Space Communications

This special issue of Space Communications contains nine papers derived from a study, ‘Global satellite communications technology and systems’, sponsored by NASA and the NSF. The purpose of this study was to compare the position of the US in commercial satellite communications technology, research, development and markets with that of the rest of the world. It included visits to over 65 satellite manufacturers, service providers and R&D Institutes located in North and South America, Europe, Asia and Africa. These papers include overviews and country by country material on R&D activities, technology status, markets and trends from this study. The conclusions of this panel indicate that the US continues to have a strong presence in this large and rapidly growing global industry but that European and Asian entities are making significant investments in their manufacturing and R&D activities and are becoming major participants in this satellite communications industry. The migration of US aerospace corporations from being primarily manufacturers of spacecraft to being primarily satellite service providers could serve to undercut necessary longer term R&D to develop new technologies.

The National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF) commissioned a panel of scientists and engineers in 1997 to benchmark the global status of commercial communications satellite technology, markets and regulatory and policy issues. After visiting or interviewing over 60 manufacturing, R&D laboratory, service provider and government institutions in North and South America, Europe and Asia, the review panel concluded as follows:

7.3cm\begin{itemize} \item Many European and Asian governments are increasing their satellite communications R&D programs and supporting demonstrations and space marketing efforts, relative to the US.

\item The US is currently the leader in new technology and its insertion into commercial satellite systems, but ambitious foreign efforts threaten this position.

\item Global commercial satellite communications is a large and rapidly growing business.

\item New technology is being inserted into satellites at an increasingly rapid pace with an increasing number of international participants.

\item Aerospace communications companies, worldwide, are consolidating their efforts and are expanding into the end user service business.

\item The ‘Direct‐to‐End User’ mass consumer satellite service industry has the potential to be quite large and is changing the way satellites are manufactured and deployed and is creating a potentially large satellite terminal industry.

\item Satellite manufacturing is increasingly becoming a design, assembly and test operation with parts and sub‐systems obtained from global suppliers. \end{itemize}

7.3cm \begin{itemize} \item This increased use of satellites for communications services is creating a shortage of spectrum and orbital slots and is resulting in spectrum utilization conflicts with terrestrial wireless service providers.

\item Future development of commercial satellite communications is dependent on the resolution of key regulatory, trade, spectrum, inter‐operability and standards issues and government leadership is vitally needed.

\item There are opportunities for international cooperation to facilitate the development of satellites technologies, systems, standards and protocols. \end{itemize}

There is concern that unless several issues are addressed, particularly an increase in long term oriented R&D and trade and regulatory issues, the US may experience a deterioration of its leading position in the manufacture of satellites for global service providers and the initiation of new services, much in the way that it lost its leading position in the launch of commercial satellites.

The last decade of the 20th century has been a period of considerable growth for the satellite communications business. This growth has been dominated by the distribution of TV to cable head ends, network affiliates and directly to the home. We expect that the next decade will continue to be a period of impressive growth for satellites. Increased demand for TV and for the transport and delivery of data and Intelsat services should drive this growth. Global demand for communications and deregulation should be a major factor as well. While new technology is important, the driving forces for this growth will be the marketplace for these services. The delivery of services directly to the home and to small businesses is expected to be a major driving force. While satellite‐based mobile telephony has experienced a disappointing start, this market and the delivery of Internet material directly to the home is expected to be a major satellite business. The 20th century relied on satellites located in GEO for these services. This will change, as constellations of LEO and MEO satellites provide global delivery of mobile and Internet services.

This increased satellite business has not gone unnoticed. Our study indicated an impressive interest in the future of satellites and their increased markets by both foreign governments and businesses. These entities have instituted significant R&D programs to ensure their future presence in this growing market. The US needs to take heed to this foreign interest and to make similar R&D investments in this technology. In addition to technology, the ability of satellites to continue their business growth is dependent on the timely addressing of such issues as; continuing deregulation, the resolution of spectrum, standards, trade agreements, globalization of business entities and business and government leadership.

In recent years there has been an explosion of interest in new satellite systems, witness the fact that in the US alone the Federal Communications Commission has received 43 filings in response to four recent Notice of Proposed Rule Makings. This paper reviews (in Part I) some of the underlying reasons for this surge of interest, as well as the filings themselves. A combination of factors seems to be at work, including a) the enormous growth in telecommunications worldwide (fueled by increased global trade, the enormous growth of the World Wide Web and e‐commerce, deregulation, and the introduction of new services) and b) changes in the structure of the commercial satellite communication industry (such as the entry of new players, e.g., Motorola and vertical integration of satellite manufacturers – Hughes, Loral, Lockheed Martin into services). In Part II the prospects for the long‐term future of the industry are examined, where it is concluded that, despite all the present interest, satellites will likely see continued use only where they offer unrivalled competitive advantages, such as for broadcasting, reaching mobile platforms and areas presently lacking adequate terrestrial communications facilities.

