Syncom

Common features The three early Syncom satellites were experimental spacecraft built by Hughes Aircraft Company's facility in Culver City, California, by a team led by Harold Rosen, Don Williams, and Thomas Hudspeth. All three satellites were cylindrical in shape, with a diameter of about and a height of about . Pre-launch fueled masses were , and orbital masses were with a 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. all three satellites are still in orbit, although no longer functioning. 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. 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 launched by NASA on July 26, 1963 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. 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. Transfer to Department of Defense control By the end of 1964, Syncoms 2 and 3 had completed NASA's R&D experiments. On January 1, 1965, NASA transferred operation of the satellites to the United States Department of Defense (DOD) along with telemetry, command stations, and range and rangefinding equipment. DOD had, in fact, provided the communications ground stations used to relay transmissions via the two Syncoms since their launch. DOD agreed to provide telemetry and ranging data of continuing scientific and engineering interest. 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. == Syncom IV (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, all using Hughes' HS-381 platform of satellite. These satellites were considerably larger than Syncoms 1 to 3, weighing 1.3 tonnes each (over 7 tonnes with launch fuel). At , the satellites were the first to be designed for launch from the Space Shuttle payload bay, and were deployed like a Frisbee. The satellites are 30 rpm spin-stabilized with a despun communications and antenna section. They were made with a solid rocket motor for initial perigee burn and hydrazine propellant for station keeping and spin stabilization. The communications systems offers a wideband UHF channel (500 kHz bandwidth), six relay 25 kHz channels, and five narrowband 5 kHz channels. This is in addition to the fleet broadcast frequency, which is in the military's X-band. The system was used by military customers in the US and later in Australia. Most of the satellites were retired in the 1990s, but one would remain operational until 2015. During the First Gulf War, Leasat would be used for personal communications between Secretary of State James Baker and President George H. W. Bush, Hughes had an insurance policy on the satellite, and so claimed a total loss for the spacecraft of about $200 million, an amount underwritten by numerous parties. 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. 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. 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. ==See also==