Communication Satellites
History


LEO
MEO
GEO

Bands

ITU

Routing

links page

H
I
S
T
O
R
Y

Arthur C. Clark wrote the first well-known article on communication satellites. "Extra-Terrestrial Relays" was published in Wireless World in 1945. In the article, Clark discussed geosynchronous earth orbit and the possibility of covering the earth with three satellites.

The actual journey into space began October 4, 1957, when the Soviet Union launched Sputnik 1, the world's first orbital spacecraft, which orbited the world for three months. A month later the Soviets launched Sputnik 2 and its passenger Laika, a dog who has the distinction of being the first known living creature to escape earth and enter outerspace. The space race was on, and in February of 1958, the United States launched Explorer 1.

The first communication satellite was launched on December 18, 1958. Signal Communication by Orbital Relay (SCORE), which broadcasted a Christmas message from President Eisenhower - "Peace on Earth, Good will toward men" - orbited the earth for 12 days until the batteries failed. The main purpose of the SCORE project was to prove that an atlas missile could be put into orbit.

Combined, the U.S. and U.S.S.R. launched six satellites in 1958, 14 satellites in 1959, 19 in 1960 and 35 in 1961. In 1962, the United Kingdom and Canada launched satellites of their own, along with the 70 satellites launched by the U.S. and U.S.S.R.

On August 12, 1960, the United States launched Echo 1, a passive reflector satellite with no amplification possibilities. Echo 1 could only reflect the radiation back to earth. At the time of its launch, it was thought that passive reflector satellites could serve a purpose in communications, but the technology was soon abandoned.

Bell Telephone Laboratories assisted in the Echo 1 project. Knowledge gained working on Echo 1 helped Bell to develop Telstar, an experimental satellite that relayed television signals. Telstar was launched into medium earth orbit in 1962. In the six months following the launch, stations in the United States, Britain and France conducted about 400 transmissions with multichannel telephone, telegraph, facsimile and television signals, and they performed over 250 technical tests and measurements.

Near complete Earth coverage (excluding polar areas) was achieved with the development of Intelsat and the launching of satellites into geosynchronous earth orbit over the Atlantic (1965), Pacific (1967), and Indian oceans (1969). A combination of more than 130 governments and international organization control Intelsat. Intelsat, along with Inmarsat, which is used in international shipping, is open to use by all nations. The Intelsat consortium owns the satellites, but each nation owns their own earth stations. In 1997 Intelsat had 19 satellites in geostationary orbit.

NASA led the new wave of communication satellite technology with the launch of Advanced Communications Technology Satellites (ACTS) in 1993. ACTS pioneered the use of spot beams, on-board storage and processing, and all digital transmission, which combined made a successful communication satellite constellation more feasible. Each of these innovations serve a certain technological purpose that makes and internet in the sky more likely.

  • Spot beams subdivide a satellite's footprint which allows the satellite to use its portion of the spectrum more efficiently
  • On-board storage and processing allows for inter-satellite communication and the caching of information until a spot beam finds its target
  • All-digital transmission allows a satellite to incorporate error codes into its signal which helps to overcome rain fade.

Following the breakthrough, several corporations decided to get invest in broadband satellites. In 1997 the FCC gave permission to 13 companies to use a portion of the sky and a portion of the electromagnetic for their satellites systems and their signals. Among the companies was Hughes, Loral, Motorola, EchoStar and Teledesic, a company with the backing of Bill Gates and Craig McCaw.

Not all of these companies will be able to make it in space, and Motorola has already failed with their 66 satellite system, Iridium, which was supposed to provide mobile telephone service. But if they succeed, accessing to their internet will be possible no matter where you are.

Bibliography

Email at
djcoffey@ufl.edu
Electronic
publishing
final project
Dec. 7, 1999