Satellite Cluster Provides Modular Growth of Communications Functions

Abstract

The orbiting antenna farm or large geostationary platform has been proposed as an efficient method for combining many satellite functions at a single orbital slot. Proponents claim that crossconnecting C, Ku, and Ka band communications networks and perhaps weather satellite readout at the spacecraft permits more efficient use of the available frequency spectrum and fixed frequency earth terminals. However, the expected economy of the large multi-functional platform is offset by its increased complexity and reduced reliability compared to a multiplicity of single-function satellites. A further disadvantage is that costs, development schedules, and introduction of new technology cannot be extended over a span of several years, as can be done with independent satellite launchings. The satellite cluster concept described here offers the platform's feature of interconnectivity, while avoiding its disadvantages. Single-function satellites can be added to the cluster as required, and maintained at distances which are small compared to those between adjacent orbital slots. This paper analyzes the marginal power and weight for providing interconnecting communications links; interconnection bandwidth, attitude control and stationkeeping requirements; and optimum satellite spacings within the cluster.