Inventor of the Week Archive
for a different Invention or Inventor
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
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