Sirius 4

Spacecraft n°:

Swedish spacecraft n°: 10

Launch data: Designation  32299 / 07057A Launch date  17 Nov 2007 - 22:39 UT Launch site  B, LC-200/39 Launch vehicle  Proton-M/Briz-M Mission  Comsat Geostationary orbit: Perigee / Apogee  35760 x 35812 km Inclination  0.07° Period  1436.09 min

Mission details:

• Operated by SES Sirius AB of Sweden, the Sirius Satellite System today consists of two Sirius satellites that provide the Nordic and Baltic regions, together with eastern and central Europe, with a choice of high quality TV, radio, data, Internet and multimedia communications solutions.
• The Sirius system is part of the world’s largest network of satellite operators, SES, with the 40 satellites in its fleet.
• Both public and private broadcasters have chosen Sirius as their TV and radio distributor. Sirius is also used by many broadcasters for occasional transmissions, such as sports, news or other ad-hoc events.
• Sirius 4 is a multi-mission Ku/Ka-band satellite built on Lockheed Martin’s reliable A2100AX platform. The satellite will be deployed at SES Sirius’ orbital position of 5 degrees East for a minimum service life of 15 years. Sirius 4 weighs 4,385 kg at liftoff and consists of 54 active transponders, making it the largest in the Sirius satellite fleet. The first mission of Sirius 4 will be to provide replacement capacity in the Nordic and Baltic markets as well as to enhance capacity and widen the coverage of Eastern Europe and Russia. This mission is supported by 46 active Ku-band transponders in the BSS and FSS frequency bands.
• The footprint of the BSS transponders are shown in the images below. The same footprint is used also for the FSS transponders, requiring larger antennas. As a second mission Sirius 4 will provide one wide beam Ka-Band transponder for interactive applications in Scandinavia and the Baltic States.
• The third mission of Sirius 4 will be to provide a sub-Saharan Africa beam complementing existing (Astra 2B, Astra 4A) African coverage within the SES Global fleet. This mission is accomplished with 6 active Ku- band transponders and another Ka-band transponder for interconnections between Africa and Europe.
  
  

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• A2100 Platform A2100 satellites are manufactured by Lockheed Martin Commercial Space Systems (LMCSS), a subsidiary of Lockheed Martin Space Systems. A2100 production occurs in the Commercial Satellite Center in Sunnyvale, one of the largest, most efficient facilities in the industry. The center’sco-located assembly and test facilities that include one of the largest Class 100,000 clean rooms in the world are dramatically cutting the production cycle.
• The A2100 geosynchronous spacecraft series is designed to meet a wide variety of telecommunications needs including Ka- band broadband and broadcast services, fixed satellite services in C-band and Ku-band payload configurations, highpower direct broadcast services using the Ku-band frequency spectrum, and mobile satellite services using UHF, L-band and S-band payloads. The A2100’s modular Sirius 4 Satellite design features a major reduction in moving parts – simplifying construction, increasing on-orbit reliability, and reducing weight and cost. The A2100 bus is produced entirely from composite materials, which makes it stronger and lighter than other bus designs and reduces launch costs. The composite structure also protects the payload from thermal distortions. The design lifetime of an A2100 satellite is 15 years. Standard dimensions are 3.0 x 2.5 x 6.0, mass characteristics vary from 3.4 to 4.7 tons. Solar arrays consist of five sections each, solar array span is 27 m, power supply system generates 13 kW. Reflectors span is 9 m.
  The A2100 family of satellites consists of “A”, “AX”, and “AXX” satellite buses, each has progressively larger payload capacity. Additionally there is an A2100M version, which fulfills military requirements.
• The A2100 satellite design features a standard core structure supporting the payload panels (transponders and earth) populated with components that reflect the mission specific design. Mission specific earth deck antennas, communication system feeds/horns, and reflectors are also unique to varying degrees for each satellite. Design activities that ensure system requirements are met include spacecraft layout, component Sirius 4 Satellite packaging, ensuring component on-orbit field of view requirements are met, rocket interface requirements, design details, drawing release, etc.
• The company has standardized on this bus. Much of the research and development is directed toward increasing the power available on the satellite and the A2100 bus, which is capable of generating 15 kW in its standard configuration. This involves work on the integration of new, higher efficiency solar cells, onto the innovative solar “pleated shades,” the use of high efficiency, radiation cooled TWTAs, the design of more efficient heat pipes and fold out radiators and improved design for thermaldissipation.
• Company engineers make extensive use of CAD tools and claim that they can deliver a satellite that uses the A2100 bus in 18 months after receipt of the order.
  
  

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• The Proton-M reached a -942 x 164 km x 51.5 deg suborbital trajectory. The first three Briz-M upper stage burns reached 173 x 173 km, 258 x 5000 km and 385 x 35681 km x 49.1 deg. At this point, the DTB fuel tank was jettisoned. A final Briz burn at 0730 UTC on Nov 18 put Sirius 4 in a 6916 x 35478 km x 17.4 deg high-perigee geostationary transfer orbit. By Nov 21 the satellite's own Leros propulsion system had raised its orbit to 12676 x 35751 km x 10.0 deg on the way to GEO.