SP-4217 Beyond the Ionosphere

 

Chapter 6

NASA Experimental Communications Satellites, 1958-1995

by Daniel R. Glover

 

[51] As the civilian agency exercising control over U.S. space activities, NASA has had a program of technology development for satellite communications since the agency was established in 1958. Part of this program has involved flying experimental communications satellites. NASA's first communications satellite project was Echo. Launched on 12 August 1960, Echo 1 was a passive satellite that reflected radio waves back to the ground.

Echo started out in 1956 as a National Advisory Committee for Aeronautics (NACA) experiment to probe the upper reaches of the atmosphere and the effects on large lightweight structures in orbit. John Robinson Pierce and Rudolf Kompfner of AT&T's Bell Telephone Laboratories had been working on ideas for communications satellites, including passive systems, for some time. They realized that the Echo sphere would provide an excellent test mirror and proposed a communications experiment. The National Academy of Sciences sponsored a meeting, held on 28 August 1958, to define the project.1 In 1958, when NASA was created and NACA dissolved, Echo became a NASA project.

The Echo satellite was a 100-foot-diameter (thirty-one-meter-diameter) aluminized-polyester balloon that inflated after insertion into orbit. The G.T. Schjeldahl Company built the Echo 1 balloon, and Grumman built the dispenser, for NASA's Langley Research Center in Hampton, Virginia. Two-way voice links of "good" quality were set up between Bell Telephone Laboratories in Holmdel, New Jersey, and NASA's Jet Propulsion Laboratory facility at Goldstone, California. Some transmissions from the United States were received in England at Jodrell Bank.

Echo demonstrated satellite tracking and ground station technology that later applied to active satellite systems. Leonard Jaffe, director of the NASA satellite communications program at headquarters, wrote: "Echo [I] not only proved that microwave transmission to and from satellites in space was understood and there would be no surprises but it dramatically demonstrated the promise of communication[s] satellites. The success of Echo [I] had more to do with the motivations of following communications satellite research than any other single event."2

Echo 2, managed by NASA's Goddard Space Flight Center in Beltsville, Maryland, left the launch pad on 25 January 1964. It had a better inflation system, which improved the balloon's smoothness and sphericity. Echo 2 investigations were concerned less with

communications and more with the dynamics of large spacecraft. After Echo 2, NASA abandoned passive communications systems in favor of active satellites. The superior performance of the U.S. Department of Defense's SCORE (Signal Communication by Orbiting Relay Equipment) satellite, launched almost two years before Echo I, already had demonstrated the viability of the active approach.

 

[52] Telstar

 

In the fall of 1960, as Echo 1 was achieving its first successes, AT&T began developing an active communications satellite system called Telstar. Although some observers felt that AT&T's early interest in communications satellites was part of a defensive maneuver to protect its commitment to cable technology, the company was investing large quantities of its own capital to create and launch its own communications satellite program.3 Initially, the operational system was to consist of fifty to 120 active satellites in orbits approximately 7,000 miles (about 9,310 kilometers) high. Using the large launch vehicles then in development, Pierce envisioned that "a dozen or more of these satellites could be placed in orbit in a single launching." With the satellites in random orbits, Bell Telephone Laboratories figured that a "system of 40 satellites in polar orbits and 15 in equatorial orbits would provide service 99.9 per cent [sic] of the time between any two points on earth." As Pierce explained, "AT&T has proposed that the system contain about 25 ground stations so placed as to provide global coverage."4

The cost of such a system would be high. In 1961, Pierce estimated the expense at $500 million, but that high price tag was not a detriment from AT&T's standpoint. As a telecommunications monopoly, AT&T's rates were regulated, and those rates included an amount that allowed AT&T to recover its costs as well as to make a profit. Thus, the cost of the proposed Telstar satellite system would be passed on to consumers, just as the high costs of undersea cables were, so AT&T found the system attractive.

Bell Telephone Laboratories designed and built the Telstar spacecraft with corporate funds. The first Telstars were prototypes intended to prove various concepts behind the large constellation of orbiting satellites. Moreover, of the six Telstar spacecraft built, only two were launched. NASA's contribution to the project was limited to launch services, as well as some tracking and telemetry duties. AT&T reimbursed NASA $6 million for those services. NASA was able to negotiate such an excellent deal with AT&T, even though Telstar was not really a NASA project, because NASA held the monopoly for launch services. Moreover, NASA claimed Telstar as a NASA-supported project and even published the results of the communications experiments, originally issued as articles in the Bell Telephone technical journal, as a NASA publication (NASA Special Publication [SP]-32). In addition, NASA obtained the rights to any patentable inventions arising from the experiments.

