The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

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Aspacecraft in Earth orbit that supports communication
over long distances by relaying or reflecting
radio signals sent from the ground to other points
on the surface.
The possibility of using artificial satellites for radio
communications over global distances had been discussed
before World War II, but the modern concept
dates from a 1945 Wireless World article by Arthur C.
Clarke. 50 Clarke envisioned three relay stations in
geostationary orbit by means of which a message
could be sent from any point on Earth and relayed
from space to any other point on the surface. As an
application of such a system, Clarke suggested direct
broadcast TV—a remarkably advanced idea, given that
television was still in its infancy and it was not yet
known whether radio signals could penetrate the
ionosphere. The concept of the geostationary orbit
had been discussed earlier by Herman Noordung, but
Clarke gave the first detailed technical exposition of
satellite communications. His vision was realized
through the pioneering efforts of such scientists as
John Pierce of Bell Labs, the head of the Telstar program
and a coinventor of the traveling wave tube
amplifier, and Harold Rosen of Hughes Aircraft, who
was the driving force behind the Syncom program.
Most early communications satellites, such as Echo,
were simply big metal-coated balloons that passively
reflected signals from transmitting stations back to the
ground. Because the signals bounced off in all directions,
they could be picked up by any receiving station
within sight of the satellite. But the capacity of such
systems was severely limited by the need for powerful
transmitters and large ground antennas. Score,
launched in 1958, was technically an active communications
satellite. It had a tape recorder that stored messages
received while passing over a transmitting
ground station, then replayed them when the satellite
came within line of sight of a receiving station. However,
real-time active communications came of age in
1962, when Telstar 1 enabled the first direct TV transmission
between the United States, Europe, and Japan.
In the 1970s, advances in electronics and more
powerful launch vehicles made geostationary satellite
communications practicable and led to its rapid
expansion. The Syncom series demonstrated the viability
of the technique, and Early Bird—Intelsat 1—
communications satellite
became the first operational geostationary satellite. It
was followed over the next three decades by Intelsat
series of increasing power and capability.
In 1972, a policy change by the FCC (Federal Communications
Commission) cleared the way for domestic
satellite services and prompted RCA in 1975 to
launch Satcom 1. This was immediately used by a
group of entrepreneurs to transmit a new type of pay
TV known as Home Box Office (HBO) to cable
providers throughout the United States.
A number of developing countries, especially those
with large areas and diffuse populations, saw satellite
communications as an attractive alternative to expensive
microwave and coaxial land-based networks.
Indonesia led the way with Palapa 1 in 1976 and
Palapa 2 in 1977.
The late 1970s also saw the beginning of a revolution
with the introduction of small, affordable satellite
dishes about 3 m across, which consumers could
purchase and install on their own property. These
units made possible the direct reception of virtually
any transmission, including unedited network video
feeds and commercial-free shows. A pioneer in this
field was Ted Turner, the owner of WTBS, an independent
cable channel based in Atlanta, Georgia. In
1976, Turner leased an available transponder and
turned WTBS into the first superstation. This led to
the rapid expansion of direct satellite TV networks,
including Turner’s own Cable News Network (CNN),
which did not have to rely on the microwave relay
network and local affiliate transmitters of the three
major American commercial networks. The expansion
of community access TV (cable TV) led to greater
demand for high-quality satellite feeds. Today, direct
broadcast satellites (DBS) deliver programs to home
antennas measuring less than 50 cm in diameter.
The falling cost of satellites and launches has allowed
a number of companies to buy and market satellites,
and it has allowed other systems to provide international
services in competition with Intelsat. The growth
of international systems has been paralleled by domestic
and regional systems such as Telstar, Galaxy, and
Spacenet in the United States; Eutelsat and Telecom in
Europe; and many single-nation indigenous systems.
The 1990s have seen the development of LEO
(low Earth orbit), nongeostationary satellite concepts.