Astra is the brand name for a number of geostationary communication satellites, both individually and as a group, which are owned and operated by SES S.A., a global satellite operator based in Betzdorf, in eastern Luxembourg. The name is also used to describe the pan-European broadcasting system provided by these satellites, the channels carried on them, and even the reception equipment.
At the time of the launch of the first Astra satellite, Astra 1A in 1988, the satellite's operator was known as Société Européenne des Satellites. In 2001 SES Astra, a newly formed subsidiary of SES, operated the Astra satellites and in September 2011, SES Astra was consolidated back into the parent company, which by this time also operated other satellite families such as AMC, and NSS.
Astra satellites broadcast 2,600 digital television channels (675 in high definition) via five main satellite orbital positions to households across Europe and North Africa. The satellites have been instrumental in the establishment of satellite TV and the introduction of digital TV, HDTV, 3D TV, and HbbTV in Europe.
A book, High Above, telling the story of the creation and development of the Astra satellites and their contribution to developments in the European TV and media industry, was published in April 2010 to mark the 25th Anniversary of SES.
There are 16 operational Astra satellites, the majority in five orbital locations - Astra 19.2°E, Astra 28.2°E, Astra 23.5°E, Astra 5°E, Astra 31.5°E. Astra's principle of "co-location" (several satellites are maintained close to each other, all within a cube with a size of 150 km) increases flexibility and redundancy.
|Satellite||Launch Date||Manufacturer||Model||Launch vehicle||Comments|
|ASTRA 19.2°E||Broadcasts 913 channels (525 SD, 381 HD, 7 UHD) to 116 million households|
|1KR||April 20, 2006||Lockheed Martin||A2100||Atlas V (411)||Launched after the failure of Astra 1K. Broadcast 28 transponders.|
|1L||May 4, 2007||Lockheed Martin||A2100||Ariane 5 ECA||Replacement for 1E/2C; Ku and Ka bands. Broadcast 30 transponders and 14 transponder on Ka band|
|1M||November 6, 2008||Astrium (now Airbus D&S)||Eurostar E3000||Proton-M||Replacement for 1G and backup at 19.2°E. Started commercial service 20 January 2009 Broadcast 28 transponders.|
|1N||August 6, 2011||Astrium (now Airbus D&S)||Eurostar E3000||Ariane 5 ECA||Started commercial service October 24, 2011 Broadcast 34 transponders.|
|ASTRA 28.2°E||Broadcasts 462 channels (392 SD, 70 HD) to 49 million households|
|2E||September 30, 2013||Astrium (now Airbus D&S)||Eurostar E3000||Proton Breeze M||Started commercial service on February 1, 2014 Broadcast 20 transponders on UK spot beam and 26 transponders on European beam.|
|2F||September 28, 2012||Astrium (now Airbus D&S)||Eurostar E3000||Ariane 5 ECA||Rolling capacity replacement at 28.2°E and provision of Ku-band DTH in West Africa and Ka-band in western Europe Started commercial service on November 21, 2012. Broadcast 6 transponders on UK spot beam, 26 transponders on European beam 3 transponders on West Africa spot beam and 1 transponder on Middle East spot beam.|
|2G||December 27, 2014||Airbus D&S||Eurostar E3000||Proton Breeze M||Rolling capacity replacement at 28.2°E Tested at 21.0°E and 43.5°E before moving to 28.2°E in June 2015 Started commercial service on June 1, 2015. Broadcast 7 transponders on UK spot beam and 17 transponders on European beam.|
|ASTRA 23.5°E||Broadcasts 244 channels (148 SD, 95 HD, 1 UHD) to 35 million households|
|3B||May 21, 2010||Astrium (now Airbus D&S)||Eurostar E3000||Ariane 5 ECA||Launch delayed for nearly two months due to launcher problems.|
|ASTRA 5°E||Broadcasts to 51.6 million households|
|4A||November 18, 2007||Lockheed Martin||A2100AX||Proton-M||Originally called Sirius 4|
|4B (now SES-5)||July 10, 2012||Space Systems/Loral||LS-1300||Proton-M||Originally Sirius 5, renamed to Astra 4B in 2010 and to SES-5 in 2011. Provides global C-band capacity and Ku-band for Sub-Saharan Africa and Nordic regions.|
|ASTRA 31.5°E||Broadcasts 247 channels (199 SD, 47 HD, 1 UHD) to 14 million households|
|5B||March 22, 2014||Airbus D&S||Eurostar E3000||Ariane 5 ECA||To add new capacity and replace existing craft at 31.5°E Entered commercial service on June 2, 2014|
|NOT IN REGULAR USE|
|1D||November 1, 1994||Hughes||HS-601||Ariane 42P||Positioned at 47.2°W
Originally at 19.2°E. Used at 28.2°E, 23.5°E, 31.5°E, 1.8°E and 52.2°E. Started moving west in February 2014 to arrive at 67.5°W in June 2014. In summer 2015 moved to 47.2°W, near SES' NSS806
|1F||April 8, 1996||Hughes||HS-601||Proton-K||Positioned at 44.5°E
Originally launched to 19.2°E. Moved in August 2009 to 51°E. Moved in May 2010 to 55°E.Moved in March 2015 to 44.5°E.
