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AlphaBus is the new European platform for the next generation of high power communications satellites and will be available on the world market from 2007. Satellites based on AlphaBus will have a launch mass in the range 6 to 8 tonnes and will be able to take full advantage of the new generation 5 meter fairings of commercial launch vehicles. The AlphaBus platform has the ability to accommodate reconfigurable missions and enable the development of new applications such as new generation mobile and broadband services, digital audio broadcast and HDTV. AlphaBus entered full development in June 2005, under a long-standing industrial sharing between Alcatel space and EADS Astrium. Alcatel Space is responsible for the mechanical and thermal subsystems, avionics and electric propulsion. Astrium is responsible for electrical power, solar array, spacecraft AIT and the chemical propulsion system.
CHEMICAL PROPULSION SYSTEM Astrium Lampoldshausen have proposed a bipropellant Unified Propulsion System for AlphaBus, featuring the high performance European Apogee Motor. The Lampoldshausen team pioneered the worldwide development of the unified propulsion system which was first used on a GEO satellite, TV-Sat, and on NASA's interplanetary spacecraft, Galileo. The propulsion system utilises monomethylhydrazine (MMH) fuel and mixed oxides of nitrogen (MON-1 or MON-3) oxidiser for feeding both the Apogee Motor and 16 x 10 N Reaction Control Thrusters. Oxidiser and fuel is each contained in 1910 litre propellant tanks. The system operates in pressure regulated mode using helium pressurant stored in three cylindrical pressure vessels. It is foreseen that the complete propulsion system will be ITAR free, comprising of all European hardware.
500 N European Apogee Motor The European Apogee Motor is being developed with the European Space Agency - ESA, and is supported by the German National Space Agency - DLR. The European Apogee Motor is ITAR free and designed for the needs of large GEO satellites such as AlphaBus, Alcatel's SpaceBus and EADS-Astrium's EuroStar family. The apogee motor will be available to worldwide customers in 2008.
10 N Reaction Control Thrusters The thruster combustion chamber and nozzle throat is manufactured from a heat and oxidation resistant platinum alloy. This material enables longer life and higher operating temperatures to maximise thruster performance. In addition, the use of this alloy avoids the need for surface coatings. The uncoated surfaces are absolutely resistant against oxidation and are invulnerable to the use of test sensors and pulse mode cycling.
Propellant Tanks The propulsion system incorporates redundancy, flexibility for adaptation, new proven technologies to enhance competitiveness and performance, including direct propellant flow monitoring to enable accurate end of life predictions.
Modular Integration The primary modules are:
All pipework is pre-formed and assembled into kits. The propulsion module is formed by integrating the PCA and PIA together with the helium pressure vessels. After integration, the propulsion module can be acceptance tested, including high pressure proof testing and functional verification at Lampoldshausen, before being transported to the customer's facilities for final integration to the spacecraft structure. Pre-integration of the propulsion module at Lampoldshausen minimises direct access to the spacecraft to just a few days for final integration and test.
Propulsion System Schematic
AlphaBus Bipropellant Propulsion Schematic
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Pressure
Control Assembly (PCA).
