Novel technologies that cope with the ever-changing conditions from launch until payload delivery in orbit are required to improve performance and reduce the cost of access to space, while remaining highly reliable.

The 'Core Technology' project, under FLPP, aims at developing these technologies and gaining the knowledge to support the development of future launchers, as well as studying potential technology spin-offs for European launchers. They address critical component, subsystem and system-level technologies, which results in the improvement of their technology and integration readiness.

The first period of FLPP concentrated on system studies and technology developments for the preparation of a Reusable Launch Vehicle, focusing on hot structures.

Activities are now focusing on the development of upgraded and new technologies to support a number of launch vehicle architectures in order to:

  • Reduce mass and improve the stage structural index
  • Improve robustness and mitigate the technological risks of future developments
  • Provide new functions
  • Decrease launcher costs

Cryogenic Upper Stage Technologies (CUST)

Versatile thermal insulation concept

A restartable upper stage responds to the need for launchers to be flexible and be able to adapt to different mission scenarios.

The programme is identifying and developing critical technologies, enabling versatile missions and improving the performances of a reignitable cryogenic upper stage.

This project is organised in three parts:

  • Activity dedicated to the selection of critical technologies
  • Activity targeting technology development to reach Technology Readiness Level 5/6
  • Flight testing of gravity-dependent technologies


The following promising technologies were identified:

  • Versatile external thermal insulation concepts
  • Inner wetted insulation/common bulk
  • Pre-chill down before reignition
  • Propellant management device
  • Propellant preconditioning
  • Gas port phase separator
  • Functional system analysis software
  • Ground connector
  • Critical helium storage


Development of a number of these technologies began at the end of 2009 and flight demonstrations are planned. The propellant management device will be tested end of 2011 on a Texus sounding rocket, in cooperation with DLR.

Structures, materials and processes

Future launch vehicles require higher structural efficiency, which in turn requires innovative materials, structural concepts and new processing technologies.

Structures and materials are being addressed as challenges on the road to the next-generation launcher, targeting a decrease in structural mass with special attention to cryogenic fuel containment and thermal protection systems.

The inert mass of an upper stage has a direct impact on launch vehicle performance. To maximise the payload mass, the upper stage must use lightweight structures to improve the mass fraction of the stage.

The technology activity is designed to demonstrate, through analysis and ground demonstrations, that system-level and technology improvements of an advanced material tank wall system and innovative upper-stage primary structure and mechanism can yield a lighter reignitable expendable upper stage that is cost-efficient and robust.

It also focuses on on the improvement and optimisation of existing manufacturing and control processes to reduce cost.

This activity covers technology developments associated with:

  • Metallic cryogenic tank
  • Carbon-Fibre Reinforced Polymer (CFRP) structures, including interstage, upper part structures and y-ring.

Avionics and pyrotechnics


Advanced avionic systems are required for any future launcher to provide the processing capability for mission and launch vehicle management, guidance, navigation and control functions.

To answer the high-level requirements of the launch vehicle, the avionics system activities cover:

  • new mission features, such as long-duration missions requiring enhanced autonomy;
  • low exploitation costs;
  • relaxed requirements for fitting avionics subsystems on the launcher (e.g. avoiding the need for specific structure such as a vehicle equipment bay or avoiding the need for specific thermal conditioning);
  • mass reduction.


The activities under study include: avionics architecture compliant with standards; use of commercial-off-the-shelf electronic devices; redundancy features allowing the use of hardware diversity; optimisation of harness; optimisation of mission, integration and operations; innovative energy and power sources.


Progress made on conventional pyrotechnics based on electro-pyrotechnics draw on the accomplishments and wide experience gained so far in Europe. These devices have been used on all Ariane rockets, including today’s Ariane 5. This technology has proven to be reliable and safe and is used on ESA’s new small Vega launcher.

However, to remain competitive, Europe needs to upgrade electro-pyrotechnic subsystems and devices to meet future needs in terms of size, cost and environmental regulations.

Opto-pyrotechnic technology is being evaluated worldwide as one of the key subsystems for the evolution of today’s launchers and new developments.

It should reduce mass and recurring costs, improving maintainability and safety by removing primary explosives from the system. This simplifies operations before the launch, increases safety and protects the system from electromagnetic interference and electrostatic discharge.

Prospective technologies

Slush production pilot

Breakthrough technologies, including those with low technology readiness levels, are under study.

Densified propellant

Furthering European knowledge in slush hydrogen technologies, there is activity in assessing the feasibility and advantages of this type of propellant for next-generation launcher concepts.

Higher density and heat capacity make the use of densified propellants very attractive. Densified propellant is achieved by adding a solid fraction to liquid hydrogen. However, a number of issues still need to be resolved to make it a potential propellant for future space transportation.

The FLPP activity is based on a promising ‘snow-gun’ preparation method, to be demonstrated at laboratory scale. In parallel, preliminary system studies were conducted to assess launch vehicle concepts based on combinations of densified propellants, which provided positive results.

The use of densified propellants in Europe’s existing launchers could increase the payload mass capability by 2% to 10%, depending on the densification level, the application stage and the target orbit. The benefits and drawbacks related to the use of slush into propulsion systems have still to be evaluated further.

CFRP cryogenic tanks and feed-lines

An important step towards mass reduction could be the use of advanced composite materials for structural components. The anisotropic strength and stiffness of carbon fibre can offer significant mass savings and cost efficiencies.

An automated manufacturing process allowing the integration of a cryogenic composite tank into an adjacent composite ring could, for instance, reduce mass and allow for the optimisation of the integration process.

Technology activities cover:

  • thermoset composite technology demonstrator, representative of a liquid hydrogen tank;
  • reinforced thermoplastic composites demonstrator;
  • CFRP cryogenic propellant feed-line with metallic liner.

Last update: 30 October 2012

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