|1G||December 2, 1997||Hughes||HS-601HP||Proton-K||Positioned at 63°E
Power problems, now max 20 transponders. Originally launched to 19.2°E. Moved to 23.5°E February 2009 following launch of Astra 1M. Then to 31.5°E (July 2010) following launch of Astra 3B. Moved east in summer 2014 to 60°E, then 63°E in November 2016 
|1H||June 18, 1999||Hughes||HS-601HP||Proton||Positioned at 43.5°E
Originally launched to 19.2°E. Moved in June 2013 to 52.2°E to establish SES' commercialization of the MonacoSat position. Returned in 2014 to 19.2°E. Started moving west in May 2014 arriving at 67.5°W in mid-August 2014. Moved in May 2015 to 47.5°W, in September 2016 to 55.2°E and in January 2017 to 43.5°E
|2A||August 30, 1998||Hughes||HS-601HP||Proton||Positioned at 113.5°E
Originally launched to 28.2°E. Inactive at 28.2°E from March 2015. Moved to 113.5°E in summer 2016
|2B||September 14, 2000||Astrium (now Airbus D&S)||Eurostar E2000+||Ariane 5G||Moving west.
Originally launched to 28.2°E. Relocated to 19.2°E in February 2013  following launch of Astra 2F to 28.2°E. Moved to 31.5°E in February 2014. Returned to 19.2°E as backup in December 2016. Started moving west at approximately 0.6°/day in June 2017.
|2C||June 16, 2001||Hughes||HS-601HP||Proton||Positioned at 60.5°E
Initially deployed at 19.2°E pending launch of 1L, then at originally intended position of 28.2°E. Moved to 31.5°E (May 2009) to temporarily replace the failed Astra 5A, then back to 19.2°E (September 2010). Returned to 28.2°E (April 2014) and then in August 2015 moved to 60.5°E.
|2D||December 19, 2000||Hughes||HS-376HP||Ariane 5G||Positioned at 57°E
Originally launched to 28.2°E. Ceased regular use in February 2013 and positioned, inactive, at 28.0°E until June 2015. Then moved west to be stationed at Astra 5°E in July 2015. In October 2015 moved to 57°E.
|3A||March 29, 2002||Boeing||HS-376HP||Ariane 4L||Positioned at 47°W
Originally launched to 23.5°E. Moved to 177°W in November 2013, unused and in inclined orbit alongside NSS 9.Then continuously moving east at approximately 1.5°/day. until positioned at 86.5°W in summer 2016. In November 2016 started moving east at approx 0.5°/day until positioned at 47°W in mid-February 2017.