On 10 July 1962, a Delta launcher placed the first Telstar spacecraft into orbit. The faceted 171-pound (about seventy-seven-kilogram) sphere had a diameter of a little more than thirty-four inches (about one meter). Telstar was the first satellite to use a traveling-wave-tube amplifier; transistor technology at the time was not capable of the three watts of power output at the required microwave frequencies.5 Bell Telephone Laboratories also developed much of the technology required for satellite communication, including transistors, solar cells, and traveling-wave-tube amplifiers. To handle Telstar communications, AT&T built ground stations at Andover, Maine; Pleumeur-Bodou, France; and Goonhilly Downs, Britain. These were similar to, but larger than, the ground station used for project Echo. The French station used a duplicate of the AT&T Holmdel horn antenna, while the British antenna was a parabolic dish.

[53] Telstar was a tremendous technical success, and the international reaction was spectacular. A U.S. Information Agency (USIA) poll showed that Telstar was better known in Great Britain than Sputnik had been in 1957. Rather than launching a useless bauble, the Americans had put into orbit a satellite that promised to tie together the ears and eyes of the world. Interestingly, the world saw Telstar as an undertaking of the U.S. government (the USIA publicity may have helped). President Kennedy hailed Telstar as "our American communications satellite" and "this outstanding symbol of America's space achievements."6

Regarding Telstar, Jaffe, head of communications satellite programs at NASA, wrote in 1966: "Although not the first communications satellite, Telstar is the best known of all and is probably considered by most observers to have ushered in the era of satellite communications."7 This impression resulted from the tremendous public impact of the first transmission of live television across the Atlantic Ocean from the United States to France by Telstar I on 10 July 1962, the very same day it was launched. In addition to television broadcasts, Telstar relayed telephone calls, data transmissions, and picture facsimiles.

Telstar was AT&T's major move into satellite communications. That move failed to extend AT&T's monopoly of terrestrial communications into space, however; changing telecommunications policy from one presidential administration to the next, and a government desire to avert a monopoly of satellite communications, kept AT&T's monopolistic aspirations in check. At the same time, NASA contracted its communications satellite work to firms other than AT&T.

When AT&T began working on Telstar, the Eisenhower administration seemed willing to allow it to extend its monopoly into space. A statement by President Eisenhower in December 1960, in which he presented his administration's policy on space communications, stressed the traditional U.S. policy of placing telecommunications in the hands of private enterprise subject to governmental licensing and regulation and the achievement of "communications facilities second to none among the nations of the world." The role of NASA was "to take the lead within the executive branch both to advance the needed research and development and to encourage private industry to apply its resources toward the earliest practicable utilization of space technology for commercial civil communication requirements."8

The election of President Kennedy ushered in a new policy on satellite communications that was openly antagonistic to monopolies, particularly to the extension of AT&T's monopoly in terrestrial communications to space communications. President Kennedy released a policy statement on 24 July 1961 that favored private ownership of satellite systems, but with regulatory and other features aimed at avoiding a monopoly.9

AT&T's preeminent position as the largest U.S. common carrier and sole international telephone carrier, together with its willingness and ability to commit large sums of money to the development of communications satellites, convincingly suggested that commercial satellite utilization would very likely become AT&T utilization. Concern over the possibility of an AT&T monopoly in space was one factor that prompted a later reorientation of the direction that commercialization seemed to be following.10

[54] On 31 August 1962, President Kennedy signed the Communications Satellite Act. The government assigned the monopoly of international satellite communications to a new corporation called Comsat. AT&T went ahead with Telstar 2, completing its experimental program. Of the six flightworthy spacecraft built by AT&T with corporate funds, only two were launched, but Telstar's publicity served AT&T very well. Nonetheless, between the success of Telstar 1 and the launch of Telstar 2 on 7 May 1963, AT&T lost its chance to control commercial satellite communications.

NASA's role in communications satellites was changing, too. A 1958 agreement between NASA and the Department of Defense gave responsibility for the development of active communications satellites to the military, leaving NASA with the development of passive satellites. In August 1960, however, NASA decided to pursue active satellite research, but not synchronous satellites. The military already had an active synchronous satellite, Project Advent, in place. NASA began developing medium-altitude satellite systems and issued a request for proposals on 4 January 1961 for an experimental communications satellite to be known as Relay. Both AT&T and Hughes approached NASA with their design concepts, but in May 1961, NASA selected RCA to build the two Relay spacecraft, instead of AT&T or Hughes. The Goddard Space Flight Center oversaw the project.

 

Project Relay

 

Although AT&T did not win the contract to build them, the Relay satellites used the same primary ground stations as those used by Bell Telephone Laboratories' Telstar 1 satellite. These were located in the United States (in Maine, New Jersey, and California) and overseas (in West Germany, Italy, Brazil, and Japan). Relay was an experimental satellite program; however, the satellites transmitted television signals between the United States and Europe and Japan. The Tokyo 1964 Olympics, however, were passed from Tokyo to the United States, and then on to Europe via Relay.

