Blackwell Reference Online

Extract

The possibility of communicating over thousands of miles using a transmitter in space was proposed by Arthur C. Clarke in a 1945 article in Wireless World , in which he described a system of “extraterrestrial relays” or repeaters in space. Clarke calculated that an object put into orbit 22,300 miles (36,000 km) above the earth would revolve around the planet in 24 hours, the time it takes the earth to rotate on its axis. Thus, the repeater would appear motionless or “geostationary” from the earth. He noted that three such repeaters located 120 degrees apart above the equator would cover the entire globe. Only 12 years later, the Soviets launched the Sputnik satellite. However, Sputnik was not a geostationary satellite; it was in low earth orbit and had to be tracked across the sky, and it simply beeped. But it spurred US scientists and engineers to develop more sophisticated satellites for commercial use. In 1963, the world saw the results as the Syncom 3 satellite transmitted television coverage of the Tokyo Olympics. In 1965, just 20 years after Clarke's article was published, the first commercial international satellite, known as Early Bird or Intelsat I, was launched to link North America and Europe. Today, there are numerous geostationary (or GEO) satellites that can provide global, regional, or national coverage. The first global system was Intelsat, still in existence today. ... log in or subscribe to read full text