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Unit 12: Space-based Wireless WANs

12.1.1 Evolution of Communication Satellites Notes

In 500 years, when humankind looks back at the dawn of space travel, Apollo’s landing on the
Moon in 1969 may be the only event remembered. At the same time, however, Lyndon B. Johnson,
himself an avid promoter of the space program, felt that reconnaissance satellites alone justified
every penny spent on space. Weather forecasting has undergone a revolution because of the
availability of pictures from geostationary meteorological satellites--pictures we see every day on
television. All of these are important aspects of the space age, but satellite communications has
probably had more effect than any of the rest on the average person. Satellite communications is
also the only truly commercial space technology- -generating billions of dollars annually in sales
of products and services.

The Billion Dollar Technology

In fall of 1945 an RAF electronics officer and member of the British Interplanetary Society, Arthur
C. Clarke, wrote a short article in Wireless World that described the use of manned satellites in
24-hour orbits high above the world’s land masses to distribute television programs. His article
apparently had little lasting effect in spite of Clarke’s repeating the story in his 1951/52 The
Exploration of Space . Perhaps the first person to carefully evaluate the various technical options
in satellite communications and evaluate the financial prospects was John R. Pierce of AT&T’s
Bell Telephone Laboratories who, in a 1954 speech and 1955 article, elaborated the utility of a
communications “mirror” in space, a medium-orbit “repeater” and a 24-hour-orbit “repeater.” In
comparing the communications capacity of a satellite, which he estimated at 1,000 simultaneous
telephone calls, and the communications capacity of the first trans-atlantic telephone cable (TAT-
1), which could carry 36 simultaneous telephone calls at a cost of 30-50 million dollars, Pierce
wondered if a satellite would be worth a billion dollars.
In 1960 AT&T filed with the Federal Communications Commission (FCC) for permission to launch
an experimental communications satellite with a view to rapidly implementing an operational
system. The U.S. government reacted with surprise-- there was no policy in place to help execute
the many decisions related to the AT&T proposal. By the middle of 1961, NASA had awarded a
competitive contract to RCA to build a medium-orbit (4,000 miles high) active communication
satellite (RELAY); AT&T was building its own medium-orbit satellite (TELSTAR) which NASA
would launch on a cost-reimbursable basis; and NASA had awarded a sole- source contract to
Hughes Aircraft Company to build a 24-hour (20,000 mile high) satellite (SYNCOM).

By 1964, two TELSTARs, two RELAYs, and two SYNCOMs had operated successfully in space. This
timing was fortunate because the Communications Satellite Corporation (COMSAT), formed as a
result of the Communications Satellite Act of 1962, was in the process of contracting for their first
satellite. COMSAT’s initial capitalization of 200 million dollars was considered sufficient to build
a system of dozens of medium-orbit satellites. For a variety of reasons, including costs, COMSAT
ultimately chose to reject the joint AT&T/RCA offer of a medium-orbit satellite incorporating the
best of TELSTAR and RELAY. They chose the 24-hour-orbit (geosynchronous) satellite offered
by Hughes Aircraft Company for their first two systems and a TRW geosynchronous satellite for
their third system.

Did u know? On April 6, 1965 COMSAT’s first satellite, EARLY BIRD, was launched from
Cape Canaveral. Global satellite communications had begun.

The Global Village: International Communications

Some glimpses of the Global Village had already been provided during experiments with
TELSTAR, RELAY, and SYNCOM. These had included televising parts of the 1964 Tokyo
Olympics. Although COMSAT and the initial launch vehicles and satellites were American,

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