NASA launched Relay 1 on 13 December 1962 into an elliptical orbit with an apogee of 4,012 nautical miles (about seven kilometers). The orbit took Relay through the Earth's inner radiation belt, so that the spacecraft could measure the levels of radiation and study its effects on satellite electronics. Relay taught many lessons in communications spacecraft design. The idea of flying experimental communications spacecraft is to try new things and to determine whether they work. Failures are expected and provide the learning experience necessary for technology advancement. Relay was no exception.

While in orbit, the power supply for Relay 1's primary transponder failed, and the spacecraft had to switch to its backup transponder, which performed well. Another problem was spurious commands. The satellite recorded 401 anomalies (errors) during its first year. Ground stations observed anomalies when the satellite was in view, which was during only 15 percent of its orbit. The main culprit was interference from the wideband subsystem. Consequently, as a corrective measure, Relay 2 carried a filter on the command receiver's transmission line and had improved circuitry to better differentiate between noise and command signals. As a result, Relay 2 recorded only sixty-two command anomalies.

Among the other problems faced by the first Relay experimental satellite was the failure of the charge controller for one of three battery packs after about three months. Yet another was the long time required for the traveling-wave tube to warm up. Normally, the tube took three minutes to warm up, but the malfunctioning tube could take as long as sixteen minutes. This delay reduced the time the satellite was usable, as Relay 1's orbit placed it in any particular ground station's view for only about thirty minutes. Relay 2, launched 21 January 1964, had increased radiation resistance plus measures that [55] improved reliability. Finally, Relay 1 had a design life of one year, but when its turnoff switch failed, it continued to operate for a second year.

 

Syncom

 

The objective of the Syncom satellite project was to demonstrate synchronous-orbit communications satellite technology. In the early 1960s, achieving a synchronous orbit was a challenge. According to Lawrence Lessing, an observer at the time (1962):

 

Nearly everyone agrees that for a short-range, experimental first venture, the medium altitude active repeater satellite, such as Telstar or Relay, is the best bet . . . . Lockheed . . . is confident that before the complex problems of operating 50 or more satellites at lower altitudes are solved . . . the U.S. will be able to put up a full-powered, simpler, high-altitude system. Other experts, however, say that the synchronous high-altitude satellite is still some order of magnitude beyond present technology.11

 

A synchronous orbit is one in which a satellite makes one orbit per day, the same period as the Earth's rotation around its axis. As a result, the satellite hovers over the same area of the Earth's surface continuously. The altitude of a synchronous orbit is 22,235 miles (19,322 nautical miles or 35,784 kilometers). At lower altitudes, satellites orbit the Earth more than once per day. For example, the Space Shuttle, at a nominal altitude of 180 miles (290 kilometers), orbits the Earth in an hour and a half. The Moon, on the other hand, at a distance of around 240,000 miles (nearly 390,000 kilometers), takes a month to orbit the Earth.

A key advantage of a synchronous satellite is that ground stations have a much easier job of tracking the satellite and pointing the transmitting and receiving antennas at it, because the satellite is always in view. With spacecraft in lower orbits, tracking stations must acquire the satellite as it comes into view above one horizon, then track it across the sky as the antenna slews completely to the opposite horizon, where the satellite disappears until its next pass. For continuous coverage, a ground station might need two antennas to acquire the first satellite, then connect with the next satellite passing overhead. In addition, continuous coverage requires the placement of ground stations distributed around the globe, so that any given satellite is rising over the viewing horizon of one ground station, while it is setting in relation to another station.

The chief communications advantage of the geosynchronous satellite, however, is its wide coverage of the Earth's surface. About 42 percent of the Earth's surface is visible from a synchronous orbit. Three properly placed satellites can provide coverage for the entire globe. Although Arthur C. Clarke published the first idea of a synchronous communications satellite in 1945, the first such synchronous-orbit spacecraft, Syncom 1, was not launched until 14 February 1963. However, when the motor for circularizing the orbit fired, the spacecraft fell silent. To demonstrate attitude control for antenna pointing and station keeping, Syncom had two separate attitude control-jet propellants: nitrogen and hydrogen peroxide. The most likely cause was a failure of the high-pressure nitrogen tank.12

[56] Syncom 2 addressed these critical problems from the first attempt at making a geosynchronous communications satellite. Launched on 26 July 1963, after improvements in the nitrogen tank design, Syncom 2 successfully achieved synchronous orbit and transmitted data, telephone, facsimile, and video signals. Its successor, Syncom 3, launched 19 August 1964, had the addition of a wideband channel for television and provided coverage of the 1964 Tokyo Olympics. Syncom 3 was different from its predecessor in other ways, notably in its orbital pattern. A particular type of synchronous orbit is the geostationary orbit--namely, a synchronous orbit around the equator. Geostationary satellites seem to be stationary over a point on the surface, as distinguished from an area of the surface. Syncom 3 had a geostationary orbit, while the orbit of Syncom 2 was inclined thirty-three degrees to the equator, so that over a twenty-four-hour period, it appeared to move thirty-three degrees north and thirty-three degrees south in a "figure 8" pattern as observed from the ground.

