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My TV comes from space

You – and millions of other people around the world – are watching the World Cup live on your TV. The images you’re seeing have travelled 36,000 kilometres up to a satellite and 36,000 kilometres back to Earth in just one second. Satellites have allowed us to see the world as it happens.

In early 1962, a National Geographic journalist visited the scientists working on Telstar 1, the world’s first telecommunications satellite. “I had visions,” he wrote, “of sitting in my own living room near Washington, DC, and seeing broadcasts of an opening of the British Parliament or some future Olympic Games in Asia.” Nearly half a century later, that vision of the future has become an accepted, integral part of our daily lives. Telstar 1 was launched later that year, and received and sent the first television images across the Atlantic Ocean on 10 July (they were received in the UK and France). By the time its mission ended in February 1963, the satellite had also been used to relay telephone, telegraph, data, telephoto and facsimile transmissions and a new era of global communications had begun.

The idea of using satellites to send sound and images around the world was first popularised by British writer Arthur C. Clarke (the author of 2001: A Space Odyssey) in 1945. In an article published in the magazine Wireless World, he theorised that satellites sent into orbits nearly 36,000 kilometres above the equator would allow for global coverage. This geostationary orbit – from which, travelling at the same speed as the planet, satellites permanently cover the same point on the Earth – meant, according to Clarke, that in theory just three satellites could together have a ‘footprint’ that covered the whole of the Earth. Things had moved on – and ambitions had grown – by 1962 and a scientist on the Telstar 1 project told National Geographic that “30 to 50 could eventually link all the countries in the world”. Since then, the ‘Clarke orbit’ has been actually been filled with hundreds of satellites, all relaying huge amounts of images, words and data from Earth and back again, allowing us to see the world in a new way.

It is television, which makes up over half of this traffic, that has perhaps been changed most radically by geostationary satellites – and not just, as you might think, for those people who receive their television from a satellite dish on their roof. Satellites are now vital to all parts of the broadcasting process – without them we wouldn’t be able to watch live news or sporting events, such as that World Cup final – and have given millions of people unprecedented access to information and entertainment.

And just as television has changed thanks to satellites, so the satellites have had to adapt to respond to ever-increasing demand. While Telstar 1 weighed just 77 kg and had just one transponder – a device that receives and retransmits the signal – today’s telecommunications satellites can weigh as much as 6,000 kg and typically have 32 transponders. (Eutelsat’s Hot Birds 8, 9 and 10, launched in 2006, 2008 and 2009 respectively, all have 64 transponders, each capable of retransmitting a dozen or so digital TV signals.) The need for ever-more powerful satellites will doubtless continue to increase as television moves into the high-definition age – which will require higher bandwidths – and because the number of digital TV channels around the world is expected to double – to 30,000 – by 2017. Satellites have changed the way we see the world – from 36,000 kilometres away.