Communication satellites - .PDF file.
Moonbounce experiments and Arthur C Clarke: our coverage of the beginnings of satellite telecommunications anticipates the launch of Telstar
London is currently the focus of the world’s telecommunications industry, with broadcasts winging their way from the Olympic Park around the world. It’s a technology that we take for granted, but its origins are barely half a century old.
Looking back into The Engineer’s September 1960 edition, the magazine’s American Editor summarised the beginnings of the communications satellite industry, following the news that the Bell Telephone Laboratories had announced plans to launch a fleet of 50 ‘relay spinning sphere’ satellites to beam telephone calls and television signals around the world. You can read the whole article here.
The article talks about Bell’s ‘first telephone terminal to outer space’, which had recently been built at Holmdel in New Jersey. Using the new maser technology developed by Bell Labs in 1957 and a horn-reflector antenna, the facility had carried out a coast-to-coast telephone conversation with the Jet Propulsion Laboratory in Goldstone, California via a wonderfully named ‘moonbounce experiment’. ‘The voice of William C Jakes, engineer in charge of the experiment, was beamed from a 60ft dish-shaped antenna to the moon, some 240,000 miles away,’ the article says. ‘Although the signal travelled at nearly the speed of light, it took three seconds to complete the trip of almost 500,000 miles to Goldstone.’ This meant a six-second time lag between a question being asked and answered, it added. Previous moonbounce experiments had included a conversation the previous year between MIT and Jodrell Bank, although the replies had gone via an transatlantic cable.
The Bell satellite system would mimic this, using satellites orbiting at 3000 miles altitude which ‘would, in effect, serve as microwave towers several thousand miles high.’ The concept had been proposed some two years before the Russians launched Sputnik 1, the article says. It also namechecks ‘imaginative writers of science fiction’ who had written of satellite communications since about 1942, and singles out the ‘first proposal in a serious vein’ made by ‘AC Clarke of Ceylon in Wireless World of October 1945’. The ingenious Mr Clarke is, of course, better known to us now as the author of 2001: A Space Odyssey and connoiseur of the mysterious, Arthur C Clarke.
Satellites would, in effect, serve as microwave towers several thousand miles high
Bell’s experiments came to fruition two years later with the launch of Telstar, which was an international collaboration between AT&T, Bell, NASA, Britain’s GPO and its French equivalent, the PTT. In 1960, the Engineer says, there was still a decision to be made as to whether the satellites would be passive — that is, simple signal reflectors — or active, incorporating amplifiers, which would allow the ground-based transmitters to be less powerful. Telstar, which was built by Bell, was an active satellite, converting 6GHz transmissions to 4GHz and amplifying them in a travelling-wave tube. Despite its amplifiers, the satellite still needed enormous ground transmitters, 54m long, weighing 340tonnes, and housed in radomes the size of a 14-storey building. This (somewhat patronising) US newscast shows some of the first broadcasts to be sent, including part of a John F Kennedy press conference.
These days, Telstar might be better remembered as the title of an early pop instrumental recorded by the British sound engineering genius Joe Meek with his house band, the Tornadoes. Written to commemorate the launch of the satellite, it included sound effects generated by Meek running a pen around the inside of an ashtray and playing the recording backwards. It was the first British record to reach No 1 in the US and it still sounds like nothing on Earth. You can listen to it here.