The Shuttle

COMMERCIAL SATELLITES

Telstar, the world's first commercial communications satellite, was developed by the American Telephone & Telegraph Company (AT&T) as a private venture, and launched by NASA on a Delta on 10 July 1962. Although the satellite relayed the first television across the Atlantic, large swivelling antennas were required to communicate with it and the 6,000-kilometre apogee restricted its use as a longdistance relay to brief periods.

On 31 August 1962 the US government passed the Communications Satellite Act and ordered the creation of a national consortium to develop and run a system to serve the domestic telecommunications industry.1 On its establishment in February 1963, this Communications Satellite Corporation (Comsat) considered a constellation of Telstars, but decided to use geostationary relays, as these would provide continuity of service. In 1959 the Hughes Aircraft Company had set out to design such a satellite, and in August 1961 was given a contract by NASA to supply three of them. On 14 February 1963 the first Syncom fell silent towards the end of the 20-second firing of its liquid-propellant rocket to circularise its orbit at the requisite 36,000 kilometres. "The culprit first seemed to be the apogee motor,'' recalled Harold Rosen, the project leader. But there were other possibilities. "The nitrogen tanks might have had too much pressure and exploded, or the critical wire that powered both the telemetry transmitter and the communications transmitter could have broken suddenly.'' On 26 July 1963, the second satellite achieved geosynchronous orbit, but was not geostationary because no attempt was made to cancel the inclination of its orbit, with the result that over a 24-hour period it nodded 33 degrees north and south of the equator. The Delta that launched the third satellite on 19 August 1964 flew a series of manoeuvres to insert its payload into geostationary orbit.2 It arrived above the International Date Line just in time to relay coverage of the Olympic Games in Japan to a fascinated American audience, and the tag 'Live Via Satellite' became the defining symbol of the time. That month, Comsat led the

The Syncom satellite that relayed the 1964 Olympic Games.

creation of the International Telecommunications Satellite Consortium (Intelsat) to establish and operate a network of geostationary satellites to relay telecommunications on a global basis, and on 6 April 1965 the first satellite, formally designated Intelsat 1, but more popularly known as the 'Early Bird', was stationed above the Atlantic; it could relay up to 240 voice channels or a single monochrome television channel.

By the mid-1970s Comsat had a fleet of Comstar satellites, and leased transponders to the US domestic market - its main customers being AT&T and General Telephone & Electronics (GTE), both of which ran lucrative businesses relaying voice for a diverse community of users. Intelsat controlled the majority of the international telephone traffic and most transoceanic television relays. Owing to the exponential growth in demand, it made financial sense to pursue the continuous development of successive generations of ever more capable satellites. Having built Syncom, Early Bird and the Comstars, Hughes had a clear lead, and exploited every development in the miniaturisation of electronics to stay ahead. It introduced the 300-kilogram HS-333, a spin-stabilised drum satellite with a conformal array of solar cells and a de-spun antenna that could relay either 1,000 voice channels or one colour television channel. The great advance was the electronics used to shape this C-Band beam to deliver all of the radiated power to a geographical 'footprint' defined by the client, enabling neighbours to share frequencies without interference. In 1972, the US Federal Communications Commission opened the market to satellite broadcasting, and cable television operators eagerly expanded into this new area because it enabled them to reach a vastly enlarged audience without the expense of laying cables. Hughes duly introduced the HS-376 with a variety of options that included the use of the higher-capacity Ku-Band. In addition to members of Intelsat buying satellites for local services, it now became possible for individual companies to purchase them for private use. When Satellite Business Systems (SBS) was spun off by Comsat in 1975, it ordered HS-376 satellites to sell an all-digital service integrating voice, data, video and e-mail to businesses having facilities widely distributed over the continental United States.

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