit about 12,500 mi (20,000 km) above the Earth.
• A satellite takes 12 hours to orbit the Earth once.
• The Russians have a system identical to the U.S. system called GLONASS.

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