BSAT-1b

BSAT-1b 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 backup of BSAT-1a to broadcast television channels for NHK and WOWOW over Japan. It had a pure K_u band payload and operated on the 110°E longitude until it was replaced, along its twin BSAT-1a, by BSAT-3a.^[2][4][6][7]

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.^[2][8]

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).^[2] Its power system generated approximately 1,200 Watts of power thanks to two cylindrical solar panels.^[8] It also had a NiH₂ batteries for surviving solar eclipses.^[2] It would serve along BSAT-1a on the 110°E longitude position for the B-SAT.^[8]

Its payload was composed of a four active plus four spares K_u band transponders fed by a TWTA with an output power of 106 Watts. Its footprint covered Japan and its surrounding island.^[2]

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.^[6] In June 1994, it orders two HS-376 satellite from Hughes (now Boeing), BSAT-1a and BSAT-1b.^[2]

During 1997 B-SAT completed its Kawaguchi and Kimitsu satellite control centers, launched and commissioned BSAT-1a.^[4] At 22:53 UTC, April 28, 1998, the Ariane-44P flight V-108 successfully launched BSAT-1b, along Nilesat 101, from Kourou ELA-2 launch pad.^[3][8]

On August 1, 1998, BSAT-1b entered into commercial service. In December 2000, due to launch delays of BSAT-2a, BSAT-1b started digital broadcasting services for B-SAT.^[4]

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. In August 2011, BSAT-1b was placed in a graveyard orbit and decommissioned.^[4][9]