SES Astra
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".
The first customer of SES Astra was
Sky Television who bought 4 transponders for their service in 1989. UK & Ireland aimed channels ceased at 19.2 East in September 2001 with the closure of Sky's analogue service, though their digital service has been the main occupier of Astra's secondary position at 28.2 East since its launch in 1998.
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.
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.
 |
The BSS 601 model |
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.
Failures
Astra 1K, the largest commercial communications 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.
*
SES Global*
SES Americom*
Nordic Satellite*
Satellite dish*
List of broadcast satellites*
Astra Digital Radio*
SES Astra - Official site
*
Astra transponder footprints (To determine size requirements of a
satellite dish - minimum diameter from 50 to 120
cm).
*
ESOA website.
*
Lyngsat frequency/channel list.
*
SatcoDX frequency/channel list.
