Syncom

Syncom (for "synchronous communication satellite") started as a 1961 NASA program for active geosynchronous communication satellites, all of which were developed and manufactured by Hughes Space and Communications. Syncom 2, launched in 1963, was the world's first geosynchronous communications satellite. Syncom 3, launched in 1964, was the world's first geostationary satellite.^[1]

In the 1980s, the series was continued as Syncom IV with some much larger satellites, also manufactured by Hughes. They were leased to the United States military under the Leasat program.

Syncom 1, 2 and 3

First generation Syncom satellite.

Common features

The three early Syncom satellites were experimental spacecraft built by Hughes Aircraft Company's facility in Culver City, California. All three satellites were cylindrical in shape, with a diameter of about 71 centimeters (28 in) and a height of about 39 centimeters (15 in). Pre-launch fueled masses were 68 kilograms (150 lb), and orbital masses were 39 kilograms (86 lb) with a 25-kilogram (55 lb) payload. They were capable of emitting signals on two transponders at just 2 W. Thus, Syncom satellites were only capable of carrying a single two-way telephone conversation, or 16 Teletype connections. As of June 25, 2009, all three satellites are still in orbit.^[2]

Syncom 1

Syncom 1 was intended to be the first geosynchronous communications satellite. It was launched on February 14, 1963 with the Delta B #16 launch vehicle from Cape Canaveral, but was lost on the way to geosynchronous orbit due to an electronics failure.^[3] Seconds after the apogee kick motor for circularizing the orbit was fired, the spacecraft fell silent. Later telescopic observations verified the satellite was in an orbit with a period of almost 24 hours at a 33° inclination.

Syncom 2

Syncom 2 was the first geosynchronous communication satellite. Its orbit was inclined rather than geostationary. The satellite was launched by NASA on July 26, 1963^[4] with the Delta B #20 launch vehicle from Cape Canaveral. The satellite successfully kept station at the altitude calculated by Herman Potočnik Noordung in the 1920s.

During the first year of Syncom 2 operations, NASA conducted voice, teletype, and facsimile tests,^[4] as well as 110 public demonstrations to show the capabilities of this satellite and invite feedback. In August 1963, President John F. Kennedy in Washington, D.C., telephoned Nigerian Prime Minister Abubakar Balewa aboard USNS Kingsport docked in Lagos Harbor; the first live two-way call between heads of government by satellite. The Kingsport acted as a control station and uplink station.

Syncom 2 also relayed a number of test television transmissions from Ft. Dix, N.J. to a ground station in Andover, Maine beginning on Sept. 29, 1963; the first successful TV transmission through a geosynchronous satellite. It was low-quality video with no audio.^[4]

Syncom 3

Syncom 3 was the first geostationary communication satellite, launched on August 19, 1964 with the Delta D #25 launch vehicle from Cape Canaveral. The satellite, in orbit near the International Date Line, had the addition of a wideband channel for television and was used to telecast the 1964 Summer Olympics in Tokyo to the United States.^[5] Although Syncom 3 is sometimes credited with the first television program to cross the Pacific Ocean, the Relay 1 satellite first broadcast television from the United States to Japan on November 22, 1963.^[6]

Turned off in 1969, Syncom 3 remains in GSO as of December 2012.^[7] In 40 years it has drifted 8 degrees to the west, to longitude 172.^[8]

Syncom IV (Leasat)

Syncom IV, Hughes owned US Military Leasat

The five satellites of the 1980s Leasat (Leased Satellite) program (Leasat F1 through Leasat F5) were alternatively named Syncom IV-1 to Syncom IV-5. These satellites were considerably larger than Syncoms 1 to 3, weighing 1.3 tonnes each (over 7 tonnes with launch fuel). At 4.26 meters (14.0 ft), the satellites were the first to be designed for launch from the Space Shuttle payload bay.

Hughes was contracted to provide a worldwide communications system based on four satellites, one over the continental United States (CONUS), and one each over the Atlantic, Pacific, and Indian oceans. Five satellites were ordered, with one as a replacement. Also part of the contract were the associated control systems and ground stations.

Leasat F1's launch was cancelled just prior to lift-off and F2 became the first into orbit on August 30, 1984 aboard Discovery on shuttle mission STS-41-D. F1 was launched successfully on November 8, 1984 aboard STS-51-A followed on April 12, 1985 by Leasat F3 on STS-51-D. F3's launch was declared a failure when the satellite failed to start its manoeuvre to geostationary orbit once released from Discovery. On August 27, 1985 Discovery was again used to launch Leasat F4, and during the same mission (STS-51-I) captured and repaired F3. F3 successfully fired its perigee motor and obtained a geostationary orbit, however F4 would later fail and was declared a loss.

The fifth and last Leasat (F5), which was built as a spare, was successfully launched by Columbia mission STS-32 on January 9, 1990.

The last Leasat was retired February 1998.

See also

• List of communications satellite firsts
• John H. Rubel

Notes

References

• "Satellite to open new Asia-U.S. link". New York Times. December 4, 1963. 
• "Syncom 3 to be lofted today". New York Times. August 19, 1964. 
• "Syncom 3 is launched into a preliminary orbit". New York Times. August 20, 1964. 
• "Syncom is pushed into second orbit". New York Times. August 21, 1964. 
• "Test of Syncom 3 called successful". New York Times. August 23, 1964. 
• "Syncom 3 now hovering on station over Pacific". New York Times. September 13, 1964. 
• "Syncom 3 relaying TV over the Pacific". New York Times. September 24, 1964. 

Additional reading

• "Boeing. Satellite Development Center. Syncom. The world's first geosynchronous communications satellite.". Archived from the original on 2010-11-11. Retrieved 2013-03-11. 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. 

External links

• "The Stay-Putnik", a March 1963 Popular Science article on Syncom 1
• Boeing: Detailed Leasat information
• Boeing: Detailed Syncom information
  • Boeing: High resolution Syncom image
• Syncom 2 satellite description
• Daniel R. Glover's page about NASA Experimental Communications Satellites
• NASA Goddard Space Flight centre descriptions:
  • Syncom 1
  • Syncom 2
  • Syncom 3
• Gunter's Space Page:
  • Syncom 1, 2, 3
  • Leasat 1-5 (Syncom-IV 1 to 5)