Today more than 80 per cent of international telecommunications are routed via communications satellites, often called comsats. These satellites handle not only telephone calls and TV signals, but telex, fax and computer data transmissions. The first experiments with the transmission of signals by satellite date from 1960, when signals were bounced off huge aluminized balloons, appropriately called Echo. This was a passive communications system. Two years later the first active comsat, Telstar, was launched. An active satellite receives the signals beamed up to it from one ground station, amplifies (strengthens) them and then retransmits the boosted signals to another ground station. Telstar pioneered transatlantic communications, carrying live TV transmissions. However, it was in a relatively low orbit, which meant that the antennas at transmitting and receiving ground stations had to scan across the sky continually to keep Telstar in 'sight'. And only for 20 minutes per orbit were communications possible. In 1964 the first comsat was placed in geostationary orbit so that it was in effect 'fixed' in the sky. This meant that ground stations could lock their antennas permanently on to it. Called Syncom 3, it was launched in time to transmit live pictures from the Tokyo Olympics. From Syncom 3 the first commercial geostationary comsat was developed. Named Early Bird, it was the first of a series developed for the Intelsat consortium, and was alternatively named Intelsat 1. The Intelsat organization now comprises more than 110 countries and dominated international telecommunications. The Intelsat network comprises comsats placed in geostationary orbit at approximately 120 degree intervals around the globe over the Equator above the Atlantic, Pacific and Indian Oceans. From these vantage points they can provide communications links between virtually every country on Earth. Among domestic communications networks, the Soviet Orbita system is one of the most extensive. It use some geostationary satellites, known as Raduga ('Rainbow'). But, because of the northerly location of much of the Soviet land mass, domestic communications cannot rely solely on geostationary satellites. It also uses satellites in highly eccentric orbits, which takes them more than 39,000 km high over the USSR, but as low as 600 km on the opposite side of the world. In such an orbit the satellites are above the horizon for Soviet ground stations for most of the time. Orbita uses two types of Molniya ('Lightning') satellites for the eccentric orbit system, Molniya 1 and 3.
