SES Astra

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Image:SES-Astra.png SES Astra SA, a subsidiary of SES Global, is a Luxembourg-based corporation which owns and operates the Astra series of geostationary satellites, which transmit approximately 1100 analogue and digital television and radio channels via 176 transponders to 91 million households across Europe.

Formed in 1985 as Société Européenne des Satellites-Astra (SES), it was Europe's first private satellite operator. Its slogan is currently "Your Satellite Connection to the World".

1 Satellite details
2 Satellite manufacturer & launch
- 2.1 Failures
3 See also
4 External links

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Satellite details

SES Astra operates twelve satellites from three orbital locations, seven at 19.2°E, three at 28.2°E and two at 23.5°E. The company also has three satellites on order to replace early Astra 1 models. Astra's principle of "co-location" (several satellites in the same orbital location) increases flexibility and redundancy.

Satellite	Position	Primary footprint	Manufacturer	Model	Launched	Launch vehicle	Comments
1A	Out of service (December 2004)		GE AstroSpace	GE-4000	December 11 1988	Ariane 44LP	In "junk orbit"
1B	19.2°E		GE AstroSpace	GE-5000	March 2 1991	Ariane 44LP	Acquired from GE Americom (Satcom K3). Out of use, although not officially recognised as so; to be replaced by 1KR.
1C	19.2°E		Hughes	HS-601	May 12 1993	Ariane 42L	To be replaced by 1KR
1D	23.5°E		Hughes	HS-601	November 1 1994		Described as "troubleshooter"
1E	19.2°E		Hughes	HS-601	October 19 1995	Ariane 42L
1F	19.2°E		Hughes	HS-601HP	April 8 1996	Proton
1G	19.2°E		Hughes	HS-601HP	December 2 1997	Proton
1H	19.2°E		Hughes	HS-601HP	June 16 1999	Proton
1K	19.2°E	Scrapped	Alcatel Space	Spacebus 3000B3S	November 26 2002	Proton	Rocket failure, ditched in Pacific Ocean.
1KR	19.2°E		Lockheed Martin	A2100	20 April 2006	Atlas V	Replacement for 1B and 1C. Launched after the failure of the Astra 1K.
1L	19.2°E	Under construction	Lockheed Martin	A2100	Due 2006		Backup for 1KR, if that is successful becomes 1L
1M	19.2°E	Under construction	EADS Astrium	Eurostar E3000	Due 2008		To replace 2C at 19.2°E
2A	28.2°E		Hughes	HS-601HP	August 30 1998	Proton
2B	28.2°E		Astrium	Eurostar E2000+	September 14 2000	Ariane 5
2C	19.2°E		Hughes	HS-601HP	June 16 2001	Proton	To be replaced by 1M, will move to 28.2°E
2D	28.2°E		Hughes	HS-376	December 19 2000	Ariane 5
3A	23.5°E		Boeing	HS-376	March 29 2002	Ariane 44L
4A	37.5°W		Alcatel Space	Spacebus-4000C3	February 3 2005	Proton M	Leased transponders of AMC-12, marketed as Astra 4A

Notes

19.2°E is the most common orbital position for direct-to-home satellite TV and radio transmission in Germany and Central Europe.
1G is also used for home satellite internet (with DVB modems) and the free-to-air TV and radio channels (Astra-Mosaic).
BSkyB broadcast their Sky Digital direct-to-home television service to the United Kingdom and Republic of Ireland from the 28.2°E satellite constellation. Eutelsat's Eurobird satellite also operates close to this position.

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Satellite manufacturer & launch

Image:Astra 2A 2C Boeing 601.JPG SES Astra operates satellites designed by Boeing Satellite Systems or BSS (formerly Hughes Space and Communications), EADS Astrium and Alcatel Space.

Astra satellites within a family are not identical, for example of the Astra 2 satellites; 2A and 2C are BSS 601HPs, 2B is an Astrium Eurostar-2000 and 2D is a BSS 376.

The satellites are launched by Arianespace rockets from Kourou, French Guiana or International Launch Services Proton rockets from Baikonur, Kazakhstan. The satellites are launched into an elliptical "temporary transfer orbit" from where they use onboard propulsion to reach their final circular geostationary orbits, at nearly 36,000 km altitude. Proton rockets fitted with a fourth stage propulsion unit are capable of launching the satellites several thousand kilometres higher (at the closest point of the elliptical orbit) than Ariane rockets. As a result most satellites launched in this way have to use less fuel to reach their geostationary orbit, increasing their flexibility.

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Failures

Astra 1K, the largest commercial communciations satellite ever built at the time, was ordered by SES-Astra in 1997. It was launched by Proton rocket on November 26, 2002. The rocket lifted off as planned and reached its "parking orbit" at which point the final stage of the rocket was to initiate a second burn to transfer the satellite to its geostationary orbit. This did not occur and the satellite was released into the parking orbit, making it unusable. The only way to recover the satellite was the use of an orbiter, however this was rejected. On December 10 SES Astra instructed Alcatel Space (the manufacturer) and the French Space Agency CNES to deorbit the satellite, it broke up on re-entry over the Pacific Ocean.

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