BSAT-1a was a geostationary communications satellite designed and manufactured by Hughes (now Boeing) on the HS-376 platform. It was originally ordered and operated by the Broadcasting Satellite System Corporation (B-SAT). It was used as the main satellite to broadcast television channels for NHK and WOWOW over Japan. It had a pure Ku band payload and operated on the 110°E longitude until it was replaced, along its backup BSAT-1b, by BSAT-3a.[3][7][8][9] On 3 August 2010, it was decommissioned and placed on a graveyard orbit.[5]
| Mission type | Communications |
|---|---|
| Operator | BSAT |
| COSPAR ID | 1997-016B[1] |
| SATCAT no. | 24769[2] |
| Mission duration | 13 years |
| Spacecraft properties | |
| Spacecraft | BSAT-1a |
| Bus | HS-376 |
| Manufacturer | Hughes |
| Launch mass | 1,236 kilograms (2,725 lb) |
| BOL mass | 723 kilograms (1,594 lb) |
| Dimensions | 3.15 m × 2.17 m (10.3 ft × 7.1 ft) (stowed for launch) |
| Power | 1,200 watts[3] |
| Start of mission | |
| Launch date | 23:08:44, 16 April 1997 (UTC) (1997-04-16T23:08:44Z)[4] |
| Rocket | Ariane 44LP V-95 |
| Launch site | Kourou ELA-2 |
| Contractor | Arianespace |
| Entered service | 1 August 1997 |
| End of mission | |
| Disposal | placed in a graveyard orbit |
| Deactivated | 3 August 2010 (2010-08-04)[5] |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Geostationary |
| Longitude | 110° east |
| Perigee altitude | 36,097 kilometres (22,430 mi) |
| Apogee altitude | 36,140 kilometres (22,460 mi) |
| Inclination | 3.33 degrees |
| Period | 24.21 hours |
| Epoch | 11 November 2014, 19:05:02 UTC[6] |
| Transponders | |
| Band | Ku band: 4 (plus 4 spares) |
| Coverage area | Japan |
| TWTA power | 106 Watts |
|
BSAT-1b → | |
The spacecraft was designed and manufactured by Hughes on the HS-376 satellite bus. This spin-stabilized platform had two main sections. One, the spinning section, was kept rotating at 50 rpm to maintain attitude, and a despun section that was used by the payload to maintain radio coverage. The spinning section included the Star-30BP Apogee kick motor, most of the attitude control, the power subsystem and the command and telemetry subsystems. The despun section contained the communications payload, including the antennas and transponders.[3][10]
It had a launch mass of 1,236 kg (2,725 lb), a mass of 723 kg (1,594 lb) after reaching geostationary orbit and a 10-year design life. When stowed for launch, its dimensions were 3.15 m (10.3 ft) long and 2.17 m (7 ft 1 in) in diameter. With its solar panels fully extended it spanned 7.97 m (26.1 ft).[3] Its power system generated approximately 1,200 Watts of power thanks to two cylindrical solar panels.[10] It also had a NiH2 batteries for surviving solar eclipses.[3] It would serve along BSAT-1b on the 110°E longitude position for the B-SAT.[10]
Its payload was composed of a four active plus four spares Ku band transponders fed by a TWTA with an output power of 106 Watts. Its footprint covered Japan and its surrounding island.[3]
Broadcasting Satellite System Corporation (B-SAT) was founded in 1993 to broadcast by satellite the analog signals of NHK and WOWOW, including analog high definition Hi-Vision channels.[8] In June 1994, it orders two HS-376 satellite from Hughes (now Boeing), BSAT-1a and BSAT-1b.[3]
During 1997 B-SAT completed its Kawaguchi and Kimitsu satellite control centers. At 23:08:44 UTC, 16 April 1997 the Ariane-44LP flight V-95 successfully launched BSAT-1a, along Thaicom 3, from Kourou ELA-2 launch pad.[2][10] On 1 August 1997, BSAT-1b entered into commercial service.[7]
During May 2005, B-SAT ordered BSAT-3a, the replacement satellite for BSAT-1a and BSAT-1b. It was successfully launched in August 2007, and accepted into the fleet the next month. During November, 2007 BSAT-3a took over the broadcasting of analog and digital signals from BSAT-1a and BSAT-1b. On 3 August 2010, BSAT-1a was placed in a graveyard orbit and decommissioned.[7][11]