 


Figure 12. Television image transmitted from Japan to the United States of the 1964 Olympic Games in Tokyo via the Relay experimental communications satellite launched in 1962.

Figure 12. Television image transmitted from Japan to the United States of the 1964 Olympic Games in Tokyo via the Relay experimental communications satellite launched in 1962. (Courtesy of NASA).

 

In addition to communications experiments, the Syncom satellites contributed to a determination of the Earth's gravitational field. They were capable of measuring range at synchronous altitude to an accuracy of less than fifty meters. The high altitude of their orbits minimized perturbations arising from local topology changes on the Earth's surface.

 

The Applications Technology Satellite Program

 

The Syncom spacecraft, built by Hughes for NASA's Goddard Space Flight Center, marked the end of NASA's experimental satellites of the early 1960s. NASA turned both Syncom satellites over to the Department of Defense in April 1965, and they were turned off in April 1969. As a continuation of its successful program of experimental communications satellites, NASA inaugurated the Applications Technology Satellite (ATS) series. These spacecraft demonstrated communications technologies and conducted weather observations and space research in response to congressional pressure. NASA and Hughes had hoped to continue the success of the Syncom project with an advanced Syncom satellite. Some members of Congress, however, feared that NASA was developing technology for the benefit of a single private company--namely, Comsat. Therefore, the advanced Syncom's objectives were broadened to include meteorology and other experiments, and the program became the ATS series.

The five first-generation ATS satellites, built by Hughes for Goddard, tested a range of new communications electronics in the Earth's orbit, as well as technology for gravity-gradient stabilization (on ATS-2, ATS-4, and ATS-5) and for medium-altitude orbits (ATS-2) on behalf of the Department of Defense. All of these first-generation ATS spacecraft were capable of carrying more signal traffic than any of their predecessors.

The first of these ATS satellites, launched 7 December 1966, carried out an impressive array of communications experiments and collected weather data. ATS-1 was the first [57] satellite to take independently uplinked signals and convert them for downlink on a single carrier. This technique, called "frequency division multiple access," conserves uplink spectrum and also provides efficient power utilization on the downlink. ATS-1 also carried a black-and-white weather camera, which transmitted the first full-disk Earth images from geosynchronous orbit. The communications hardware functioned for another two decades until 1985, when the spacecraft failed to respond to commands.

The second of these ATS satellites, in addition to communications experiments and space environment research, was to conduct technological testing of gravity-gradient stabilization for the Department of Defense. Launched 5 April 1967 atop an Atlas-Agena D rocket, ATS-2 never achieved circular orbit, because the Agena upper stage malfunctioned. Only a few experiments were able to return data. ATS-2 reentered the atmosphere on 2 September 1968.

The following ATS is the oldest active communications satellite by a wide margin. Launched in November 1967, it is still in service more than 28 years later. Among its widest known achievements are the first full-disk, color Earth images transmitted from a satellite. Its imaging capability has served during disaster situations, from the Mexico earthquake to the Mount St. Helens eruption. ATS-3 experiments included VHF and C-band communications, a color spin-scan camera, an image dissector camera, a mechanically despun antenna, resistojet thrusters, hydrazine propulsion, optical surface experiments, and the measurement of the electron content of the ionosphere and magnetosphere. Because of failures in the hydrogen peroxide systems on ATS-1, ATS-3 was equipped with a hydrazine propulsion system. Its success led to its incorporation on ATS-4 and ATS-5 as the sole propulsion system.13

The ATS-4 and ATS-5 satellites, because of the unsuccessful ATS-2 mission, again attempted to test technology for gravity-gradient stabilization for the Department of Defense--a key objective of the first generation of the ATS series. Gravity-gradient stabilization was chosen to maintain satellite stability, because it uses low levels of onboard power and propellant. The real goal, however, was to move away from spin-stabilized spacecraft to three-axis stabilization. Spin stabilization has the advantage of simplifying the method of keeping a spacecraft pointed in a given direction. A spinning spacecraft resists perturbing forces, similar to a gyroscope or a top. In space, forces that slow the rate of spin are very small, so that once the spacecraft is set spinning, it keeps going.

