Thailand's First Domestic Satellite System

STOWED

Diameter	2.16 m (10 ft 1 in)
Height stowed	2.8 m (9 ft 4 in)

IN ORBIT

Height deployed	7.7 m (25.3 ft)
Weight	723 kg (1593 lb), beginning of life

Mindful of the growing population and business base in Thailand, Shinawatra Computer and Communications Co. Ltd. (SC&C) signed a contract with Hughes Space and Communications Company, today Boeing Satellite Development Center, in October 1991 to develop the country's first dedicated communications satellite system. Two satellites, light-weight versions of Hughes' popular Hughes 376 model, were ordered to be built and delivered in 24 and 28 months, respectively. The system was named "THAICOM" by His Majesty King Bhumiphol, to symbolize the link between Thailand and modern communications technology.

Thailand is not without satellite telecommunications service; companies have been using regional systems operated by Indonesia and INTELSAT.

The Thai government in 1991 granted Shinawatra a 30-year concession to operate communications satellites for the country. Shortly thereafter Shinawatra signed the approximately $100 million contract with Boeing, which includes the spacecraft, ground equipment, and training of Shinawatra employees to be satellite controllers.

SC&C has other concessions in Thailand, such as cable television, cellular telephone services, digital paging, and data services. The THAICOM satellites allow SC&C to continue offering these services and provide the capability for private VSAT networks, direct-to-home television and digital audio broadcasting, mobile telephone services, and videoconferencing. SC&C's concession also calls for it to lease transponders to other companies and government agencies. Shinawatra Satellite Public Co. Lt., an SC&C subsidiary, operates the spacecraft.

Based on the reliable Boeing 376 bus, each THAICOM satellite has two Ku-band transponders (plus one spare), powered by 47-watt traveling-wave tube amplifiers. The effective isotropic radiated power over Thailand is 50 dBW. The spacecraft also carry 10 C-band transponders (plus two spares), linked to 11-watt solid state power amplifiers. These have a broader coverage area, from Japan to Singapore, and provide 33 to 38 dBW.

The THAICOM Boeing 376L satellites share some characteristics with the other Boeing 376 spin-stabilized models sold to customers around the world. The outer and inner cylindrical solar panels slide together for launch, and in orbit, the outer panel is lowered and the round, dual-polarized antenna is raised. Silicon solar cells provide electrical power (700 watts at beginning of life for THAICOM), and a nickel-hydrogen battery provides power during eclipse.

The THAICOM satellites weigh approximately 629 kg (1384 lb), with their hydrazine stationkeeping fuel, at beginning of life in orbit. Because of the light electronics payload, the satellites will be able to carry several years' worth of additional fuel. The THAICOM contract calls for 13.5 years of service, versus 8 to 10 years for other HS 376 models with more transponders.

THAICOM 1 was launched on an Arianespace rocket from Kourou, French Guiana, on December 17, 1993. The satellite's size allowed it to share the launch vehicle with another Boeing spacecraft. THAICOM 2 was successfully launched October 7, 1994, also sharing an Ariane rocket with another Boeing satellite. In an Ariane launch, the spacecraft is injected directly into geosynchronous transfer orbit, so no perigee stage is needed. A Thiokol Star 30 apogee kick motor is used to circularize the spacecraft's orbit around the equator. Four 22.2 Newton thrusters are used for stationkeeping. The satellites are designed to operate between 78 degrees and 120 degrees East longitude. Telemetry, tracking, and control are done through the Boeing-built ground station in Nonthaburi, a province 15 km north of Bangkok.

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