The World's First Geosynchronous Communications Satellite

Diameter:
  0.71 m (2 ft 4 in)

Panel Height
  0.39 cm (1 ft 3 in)

Weight in Orbit
  35 kg (78 lb)

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The 1963 launch of Syncom, the world's first geosynchronous communications satellite, vanquished forces of time, cost, and geography to begin a communications revolution.

Today more than 180 active descendants circle the equator as Syncom once did.

Few would have predicted such all-pervasive global consequences on July 26, 1963, when a Thor-Delta rocket blazed up from Cape Canaveral, Fla., to start Syncom on its journey into synchronous orbit and into history.

As early as 1929, Austrian engineer Hermann Noordung envisioned that an object placed over the equator at a height of 22,238 miles and a speed of 6,878 mph would match, or synchronize with, Earth's daily rotation. To a ground observer, an object in this synchronous orbit would seem to stand still, thus the term "geostationary."

English scientist and writer Arthur C. Clarke took this theory a giant step further in 1945. He postulated that three spacecraft set equidistant in synchronous orbit could virtually blanket the planet with continuous radio and television coverage.

Theory began to become reality in 1959. In that post-Sputnik era, enthusiasm for space was at fever pitch. Hughes Aircraft Company, later known as Hughes Space and Communications Company, and now Boeing Satellite Systems, Inc., assigned Dr. Harold Rosen and his team of Donald D. Williams and Thomas Hudspeth to find a new project. Rosen thought that a communications satellite was the best project and a geostationary orbit the most promising.

Communications satellites before Syncom used low orbits. Huge swiveling ground antennas and expensive tracking computers were needed to stay in contact with them during the brief time they raced overhead. In contrast, a synchronous satellite could communicate directly and continuously with any ground station in its line of sight, using fixed antennas. No complex tracking antennas would be necessary. Synchronous altitude also meant that a satellite would be in sunlight 99 percent of the time over the course of a year, eliminating the need for an active temperature control system.

Moreover, from his college days Rosen remembered how a spinning body like a football is much more stable in flight and more resistant to external influences than the same body when not spinning. Rosen reasoned that a spinning satellite configuration was the easiest way to simplify attitude and velocity control and achieve the low weight necessary for the limited launch vehicle capacity then available.

Using company funds, Williams invented and patented a device for controlling the attitude of a spacecraft through "precession," a type of motion achieved by spin-synchronous pulsing of thrusters.

The Syncom project demanded many design firsts. Hudspeth recalled, "We tried to fix everything foreseeable, but despite its simplicity, Syncom was still pretty complex. There was no standard way of doing things. For example, no transistor amplifiers existed, and transistors then didn't work well at frequencies above 70 MHz. We had to get up to 10 GHz. So we used a chain of diode frequency multipliers, or doublers. The fight was to get enough efficiency out of the doublers, because every time you go through a doubler, you lose power. We managed to provide signal power to the traveling-wave tube through five stages of doublers in four nested boxes no bigger than two stacked decks of cards."

By 1961, the Hughes team had designed and built a flyable prototype satellite. In search of a customer, they took it to the Paris Air Show. They shot video images of show visitors passing the Hughes booth, relayed the signal across the booth by means of the prototype, received and displayed the image on a TV screen, took a picture of the screen with one of the recently invented Polaroid cameras, and handed out the instant photos as souvenirs. They also displayed the prototype atop the Eiffel Tower. One naysaying spectator declared, "This is as high as it will ever get."

In August 1961, Hughes won a $4 million contract from NASA Goddard Space Flight Center and the Department of Defense to build three synchronous communications satellites. The three major project objectives were to:

• Place a satellite in synchronous orbit.
• Demonstrate on-orbit stationkeeping.
• Perform communications and engineering tests on a high-altitude synchronous satellite.

Launch of the first Syncom on Valentine's Day, 1963, proceeded smoothly at the outset. The ground crew began confirming that the electronics worked by playing "The Star-Spangled Banner" via satellite signal. The telemetry, command, and communications systems all functioned.

Then the crew ordered the satellite's onboard apogee motor to fire to inject Syncom into final orbit. Twenty seconds later, about one second before the expected burnout of the apogee motor, the sound ceased and all communication was lost.

"The culprit first seemed to be the apogee motor," Rosen explained. But upon reflection, other possible causes surfaced. "The nitrogen tanks might have had too much pressure and exploded, or the critical wire that powered both the telemetry transmitter and the communications transmitter could have broken suddenly." Undeterred by the setback, the Hughes team quickly made three improvements on Syncom 2 to enhance reliability. First, they reduced the pressure in the nitrogen system. Second, they made the wiring redundant. Third, they used a different apogee motor.