Spin stabilization, however, is inherently inefficient. Only some of the satellite's solar cells are illuminated at any one instant. Also, because the radio energy from the nondirectional antennas radiates in all directions, only a fraction of that energy is directed toward the Earth. Three-axis stabilization allows the solar panels to be always pointed at the Sun and enables the use of a directional antenna that not only remains pointed toward the Earth, but concentrates the radio energy into a beam, rather than a scattering pattern.

How, then, does one achieve three-axis stabilization? Gravity-gradient stabilization uses the Earth's gravitational field to keep the spacecraft aligned in the desired orientation. The spacecraft is designed so that one end is closer to the Earth than the other. The spacecraft end farther from the Earth is in a slightly weaker gravity field than the end closer to the Earth. Although this technique had been used in low orbit before the advent of the ATS program, the question to be addressed was whether or not the difference in gravity fields (the gradient) was too weak to be useful at higher altitudes. That was the objective of both ATS-4 and ATS-5.

 


[
58]

Figure 13. ATS-3, the third in NASA's Applications Technology Satellite (ATS) series of experimental communications satellites.

Figure 13. ATS-3, the third in NASA's Applications Technology Satellite (ATS) series of experimental communications satellites. Launched in November 1967, ATS-3 is still in service today. Among its most acclaimed successes is the first full-disk, color image of the Earth transmitted from a satellite. (Courtesy of NASA, photo no. 67-HC-612)

 

[59] ATS-4 was launched 10 August 1968 atop a powerful Atlas-Centaur rocket, but it reentered the atmosphere on 17 October 1968 because the Centaur upper stage failed to re-ignite. The ATS-5, then, was the final attempt at a synchronous gravity-gradient spacecraft. Launched 12 August 1969 on an Atlas-Centaur rocket, ATS-5 developed problems in its parking orbit and expended large amounts of propellant to stabilize itself. To try to salvage the mission, NASA injected the satellite into its final orbit ahead of schedule.

Although ATS-5 was to be a gravity-gradient stabilized satellite, spin stabilization was used during orbit insertion (a common practice). The spacecraft carried a device to remove the spin after it reached its final orbit. The device deployed booms to slow the spin, which is very similar to spinning figure skaters who extend their arms to slow down. Thus, ATS-5 successfully achieved a synchronous orbit, but the spacecraft's spin was in the wrong direction for this device to work. As a consequence, the gravity-gradient stabilization experiment was useless. The communications experiments were severely handicapped because the antennas were spinning with the spacecraft and could only work as a lighthouse beacon, rather than as a spotlight. Some communications experiments were later carried out in a pulse mode, and some secondary experiments were conducted as late as 1977.14 Among those experiments were an L-band aeronautical communications package, an ion engine, a charge neutralizer, solar cell tests, and research on particles, electric and magnetic fields, and solar radio waves.

 

Applications Technology Satellites: The Next Generation?

 

The first of the second generation of the ATS program, known as ATS-6, also was the last ATS mission. Congress canceled the program in 1973 as a budget-cutting measure and to allow the commercial communications satellite industry to underwrite its own research and development. In 1974, NASA unsuccessfully attempted to reinstate the ATS program. Thus, the impressive ATS-6 spacecraft, launched 30 May 1974, marked the end of an era and the beginning of a dry spell for NASA experimental communications satellites.

Built by Fairchild Space and Electronics Company for Goddard, the ATS-6 spacecraft was much larger than its predecessors, weighing 1,336 kilograms (compared with 431 kilograms for ATS-5) and standing just over eight and a half meters tall and sixteen meters across its booms (ATS-5 was 1.8 meters tall and 1.4 meters in diameter). In addition to being the largest geosynchronous communications satellite launched to date, it was the first three-axis stabilized communications satellite. ATS-6 incorporated many significant design firsts, such as a 9.14-meter parabolic reflector, a digital computer for attitude control, solid-state high-power radio frequency transmitters, a primary structure made of graphite composite material, heat pipes for primary thermal control, monopulse tracking for attitude control, and a radio frequency interferometer for attitude determination and control.15

Equally significant was the demonstration of technology for tracking and data relay satellites that led to the Tracking and Data Relay Satellite System (TDRSS) program. In the TDRSS, a tracking and data relay satellite uses the geosynchronous orbital vantage point to look down on low-altitude satellites. Data are relayed from the low-altitude [60] satellite to a ground station through the geosynchronous satellite. Without this space relay capability, NASA needed ground stations all over the globe to collect data from satellites as they passed overhead. Because a low-altitude satellite orbits the Earth in a matter of a few hours, it is only in view of a single ground station for typically 20 minutes at a time. ATS-6 tracked the Nimbus 5 and 6 and the GEOS 3 (Geodynamics Experimental Ocean Satellite) satellites with a roll-and-pitch accuracy of better than 0.2 degree.

