JSAT Expands Constellation with JCSAT-5 and JCSAT-6
| Height stowed | 4.3 m (14 ft) |
|---|---|
| Width stowed | 2.8 m x 3.8 m (9.2 ft x 12.4 ft) |
| Solar Arrays deployed | 26.2 m (86 ft) |
| Antennas deployed | 7.5 m (24.6 ft) |
| Weight, beginning of life | 1841 kg (4060 lb) |
In June 1996, Hughes Space and Communications International, Inc. (HSCI), signed a contract with Japan Satellite Systems, Inc., (JSAT) of Tokyo, to build a fifth communications satellite. In December 1996, JSAT contracted for a sixth satellite. The new satellites, JCSAT-5 and JCSAT-6, are Hughes 601 body-stabilized model spacecraft. JCSAT-5 was successfully launched on December 2 1997 on an Ariane rocket from Kourou, French Guiana. JCSAT-6 was launched February 15, 1999 from Cape Canaveral, Fla., on an Atlas IIAS rocket. These new satellites will allow JSAT to meet increased customer demand for multimedia and Internet access and will carry voice, data and television signals to Japan.
More than 81 satellites have been ordered since the body-stabilized model became available in 1987. Other Hughes-now Boeing-601s built for JSAT include JCSAT-3, which was launched in August 1995, and JCSAT-4, which was launched in February 1997. Japan's first commercial communications satellites, JCSAT-1 and JCSAT-2, were launched in 1989. These 393 spin-stabilized spacecraft were also built by Hughes.
As Hughes 601 satellites, JCSAT-5 and JCSAT-6 consist of a cube-shaped center payload section, with the solar panel wings extending from the north and south sides, and an antenna array. The 601 contains two modules. The first is the bus module which carries all launch vehicle loads and contains the propulsion system, bus electronics and battery packs. The second module is the payload module, which holds communications equipment and isothermal heat pipes. Reflectors, antenna feeds, and solar arrays mount directly to the primary structure, and antenna configurations can be placed on three faces of the bus. This modular approach enables work to proceed in parallel on both structures, which shortens manufacturing and test time. JCSAT-5 and JCSAT-6 were built in the Integrated Satellite Factory of Hughes Space and Communications Company in El Segundo, Calif.
Each satellite has a pair of four-panel sun-tracking solar array wings. Each wing extends 11.9 meters north and south from the body for an overall deployed length of 26.2 meters. These panels are designed to generate approximately 5,000 watts with the wings deployed, using K-4 3/4 solar cells. Additionally, a single 30-cell 200 Amp-hour, nickel-hydrogen battery provides power during eclipse periods.
The JCSAT-5 payload consists of 32 active Ku-band transponders. There are 16 transponders operating with 27 MHz bandwidth, each with 60 watts provided by a traveling-wave tube amplifier (TWTA); four operating with 36 MHz bandwidth, using 60-watt TWTAs; and 12 operating with 36 MHz bandwidth, each with 95-watt TWTAs. JSAT, using commands from the ground station, can combine four of the 36-Mhz transponders, resulting in two 76 MHz transponders with 95 watts. JCSAT-6 also has 32 active Ku-band transponders with 27 MHz bandwidth, each with 75 watts provided by a TWTA.
JCSAT-5 and JCSAT-6 each have two octagonal reflectors, located on the east and west side of the bus. These reflectors make use of Hughes' patented shaped reflector technology, which eliminates the need for complex feedhorn arrays. With east and west reflectors deployed, the satellites measure 7.5 meters in width.
The primary on-station beam pointing control is provided by means of a tracking beacon from either of the two Japanese ground control stations, using upgraded equipment provided by Hughes. The main station is in Yokohama, with backup control in Gunma.
JSAT contracted for launch directly with Arianespace for JCSAT-5 and with Lockheed Martin for JCSAT-6.
For launch, the solar wings and reflectors fold alongside the spacecraft bus, forming a box 2.8 meters by 4.3 meters by 3.8 meters. After separation from the launch vehicle, the satellite's on-board 490-Newton (110 lbf) liquid apogee motor is fired to circularize the orbit at the 36,000 km (22,300 miles) geosynchronous altitude. The liquid bipropellant subsystem provides 12 thrusters of 22 Newtons (5 lbf) for stationkeeping. Once on-station, the satellites weigh approximately 1841 kg. JCSAT-5 is stationed at 150° East longitude and JCSAT-6 is at 124° East.
The Boeing 601 is the most-purchased commercial communications satellite model. Boeing Satellite Systems, Inc. is the world's leading manufacturer of commercial communications satellites, and is also a major supplier of spacecraft and scientific instruments to the U.S. government, and builder of weather satellites for the United States and Japan.