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1945 __ Extra-Terrestrial Relays — Geostationary satellites
Arthur C. Clarke (1917-2008)
Comment : Arthur C. Clarke proposes geostationary satellites. Up until this time all international communications relied on either short wave radio transmissions or cable links. Short wave radio was unreliable and subject to high levels of interference, and international telephone cables were exceedigly expensive. In 1945 the author Arthur C Clarke wrote a historic article in Wireless World describing a system that used satellites in geostationary orbit. Signals would be transmitted up to the satellite that would rebroadcast them back to the earth. In view of their altitude above the earth the signals would be able to be received many thousands of miles away from the original transmitting station. Clarke calculated that only three satellites would be required to cover around the globe. His idea was revolutionary, and it took many years before the technology was available for it to be implemented.The first reference to geostationary satellites is Clarke's letter to the editor titled Peacetime Uses for V2 published in the 1945 February issue of Wireless World (page 58). Clarke privately circulated in 1945 May a proposal titled The Space-Station: Its Radio Applications in six typed manuscripts. The top copy of that is now in the National Air and Space Museum, Smithsonian Institution, Washington D.C. It was reprinted in Spaceflight, Vol 10. no 3, March 1968 pp 85-86 and in Ascent to Orbit pp 57-58. In Ascent to Orbit Clarke says the paper with original title The Future of World Communications was written in late June and submitted to the RAF censor on July 7th. It was sent to Wireless World on August 13th and accepted on September 1st. The editor had changed title to Extra-Terrestrial Relays and published it in the 1945 October issue of Wireless World (pages 305-308). (Compiled from various sources)
Original excerpt : « V2 for Ionosphere Research?.ONE of the most important branches of radio physics is ionospheric research and until now all our knowledge of conditions in the ionosphere has been deduced from transmission and echo experiments. One of the more modest claims of the British Interplanetary Society was that rockets could be used for very high altitude investigations and it will not have escaped your readers' notice that the German long-range rocket projectile known as V2 passes through the E layer on its way from the Continent. If it were fired vertically without westward deviation it could reach the F1 and probably the F2 layer. The implications of this are obvious: we can now send instruments of all kinds into the ionosphere and by transmitting their readings back to ground stations obtain information which could not possibly be learned in any other way. Since the weight of instruments would only be a few pounds--as compared with V2's payload of 2,000 pounds--the rocket required would be quite a small one. Its probable take-off weight would be one or two tons, most of this being relatively cheap alcohol and liquid oxygen. A parachute device (besides being appreciated by the public!) would enable the rocket to be re-used. This is an immediate post-war research project, but an even more interesting one lies a little farther ahead. A rocket which can reach a speed of 8 km/sec parallel to the earth's surface would continue to circle it for ever in a closed orbit; it would become an ``artificial satellite.EXTRA-TERRESTRIAL RELAYS - Can Rocket Stations Give World-wide Radio Coverage? By ARTHUR C. CLARKE.ALTHOUGH it is possible, by a suitable choice of frequencies and routes, to provide telephony circuits between any two points or regions of the earth for a large part of the time, long-distance communication is greatly hampered by the peculiarities of the ionosphere, and there are even occasions when it may be impossible. A true broadcast service, giving constant field strength at all times over the whole globe would be invaluable, not to say indispensable, in a world society. Unsatisfactory though the telephony and telegraph position is, that of television is far worse, since ionospheric transmission cannot be employed at all. The service area of a television station, even on a very good site, is only about a hundred miles across. To cover a small country such as Great Britain would require a network of transmitters, connected by coaxial lines, waveguides or VHF relay links. A recent theoretical study has shown that such a system would require repeaters at intervals of fifty miles or less. A system of this kind could provide television coverage, at a very considerable cost, over the whole of a small country. It would be out of the question to provide a large continent with such a service, and only the main centres of population could be included in the network. The problem is equally serious when an attempt is made to link television services in different parts of the globe. A relay chain several thousand miles. long would cost millions, and transoceanic services would still be impossible. Similar considerations apply to the provision of wide-band frequency modulation and other services, such as high-speed facsimile which are by their nature restricted to the ultra-high-frequencies. Many may consider the solution proposed in this discussion too farfetched to be taken very seriously. Such an attitude is unreasonable, as everything envisaged here is a logical extension of developments in the last ten years--in particular the perfection of the long-range rocket of which V2 was the prototype. While this article was being written, it was announced that the Germans were considering a similar project, which they believed possible within fifty to a hundred years. Before proceeding further, it is necessary to discuss briefly certain fundamental laws of rocket propulsion and ``astronautics. » (A rocket which achieved a sufficiently great speed in flight outside the earth's atmosphere would never return. This ``orbital velocity is 8 km per sec. 5 miles per sec, and a rocket which attained it would become an artificial satellite, circling the wor)
Urls : http://www.radio-electronics.com/info/radio_history/radiohist/radio_history.php (last visited ) http://lakdiva.org/clarke/1945ww/ (last visited )

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