Only five months later, on July 26, 1963, Syncom 2 successfully reached synchronous orbit over the Atlantic Ocean-considerably higher than the Eiffel Tower.

But the ultimate test remained. Two contact crews, one at Lakehurst, N.J., and the other aboard the U.S Navy ship Kingsport at the African port of Lagos, Nigeria, were trying to use conventional static-plagued radio-telephone circuits. Suddenly a voice burst clearly from a shipboard speaker. "Kingsport, this is Lakehurst. Kingsport, this is Lakehurst. How do you hear me?" These ordinary words resonated with extraordinary significance. Syncom 2 had opened the door to instant global communications.

The public began to awake to what Syncom 2 offered when President John F. Kennedy in Washington, D.C., telephoned Nigerian Prime Minister Abubaker Balewa in Africa later in 1963. This was the first live two-way call between heads of state by satellite relay.

During Syncom 2's first year, NASA conducted voice, teletype, and facsimile tests, as well as 110 public demonstrations to acquaint people with Syncom's capabilities and invite their feedback. Rosen recalled one such demonstration for Hughes staff at the company's plant in Culver City, Calif. "We had a portable terminal with a soldier at an army base on the other end. My wife said, 'Hello.' The soldier said, 'Hello.' She dropped the receiver and said, 'My God, Harold, it works!'"

Syncom 2 went on to prove that its maneuvering and stationkeeping system worked as well as its communications system. By firing its gas jets in brief pulses, the satellite moved under its own power from its initial position over the Atlantic to a location above the Indian Ocean. It also maintained the correct orbit in both locations. Syncom 2 successfully passed all tests and fulfilled all mission objectives.

Meanwhile, Hughes engineers were racing to prepare Syncom 3 for launch. Their goal was live television coverage of the 1964 Olympic Games in Tokyo. On August 19, one month before the Games and in time to bring their pageantry to American homes in the first continuous trans-Pacific broadcast, Syncom 3 ascended into true geostationary orbit.

Syncom 2 had an orbital inclination of 33° due to its launch from a site north of the equator. This meant that Syncom 2 was not actually stationary over one point on the Earth's surface, but moved in an elongated figure-eight pattern between 33° north and 33° south of the equator. By 1964, however, launch vehicle technology had advanced sufficiently for Syncom 3 to achieve a geostationary orbit (inclination less than 1°) through a pioneering series of complex space maneuvers.

The pair of Syncom satellites expanded direct, 24-hour communications access to two-thirds of Earth's surface. After the Department of Defense assumed stewardship of Syncom 2 and 3, they not only carried television and telephone transmissions, but served as the primary communications link between Southeast Asia and the Western Pacific during part of the Vietnam conflict. By February 1966, the Syncom 2 and 3 repeaters had accumulated 27,000 hours of operation.

The Syncom satellites remained active through 1966, far exceeding their one-year design life. Finally, as their ever-more-capable successors joined them in space, they were decommissioned and retired in April 1969.

Syncom 2 measured 2 feet, 4 inches (0.71 meter) in diameter, with a solar panel height of 1 foot, 3 inches (0.39 cm). Its weight in orbit was 78 pounds (35 kg). The satellite was a spin-stabilized cylinder faced with 3,840 positive-on-negative silicon solar cells. The solar cells provided power of 28 watts initially and 19 watts minimum after one year. Syncom 3 used negative-on-positive solar cells for superior radiation resistance and longer life.

The nozzle of the apogee motor protruded from the aft end of the cylinder and the communications antennas from the forward end. The motor provided a 4,696-foot-per-second velocity increment. The 6-dB-gain communications transmit antenna was a three-element, colinear slotted array configuration. The communications receive antenna was a single 2-dB gain dipole on top of the transmit antenna. Four whip antennas evenly spaced around the aft end of the spacecraft conveyed omnidirectional VHF telemetry and commands.

For attitude and velocity control, Syncom 2 was equipped with both a nitrogen and a hydrogen peroxide gas system. Each system had two jets, one parallel to the spin axis and the other perpendicular to it. Syncom 3 employed an all-hydrogen peroxide system.

The Syncom 2 payload included two 1815-MHz transmitters with dual 2-watt traveling-wave tubes, one on and one standby, and two 7363-MHz receivers with a 10-dB noise figure. In this redundant configuration, either receiver could be operated with either transmitter, as selected by ground command. Two 500-kHz channel, double-conversion repeaters accomplished narrowband two-way communication, and a single 5-MHz channel, double-conversion repeater performed one-way wideband communication. This was equivalent to one two-way telephone channel or 16 teletype channels. These capabilities were usable alternately. Syncom 3 was changed to one 5-MHz and one switchable (50 kHz or 13 MHz) double-conversion repeater. The increased bandwidth improved television transmissions.