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:''For the educationalist, see Harold Rosen (educationalist).'' Harold A. Rosen (born 1926 in New Orleans, Louisiana) is an American electrical engineer, known as "the father of the geostationary satellite", and "father of the communications satellite".〔''AW&ST'', 24 March 2014, p. 51〕 He formed and led the team that designed and built the first geosynchronous communications satellite, Syncom, for Hughes Aircraft Company. ==Career== Rosen graduated from Tulane University in 1947 with a Bachelor of Engineering degree in electrical engineering. He received his M.S. (1948) and Ph.D. (1951) in electrical engineering from the California Institute of Technology. While still in graduate school, he began working for Raytheon, where he helped develop early anti-aircraft guided missiles, making many innovations in the fields of radar and missile guidance and control. After joining the Hughes Aircraft Company in 1956, and while he was working on the development of airborne radars, the world was catapulted into the space age by the 1957 launch of Sputnik, the world's first artificial satellite. At the same time, his department’s most important program was cancelled. His boss, Frank Carver, challenged him to find a worthwhile new project that could keep the skilled staff gainfully employed. Stimulated by the possibilities of the new Space Age, Rosen wanted it to be some kind of space program. Because at that time international telephony was very expensive and hard to arrange, and transoceanic television was impossible, he decided it should be some kind of communication satellite since these problems could be solved that way. He began to research what kind of communication satellite system would work best for this purpose. At the time, Rosen was unaware of science writer Arthur C. Clarke's 1945 description of a geosynchronous satellite, but he was aware of the conventional wisdom regarding geostationary satellites, expressed most stridently by the highly-regarded Bell Labs, at that time the world’s leading communications R&D entity, in a March 1959 IRE Journal titled “Transoceanic Communications Via Satellites,” written by John Pierce and Rudy Kompfner. They expressed the view that geostationary satellites would be too heavy to be launched by the rockets that were then available. And, even if geostationary satellites could be launched, their presumed complexity would prevent them from having a long enough lifetime to be commercially viable. Rosen, in reading their paper, felt otherwise. He reasoned that since Bell Labs designed communication equipment for ground applications, it had little incentive for keeping the weight down. Also, he was confident that his previous experience in guided missile design was more relevant for designing the control system for such a satellite and that the supposedly-complex control system the authors claimed would be necessary would not be needed. Rosen had an epiphany when it occurred to him that if he used spin-phased impulses on a spin-stabilized satellite, he could have a simple, long-lived control system to go along with the satellite's lightweight electronics. He gathered a small team of gifted colleagues (most notably, Don Williams, Tom Hudspeth and John Mendel) to convert the concept into a design for a practical geostationary communication satellite system. He was able to convince an initially reluctant management to invest in the development of a prototype, and subsequently convince the U.S. government to fund the Syncom program, a flight program that was based on the Hughes prototype. After a discouraging rocket failure that doomed Syncom I in February 1963, Syncom II was successfully launched in August 1963. It was followed by Syncom III in 1964, in time to relay live television signals from Tokyo during the Summer Olympics. The first commercial satellite, Early Bird, was launched in 1965. With communication satellites a commercial reality, Hughes formed a division to pursue this as a business, and Rosen became its technical director. He later became a vice president of Hughes and a member of its policy board in 1975. In these roles he was key in helping to build the world’s largest communications satellite business at Hughes Aircraft Company. Upon his retirement from Hughes in 1992, he joined with his brother Benjamin in another development project. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Harold Rosen (electrical engineer)」の詳細全文を読む スポンサード リンク
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