The problem to solve
Before satellites, long-distance communication used wires, radio and cables. Telephone and telegraph lines crossed continents, and undersea cables connected continents, but cables were expensive and had limited capacity. Radio could cross the oceans on shortwave, though quality depended on conditions in the upper atmosphere. Live television could not cross the Atlantic at all, because the high frequencies it needed travel in straight lines and do not follow the curve of the Earth. A relay placed high above the planet looked like a way around that limit, because a signal sent up could be seen from far apart on the ground.
Clarke’s 1945 proposal
The idea is most often credited to Arthur C. Clarke, then a British engineer and writer, who published an article titled “Extra-Terrestrial Relays” in the magazine Wireless World in October 1945. He described how a station in an orbit about 35,800 kilometers above the equator would circle the Earth in 24 hours, so that it would stay over one spot. He suggested that three such stations, spaced around the globe, could provide coverage for nearly the entire world. He envisioned crewed stations with people to maintain them, which turned out not to be necessary.
Clarke did not invent the underlying physics. Others had written about orbits and space stations earlier, as noted in our article on satellite pioneers, and the geostationary orbit had been mentioned by Hermann Potočnik (writing as Noordung) in 1929. Clarke’s contribution was to spell out the communications use and its design in clear terms. He also did not patent the idea, and he later joked that he might have been rich if he had. It is sometimes called the Clarke orbit.
A bridge idea: passive reflectors
Nothing could be launched until rockets existed. After 1957, the first communications experiments used simple methods. SCORE, launched in December 1958, was a U.S. Air Force satellite that stored and rebroadcast a recorded Christmas message from President Eisenhower. In 1960, NASA launched Echo 1, a large aluminum-coated balloon that reflected signals back to the ground. This “passive” satellite needed no equipment of its own, and the signals it returned were very weak. John R. Pierce at Bell Laboratories had written about the possibilities in the mid-1950s and was involved in these experiments.
Telstar
The next step was an “active” satellite that received a signal, amplified it and sent it back. Telstar 1, built by Bell Laboratories for AT&T and launched by NASA on July 10, 1962, was the first satellite of this kind to be widely noticed. It was a small sphere about 88 centimeters across, in an elliptical orbit that took it around the Earth in a bit over two and a half hours. Because it was not stationary, ground antennas had to track it, and a given pair of stations could use it only for a short time each pass.
Within days, Telstar relayed the first live television pictures between the United States and Europe, with ground stations in Maine, England and France. The programs were short and the images were of limited content, but the public took notice. Telstar also carried telephone calls and fax, and it was a media sensation, even inspiring a popular instrumental record. Radiation in orbit damaged its electronics, and it stopped working in early 1963. The relay of television in this period is related to the developments in our article on television broadcasting.
Geostationary satellites
Clarke’s geostationary design was harder to achieve, because the satellite had to be lifted to a high orbit and then maneuvered precisely. Hughes Aircraft engineers, including Harold Rosen and Donald Williams, built the small Syncom satellites for NASA. Syncom 2, launched in July 1963, reached a geosynchronous orbit, meaning that it returned to the same place daily, though its orbit was slightly inclined so it drifted in a figure eight. Syncom 3, launched in August 1964, was nearly stationary and was used to carry television coverage of part of the Tokyo Olympics in October 1964 to North America.
The first commercial geostationary communications satellite was Intelsat I, often called Early Bird, launched in April 1965. It could carry roughly 240 telephone circuits, or a single television channel, between Europe and North America. By today’s standards that is a tiny capacity, yet it was a first, and it was operated by an international organization, Intelsat, which had been formed by a group of countries in 1964. In the United States, Congress had created the Communications Satellite Corporation (Comsat) in 1962 to take part in the project. The Soviet Union developed a separate system, Molniya, using highly elliptical orbits suited to high-latitude regions.
What satellites changed
Communications satellites made it practical to broadcast live events around the world and to connect places that cables could not reach easily. In the late 1960s and 1970s, networks of satellites carried international telephone traffic, news feeds and television, and large Earth stations proliferated. Later, smaller dishes allowed direct delivery of television to homes, and portable terminals supported ships, aircraft and remote regions. Many of the applications that grew from these are described in our article on satellite radio.
The effect was not only technical. Live international television gave viewers a sense of shared events, and governments took an interest in who controlled satellite capacity. Over time, fiber optic cables took over most of the heavy long-distance traffic, since glass fibers have large capacity and lower delay, while satellites remain important for broadcasting, mobile and remote services. The hope that the new systems would provide a cheaper phone service everywhere was only partly met.
A note on credit
Clarke’s article is rightly famous, but satellite communications was built by many engineers at Bell Labs, Hughes, NASA, RCA and elsewhere. It is a good example of how an idea, a physical principle and a successful device often have different authors. Clarke himself was generally modest in discussing his role.