(originally run September 8, 1995)
This author has recently relocated to a relatively secluded area of the southern New Mexico mountains. The serenity offered by the quiet countryside and the clear and dark nighttime skies were strong inducements to this move but, as in any endeavor, there are a few drawbacks. One of these concerns the receipt of television signals; the use of an antenna would produce only spotty results at best, and no cable companies operate in this particular area. Ordinarily, this would not be much of an issue to this author since, apart from The Simpsons and the various incarnations of Star Trek, his life does not revolve around the television set. But, as the autumn months start to bring the first chills to the mountain air, along comes football season, and this author would be very hard put to miss his beloved Dallas Cowboys and the rest of the NFL action.
The solution to this author's dilemma began back during the latter days of World War II, when a young British man, Arthur C. Clarke, began to experiment with some of the calculations involved in computing orbits. While Clarke has since become a world-renowned science fiction author, and is perhaps best known among the general public as having written the screenplay of the 1968 motion picture 2001: A Space Odyssey, at that time he was a radar officer in the Royal Air Force.
Clarke's calculations started with Isaac Newton's law of gravity, with which it is possible to determine the orbital speed of an object around another object, and how this relates to their distance from each other; from this one can also calculate how long it takes the orbiting object to complete one circuit. Up until that time, most such calculations were concerned with the orbits of the planets and other bodies in our solar system, but Clarke was concerned with the orbits of artificial objects around the Earth.
One consequence of Newton's law is that, the smaller the orbit, the faster the speed of the orbiting object, and the shorter the orbital period; for this reason, a Space Shuttle orbiting a couple of hundred miles up completes one circuit of the Earth in about 1 1/2 hours, while a satellite several hundred miles higher takes significantly longer to do so. Clarke calculated that, at an altitude of 22,300 miles above the Earth's surface, such a satellite would take exactly 24 hours to orbit the Earth once. While this is occurring, of course, the Earth is also turning on its axis, taking 24 hours to do so; if the satellite were to be located over the Earth's equator, its orbital speed would exactly match the Earth's rotation, and the satellite would appear to be stationary over the same point of the Earth's surface. Such a satellite could be described as "geosynchronous" (or sometimes as "geostationary").
Having arrived at this result, Clarke went on to envision a string of such satellites placed around the Earth over its equator, which could then be used for relaying television and other signals between various locations on the Earth's surface. Along with his calculations, he wrote up this idea into a short article entitled "Extra-Terrestrial Relays" which was subsequently published in the October 1945 issue of the journal Wireless World.
At that time Clarke had no serious reasons for believing that such a scenario would come to pass anytime in the near future, but twelve years later came the launch of Sputnik 1, and the Space Age was on. The first communications satellites were low-orbiting passive reflecting devices such as the Echo 1 balloon launched in 1960, and then in July 1962 the first active communications satellite, Telstar 1, was launched. While Telstar 1 functioned less than a year, it allowed the first live television transmissions between Europe and America.
The first use of the geosynchronous orbit for communications came with the launches of the Syncom series of satellites in 1963 and 1964, and the first commercially operated geosynchronous communications satellite, Early Bird, was launched in 1965. Since that time, numerous such satellites have been launched, until today there are over two hundered of them ringing the skies above the Earth's equator. With the advent of personal satellite receivers during the mid-1970s, today it is possible, from almost anywhere on the Earth's surface, to receive television signals that originate from almost anywhere else.
The potentials offered by geosynchronous communications satellites has led to a revolution in news reporting; today we almost think nothing of seeing live broadcasts and reports from locations half a world away. It hasn't just been television transmissions that have been affected either; today it is almost as easy to place a telephone call to a point on the other side of the world as it is to call across town. This revolution in communications has resulted in a virtual shrinking of the Earth from a cultural standpoint, and is helping to move us in the direction of what some have called the "global village." Much of this was foreseen by Clarke in his 1945 paper and his subsequent writings, and today there is a movement toward referring to geosynchronous orbits as "Clarke" orbits in his honor.
In the meantime, on these fall weekends this author's backyard satellite dish will be aimed toward the Telstar 303 satellite, perched 22,300 miles above a point in the Pacific Ocean 2600 miles south of San Francisco. Since it carries the full schedule of NFL games every weekend, it allows this author to enjoy both the mountain serenity and his football games as well. (In other words, humanity's exploitation of the opportunities provided by space permits this author, and others like him, to have their cake and eat it, too.)
Well, it's time to go, now. The Cowboys game is coming on . . .
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