The nine-meter antenna enabled small ground receivers to pick up a good quality signal. A demonstration in India, in 1975, relayed television signals from a six-gigahertz uplink through the ATS-6 spacecraft and back to Earth at 860 megahertz, directly to three-meter antennas installed in approximately 2,000 villages. The large deployable antenna required tight pointing by the spacecraft, which is why it used three-axis stabilization.

ATS-6 carried out radio-wave propagation studies at frequencies up to thirty gigahertz; it also established L-band (1,550 to 1,650 megahertz) relay links to aircraft and demonstrated multiple aircraft tracking.

ATS-6 experienced a failure of three of its four orbit control jets in May 1979. That failure led to the decision to power down the spacecraft on 3 August 1979. Subsequently, its telemetry system was activated between November 1979 and February 1980 to collect particle data for correlation with similar data being collected by other satellites.16

 

NASA Quits

 

Although the launch of the ATS-6 spacecraft in 1974 marked the end of NASA's program of experimental communications satellites, the space agency also participated at the same time in a Canadian satellite venture known initially as "Cooperative Applications Satellite C" and renamed Hermes. This joint effort involved NASA and the Canadian Department of Communications. NASA's Lewis Research Center provided the satellite's high-power communications payload. Canada designed and built the spacecraft; NASA tested, launched, and operated it. Also, the European Space Agency provided one of the low-power traveling-wave tubes and other equipment.17 Hermes was launched 17 January 1976 and operated until October 1979.

Canada also created a telecommunications policy that the United States would emulate, and this would lead to the end of NASA's communications satellite research and development program. In late 1969, Canada announced that any financially qualified organization could apply for, and expect to be granted, authority to operate a domestic satellite system. As a result, in November 1972, that country put into orbit the world's first domestic satellite. In addition, the Canadian government abandoned sponsored research in the hope of motivating competition in the development of satellite technology. This Canadian "Open Skies" policy represented a striking contrast to past U.S. policy,18 but it was in tune with the Nixon administration's advocacy of competition.

[61] Subsequently, in January 1973, budget pressures caused NASA essentially to eliminate its communications satellite research and development program, much of which was carried out at the Goddard Space Flight Center, although the Lewis Research Center was working on advances in traveling-wave tube design and was participating in the Canadian Hermes project. Goddard had been responsible for most NASA experimental (as well as operational) communications satellites, including the ATS series.

Meanwhile, the danger of foreign competition, especially from Japan and Europe, loomed large. The Japanese launched the first commercial Ka-band operational satellite, called Sakura 2a, on 4 February 1983. Built by Ford (now Loral) and Mitsubishi, and launched on a Japanese N2 rocket, Sakura 2a also was Japan's first commercial communications satellite. It was replaced by Sakura 3a, which was launched 19 February 1988. In the 1990s, Loral also built the Superbird and N-Star satellites for Japan, and with Japanese contractors led by Toshiba, Japan's National Space Development Agency designed and built the ETS 6 (Kiku 6) spacecraft.19

At the same time, the Europeans were catching up. The Olympus satellite began development in 1979 as L-Sat and was built by European aerospace companies, of which British Aerospace was the prime contractor. Launched on 12 July 1989 on an Ariane 3 rocket, Olympus was a large multipurpose satellite demonstrating and promoting new applications in television broadcasting, intercity telephone routing, and the use of the Ka-band for videoconferencing and low-rate data transfer for business communication.20

Foreign competition provided NASA a strong argument for reinstating its commercial satellite development program. The question was: what technology ought to be developed? Market studies conducted during the 1970s revealed the crowding of synchronous orbits. The obvious solution to overcrowding was to use higher frequency Ka-band communications satellites.

A compelling synergy exists among the use of Ka-band frequencies, spot beams, and onboard processors. In general, higher frequencies produce smaller beam widths with a given antenna, and so it is easier to make antennas that produce spot beams at Ka-band frequencies. A spot beam covers a smaller area, such as a major metropolitan area, compared to typical beams covering the entire country. These spot beams improve the problem of rain fade at Ka-band by concentrating the signal strength to punch through clouds. Once there are spot beams, it is a natural extension to switch signals between various spot coverage areas (such as routing one signal from New York to Chicago and another from New York to Los Angeles) aboard the spacecraft.

Despite the virtual shutdown of the NASA communications satellite research and development program, NASA systems engineers throughout the mid-1970s sought ways to revive their canceled program. Work continued on satellites that were still operating in space, as well as on projects that were too far along to stop. Both the Lewis Research Center and the Goddard Space Flight Center advocated reviving the space communications programs, but along very different lines. Goddard championed public service satellites directly in competition with industry. The technology development program at Lewis supported U.S. industry, although some companies saw the Lewis approach as subsidizing competitors. The Nixon administration's advocacy of competition thus favored the Lewis approach.

