ANTONIO LÓPEZ | Tungsteno
The famous science fiction writer Arthur C. Clarke (1917-2008) was still an unknown quantity at the age of 28 when he wrote two scientific articles that would earn him the title of the father of satellite communications. One was a letter for private circulation and the other, published in Wireless World magazine, explained how artificial satellites could revolutionise communication systems if they used a particular orbit: the geostationary orbit.
If a satellite is placed in orbit at an altitude of 35,786 kilometres above the terrestrial surface, coinciding with the line of the equator and following the direction of the planet’s rotation, it will move at a constant speed, similar to that of Earth. In this way, it becomes synchronised with our planet and, for all practical purposes, in constant (visual) contact with a fixed area of the surface (as if our natural satellite, the Moon, never moved from a fixed position in the sky). This system is used today not only for telecommunications, but also for geostationary satellites that monitor the weather and make it possible to produce weather forecasts, detect fires or monitor clouds of volcanic ash.
The first satellite to reach Clarke orbit, Syncom 3, enabled live television broadcasting of the 1964 Tokyo Olympics. Credit: NASA.
Precursor to the geostationary orbit
Although Clarke was not the first to propose the idea of the geostationary orbit (GEO), he was responsible for its popularisation. In recognition of this bold thinker —who was 12 years ahead of Sputnik (the first artificial satellite in orbit) and 17 years ahead of the first satellite that allowed live television broadcasting, the Telstar 1— this unique imaginary strip is known today as the Clarke orbit.
Clarke thought that the specific location of the geostationary orbit (where the inclination is zero degrees with respect to the Earth's surface) would allow communications satellites to send signals in a straight line to a fixed antenna on the surface, a system that would optimise resources and reduce costs. This is how cable television works, for example, whose local broadcasting stations also receive signals from space via satellite dishes and then distribute them by cable to homes.
However, the Clarke orbit is not infinite and, although it is currently occupied by hundreds of satellites, a total of 9,869 artificial satellites currently orbit the Earth, according to official data from the United Nations Office for Outer Space Affairs (UNOOSA) for September. To make the most of the Clarke orbit, a peripheral area where the satellites oscillate vertically has been defined: the Clarke belt. This zone houses a set of geosynchronous orbits (GSO) in which the satellites do have a variable inclination over the Earth.
The first satellite launched by NASA that managed to reach geostationary orbit was Syncom 3, launched on 19 August 1964. A year earlier, Syncoms 1 and 2 (launched on 14 February and 26 July, respectively) had reached geosynchronous orbits. It had been almost 20 years since Clarke described the idea. That same year, the Summer Olympic Games were broadcast live for the first time; the opening ceremony of the 1964 Tokyo Games could be seen almost instantly in America and Europe, something that a few years earlier was difficult to imagine, thanks to the brand-new technology of telecommunication satellites.
The system devised by Clarke made possible the live broadcast of the first Moon landing in history, thanks to the Intelsat I communications satellite. Credit: NASA.
From monitoring the weather to communicating with outer space
These satellites are undoubtedly a key tool for many of the technologies we use in our daily lives, and also an essential instrument for scientists. Geostationary satellites make it possible to accurately track weather from space and improve the prediction of geomagnetic storms or solar flares capable of disrupting communications. In addition, these satellites are starting to be used to improve and correct the accuracy and availability of navigation systems, such as GPS. They compensate for failures recorded by navigators broadcasting signals amplified through SBAS (satellite-based augmentation system). Geostationary satellites are also essential for monitoring the Earth's climate and predicting the development of severe thunderstorms or assessing air quality. Even NASA uses geosynchronous satellites to communicate with the International Space Station and the Hubble Space Telescope.
Arthur C. Clarke ended up being an acclaimed writer, as well as a physicist, mathematician and scientific popularizer. He even worked as a screenwriter with Stanley Kubrick on 2001: A Space Odyssey (1968), one of the masterpieces of science fiction. While imagining future worlds, Clarke continued to stand out for his ability to anticipate history, as his idea of the space elevator, popularised in the science fiction novel "The Fountains of Paradise" (1979), currently has the backing of science. His scientific and cultural impact is undeniable, but his influence guided human civilisation much further; his non-fiction book "The Exploration of Space" (1951) was used by NASA rocket designer Wernher von Braun to convince John F. Kennedy that Americans should, and could, go to the Moon. In fact, images of the first ever Moon landing were broadcast live into homes around the world by a communications satellite, Intelsat I. The greatest television event in the history of the 20th century became a reality thanks to the system Clarke had devised more than two decades earlier.
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Tungsteno is a journalism laboratory to scan the essence of innovation. Devised by Materia Publicaciones Científicas for Sacyr’s blog.