ITH a modest beginning in the early 1960s, satellite technology has matured enough to be accepted on a worldwide basis as one of the major media for the communication networks. Communication satellites have grown rapidly in size and complexity during the 1970s and have proved their worth through steadily decreasing unit circuit cost as well as exceptional reliability.1>2 However satellite technology development is nowhere near saturation, and significant advances that will provide further reduction in cost as well as introduction of several new types of services are to be expected.3 This paper presents salient aspects of the major technological challenges ahead in this field. While international communication has been emphasized, most of the areas identified are relevant to domestic and regional satellite systems as well. The emphasis throughout is on individual technologies, rather than on specific system or network growth, except in situations where these aspects are germane to the development of the technologies themselves. The overall system aspects influencing the choice of technologies during the 1980s are: the need to provide increased system capacity through more efficient utilization of available bandwidth, introduction of new frequency bands, optimum utilization of newer launch vehicles, longer spacecraft life through progressive elimination of limited-life devices and subsystems, and flexibility to meet and adapt to a variety of space segment requirements. The very first communication satellite itself represented a frequency reuse application, since the 6/4 GHz bands were simultaneously utlized by terrestrial and space systems. Once the total 500 MHz band had been utilized in the INTELSAT IV class spacecraft, the reuse of this bandwidth in the space segment itself assumed importance. Arising out of these efforts, INTELSAT IVA achieved a modest spatial reuse. The INTELSAT V spacecraft will have a combination of both spatial and polarization reuse as well as a new 14/11 GHz band. The next generation of spacecraft currently being planned is expected to have extensive reuse (up to 6-20 times depending on application) of some or all the frequency bands available today for satellite communication. Success in achieving such a high degree of frequency reuse is dependent on several system and payload technologies as well as the ability of the spacecraft bus and other support subsystems and launch vehicles to accommodate the increased capability efficiently. Multiple reuse of frequency bands through a large number of physically separate antenna beams requires an appreciable level of interconnecti vity onboard the spacecraft. Satelliteswitched time divisional multiple access (SS-TDMA) and other digital technologies provide the necessary tools for providing this interconnectivity between different beams from a single satellite. From the point of view of an overall global network, all satellites—whether domestic, regional or international—are integrated with one or more telecommunication networks. Such networks achieve maximum flexibility when all the nodes are capable of being interconnected, generally in a hierarchial fashion. Both from the point of view of providing network flexibility and of mitigating the effects of propagation time delays in certain situations, direct links between satellites [ inter satellite or cross links (ISL)] are emerging as one of the important tools for the 1980s. Beginning with a point-to-point role, the ISLs combined with onboard digital technology are expected ultimately to develop an efficient and flexible role as switchboards in the sky for geostationary satellites in the global communication networks. This paper highlights some of the principal facets of the technologies enumerated above.