Satellite communications


* Comunicaciones vía satélite

Today's Olympics or FIFA World Cups would not be the big festivities they are if not for their audience, which go far beyond the ultra-modern stadiums. And this is due largely to satellite transmissions. Let's see a little of the history of this technology.

In 1825 the painter Samuel Morse, while traveling, received a terrible letter: his wife had died. This would had have a profound effect on him, especially because the news took two weeks to arrive. Years later, he learned of the experiments of Joseph Henry, in which a long electrical cord magnetizes an iron bar at the pressing of a button. Morse was so impressed that he asked himself if a cable long enough would be able to turn on and off, in sucession like a code, a remote device. This could send messages almost instantly. He even philosophized that he saw "no reason why intelligence might not be instantaneously transmitted by electricity to any distance." He devoted himself to the development of this "telegraph", and by 1844 he made ​​a public demonstration by sending a message between Baltimore and Washington, D.C..

By 1876 Alexander Graham Bell demonstrated that even voice could be encoded in electromagnetic signals, and patented the telephone. This became one of the most lucrative business of his time.

Gugliermo Marconi went much further and applied a recent discovery by Heinrich Hertz, based on studies of James Maxwell, that electromagnetism can be propagated in vacuum too, without a conducting medium. In 1901 he sent a message across the Atlantic. Radio was being born and Marconi won the Nobel Prize in Physics for this.

Charles Jenkins, John Baird, Philo Farnsworth, Vladimir Zworykin and other refined methods to encode images in the signals, and the first modern television system appeared in 1936. Now people could see and hear what was happening in remote places, almost instantly, without having to be present.


But there were some problems that were difficult to solve: the electromagnetic signals were struggling to overcome obstacles such as mountains, especially at frequencies that television uses. And in fact, because the Earth is round, it was not possible to transmit television from one continent to another.

What was needed was an relay antenna thousands of kilometers high. But as there was no way to build it, science fiction writer Arthur C. Clarke published in 1945 the following idea: place the transmission equipment in an artificial satellite high enough for it to be visible from two separate continents at the same time. The signal would be sent from one continent to the satellite, and the re-transmitted from the satellite to another continent. ("Extra-terrestrial relays: Can rocket stations give world-wide radio coverage?", Wireless World, London, October 1945, pages 305-308).

At one point Clarke consulted with an attorney about the possibility of patenting the idea, but he apparently explained to him that without the technology to materialize it, it would have been rejected.


Actually, the idea began in a 1687, with Isaac Newton. Legend has it that when he was 22, he spent a vacational season in his family's estate (Cambridge University was closed due to the bubonic plague). They had apple plantations there, and Newton would have been lying to rest at the foot of a tree. But his sleep would had been interrupted by the fall of an apple, some even adding that it fell on his head. Newton awoke, and asked himself a childish question: Why does the apple fall? Because the earth attracts it, of course. And then came another childish question that changed the history of humankind: if the apple falls, why the moon does not fall too?

He thought that the reason must be the motion of the moon. He imagined a person throwing a stone (or kicking a ball) with great force: it flies a considerable distance before hitting the ground, falling with a curved line. The higher the casting speed, the further the fall. With a giant force its speed will be high enough to hit the ground far away in another city. If it is casted with still greater force it could strike the ground just in another country. If it is casted with still more force it may cross the ocean and get to another continent. But if it is casted with a really great speed, it will be possible for it to go so far as to hit the ground just on the other side of the world. And if we increase the speed of release further, the stone (or ball) would go so far away that it could travel all the way around the world, without touching the surface, and return to the launch site from the other side. If this latest release occurs from a high place where there is no air, there would be no wind to slow it down, and the stone (or ball), returning to the launch site after going around the world, would continue with the same speed with which it left, which could lead to another lap around the world, and then another lap, and then another. In fact its inertia will make it continue spinning indefinitely: it will be in orbit, making a curve so large (larger than the Earth itself) that never finds the surface in spite of falling forever. It will have become an artificial satellite.


The higher the satellite is the longer it takes to do the lap, because the curve that goes around the Earth is bigger, and because the Earth's gravity is lower. At about 100-km high it would take 1 ½ hours to go around, at about 1000 km about 2 hours and at 36 000-km altitude, 24 hours. What Clarke thought in 1945 was that it would be very helpful to place the satellite in this orbit of 24 hours, as it would fly accompanying the rotation of the Earth. If we put the satellite over a particular continent, the movements will be synchronized, and people (or antennas) in that continent will always see the satellite.

By 1954, the post-war development of rockets made that in the scientific literature concrete solutions to the placement in orbit of small satellites abound. But now it was too late for Clarke: the initial idea was already widely spread, so that they could not grant him exclusivity.


In 1957, the Soviets managed to launch the first artificial satellite. The first geostationary satellite (which uses Clarke's principle), Syncom 3, was launched in 1964, and served to broadcast live the Tokyo Olympics. Then the satellite transmissions would become one of the main business of telecommunications companies, and give tremendous power to show organizers and news anchors.

The funeral of Pope Paul VI, in 1978, was one of the first live news events seen from much of the Third World. In the 80's, Formula 1 multiplied dramatically its sponsors, which now have at their dispossal a global audience. The 1991 Gulf War was the first to be broadcasted live and direct from the battlefield, turning distant conflicts much more real, and bin Laden attacks would not have had the same impact without the unwitting help of satellite television.

Pelé reflected that a major difference between soccer football of his time and now is the multi-million-dollar salary of the star players, made ​​possible by broadcasting the games to huge audiences.

A FIFA World Cup is now the biggest TV show on Earth. The last World Cup was seen in 214 countries and territories, virtually all in the world. The final match between Spain and the Netherlands was seen by an average of 531 million people, although it was early morning in many countries (2010 FIFA World Cup South Africa Television Audience Report, Kantar Sport, London). In fact, during that month a total of 2023 million people watched from home at least half an hour of soccer football broadcasted from South Africa (Kantar Sport, in the same place), generating an income of U.S. $ 2408 million for FIFA (Financial Report 2010, 61st. FIFA Congress, Zurich, 31 May 31 and 1 June 2011).

So, as we saw in this example, thanks to communications satellites, the show came out from only a dozen stages to reach magically almost a third of the World's population.

Aldo Loup.

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Originally published in ABC Color, on 11 June 2006. Drawing: An Intelsat IV series communications satellite drops its nose fairing. At this point, it is still mated to the Centaur stage of its launch vehicle. Credit: Reproduced by Helen Wells, Susan Witheley and Carrie Karegeannes in "Origins of NASA names", NASA Special Publication 4402, U.S. National Aeronautics and Space Administration, Washington, D. C., 1975, Chapter 2, "Satellites", page 56. Document available at the NASA History Program Office.