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Syncom (for " synchronous communication satellite") started as a 1961 NASA program for active geosynchronous communication satellites, all of which were developed and manufactured by the Space and Communications division of Hughes Aircraft Company (now the Boeing Satellite Development Center). 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.
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.
During the first year of Syncom 2 operations, NASA conducted voice, teletype, and facsimile tests, 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 Tafawa Balewa aboard (the first satellite communication ship) 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 Fort Dix, New Jersey to a ground station in Andover, Maine, beginning on September 29, 1963. Although it was low-quality video with no audio, it was the first successful television transmission through a geosynchronous satellite.
In 1965, Syncom 3 was implemented to support the DOD's communications in Vietnam.
Turned off in 1969, Syncom 3 remains in geosynchronous orbit In 50 years it has drifted east, to longitude 123 W. Requires Javascript.
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 Ocean, Pacific Ocean, and Indian Ocean oceans, spaced about 90 degrees apart. Five satellites were ordered, with one as a replacement. Also part of the contract were the associated control systems and ground stations. The lease contracts were typically for five-year terms, with the lessee having the opportunity to extend the lease or to purchase the equipment outright. The US Navy was the original lessee.
Leasat F1
However, with another satellite planned to be launched, it was determined that a space walk by a subsequent Shuttle crew might be able to "wake" the craft. The best guess was that a switch had failed to turn on the satellite. A "bypass box" was hastily constructed, NASA was excited to offer assistance, the customer was supportive, and the insurance underwriters agreed to fund the first ever attempt at space salvage.
On August 27, 1985 was again used to launch Leasat F4, and during the same mission (STS-51-I) captured the 15,000 lb stricken F3. Astronaut James van Hoften grappled and then spun down the F3 satellite. After the bypass box was installed by van Hoften and Bill Fisher, van Hoften manually spun the satellite up. Once released, the F3 successfully powered up, fired its perigee motor and obtained a geostationary orbit. (This scenario would play out again in 1992 with Intelsat 603 and .) While F3 was now operational, Leasat F4 soon failed and was itself declared a loss after only 40 hours of RF communications.
The stricken F4 did not remain a complete failure. Data from F4's failure permitted the saving of F1 from a premature failure. Since all of the Leasats are spin-stabilized, they have a bearing that connects the non-rotating and rotating parts of the spacecraft. After F4's communication failure, it suffered a spin lock while attempting to jostle the communications payload: the spun and despun sections locked together. Remembering this second failure of F4, and with F1 beginning to wear out at the spin bearing, it was decided to "flip" F1 every six months to keep the payload in the sun. Thus F1 went on to operate smoothly for its remaining life and never encountered a locked despun section.
Leasat F4 was subsequently powered down and moved to a graveyard orbit with a large amount of station keeping fuel in reserve. This was fortuitous; when another satellite suffered a loss of its fuel ten years later, Hughes engineers pioneered the use of alternative propellants with Leasat F4. Long after its primary mission had failed, F4 was powered back on to test whether a satellite could be kept on station using nonvolatile propellants. F4 was used to perform numerous tests, including maneuvers with oxidizer for propulsion once the hydrazine ran out.
The fifth and last Leasat (F5), which was built as a spare, was successfully launched by mission STS-32 on January 9, 1990. The last active Leasat, it was officially decommissioned on September 24, 2015, at 18:25:13 UTC. F5 was one of the longest-serving and most successful commercial satellites. Towards the end of its 25-year life, F5 had been leased by the Australian Defence Force for UHF service.
| +Syncom / Leasat satellites | |||
| 1963-02-14 | Syncom 1 | 1963-004A | Delta B |
| 1963-07-26 | Syncom 2 | 1963-031A | Delta B |
| 1964-08-19 | Syncom 3 | 1964-047A | Delta D |
| 1984-11-10 | Syncom IV Leasat F1 | 1984-093C | , STS-51-A |
| 1984-08-31 | Syncom IV Leasat F2 | 1984-113C | , STS-41-D |
| 1985-04-12 | Syncom IV Leasat F3 | 1985-028C | , STS-51-D |
| 1985-08-29 | Syncom IV Leasat F4 | 1985-076D | , STS-51-I |
| 1990-01-09 | Syncom IV Leasat F5 | 1990-002B | , STS-32 |
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