This paper is based on material extracted from the WTEC Panel Report Global Satellite Communications Technology and Systems, December 1998. It presents an overview of key technology trends in communications satellites in the last few years. After the introduction which deals with such issues as the transformation of the one‐at‐a‐time approach for building satellites to a production‐oriented one, there follows a discussion of critical technologies for large geosynchronous earth orbit (GEO) satellites with power systems growing to 20 kW and more. Satellite antenna technology, one of the most critical areas in measuring progress, is next reviewed, including large reflector antennas, phased arrays and optical beam formers. This is followed by a discussion of onboard processing (analog and digital), progress in satellite traveling wave tubes, solid state power amplifiers and optical satellite technologies including intersatellite links (ISLs). Last some pertinent satellite bus issues (electric propulsion, thermal control and attitude control) are reviewed. Small and mini‐satellites are discussed, but not treated in great detail as much of their technology is derived from that of GEO satellites.

This paper presents an overview of the status of pertinent technologies for the ground segment of communications satellite systems. It is derived from the 1997/98 NASA/NSF sponsored commercial communications satellite study of technology, markets and services. It is recognized that the ground system technology is often more important than that of the satellites, especially as satellites are increasingly being used to provide services directly to the end‐customer. The current state of technology for several classes of ground terminals is reviewed. This includes Very Small Aperture Terminals (VSAT) for Ku‐ and Ka‐bands, Television Receive‐Only (TVRO) Terminals, handheld terminals, portable and mobile terminals for multimedia and business use, airborne and ship‐borne terminals, hubs and gateways and military terminals.

Global commercial launch service capacity has been increased in the past five years to meet the challenge of the anticipated large increase in demand for launches of commercial communications satellites to LEO, MEO and GEO. The lift‐off weight capability of rockets has also been increased in response to the increased mass of new higher power, wider bandwidth GEO satellites and the prospects of launching several satellites at a time. Several countries and private companies have initiated new launch efforts to meet this anticipated demand. This paper describes the capability of launch service providers, trends in launch technology and challenges facing this industry.

Traditionally, fixed satellite services have chiefly been used to support voice communications using capacity allocated to switched circuits, broadcast applications where capacity is allocated to regular TV transmissions, and low speed interactive data applications. Increasingly, however, satellites are being required to serve as high speed links in data networks handling data packets. To function efficiently on terrestrial packet networks (where errors are rare and the delays are short), the protocols, designed in an earlier era, are unsuited to satellite circuits, and considerable work is now underway to try to remedy these shortcomings. This paper reviews the problems encountered when Internet traffic must be carried over satellite and changes being considered and/or implemented in the Transmission Control Protocol/Internet Protocol (TCP/IP) suite to improve its efficient operation over satellites. Also discussed are strategies that can be employed at satellite earth stations to aid in integrating satellite links seamlessly into terrestrial data networks.

The field of satellite communications is becoming at least as constrained and shaped by policy, regulatory and standards issues as it is by technology. Satellite communications is currently facing a host of challenging issues, including national economic competition, open trade issues, standards and protocols, spectrum and frequency allocation, definition of essential space services requiring public funding, institutional reform, international industrial patterns of change and consolidation, technology transfer, and the proper role of government in future space communications development. This article seeks to identify possible areas for reform with regard to ‘paper satellites’, multi‐purpose frequency allocations, longer range spectrum planning, new standards‐making approaches to seamless satellite‐fiber interconnectivity, and reforms to more open international trade and licensing of satellite systems. Specific issues addressed include:

Global trade and access to national markets in the new ‘open markets’ trading environment. Interoperability standards and protocols. Issues of compatibility among the satellite systems of the world. Access to needed frequency allocations for satellite services amid growing global demand for broad band multi‐media services and the need to revise ITU planning processes. The difference in policy perspective and objectives between developed and developing countries in the field of satellite communications and its applications. The on‐going problem of ‘paper satellites’ and the fact that ‘due diligence’ has not solved this problem. Needed regulatory reforms to encourage new types of interactive broadband, multi‐media satellites. Institutional reforms of key entities (the ITU, INTELSAT, Inmarsat, etc.) in the coming decade.

Technology transfer issues, especially those that involve sensitive or strategic issues as well as streamlined methods to protect international property rights. New patterns of industrial cooperation, merger and as the new global market emerges. The proper role of governmental R&D support in developing new technology, applications and markets.

A single satellite located at GEO provides communications coverage over 1/3 of the surface of the Earth. Thus, by their very nature, satellites are an international communications media. A NASA and NSF sponsored study of satellite technology and markets included visits by a group of experienced satellite communications engineers and policy makers to over 60 locations located in North and South America, Europe and Asia. They concluded that the rapidly growing and large market for communications satellite services has attracted the attention of numerous countries and companies located over the entire globe. These countries are investing in R&D and the establishment of manufacturing facilities to enable them to be not only users of such services but significant participants in this growth market in the future. This paper summarizes the visits to satellite communication facilities located all over the globe and describes their R&D activities in support of this rapidly growing business. The participants in this study concluded that the major investment in satellite communications R&D in numerous countries, located all over the globe, represents a serious threat to the United States’ continued long term dominance in the manufacture of satellites and in the development of new satellite based services.