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 August 1, 2005 The Evolution of Satellite CommunicationsTurn on your TV and it’s impossible to avoid watching pictures from space. Even if you don’t have a satellite dish of your own, your local station gets most of its programming by satellite, as does your cable company, if you subscribe to one. Even the local newscast, which is produced in the town you live in, probably has segments that came from the sky. It’s sometimes hard to realize that this development is quite recent, and what a long road we have traveled to be able to beam images and sounds by satellite around the planet. People have always wanted to fly. Images of humans with wings have long been common, from the ancient Greek statue The Winged Victory of Samothrace to medieval angels. It was only through the relentless curiosity of 18th-century Europe that anyone figured out how to get off the ground. The irony is that the earliest men aloft never understood what made their balloons fly. Balloons of various sorts have been with us ever since, both the hot-air variety, now used exclusively for recreation, and airships with enclosed bags filled with lighter-than-air gases. But gas-filled aircraft were always too cumbersome and slow, and they had to be so large in relation to their cargo that they never became the primary means of air travel. That would fall to the powered airplane, whose story is almost entirely one of the past century. Wilbur and Orville Wright began with gliders, which had been around for some years, and which had demonstrated Bernoulli’s principle that it was the shape of the wing that made powered lift possible. The Wrights first modified existing glider designs to increase the control the pilot had over lift and vertical direction, then added an engine and propeller. They made the first powered flight on December 17, 1903. In 1919, commercial service began between London and Paris. The role of the aircraft in moving people from place to place dated from that small beginning; by half a century later it had completely supplanted ships and trains for long-distance travel. The airplane revolutionized terrestrial travel, but there was some feeling that we needn’t stop there. The problem was that airplanes could not take humans into space. For one thing, by definition, an airplane needs air, which runs out pretty soon when you head for space. For another, they need to develop an enormous amount of power to overcome gravity, and no conventional engine was strong enough. The answer: rockets. As early as 1926, Robert H. Goddard had launched a liquid-fuel rocket in the US, and made ever-larger ones over the next few years. While by 1935 his rockets had thrust enough to move faster than the speed of sound, they remained difficult to control. Throughout World War II, a team of German scientists worked at the Baltic town of Peenemunde to perfect a guidance system, and by war’s end they were using it to fire V2 missiles at London. Many of the team, including leader Werner von Braun, were acquired by the US after the war, to work on that country’s missile and space programs. Other members of the German team went to the USSR, which then pulled quickly ahead and launched the first artificial satellite -- Sputnik I -- in 1957. That jolted the American psyche, and the US cranked up its space industry to such a pace that men walked on the moon only 12 years later. Space travel carried a lot of glamour, but it was also controversial. In the socially conscious 1960s and ’70s, many were critical of the enormous sums spent on space missions, which could be better spent helping the poor both at home and in developing countries. But ultimately, the benefits of those early missions were immense. One was the advance in computer technology, which was necessary to control the spacecraft. The most notable result of the space program, however, was the revamping of the world’s telecommunications system by means of satellites. Sputnik I had no real function other than to prove that a satellite could be successfully placed in orbit around the earth. Within five years, however, artificial satellites were being used to ferry television and other signals across great distances. A decade later, geostationary satellites, which sit above a fixed spot on earth, made the reception of satellite-borne signals much simpler, as they dispensed with the need for expensive and complex tracking mechanisms for the receiving dishes. Today, thousands of satellites circle the planet, mapping the earth and skies, assisting in navigation, monitoring the weather, and performing a host of other functions. For most of us, the greatest impact comes from their ability to bounce communications signals from one point on earth to another. Chances are, every time we watch television, surf the Internet, or make a long-distance phone call, a satellite is somehow involved. Humans still make the trip into space, but not to walk on distant planets. Now they serve to deliver and repair the satellites on which we so heavily depend. ...Ian G. Masters
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