The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.
NASA had a very significant role in the establishment of satellite communications, first with the Syncom program to prove the feasibility of the geo-synchronous orbit and later with the ATS and CTS programs, which developed the C and Ku bands and led to the establishment of the commercial satellite communications industry. At this point, NASA directed its efforts to other space endeavors, expecting that the industry would continue the needed technology development to keep the industry viable and competitive.
NASA's Re-entry into Communication R&D
In 1974, several organizations began to assess the consequences of NASA's decision to essentially eliminate satellite communication activities that focused on commercial applications . The Electronic Industries Association (EIA) issued a position paper in January 1974, which urged NASA to reconsider its decision. In January 1975, the American Institute of Aeronautics and Astronautics (AIAA) issued a similar report. It urged NASA to re-enter the communication satellite field by sponsoring new families of application technology satellites. The report argued that from 1960 to 1973, "the federal government took the dominant role in communication satellite research and development, thereby providing the basis for low-risk operational system development by private enterprise in the 1960s and 1970s."
In the fall of 1975, NASA asked the National Research Council (NRC) to consider and report on the question: "Should federal research and development on satellite communication be resumed and, if so, what is the proper federal role in this field?" To undertake the study, the NRC formed a Committee on Satellite Communications, under the auspices of the Space Application Board. After studying this question, the consensus of the committee was that major advances in communication satellite technology required government investment, particularly in the areas where high technical risks were involved. This committee concluded that satellite communication R&D was an appropriate federal responsibility, and that NASA should resume the research and development activities needed to provide the new technology for future commercial communication needs. The NRC committee recommended, in a 1977 report , that NASA implement an experimental satellite communication technology flight program based on an assessment of need, technology projections, and service concept development. It recommended that the technical design of any NASA experimental communication satellite should support several end user service concepts, and that appropriate user groups should assist in the conceptual definition of both the needed technology and the experiments themselves.
Based on the results of the NRC report, the increasing demand for domestic voice, video, and data traffic, and the foreign competition and prospects of trade disparity, President Jimmy Carter saw fit to reinstate federal sponsorship of communication satellite technology. Official sanction for NASA to resume its responsibility was contained in the October 1978 Presidential Directive (PD-42). This directive stated, "NASA will undertake carefully selected communication technology R&D. The emphasis will be to provide better frequency and orbit utilization approaches."
The NASA Satellite Communication Program for the 1980s
In 1978, as a result of the Presidential Directive, NASA began the process of rebuilding its R&D activities in the communication satellite arena [13,14,15]. The future technology program was planned in cooperation with the National Research Council's Space Applications Board Subcommittee on Satellite Communications, whose membership consisted of leading common carriers, spacecraft manufacturers, and representatives of communication users.
Market & System Studies
In this first phase of the NASA program, market and system studies were conducted to determine future service demand and whether or not C- and Ku-band satellites could satisfy it. Two contracts were awarded to common carriers: Western Union Telegraph Company, and U.S. Telephone and Telegraph Company, which was a subsidiary of International Telephone and Telegraph (ITT) [16,17]. The emphasis of these studies was to forecast the telecommunications traffic that could be carried by satellite competitively. During this same time frame, two other system studies were conducted: one each by Hughes Aircraft and Ford Aerospace, with supporting studies by TRW, GE, and the Mitre Corporation [18,19]. Their purpose was to identify the technology needed to implement cost-effective and spectrum-conservative communication systems. The results were combined to define potential commercial system configurations that could address the market for trunking and customer premises services that was expected in the early 1990s. System requirements derived from these postulated commercial configurations formed the basis for the technology development program that followed.
The market studies predicted that rapid growth in domestic voice, data, and video traffic would lead to a five-fold increase in U.S. communication demands by the early 1990s. A combination of these market projections and communication satellite license filings with the FCC portended a saturation of North American orbital arc capacity using the C- and Ku-band frequencies. To relieve the pressure of this expanding market, the 30/20 GHz frequency band was needed. As a result, the new NASA communication program for commercial application was named the 30/20 GHz Program and was structured to:
- Develop selective high-risk, 30/20 GHz technologies that focused on relief of orbit and frequency congestion and developing new and affordable services
- Promote effective utilization of the spectrum and growth in communications capacity
- Ensure continued U.S. preeminence in satellite communications
Satellite Addressable Market Demand
The technologies required to meet these objectives were judged to be of such high technical risk that they were beyond the capability of any one company to finance.
