Introduction to Satellite Communications

The advent of satellite communications has revolutionized the world's ability to communicate. The first true communications satellite, which is the US Army's experimental Signal Communications by Orbiting Relay Equipment (SCORE), was developed by the Defense Department and launched on December 18, 1958 into an elliptical orbit ranging from about 100 to 900 mi. Throughout the 1960s, however, the main focus of commercial communications satellite activity was International Telecommunications Satellite (INTELSAT), which relied entirely on geosynchronous equatorial orbit (GEO), C‐band satellites. To a large extent, the geostationary technology that supports both domestic and international communications satellites has been built on the same National Aeronautics and Space Administration (NASA) and US military technological foundation. Commercial communications satellites split mainly between GEO and low earth orbiting (LEO). These were complemented by around 100 military and 100 civil government communications satellites, most of which were GEO.