HYPROGEO in a Nutshell

Hybrid Propulsion System for LEO, MEO and GEO transfer

Independent access to space is a key element of the European Space Policy. The competition is increasing in this area both for full launching systems and for key subsystems. Cost-effectiveness has thus become a driving factor.

The ambition of the HYPROGEO project, which is co-funded by the European Commission under the Horizon 2020 programme, is to develop a propulsion engine based on hybrid chemical propulsion1 Hybrid propulsion is not a new technology per se, but its application to a transfer module2 or to a re-ignitable upper stage is very innovative. It is an interesting alternative for the GEO transfer3, which is currently limited to two options: either to rely on chemical (liquid) propulsion or on the newly developed Electrical Propulsion (EP) technology4. Hybrid propulsion features very good synergies and complementarities with those solutions as its thrust level lies between what they are capable of. Moreover, it presents two benefits are: green and simpler design (compared to bi-liquid), shorter transfer time and reduced cost of operations (compared to electric propulsion).

As the proof of concept (achieving a certain threshold of specific impulse5 and thrust) has been demonstrated already, the main technical challenge is the long duration firings. The future development of an operational system, already identified in the current roadmaps, requires advanced R&D work on 4 critical technologies:

  •  the combustion chamber;
  •  the high endurance nozzle;
  •  the catalytic injector; and
  •  the production, storage and use of high concentration hydrogen peroxide propellant.

An innovative aspect of the project is that these R&D activities are directly driven by the evolution of market needs and system requirements. A TRL 4 (for the combustion chamber, catalytic injector, and high concentration hydrogen peroxide) to 56 (for the full engine and the nozzle) is expected at the end of the project.

The impact of the project is ensured by a consortium of European actors of hybrid propulsion technologies led by Airbus Defence & Space. The team contributes thus to the consolidation of the European industrial supply chain for hybrid propulsion. The consortium embodies a true European dimension, with 12 partners from 7 countries: Belgium, France, Germany, Italy, Norway, Poland, and United Kingdom.

The project kicked off in February 2015 for a duration of 36 months.


1 A hybrid propulsion system uses rocket propellants in two different phases – one being solid, the other being gaseous or liquid. This combination allows the system to combine the best of both worlds; the simplicity of a solid propulsion system (a hybrid system is a bit more complex though) and the throttle ability, which is attributed to the much more complex liquid chemical propulsion systems.

2 The component of the launch system that is responsible for the transfer of a satellite payload to its orbit after the main boosters have completed their mission

3 A GEO transfer – short for geosynchronous or geostationary transfer. The transfer is realised as a Hohmann-type transfer orbit, which is used to reach geosynchronous or geostationary orbit, the orbit, at which an object will circle the Earth in 24 hours and hence will remain stationary above a fixed point on the Earth's surface.

4 ESA provides for a very good comparison between these two propulsion types on a dedicated website

5 Specific impulse (usually abbreviated Isp) is a measure of the efficiency of rocket and jet engines; the higher the number is, the less fuel is used to achieve a certain velocity increment (also called Delta-V).

6 TRL: Technical Readiness Level - TRL 3 = "experimental proof of concept", TRL4 = "technology validated in lab", TRL5 = “technology validated in relevant environment”.

© Picture: ESA – D. Ducros, 2009 

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