In 1979, NASA designated the Lewis Research Center (LeRC) in Cleveland, Ohio, to be its lead center in planning and executing the commercial communication satellite technology R&D Program. In 1999, the Lewis Research Center's name was changed to the Glenn Research Center (GRC), in honor of John Glenn, astronaut and U.S. Senator from Ohio.
Early communication satellite systems employed simple, bent-pipe transponders with a single antenna beam to cover a large region (such as the continental United States). The new NASA program needed to develop technology that would allow the frequency spectrum to be used more efficiently. One technique to accomplish this was to cover the region with many small spot beams so that the same frequency could be reused simultaneously in non-adjacent beams. Such frequency reuse increased the capacity of satellites by a factor of five to ten times that of a single beam satellite, with only a modest increase in spacecraft size, power, and weight. The technology to accomplish this high degree of frequency reuse employed antennas with high-gain spot beams and electronic systems with onboard switching and processing to inter-connect the spot beams. In addition, the high-gain antenna allowed for smaller aperture user terminals at higher data rates. This was the technology developed by NASA.
Technology Feasibility & Flight System Definition
In 1980, the program moved forward in two phases. The first phase was to 1) continue the market studies to increase confidence in the forecast for orbit saturation and 2) to do proof-of-concept development of the identified technologies. The proof-of-concept program was a laboratory (breadboard) type of development to prove that the technologies were feasible. Approximately $50 million was expended on the first phase. If the first phase proved successful, the second phase would consist of developing an experimental flight system to demonstrate that the technologies could provide reliable communications services.
The first phase was fully supported by the entire service provider and satellite manufacturing community. The second phase of the program was the one that became controversial. The service providers had great concern about how reliably the technology would work in space, and therefore, argued for a flight program. Some satellite manufacturers, however, had reservations about proceeding with a flight program because they felt it would give the winning contractors of the NASA procurement an unfair competitive advantage. This controversy continued throughout most of the life of the ACTS program.
Program Coordination with Industry
Two industry committees were formed to guide the program. The NASA Ad Hoc Advisory Committee was created to provide general policy direction. The committee included notable representatives of both the system supplier and service supplier industry. Their contribution provided timely and sage review of the program, as well as providing NASA with insight into the industry philosophy relative to the roles and responsibilities of both government and the private sector.
The second industry committee was a Carrier Working Group (CWG), consisting of representatives from all the major satellite service providers. The CWG was charged with helping NASA formulate the technology and flight system requirements, develop experiments, and provide overall guidance. These requirements and experiments were deemed necessary by the CWG to demonstrate the readiness of not only the technology, but of its service applications as well. Coordination was also established between the Department of Defense and NASA, especially in the development of various critical advanced technology components.
The purpose of the proof-of-concept (POC) technology development was to demonstrate the technical feasibility of the key component building blocks [20,21]. The approach NASA used was to issue multiple contracts to various aerospace and related companies for the development of each high risk technology: multiple spot beam antenna, base band processor, TWTA, wide-band switch matrices, low-noise receiver, GaAs FET transmitter, GaAs IMPATT transmitter, and ground antenna. Duplicate awards for most of the critical technology components were employed to increase the probability of successful development, and to produce multiple sources for communication hardware. In addition, multiple awards helped to ensure that a variety of perspectives and technical approaches were brought into each development. These contracts called for the development of the technology, the construction of POC versions of the components, and their testing in the laboratory to verify performance.
The POC hardware substantially reduced the risk associated with the planned development of the flight system. Another product of these technology contracts was the prediction of feasible component, subsystem, and system performance levels. NASA used these performance predictions to provide guidance for follow on technology development. Service providers and manufacturers could also use these predictions in planning activities for the commercial system designs of the early 1990s.
The Department of Defense (DOD) participated in the NASA POC program. Several of the critical technology POC elements that were of interest to the DOD were co-funded by DOD and NASA. To enable the effective transfer of information that was generated in the program, all contractors were required to prepare task completion reports. These reports were presented at periodic industry briefings (only for interested U.S. parties) hosted by NASA.
NASA's Advanced Communications Technology Satellite (ACTS)