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From Wikipedia, the free encyclopedia

Superbird-A2
NamesSuperbird-6
Mission typeCommunications
OperatorSKY Perfect JSAT Group
COSPAR ID2004-011A [1]
SATCAT no.28218
WebsiteArchived official page
Mission duration13 years (planned)
Failed on orbit (achieved)
Spacecraft properties
SpacecraftSuperbird-6
Spacecraft typeSuperbird
BusBSS-601
ManufacturerBoeing
Launch mass3,100 kg (6,800 lb)
BOL mass1,528 kg (3,369 lb)
Dry mass1,477 kg (3,256 lb)
Dimensions26.2 m × 7.5 m × 4.5 m (86 ft × 25 ft × 15 ft) with solar panels and antennas deployed
Power4378 watts
Start of mission
Launch date16 April 2004, 00:45:00 UTC [2]
RocketAtlas IIAS
Launch siteCape Canaveral, LC-36B
ContractorInternational Launch Services (ILS)
Entered serviceNever in service
End of mission
DisposalGraveyard orbit
Last contactFailed on orbit
Orbital parameters
Reference systemGeocentric orbit [3]
RegimeGeostationary orbit
Longitude158° East
Transponders
Band23 Ku-band 36 MHz
4 Ka-band 100 MHz [4]
Bandwidth1228 MHz
Coverage areaJapan, South Asia, East Asia, Hawaii
TWTA powerKu-band: 85 watts
Ka-band: 70 watts [4]
 

Superbird-A2, known as Superbird-6 before launch, was a geostationary communications satellite ordered and operated by Space Communications Corporation (SCC) that was designed and manufactured by Hughes (now Boeing) on the BSS-601 satellite bus. It had a mixed Ku-band and Ka-band payload and was expected replace Superbird-A at the position at 158° East longitude. It was expected to provided television signals and business communications services throughout Japan, South Asia, East Asia, and Hawaii.[5][6][4]

While the launch was within the margins specified by the satellite manufacturer, the trajectory analysis had been inexact and the satellite suffered severe life and power degradation. It tried to use a supersynchronous transfer strategy, but Boeing had failed to take into consideration the effect of the Moon. Thus, the lowest part of the orbit dropped too fast and much propellant had to be spent on a fast transit to geosynchronous orbit. Additionally, the solar panels suffered damage from the extreme contact with the atmosphere. Given the damage to the spacecraft, it was never put into service.[5][7]

Satellite description

The spacecraft was designed and manufactured by Boeing Satellite Development Center on the BSS-601 satellite bus. It had a launch mass of 3,100 kg (6,800 lb), a beginning of life mass of 1,528 kg (3,369 lb) and an end of life mass of 1,477 kg (3,256 lb). It was designed for a 13-year life. When stowed for launch, it measured 4.5 m × 3.5 m × 3.5 m (15 ft × 11 ft × 11 ft). It had two wings with four solar panels each, that generated 4378 watts at the end of its design life. When fully deployed, the solar panels spanned 26.2 m (86 ft), with its antennas in fully extended configuration it was 7.5 m (25 ft) wide.[5][6] It had a 29-cell NiH2 battery with a power charge of 200 Ah.[6]

Its propulsion system was composed of a liquid apogee engine (LAE) with a thrust of 445 N (100 lbf). It also used had 12 22 N (4.9 lbf) bipropellant thrusters for station keeping and attitude control. It included enough propellant for orbit circularization and 13 years of operation.[6]

It had a dual Ku-band and Ka-band payload. The Ku-band section had its 2.2 m (7 ft 3 in) dual-grid shaped antenna on the West side. It had twenty three transponders powered by Traveling-wave tube#Traveling-wave-tube amplifier (TWTA) with and output power of 85 watts. It had a wide beam footprint that covered Japan, South Asia, East Asia, and Hawaii.[6][4][5]

Its Ka-band section had a 2.2 m (7 ft 3 in) single-grid shaped antenna on the East side for the wide beam, and a nadir 1.2 m (3 ft 11 in) shaped surface antenna for the steerable beam. It had four 100 MHz transponders powered by TWTA with and output power of 70 Watts. The wide beam covered Japan, South Asia, East Asia, and Hawaii, while the steerable beam could be focus on any zone that had line-of-sight to the satellite.[6][4][5]

History

Space Communications Corporation (SCC) was founded in 1985, the same year as the original companies that later formed JSAT.[8] In September 2001, SCC ordered its third BSS-601 based spacecraft, Superbird-6. It was to use the 158° East position and offer a Japan wide beam service in Ku-band and Ka-band, plus steerable Ka-band spot beams. It was expected for a fall of 2003 launch aboard an Atlas IIAS.[5][7]

It was decided to launch Superbird-6 into a 2895 minutes period supersynchronous orbit with an apogee of 120,679 km, a perigee of 1138 km and a 25.5° inclination. This extreme perigee and a six-maneuvers circularization program would reduce the propellant expenditure to its final position in geosynchronous orbit.[5][7]

It was launched on 16 April 2004 by an Atlas IIAS that injected in the supersynchronous orbit specified by the satellite manufacturer, at which point it was named Superbird-A2. But the orbit analysis had failed to take into consideration the influence of the Moon at such high apogees and the perigee started to drop dangerously fast. Most of its propellant had to be spent and the solar panels suffered damage that reduced the power production. The satellite can not enter service as planned in July 2004. One of two main fuel tanks on the spacecraft lost pressure on 28 November 2004. The satellite was never commissioned into regular service.[5][7]

See also

References

  1. ^ "Display: Superbird 6 2004-011A". NASA. 10 February 2021. Retrieved 19 March 2021.
  2. ^ "Trajectory: Superbird 6 2004-011A". NASA. 10 February 2021. Retrieved 19 March 2021.
  3. ^ "SUPERBIRD 6". N2YO.com. 22 March 2021. Retrieved 22 March 2021.
  4. ^ a b c d e "Main specifications of SUPERBIRD-A2". Space Communications Corporation. Archived from the original on 26 June 2004. Retrieved 26 August 2016.CS1 maint: bot: original URL status unknown (link)
  5. ^ a b c d e f g h Krebs, Gunter (11 December 2017). "Superbird 6 (Superbird A2)". Gunter's Space Page. Retrieved 22 March 2021.
  6. ^ a b c d e f "Superbird-6". Boeing. Archived from the original on 15 December 2009. Retrieved 26 August 2016.CS1 maint: bot: original URL status unknown (link)
  7. ^ a b c d "Superbird". Global Security. Retrieved 26 August 2016.
  8. ^ "History". SKY Perfect JSAT. Retrieved 26 August 2016.
This page was last edited on 7 April 2021, at 09:10
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