Harold Rosen
Born 1926

Spin Stabilized Synchronous Communications Satellite
Patent Number(s): 3,133,282

Inducted 2003

In 1957, the United States was facing a problem. The Russians had successfully launched Sputnik and effectively beat them into space. As a result, Harold Rosen, an engineer at Hughes Aircraft Company, found himself heading in a completely new direction from the airborne radar project on which he was working.

The need to develop global communications was clear. Global telephone calls were expensive, relying on cables to transmit signals, and global television transmission was nonexistent. Technology available at the time provided limited international communication with the use of numerous aluminum-coated balloons in a low-orbit above the Earth.

Given the demand for better international communication and new opportunities in aerospace, Harold Rosen began to pursue work on a new communications satellite.

Invention Impact

Rosen knew that to provide consistent 24-hour communication, he would need to develop an active communications satellite that remained in orbit with the Earth. To do this required a simple and lightweight design with a spin-stabilized control system to keep the satellite in synchronous orbit. The ultimate solution for a satellite that would maintain an orbit above a fixed point on earth came with "spin-stabilized configuration." One of the challenges of maintaining a satellite in this fixed orbit came from the heavy weight of its stabilizing devices. Rosen's ingenious solution was for a lightweight satellite that stabilized itself by continuous spinning.

Rosen's team, including Don Williams, an engineer with previous work on the development of a navigation satellite that became the predecessor to GPS, along with Tom Hudspeth and John Mendel, began work on creating a lightweight transmitter and receiver for use in the satellite. The team began building a ground model of the satellite for Hughes Aircraft in 1958 and received additional funding in 1960 to build a prototype. The team took their satellite to the Paris Air Show in 1961 and demonstrated the satellite's capabilities by taking pictures of the crowd, relaying them through the transmitter and receiver to beam the images back to the crowd. When they returned from Europe, the team received a contract from the government to build a flight model.

The government project, titled Syncom (Synchronous Communication) continued for another two years before the satellite launched in 1963. Syncom 1, a model of the satellite only intended for a few voice channels never made it off the ground, exploding at launch in February 1963. A few months later the team successfully launched Syncom 2 and the next year launched Syncom 3. With a wider band receiver, Syncom 3 could accommodate television signals and was used during the Tokyo Olympics to deliver the first continuous transoceanic television broadcast.

With the launch of Syncom 1, CommCast Corporation was formed by an act of Congress, charging it with a charter to provide commercial communications via satellite. With the success of Syncom 2 and Syncom 3, Hughes Aircraft was selected to build a satellite based on its previously demonstrated technology but with commercial frequencies. This new satellite was first launched in 1965.

CommCast worked with European affiliates to form an international communications satellite organization, IntelSat, thus leading the way to international commercial communications via satellite.

Inventor Bio

Born in 1926 in New Orleans, Louisiana, Harold Rosen graduated from Tulane University in 1947 with a degree in Engineering and went on to receive degrees from the California Institute of Technology. Always interested in math and science while growing up, Rosen built a crystal radio, became a radio amateur in high school and was a transmitter engineer at a radio station in college.

Harold Rosen has received such honors as the Lloyd V. Berkner Award from the American Astronautical Society in 1976 and Presidential Medal of Technology in 1985. He was also inducted into the Society of Satellite Professionals International Hall of Fame in 1987, and during his lifetime he has been the recipient of more than fifty patents.