Thaicom 1 [Boeing BSS]
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 in October 1991 to develop the country's first dedicated communications satellite system. Two satellites, light-weight versions of Hughes' popular Hughes HS-376 model, were ordered to be built and delivered in 24 and 28 months, respectively. The system was named "Thaicom" by King Bhumiphol, to symbolize the link between Thailand and modern communications technology. The satellites were called Thaicom 1 and Thaicom 2
Based on the reliable HS-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 HS-376L satellites share some characteristics with the other HS-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 Ariane-44L H10+ rocket from Kourou, French Guiana, on December 18, 1993. The satellite's size allowed it to share the launch vehicle with another Hughes spacecraft. Thaicom 2 was successfully launched October 7, 1994, also sharing an Ariane-44L H10+ rocket with another Hughes satellite. In an Ariane launch, the spacecraft is injected directly into geosynchronous transfer orbit, so no perigee stage is needed. A Thiokol Star-30 class 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.
Thaicom 1 was relocated in May-June 1997 to an orbital position of 120 degrees East, and was renamed Thaicom 1A.
Thaicom1A was moved to a grave yard orbit on 12 January 2010 and Thaicom 2 followed on 30 October 2010, both retiring after 16 years of service.
|Type / Application:||Communication|
|Operator:||Shinawatra Computer and Communications Co. Ltd. (SC&C)|
|Equipment:||2 (+1) Ku-band transponders, 10 (+2) C-band transponders|
|Propulsion:||Star-30BP (#1), Star-30CBP (#2)|
|Power:||Solar cells (body mounted and drop-skirt), batteries|
|Lifetime:||13.5 years (planned), 16 years reached|
|Mass:||1080 kg (launch); 629 kg (BOL)|
|Thaicom 1 → Thaicom 1A||18.12.1993||Ko ELA-2||Ariane-44L H10+||with DirecTV 1|
|Thaicom 2||08.10.1994||Ko ELA-2||Ariane-44L H10+||with Solidaridad 2|