Alphabus

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Alphabus is a European satellite bus from Astrium and Thales Alenia Space (abbr.TAS), which was newly developed with the help of the space agencies ESA and CNES to carry even heavier and more powerful geostationary communication satellites than the existing Eurostar E3000 satellite buses from Astrium and Spacebus 4000 from Enable TAS.

construction

Alphabus has a modular structure and consists of a service module, a payload module and an antenna carrier attached to it. The structure of the service module mainly consists of a tube in which the two tanks for MMH and MON 3 are installed. The tanks are particularly light and are made of titanium wrapped with carbon fibers for stabilization. Each of the two tanks holds 1925 liters of fuel. The total fuel weight is 3500 to 4200 kg, plus three tanks of 90 l each for the helium used as the compressed gas . These supply an EAM apogee motor with 500 N thrust. The engine has a ceramic combustion chamber and thrust nozzle. Alternatively, an S400 apogee engine with 400 N thrust can be installed. There are also 16 steering engines. The system for the four ion thrusters has tanks for 350 kg of xenon . The auxiliary units required for this are distributed on sandwich panels made of carbon fiber reinforced plastic and aluminum, which are attached to the central tube.

The payload module has three levels to accommodate the communication electronics, and the antenna module is attached to the payload module or on its sides. A maximum of 12 parabolic mirrors are possible, two of which with a diameter of 3.5 m may be larger than the others with a diameter of 2 m. However, it can also carry an expandable antenna with a diameter of over 10 m for mobile communication. However, before this can be aligned with the earth, the satellite must change its alignment in geostationary orbit by 90 ° compared to normal alignment. The two solar panels facing north and south each consist of four to six elements. Elements five and six fold down to the side of element three. The elements of the solar panel use GaAs triple junction solar cells . A modular lithium-ion battery is available for the time when no electricity is available from the solar cells .

Alphabus is for a maximum of 22 kW energy consumption, a starting weight of max. 8.8 t and 230 transponders payload.

The first satellite based on this bus is the Alphasat I-XL , which was launched on July 25, 2013 with an Ariane 5 ECA .

Individual evidence

  1. ↑ a b ALPHABUS. Europe's solution for the high-power satcom market. (PDF; 2.4 MB; 14 pages) ESA, May 2010, accessed on November 5, 2012 (English).
  2. ↑ a b c Factsheet Alphasat. (PDF; 0.1 MB) ESA, June 10, 2011, accessed on November 5, 2012 (English).
  3. ↑ a b Factsheet: Increasing European Capability. (PDF; 0.1 MB) ESA, June 10, 2011, accessed on November 5, 2012 (English).