Although the performance of communication satellites could be predicted theoretically, until 1962 or 1963 there was considerable doubt concerning whether their actual performance would match the theory. This was one of the basic motivations for the early communication satellite experiments. Two other important factors were the desire to prove the satellite hardware (since space technology in general was still in its infancy) and the need to test operational procedures and ground equipment. Whereas the first few experiments (SCORE, Courier, and Echo) were very brief beginnings, the Telstar, Relay, and Syncom satellites laid definite foundations for the first operational satellites.

Communication satellites have been in commercial operation and military service since 1965 and 1967, respectively. However, there was, and still is, the need for additional experimental satellites. These are used to prove new technologies for later introduction into operational satellites. Some satellites combine experimental objectives with preoperational demonstrations. Discussions of such satellites are included in this chapter if their emphasis is primarily experimental; those directly continued by operational satellites are described in later chapters.

West Ford

• The West Ford concept [1–4] grew out of a 1958 summer study on secure, hard, reliable communications. The following conclusions were reached
• Use satellites and microwave frequencies for long-distance communications. Put all active equipment on the ground for increased reliability
• Use a belt of dipoles instead of a single satellite for hardness

When the concept was defined openly, there was some adverse reaction because of the uncertain effects on optical and radio astronomy. After some time, the project was allowed to proceed under certain restrictions.

West Ford and Echo (last month's satellite history subject) were the only two passive communication reflectors put into orbit. Echo could rightly be called a satellite, but the West Ford reflector consisted of 480 million copper dipoles. The length was chosen to correspond to a half wavelength of the 8 GHz transmission frequencies used in the program. Other West Ford details are as follow.

Satellite

• 480 million copper dipoles, each 0.72 in. long, 7 x 10–4 in. diam
  88 lb dispenser plus dipoles; dipoles weighed 43 lb

Frequencies

• 7750, 8350 MHz

Orbit

• 1970 nmi nominal altitude
• Dispersion: 8 nmi cross-orbit, 16 nmi radially, 1300 ft average distance between dipoles

Orbital History

• First: launched 21 October 1961, dispenser did not release dipoles
• Second: launched 9 May 1963, fully dispersed August 1963
• Atlas—Agena B launch vehicle
• Management—developed by MIT Lincoln Laboratory

The dipoles were dispensed from an orbiting container in May 1963. At first, all were concentrated in one portion of the orbit. During the first few weeks, voice and frequency shift keying (FSK) data up to 20 kbps were transmitted from Camp Parks (Pleasanton, California) to Millstone Hill (Westford, Massachusetts—the source of the project name). Four months later, when the belt was fully extended, the density was much lower, and only 100 bps data were transmitted. Because of this low capacity and the increasing performance of active satellites, no further experiments of this type were attempted.

The last transmission of signals was accomplished in 1965, and a combination of measurements and analytic predictions indicated that all the dipoles would reenter the atmosphere before the end of the 1960s.

The first Courier launch was unsuccessful due to of a booster failure. The second launch, in October 1960, was successful. Two ground terminals, located in New Jersey and Puerto Rico, performed the communication tests. The satellite performed satisfactorily until 17 days after the launch, when communications were stopped by a command system failure.

Special Issue on Project West Ford, Proceedings of the IEEE, Vol. 52, No. 5 (May 1964).
2. I. I. Shapiro, “Last of the West Ford Dipoles,” Science, Vol. 154 (16 December 1966).
3. W. W. Ward and F. W. Floyd, “Thirty Years of Research and Development in Space Communications at Lincoln Laboratory,” The Lincoln Laboratory Journal, Vol. 2, No. 1 (Spring 1989).
W. W. Ward and F. W. Floyd, “Thirty Years of Space Communications Research and Development at Lincoln Laboratory,” in Beyond the Ionosphere: Fifty Years of Satellite Communication, A. J. Butrica, ed., NASA History Office, Washington, D.C. (1997), ch. 8.

Author Biography
Donald H. Martin is a senior engineering specialist in The Aerospace Corporation’s Architectures and Spectrum Management Office. Martin joined the Communications Department in the Engineering Group at Aerospace in 1968 after receiving B.S. and M.S. degrees in engineering from the University of California, Los Angeles. He has been collecting information on satellite communications since 1972. Wen his manager offered him a choice of assignments, of the three options, he chose to write a description of communication satellites then in orbit. The assignment grew the next year to include a report describing satellites being built and gradually expanded to the first edition of Communication Satellites in 1986, with the book now in its Fifth Edition.

Reprinted from:
Communication Satellites (5th Ed.)
Authored by
Donald Martin, Paul Anderson, Lucy Bartamian
Courtesy of The Aerospace Corporation