Astra 1B was the second of the Astra

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

s launched and operated by

SES SES, S.E.S., Ses and similar variants can refere to: Business and economics * Socioeconomic status * Scottish Economic Society, a learned society in Scotland * SES, callsign of the TV station SES/RTS (Mount Gambier, South Australia) * SES S.A., ...

(Société Européenne des Satellites) to add extra capacity to the

satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...

(direct broadcasting) services from 19.2° East, serving Germany, the United Kingdom and Ireland.

Satcom K3

SES bought the satellite in 1989 from failed

direct broadcast satellite Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...

(DBS) company Crimson Satellite Associates while still under construction by GE Astro Space (as Satcom K3). Twelve years later, in 2001, SES acquired

GE Americom SES Americom was a major commercial satellite operator of North American geosynchronous satellites based in the United States. The company started as RCA Americom in 1975 before being bought by General Electric in 1986 and then later acquired by ...

, which originally was to operate the Satcom K3 satellite (and was itself the result of

General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...

's purchase of

RCA Corporation The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Comp ...

in 1986) and renamed it "SES Americom". It was merged with SES New Skies to form

SES World Skies SES World Skies was a short lived company formed as a result of the merger between the two SES subsidiaries, ''SES Americom'' and ''SES New Skies''. The company was merged into its parent company, SES S.A. in 2011. History SES Americom ...

before the company was merged into its parent company, SES S.A. in 2011.

Mission

On 4 June 1991, Astra 1B suffered an

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

failure, causing minor drift in north–south direction, meaning that it became difficult to obtain a steady lock on the satellite. This was most notable on analogue transmissions where the picture would move from clear to carrying

sparklies Sparklies is a form of interference on analogue satellite television transmissions. Sparklies are black or white 'hard' interference dots (as opposed to the 'soft' interference patterns of terrestrial television), caused either by too weak or too ...

and back again. The failure was likely caused by recent

solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...

s which impacted the electronics on both the primary and the backup momentum wheels. In September 1991, SES dealt with the failure by permanently deactivating the automatic control mode for the attitude subsystem. Along with

Astra 1C Astra 1C was a geostationary communications satellite launched in 1993 by the Société Européenne des Satellites ( SES), now SES Astra. The satellite remained in service until 2011 and is now derelict. History Astra 1C was the third commu ...

, Astra 1B was to be replaced in 2002 with

Astra 1K Astra 1K was a communications satellite manufactured by Alcatel Space for SES. When it was launched on 25 November 2002, it was the largest civilian communications satellite ever launched, with a mass of . Intended to replace the Astra 1B sat ...

, which failed to launch successfully, and as a result it continued to serve a longer life than expected, only falling from use when

digital television Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advanc ...

Astra 2A Astra 2A is one of the Astra communications satellites owned by Société Européenne des Satellites. Launched in 1998 into the 28.2° East orbital position, half its expected end-of-life capacity of 28 transponders were pre-booked by BSkyB, w ...

removed the majority of United Kingdom and Ireland targeted channels from 19.2° East. From 2005, SES claimed that the satellite was in use for

VSAT A very-small-aperture terminal (VSAT) is a two-way satellite ground station with a dish antenna that is smaller than 3.8 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Bit rates, in most cases, range from 4 kbit/s up to 1 ...

services, however no transponders were powered, and the satellite drifted to around 19.5° East. One transponder was reactivated in October 2005, but was carrying only colour bars.

Decommissioning

On 16 June 2006, SES confirmed that Astra 1B would be decommissioned and de-orbited within weeks after

Astra 1KR Astra 1KR is one of the Astra geostationary satellites owned and operated by SES, was purchased in June 2003. It was launched on 20 April 2006, 20:27:00 UTC as a replacement for Astra 1K, which failed to reach orbit on launch in November 20 ...

, the satellite which would replace Astra 1B and 1C, reached the operational orbital position of 19.2° East. It was officially end-of-lifed on 14 July 2006; close to four years after it had ceased carrying signals, ending SES's claims that the craft was operational.

Transponders

Astra 1B transponders were used in the following ways during the operational life of the satellite:

References

{{Orbital launches in 1991 Astra satellites Derelict satellites orbiting Earth 1991 in Luxembourg Satellites of Luxembourg Spacecraft launched in 1991

Satcom K3

Mission

Decommissioning

Transponders

See also

References