Launcher system activities in ESA’s FLPP are identifying and studying launch vehicle concepts that answer top-level mission requirements, in terms of performance and cost.

Concepts are gradually down-selected to a limited number of reference launch systems, and required technologies and readiness levels are identified.

Defined requirements

The main objective of the Next Generation Launcher is to serve Europe’s institutional needs. The capability of the launch system to perform commercial missions is seen as an opportunity to support a cost-efficient exploitation.

As far as launcher performance is concerned, the following needs have been identified:

• Performance range of 3-5 t for institutional missions in low, medium and geostationary orbits.
• Performance range of 2-8 t in geostationary orbit for commercial telecommunications satellites.

The characteristics that were defined for the NGL's reference mission, strongly oriented towards answering European institutional needs, are:

• Medium launch vehicle with a single payload capability
• Target performance equivalent to 3 t in geostationary transfer orbit, with modularity allowing an increase to 8 t with the addition of strap-on boosters
• Versatile vehicle with a reignitable upper stage
• Compliance with regulations on space debris and environment

The key driver for the next-generation launcher is the reduction of the total cost of exploitation and its capability for future evolutions.

System studies

The objectives of the system concept studies are to:

• Define the technical features of the most promising Expendable Launch Vehicle (ELV) architecture and propulsion concept.
• Establish programmatic data for development and recurring costs, highlighting the main milestones of the development plan.

A step-by-step approach is carried out, starting with a large screening of possible concepts and then down-selecting them.

The first industrial activities of the second period of FLPP, the system concept investigations, were performed between 2006 and the end of 2008. They identified the most promising ELV architectures and propulsion concepts for the lower and upper stages; established propulsion system requirements; and defined the preliminary development plan and estimations of the total cost, including exploitation.

These activities were conducted for two types of launchers:

• An expendable launch system in the medium term, relying on existing elements and technologies, or ‘Building Blocks’, from the Ariane and Vega launchers to be operational by 2015.
• A new launch system in the long term, the Next Generation Launcher (NGL), to be operational by 2025.

A total of 52 launch system concepts were analysed. This number was reduced to four, based on the capabilities of each architecture to match FLPP performance requirements.

Four concepts for the next-generation launcher

Four launcher configurations were identified with two and three stages to orbit, using different types of chemical propellants, liquid and solid, and a cryogenic upper stage.

Two-stage configuration: main stage powered by a cryogenic liquid oxygen and hydrogen engine (staged combustion cycle), with a cryogenic reignitable engine for the upper stage (expander cycle).

Two-stage configuration: main stage powered by a cryogenic liquid oxygen and hydrogen engine (gas generator cycle), with a cryogenic reignitable engine for the upper stage (expander cycle).

Two-stage configuration: main stage powered by a liquid oxygen and methane engine (staged combustion cycle), with a cryogenic reignitable engine for the upper stage (expander cycle).

Three-stage configuration: first two stages powered by solid propulsion, with a cryogenic liquid oxygen and hydrogen for the upper stage (expander cycle).

To ensure that the launcher is able to respond to different mission requirements, two to six strap-on solid-propellant boosters are clustered around the central core to increase the geostationary transfer orbit payload capability from 3 t to 8 t.

Where are we now?

A first step towards the Next Generation Launcher was achieved with the signature of a 15-month contract with Astrium in June 2010. The contract covers two lines of activity.

The first is dedicated to design activities on reference launch system concepts. It is divided into three different phases that aim at consolidating the NGL system concept definitions, identifying the required novel technologies and estimate the cost of building and operating the new launch vehicle.

In parallel, concurrent activities focus on trade-off studies of technologies and launcher systems and sub-systems. Two major milestones between the three phases of the design activities allow to assess the results of the different trade-offs and to adapt the launch system definition if needed.

A second major objective of the concurrent activities is the establishment of a dedicated NGL Technology Development Plan.

The first phase of the design activities is expected to be completed in mid-2011.