|NO LONGER OPERATIONAL|
|1A||December 11, 1988||GE AstroSpace||GE-4000||Ariane 44LP||The first Astra satellite. Now retired in graveyard orbit.|
|1B||March 2, 1991||GE AstroSpace||GE-5000||Ariane 44LP||Acquired from GE Americom (Satcom K3). Now retired in graveyard orbit.|
|1C||May 12, 1993||Hughes||HS-601||Ariane 42L||Originally launched to 19.2°E. Used at 5°E. Unused and in inclined orbit at 72°W (summer 2014) 1.2°W (September 2014) 40°W (November 2014). From February 2015, continuously moving west at approx 5.2°/day.|
|1E||October 19, 1995||Hughes||HS-601||Ariane 42L||Originally at 19.2°E. Used at 23.5°E pending launch of Astra 3B. Used at 5°E September 2010, pending launch of Astra 4B/SES-4, then moved April 2012 to 108.2°E where, as of November 2013, in inclined orbit. Moved in February 2014 to 31.5°E pending launch of Astra 5B. Returned to 23.5°E in February 2015. From June 2015, continuously moving west at approx 5.4°/day.|
|1K||November 26, 2002||Alcatel Space||Spacebus 3000B3S||Proton||Launched to 19.2°E but failed to reach geostationary orbit, and intentionally de-orbited on December 10, 2002.|
|5A||November 12, 1997||Alcatel Space||Spacebus 3000 B2||Ariane 44L||Formerly known as Sirius 2. Moved to 31.5°E and renamed Astra 5A on April 29, 2008. Failed in-orbit January 16, 2009|
Manufacture and launch
Astra satellites have been designed by Boeing Satellite Systems (formerly Hughes Space and Communications), Airbus Defence and Space (formerly Astrium), Alcatel Space, and Lockheed Martin. The 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 E2000+ and 2D is a BSS 376.
The satellites have been launched by Arianespace rockets from Kourou, French Guiana, International Launch Services Proton rockets from Baikonur, Kazakhstan, and ILS Atlas rockets from Cape Canaveral, Florida, USA. 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 kilometres (22,000 mi) 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 lifetime.
Sirius and Astra 4A
The Sirius series of satellites (not connected with the North American Sirius Satellite Radio service) was started in 1993 with the purchase of the BSB Marcopolo 1 satellite (renamed Sirius 1) by Nordic Satellite AB (NSAB) for direct to home broadcasts to the Nordic and Baltic regions from the 5° east orbital position. Subsequent satellites launched to this location include Sirius 2 (1997), Sirius 3 (1998) and Sirius 4 (2007) and the position’s coverage has been expanded to include Eastern Europe and Africa.
In 2000, SES (then SES Astra) bought the 50% shareholding in NSAB owned by Teracom and Tele Danmark and in 2003 increased that holding to 75%, renaming the company SES Sirius AB. In 2008 Astra acquired further shares to take its shareholding in SES Sirius to 90% and in March 2010 took full control of the company. In June 2010, the affiliate company was renamed SES Astra and the Sirius 4 satellite renamed Astra 4A.
The Astra 4A designation was originally given in 2005 to part of the NSS-10 craft (33 transponders) owned by another subsidiary of SES, SES New Skies, and positioned at 37.5° west for broadcast, data, and telecommunications into Africa, and in 2007 to part of the Sirius 4 satellite (six transponders of the FSS Africa beam) owned and operated by SES Sirius. From June 2010, the Astra 4A designation has applied to the entire satellite previously known as Sirius 4.
Astra 1K, the largest commercial communications satellite ever built at the time, was ordered by SES 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 would have been the use of a Space Shuttle, however this was rejected. On December 10, 2002 SES 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.
On January 16, 2009 Astra 5A at 31.5° east "experienced a technical anomaly leading to the end of the spacecraft’s mission" some four years ahead of the spacecraft's expected end of life. Traffic carried by the satellite (especially channels for German cable service, Kabel Deutschland) was transferred to Astra 23.5°E. In March 2009, SES (then SES Astra) announced that in April, the Astra 2C satellite was to be moved from the 28.2° east position to 31.5° east to temporarily take over Astra 5A's mission until Astra 3B is launched to 23.5° east, when another craft currently there can be released to 31.5° east. The move of Astra 2C was started in May and completed on May 11 with the first transponders coming into use at the new position in the subsequent two weeks.
At the end of 2015, Astra satellite broadcasts were received in 156 million households in Europe. In all, 35% of all European TV households receive DTH satellite TV, 26% receive cable TV, 12% receive IPTV, and 27% receive terrestrial broadcasts. With provision via DTH, cable and IPTV, 61% of European TV homes receive TV from Astra satellites. 71% of all European homes that receive satellite TV, receive TV from Astra satellites; and 93% of all homes that receive IPTV or cable, receive TV from Astra satellites.
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