Telstar

On 10 July 1962, AT&T launched Telstar 1 ^1,2,3, which was the first satellite to provide repeated transmission without delay. Telstar was the first satellite to provide real-time repeater transmission of voice, TV, and data. The 88-cm sphere has a mass of 77 kg and was powered by 3,600 solar cells. Telstar was launched on Douglas Thor-Delta (Delta A) launch vehicle into an elliptical orbit between 952 km and 5,933 km with 44.8º inclination and an orbital period of 157.8 minutes. Telstar contained 2,528 semiconductor devices and only one traveling wave tube amplifier (TWTA)—the first to be carried on a satellite—providing a gain of 40 dB (10,000 times amplification). Andover, Maine and Holmdel, New Jersey had two large horn antennas—transmit/receive at Andover and receive only at Holmdel. For the first time, a satellite used FM analog signals: relay TV, telephone, and telegraph images. Due to its non-geosynchronous orbit, availability of Telstar 1 for transatlantic signals was limited to the 30 minutes in each 157.8-minute orbit when the satellite passed over the Atlantic Ocean.

Telstar was a simple repeater that received signals at 6.390 GHz, amplified them and retransmitted them at 4.170 GHz. These C-band frequencies were chosen because of the ready availability of existing terrestrial microwave radio-relay equipment in that band. The satellite’s solar cells generated 14 W, and the power amplifier used a specially developed 50-MHz bandwidth, 2-W broadband TWTA allowing the first color TV signals to be relayed across the Atlantic. The telemetry link operated at 136 MHz.

After five orbits of Earth—tracked by stations in South Africa, South America and Australia—the first live telephone call was between Vice-President Lyndon Johnson in Washington and Frederick R. Kappel, Chairman of the Board of AT&T in Andover. To support Telstar, six ground stations were constructed in the US, France, the UK, Canada, West Germany, and Italy.

Telstar’s significance extended far beyond engineering. For the first time, live TV pictures crossed the Atlantic, allowing audiences in Europe and North America to share events in real time. The initial broadcasts on 11 July 1962 included the US flag at Andover, a baseball game between the Philadelphia Phillies and the Chicago Cubs, and a press conference by US President John F. Kennedy. The following day, the BBC and Eurovision sent images from Europe to the United States, including footage of Big Ben and the Eiffel Tower. On 11 July 1962, the first live TV signals were exchanged. On 23 July, full-scale program exchanges took place, reaching more than 200 million viewers in North America and Europe, an unprecedented, shared experience that vividly demonstrated the potential of global satellite communications.

Telstar also captured the public imagination. Its name quickly became synonymous with the dawning “space age,” and it inspired popular culture. Most famously, the British band The Tornados released the instrumental single “Telstar” in August 1962, which topped charts in both the UK and the United States. The song’s futuristic electronic sound, created with a Clavioline keyboard, reflected the sense of wonder surrounding satellite communications. To this day, Telstar remains one of the few satellites to have left such a lasting imprint on both technology and popular culture.

Although Telstar 1 was expected to operate until 1964, its electronics were soon damaged by radiation in the Van Allen belts. The problem was worsened by high-altitude nuclear tests, notably the US “Starfish Prime” explosion on 9 July 1962, which greatly increased radiation levels. Telstar 1 ceased continuous operation by 21 February 1963. A more radiation-resistant Telstar 2 was launched on 7 May 1963 into orbit at 1,322 km perigee, 7,439 km apogee, at an inclination of 47.7°, with a period of 225 minutes. Telstar 2 was used for telephone, TV, facsimile, and data transmission until its VHF system was switched off on 16 May 1965. Neither satellite was actively de-orbited. Both remain in their high orbits today as a derelict space asset.

It should be noted that later satellites carrying the Telstar name, beginning in the 1980s, were more advanced commercial geostationary spacecraft that shared only the name with Telstar 1 and 2.