EAM - European Apogee Motor

Status date

The scope of the EAM activities is to define and to develop a competitive high thrust, high specific impulse European Apogee Motor (EAM).

The first phase consists in establishing the baseline design criteria for the EAM and finally the requirement specification as a result of an extensive market survey indicating the EAM competitiveness within the market place in terms of performances and costs.

The central phase of the project reflects the development and optimization of the high performance injector and combustion chamber according to the requirements to obtain the best motor on the market. The product shall have exclusively European components to be Itar free and shall provide the versatility of all the interfaces for the use on board of existing platforms (SpaceBus, Eurostar, etc) as well as for the use on AlphaBus.

In the last phase of the project the EAM design has to demonstrate the ability to meet all specification requirements. The suitability of the EAM design shall be assessed to proceed finally into a formal qualification program with a flight like EAM hardware. A Critical Design Review (CDR) shall be held before starting the qualification phase.

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Three major technologies are the basis for the motor concept:

  • Development of an optimized injector system to achieve the required high performance over a wide operation box,
  • Development of an advanced combustion chamber material to cope with the high combustion temperatures as well as the combustion products and also to withstand vibration and shock loads,
  • Development of an adequate interface technology to connect the ceramic motor part to the metallic injector housing to offer an all welded design.

The motor shall be completely Itar free and easily be implemented and adapted to the customers S/C requirements (versatility of EAM).

An additional important development target is to minimize the production costs in order to achieve a competitive product price and to place the EAM successfully in the market.


The EAM shall be competitive on the world market in terms of form, fit function and costs. Therefore, the dominating requirements for the development are:

  • High Performace
  • Non-Itar
  • High Reliability
  • Competitive Price.

The main benefits for the customers using the EAM are in the strategic and commercial fields.

One strategic advantage is the Independency for Europe. Currently only two potential candidates for the commercial market are available (Aerojet from US and EADS-ST in Europe). As the US product has a higher performance than the actual European product, the US company could become a monopolist dictating commercial requirements. The second strategic advantage is a full Itar free product. The EAM will be not subject to US export licence restriction and therefore worldwide customers can be served by the European Satellite Industry.

The main commercial advantages are High Performance and Competitive Product Price. EAM will make satellite suppliers more competitive (EAM ISP = 325 - 327 sec) compared to the US industry (HIPAT ISP = 323 sec). The production costs will be minimized by using advanced materials and related processes (i.e. all-in-one ceramic combustion chamber and nozzle versus multiple welded metallic chambers of competitors) resulting in a product price competitive on the world market.

The most effective S/C Mass Reduction will be performed by lowest EAM mass combined with highest specific impulse saving 30kg to 60kg propellant mass in favour for more payload.


The European Apogee Motor (EAM) is a high performance bi-propellant engine operating with the propellants MMH (Monomethyl Hydrazine) and MON (Mixed Oxides of Nitrogen) for use in the Chemical Propulsion System (CPS) of a large satellite platform as well as in existing propulsion systems like Alcatel's SpaceBus or Astrium's Eurostar platform or others.

EADS-ST's 500N EAM consists of the following major assemblies (see sketch below):

  • Injector Assembly and Housing
  • Ceramic Combustion Chamber with Expansion Nozzle
  • Propellant flow Control Valve (Fuel and Oxidizer)
  • Trim Orifices

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The Fuel and Oxidizer valves are mounted perpendicular to the axial direction optimized for minimum motor overall length, small dribble volume and maximum performance. The valves are mounted on the injector housing with an angle of 120º to each other to enable proper mounting of the motor to the S/C. The interface from EAM to S/C is realized by three attachment points with alignment capabilities.

A heat shield configuration can be mounted to the injector housing, if required. The atomization is achieved through a Micro Showerhead injector delivering the appropriate droplet size for effective and stable combustion over a large EAM operation box.

All parts in contact with the propellants are manufactured from stainless steel (valves), titanium (injector) and ceramic material (chamber and nozzle). The combustion chamber and expansion nozzle must withstand the maximum temperatures of combustion and the vibration loads during launch with sufficient marg


The development logic follows ESA's SOW:

Phase 1: Baseline Program Requirements

  • Define baseline program requirements,
  • Verify the necessity of the new motor development,
  • Verify that the defined development goals are achievable.

Phase 2: Design and Development Model Testing of the EAM

  • Definition of detailed EAM design,
  • Perform core developments of injector system and combustion chamber, technologies and bring them to maturity,
  • Testing the Development Model,
  • Complete the basic development activities with the PDR.

Phase 3: Full Development and Validation of the EAM

  • Demonstrate the ability of the EAM design to meet all specified requirements (Pre- Qualification Test Program),
  • Complete the development activities with the CDR.
Current status

The EAM Phase 1 activities were completed by end of March 2004 resulting in the establishment the EAM requirements.

Phase 2 activities are running. The baseline design of EAM has been established, the corresponding baseline design review (BDR) has been performed successfully in September 2004. At present, the development activities are concentrated on the final injector system design, the EAM valve development and on the Development Model configuration.

The ceramic chamber development has been completed with the Combustion Chamber Optimisation Review (COR) in March 2006. It was demonstrated that all required processes for the manufacturing are available, that the coating technology is established to protect the chamber against oxidation and erosion and that an interface technology exists to join the ceramic chamber to the metallic injection system. The injector development is in the final tuning phase to achieve the maximum performance. Sea level test results show to date the injector performance close to target efficiency. The combustion is very smooth all over the development box (13 bar to 19 bar inlet pressure) and robust even outside this box.

Production models (PM) had been manufactured to verify ceramic chamber development maturity. Based on the excellent PM quality, the production of the Development Model (DM) has been started which shall demonstrate the EAM performance data and will be the milestone for the PDR.

The newly developed engine will be the most competitive motor within the satellite market with respect to performance and costs.