JCSat 3 [Boeing BSS]

Foreseeing the growth of the communications business, Japan Satellite Systems, Inc.,(JSAT) of Tokyo signed a contract in October 1993 for a HughesHS-601 satellite from Hughes Space and CommunicationsInternational, Inc. The satellite,JCSAT-3, was designed to relay voice, data, andtelevision signals via Ku-band to eastern Asia, Australia, New Zealand, and India; and viaC-band to eastern and southern Asia and Hawaii. In December 1995, JSAT returned to Hughesfor another spacecraft,JCSAT-4, with similar coverage and increased power. In October2000, HSCI became Boeing Satellite Systems International, Inc.

Hughes contracted with Lockheed Martin for launch of JCSAT-3, which took placesuccessfully on Aug. 28, 1995, aboard anAtlas-2ASrocket from Cape Canaveral, Fla. JSAT contracted separately with Lockheed Martin to launchJCSAT-4 on anotherAtlas-2AS, on Feb. 16, 1997.

Like others in the HughesHS-601 series, JCSAT-3and 4 consist of a cube-shaped center payload section, with solar wings and an antennaarray. TheHS-601 is composed of two modules. Theprimary structure carries all launch vehicle loads and contains the propulsion system, buselectronics, and battery packs. The payload module holds communications equipment andisothermal heat pipes. Reflectors, antenna feeds, and solar arrays mount directly to theprimary module, and antenna configurations can be placed on three faces of the bus. Such amodular approach allows work to proceed in parallel on both structures, thereby shorteningthe manufacturing schedule and test time. The satellites are built at Hughes Space andCommunications Company facilities in El Segundo, Calif.

Both JCSAT-3 and 4 have a pair of four-panel sun-tracking solar array wings. Each wingextends 11.9 meters north and south from the body for an overall deployed length of 26.2meters. These panels are designed to generate approximately 5,000 Watts with the wingsdeployed, using K-4 3/4 solar cells. Additionally, a single 30-cell, 200 Amp-hr,nickel-hydrogen battery provides power during eclipse periods.

Both JCSAT-3 and 4 have a C-band payload consisting of 12 active transponders operatingat 36 MHz, powered by 34 watt solid-state power amplifiers. JCSAT-3's Ku-band payload has12 active transponders operating with 36 MHz of bandwidth, and 16 active transpondersoperating with 27 MHz, each using 63 watt linearized traveling-wave tube amplifiers(LTWTAs). JCSAT-4 also has a total of 28 active Ku-band transponders, but theconfiguration is different. There are eight transponders with 36 MHz of bandwidth and 16with 27 MHz, powered by 63 watt LTWTAs. In addition, there are four transponders using95 watt LTWTAs, operating with 36 MHz of bandwidth. Also, four of the 27 MHz transponderscan be switched by ground command to 54 MHz with 125 Watts.

On both spacecraft, the flexibility of the communications payload design allows theinterconnection of up to 10 C-band uplink channels to Ku-band downlink channels, and 10Ku-band uplink channels to C-band downlinks.

Each satellite has four octagonal reflectors, one each on the east (for Ku-band) andwest (for C-band) and two on the Earth-facing, or nadir, surface (for Ku-band). Each ofthese reflectors makes use of Hughes' patented shaped reflector technology, whicheliminates the need for complex feedhorn arrays. With east and west reflectors deployed,the satellites measure 7.5 meters in width.

For launch, the solar wings and reflectors fold alongside the spacecraft bus, forming abox 2.8 meters by 4.9 meters by 3.8 meters. The booster places the spacecraft into asuper-synchronous transfer orbit of about 167 km by 80,000 km. The super-synchronous orbitoptimizes use of the satellite's own propellant during the transfer to geosynchronousorbit. After separation from the launch vehicle, the satellite's on-board 490-Newton (110lbf) liquid apogee motor is fired to circularize the orbit at the 36,000 km geosynchronousaltitude. The liquid bipropellant subsystem provides 12 thrusters of 22 Newtons (5 lbf)for stationkeeping. Once on-station, the satellites weigh approximately 1841 kg, includingfuel required for 12 years of life. JCSAT-3 operates from 128 degrees East longitude.JCSAT-4 operates at 124 degrees East. After becoming operational, the JCSat 4 is refered by the designatorJCSat R

In late 2009 Intelsat purchased the aging JCSAT R satellite to operate as a place holder under the designationIntelsat 26. It will be loaned to Turksat.

References:

• Boeing:JCSAT-3, 4

Cite this page:

• Copy to clipboard