The question of federal funding of communications satellite technology development by NASA came before the National Research Council, whose Committee on Satellite [62] Communications released a report on the subject in 1977. The committee considered several options and recommended funding a NASA experimental communications satellite technology flight program and an experimental public service communications satellite system. The committee opposed creating an operational public service system on the grounds that it was "inappropriate for NASA."21

In 1978, five years after budget pressures forced NASA to eliminate its commercial communications satellite research and development program, the space agency reentered the field.22 The Lewis Research Center, not the Goddard Space Flight Center, acted as the lead center, in light of the program's emphasis on technology. Lewis worked on the next NASA experimental communications satellite and began a $45 million program of technology development using duplicate contracts, to have the new designs needed for a radically new spacecraft. NASA involved the five major builders of communications satellites--TRW, Hughes, Ford, General Electric, and RCA--by awarding each a study contract. These contracts ranged in cost from $264,000 (RCA) to $1,213,000 (TRW), and all were completed in the summer of 1981.

Joe Sivo, chief of the communications division at Lewis, brought U.S. communications carriers--the users of the technology--into the program to develop a consensus on advanced technology requirements. Between November 1979 and May 1983, the Carrier Working Group, formed by Sivo, met nine times to define flight system requirements and experiments and to review spacecraft designs as they became available from the study contractors. The Carrier Working Group consisted of representatives from American Satellite, AT&T Long Lines, Bell Telephone Laboratories, Comsat, GTE Satellite, Hughes Communications, ITT, RCA, Satellite Business Systems (MCI), Southern Pacific, and Western Union.

 

The Advanced Communications Technology Satellite

 

The efforts of the Carrier Working Group and the industry study contracts led directly to the design and construction of the next NASA experimental communications satellite, known as the Advanced Communications Technology Satellite (ACTS). Its unique feature is that it acts as a "switchboard in the sky." The communications payload incorporates steerable, spot-beam antennas and onboard switching that allows signals to be routed aboard the spacecraft. The Ka-band frequencies used by the ACTS (thirty gigahertz for the uplink and twenty gigahertz for the downlink) were new capabilities for U.S. communications satellites, but the Japanese already had used them on their own satellite. NASA makes the satellite available for experiments by industry, universities, and other government agencies, as well as for tests of new service applications.

Launched 12 September 1993, the ACTS has been perhaps the most successful of NASA's communications satellites. To date, it has operated for two years without failures and has conducted more than 100 experiments and tests. Furthermore, several commercial systems have proposed using ACTS technologies. For example, Motorola, which built the satellite's baseband processor, is incorporating onboard switching in its Iridium system, while Hughes is working on Spaceway, a Ka-band system with spot beams. Despite [63] these technical and commercial successes, the ACTS had a long and tortuous existence during the 1980s, as Congress and the White House debated the philosophy of having NASA develop technology for the U.S. communications satellite industry. While the satellite was still in the design phase, for example, the Reagan administration deleted the satellite from its budget, only to have Congress reinstate the project.

 

Conclusion

 

NASA's commercial communications satellite program has produced many significant results over the past 35 years. Although some critics have argued that NASA has overstated its contribution to satellite communications,23 one can contend that the program has returned far more to the industry than its cost.

One often overlooked key to understanding the value of NASA's experimental communications satellite program is the concept of risk in space design. The high cost of launching spacecraft, coupled with the current impossibility of repairing hardware in synchronous orbit, means that the design of space hardware is driven by the risk of failure. As a result, space hardware designs have been very conservative, using old technology, because of the perceived risk associated with using anything new. Even if a new item can produce greater capability at lower cost, if it increases the risk of failure, it will not be used. For a new technology to fly, its benefits must be overwhelming, thereby precluding incremental improvements in space technology. As a result, space hardware can lag behind the state of the art by more than a decade.

A high risk of failure overshadowed the early years of satellite communications. NASA's launch record in the early 1960s reflected the state of rocket science at the time--namely, rockets failed quite often. Also, the space environment was not well known. The period was a critical time for NASA's involvement in the development of communications satellites. Without NASA, Hughes's Syncom would never have gotten off the ground, and Hughes would not be the world's largest communications satellite maker today.

Despite the benefits that NASA's experimental communications satellite program has brought industry, industry does not look kindly on NASA's development of spacecraft or technology that might undermine a firm's competitive advantage. In other words, a NASA spacecraft must develop new technology that all U.S. companies can use, but the space agency must avoid the construction of spacecraft that might seem to compete with any company. Hughes benefited enormously from NASA's involvement in the early days of communications satellites. Today, as a result, Hughes is the largest builder of commercial communications satellites. In the 1995 Space News "Top 50" list of space companies, Hughes was ranked second.24

The 1973 cancellation of NASA's commercial communications satellite research and development program, in retrospect, benefited the space agency. It forced a complete rethinking of the program. To be reinstated in 1978, NASA had to justify the program from scratch and transform it from a public service demonstration into a technology development program. The public service satellite program looked too much like competition to industry, even though the services NASA provided would not have been affordable to public service users.

