Some orbits for communication-satellite systems affording multiple access

The paper considers the influence of orbital parameters on the economic provision of simultaneous multiple interconnections between large numbers of earth stations in a global communication-satellite system. In order to provide direct communication between many countries which may be widely separated geographically, and also to avoid certain technical problems, it is most important to provide the interconnections wherever practicable on a one-hop basis. It is also desirable that each earth station shall work simultaneously to as few satellites as possible. These requirements can most readily be met by a system of geostationary satellites. However, such a system may prove unacceptable from other points of view (e.g. that of transmission delay). From an examination of the relations between coverage zones, orbital parameters and number of satellites required, it is concluded that large coverage zones may also be obtained with relatively few satellites by using systems in which each satellite follows the same earth track as its predecessor. The coverage provided by a number of such systems is discussed.