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Rosen

Geosynchronous Satellite

Rosen Harold Rosen turned a prediction of science fiction into a reality, inventing the geosynchronous satellite --- the essential element of global telecommunications.

Harold Rosen was born in New Orleans, Louisiana in 1926. He resolved to become an engineer while still a child, even though the only engineer his family knew was forced by the Great Depression to drive a taxicab to earn a living. After receiving a BSEE from Tulane University in 1947, Rosen went on to earn an MS (1948) and PHD (1951) from the California Institute of Technology.

Rosen's first professional position was with Raytheon Company, working on guidance and control systems for early missiles. At Raytheon, he invented an improved homing guidance system for the Sparrow missile, based on radar- and accelerometer-based feedback, as well as a desktop-model analog computer.

In 1956, Rosen joined Hughes Aircraft Company, where he first worked on the research and development of anti-aircraft missiles, fire control systems, and radar. In 1957, he was assigned to new products for the radar division. Like many American engineers, Rosen felt both inspired and challenged by the launch of the first Soviet Sputnik satellite that year. He also learned from colleagues that in 1945, science fiction writer Arthur C. Clarke had described the benefits of a geosynchronous satellite --- that is, a satellite that held its position above a fixed point on the rotating earth.

Rosen's team decided to develop a communications satellite that could maintain such a geostationary "orbit." Other researchers had designed such satellites on paper, but these were far too heavy to be launched in the 1950s and '60s. After two years of effort, Rosen solved the problem, relying on a principle of physics that he had worked on in graduate school with the Nobel Prize-winning physicist Carl Anderson (discoverer of the positron), namely spin-stabilization.

Spinning objects are many times more impervious to outside forces, including resistance, than inert objects (which is why footballs and bullets are spun as they fly). Rosen's major insight was that a satellite made to spin at a constant rate would have the necessary stability that previous versions had lacked. Rosen's system used solar panels and spin-based impulses to control the satellite's thrusters economically, and a revolving antenna pattern that always encompassed the earth as the satellite spun. Improvements in communications design by Rosen, John R. Pierce, and their colleagues --- e.g., smaller repeaters and receivers, and a traveling-wave tube suitable for space --- allowed the satellite to be built small enough to be launched.

Rosen helped Hughes win additional funds from NASA and the US Department of Defense, which allowed the first geosynchronous satellite, Syncom I, to be launched in 1961. Syncom I exploded before reaching its final orbit. But just five months later, Syncom II succeeded, establishing orbit at 22,300 miles above the earth's surface: it went into service as an international telephone link in 1963. In 1964, Syncom III provided the world's first transoceanic television broadcast (of the Olympics), after Rosen and his team constructed a special earth terminal to receive its transmissions. Today, the importance---indeed, the absolute necessity---of geosynchronous satellites for telecommunications, television, and the Internet needs no elaboration.

Rosen remained at Hughes Aircraft, rising to Vice President before his retirement in 1992. From 1993-97 Rosen and his brother Benjamin operated Rosen Motors, whose focus was developing a hybrid motor vehicle with a special "turbogenerator" that could both generate and store energy.

Though unknown to the public, Harold Rosen is rightly famous in his field. Among the many honors he has won are the IEEE's Alexander Graham Bell Medal (1982), the National Medal of Technology (1985), and the National Academy of Engineering's Draper Prize (1995).



[Sept. 2000]

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