[64] NASA currently is reorganizing its commercial communications program to prepare for the next generation of research and development following the ACTS, although a need for a followup project is not perceived at the moment. Therefore, NASA plans to develop long-term technology improvements and work on both spectrum management and issues of interoperability between satellite systems. NASA has benefited from the Satellite Industry Task Force, an industry advisory committee chaired by Hughes's Thomas Brackey. At a presentation of its findings on 12 September 1995, attended by Vice President Al Gore, the task force expressed support for the ACTS, but it did not call for NASA undertaking another satellite project.

 


END NOTES

1. Leonard Jaffe, Communications in Space (New York: Holt, Rinehart and Winston, 1966), p. 67.

2. Ibid., p. 80.

3. Delbert D. Smith, Communication Via Satellite: A Vision in Retrospect (Boston: A.W. Sijthoff, 1976), p. 71.

4. John Robinson Pierce, "Communication Satellites," Scientific American 205 (October 1961): 101.

5. Telstar I, 3 vols. (Washington, DC: NASA SP-32, Goddard Space Flight Center, June 1963). Also published as A.C. Dickieson, et al., "Telstar I," Bell System Technical Journal 42 (July 1963). In December 1965, Goddard issued volume four of NASA SP-32, which related Goddard Telstar experiments. The four-volume set of NASA SP-32 consequently provides a useful compendium of Telstar information.

6. Typed manuscript, Peter Cunniffe, "Misreading History: Government Intervention in the Development of Commercial Communications Satellites," Report no. 24, Program in Science and Technology for International Security, Massachusetts Institute of Technology, May 1991, p. 29, ACTS Project Office, NASA Lewis Research Center, Cleveland, OH.

7. Jaffe, Communications in Space, p. 107.

8. Cited in Lloyd D. Musolf, ed., Communications Satellites in Political Orbit (San Francisco: Chandler, 1968), pp. 17-18.

9. John F. Kennedy, Public Papers of the Presidents of the United States (Washington, DC: Office of the Federal Register, National Archives and Records Service, 1961), p. 530.

10. Smith, Communication Via Satellite, p. 74.

11. Lawrence Lessing, "Launching a Communications System in Space," in The Editors of Fortune, eds., The Space Industry: America's Newest Giant (Englewood Cliffs, NJ: Prentice-Hall, 1962), pp. 140-41.

12. Richard M. Bentley and Albert T. Owens, "SYNCOM Satellite Program," Journal of Spacecraft and Rockets 1 (July-August 1964): 395.

13. Paul J. McCeney, "Applications Technology Satellite Program," Acta Astronautica 5 (1978): 299-325.

14. Ibid., p. 324.

15. Robert O. Wales, ed., ATS-6 Final Engineering Performance Report (Washington, DC: NASA Research Publication [RP]-1080, 1981).

16. In 1985, the ATS program was transferred from Goddard to the Lewis Research Center in Cleveland to consolidate NASA's communications program. ATS-3 is still operational. Michael A. Cauley, "ATS-3: Celebrating 25 Years of Service in Space," unpublished manuscript, no date, p. 1, ACTS Project Office, NASA Lewis Research Center.

17. Harold R. Raine, "The Communications Technology Satellite Flight Performance," Acta Astronautica 5 (1978): 343-368.

18. A.D. Wheelon, "Von Karman Lecture: The Rocky Road to Communication Satellites," in AIAA 24th Aerospace Sciences Meeting: January 6-9, 1986, Reno, Nevada, Paper No. AIAA-86-0293, Vol. 4 (New York: American Institute of Aeronautics and Astronautics, 1986), p. 21.

19. Andrew Wilson, ed., Jayne's Space Directory 1993-1994 (Surrey: Jayne's, 1993), pp. 66, 359-60.

20. Ibid., pp. 330-32.

21. Committee on Satellite Communications, Space Applications Board, Assembly of Engineering, National Research Council, Federal Research and Development for Satellite Communications (Washington, DC: National Academy of Sciences, 1977), p. 30.

22. Robert R. Lovell, "The Status of NASA's Communications Program," Pacific Telecommunications Conference, January 1982, p. 4, preprint copy supplied by author.

23. See, for instance, Cunniffe, "Misreading History," passim.

24. Laura K. Browning, "The Top 50 Space Companies," Space News 6 (24-30 July 1995): 8.


previousindexnext