Japan's First Commercial Communications Satellites
| Diameter | 3.7 m (12 ft) |
|---|---|
| Height stowed | 3.4 m (11 ft 2 in) |
| Height deployed | 10 m (32 ft 11 in) |
|---|---|
| Weight in orbit | 1364 kg (3006 lb) beginning of life |
Japan's first commercial communications satellite services began in 1989 when a small consortium, Japan Communications Satellite Company (JCSAT), now Japan Satellite Systems, Inc. (JSAT), launched two satellites, JCSAT 1 on March 6, and JCSAT 2 on December 31.
The satellites relay signals for voice, television, facsimile and high-speed data services for business use throughout Japan. The JCSAT spacecraft also transmit high-quality broadcast video and data directly to customer sites.
The satellite contract, which JCSAT awarded in June 1985 to Hughes Space and Communications International, Inc. (HSCI), included two Hughes 393 spin-stabilized spacecraft and two control stations in Japan. JCSAT 1 and 2 were built at Hughes' Integrated Satellite Factory in El Segundo, Calif. Launch, mission and insurance arrangements were made with Hughes Communications, Inc. (HCI), which, like HSCI, was part of Hughes Electronics Corporation.
In October 2000, The Boeing Company acquired three units within Hughes Electronics Corporation: Hughes Space and Communications Company, Hughes Electron Dynamics, and Spectrolab, Inc., in addition to Hughes Electronics' interest in HRL, the company's primary research laboratory. The four are now part of Boeing's newest subsidiary, Boeing Satellite Systems, Inc.
The Hughes 393 is similar to the popular Hughes 376 model, now the Boeing 376, but has nearly twice the size, power and channel capacity. The satellite's high power and large antenna permits the use of ground antennas as small as 1.2 meters (4 feet) in diameter, significantly cutting the cost of data distribution for business customers.
Operating at the Ku-band frequency, JCSAT 1 and 2 each provide thirty-two 27-MHz wide channels and use a 20-watt transponder. On orbit, with solar panels deployed and antenna raised, the satellites measure 10 meters (32 feet 11 inches) high and at beginning of life weigh 1364 kg (3006 pounds). Stowed compactly for launch, with solar panels telescoped together, antenna reflector folded down, and perigee motor tucked inside, each measures only 3.4 meters (11 feet 2 inches) in height and 3.7 meters (12 feet) in diameter.
The K7 and K4-3/4 solar cells cover the surface of each satellite's two cylindrical solar arrays and generate 2350 watts at the beginning of life. Two 38 ampere-hour nickel-hydrogen batteries provide power when a satellite is in the earth's shadow.
JCSAT 1 was launched on an Ariane 4 booster and was placed directly into a synchronous transfer orbit. The spacecraft's onboard liquid bipropellant system was then fired to circularize the orbit at the 36,000 km high synchronous orbit. For this function, the propulsion system used two 110 pound-force Marquardt R-4D thrusters. The system uses six 5 pound-force thrusters to provide impulse for stationkeeping.
JCSAT 2 was launched on a Titan booster and placed directly into geosynchronous orbit.
The satellites are located at 150 degrees and 154 degrees East longitude respectively. JCSAT 1 is due to be retired in 1997. JCSAT 2 is expected to operate until early 2000.
The JCSAT consortium was formed to combine the technical, marketing, and satellite expertise of HCI with the business, financial, and marketing strengths of the Japanese companies ITOCHU Corporation and Mitsui and Company, Ltd. In 1993 HCI sold its interest in JCSAT, enabling the remaining partners to merge with a newly licensed satellite operator, Satellite Japan, Inc. This new company became Japan Satellite Systems Inc., but continued to operate under a JCSAT trademark.
Hughes, now Boeing Satellite Systems, is the leading manufacturer of commercial communication satellites, having built more than 40 percent of those in operation today.