Key technologies for the European Space Agency's next-generation launcher (NGL) began testing this month as details emerged of the timetable for ESA's decision for a new rocket by 2025.
In 2011, ESA's members states could decide what should replace the EADS Astrium Ariane 5 and this month France's Vulcain X cryogenic propellant engine demonstrator's turbomachinery is being tested.
This follows a €20 million ($27.9 million) contract signed in June for the NGL's High Thrust Engine (HTE) demonstrator. The HTE demonstrator is for an NGL first-stage engine.
It forms part of ESA's Future Launcher Preparatory Programme (FLPP) that has developed rocket technology since it began in 2004.
Although more than two years of further development work will be done before the 2011 meeting, Flight International has learnt that member state consultations begin this September.
ESA's director of launchers, Antonio Fabrizi, set out the timetable for work leading to the 2011 meeting at the 3rd European conference for Aerospace Sciences (EUCASS), held in Paris from 6-9 July.
By December, ESA expects to have the NGL's launch service requirements set out and in February 2010, studies will begin for launcher selection.
Fabrizi said system studies would be important to enable decisions about the next family of European launchers. The current family has the Vega rocket, able to carry 1,500kg (3,300lb) into a 700km (434-mile) circular polar orbit and nothing to GTO; the Soyuz 2-1b (the more powerful of the two versions to be flown from French space agency CNES/ESA French Guiana spaceport), able to place 3,150kg in geostationary transfer orbit (GTO); and the Ariane 5 ECA, which achieves 10,000kg to GTO. Vega and the Soyuz 2-1b are expected to have their maiden flights from French Guiana in the latter half of 2010.
Fabrizi said the system studies would be followed by the first "future environment" market forecast, to be published in March next year.
A second forecast will be completed 12 months later. By December 2010, the agency plans to confirm its "reference scenario" for launchers.
Finally, the first draft of a strategic launchers plan is scheduled for March 2011, along with related programme proposals. The strategic launchers plan is likely to focus on expendable options.
Although FLPP originally included reusable vehicles, the 2008 ESA ministers meeting cut funding for further work from the preparatory programme. Fabrizi told the EUCASS delegates: "We will not have reusable launchers for another 40 years."
The known NGL candidates are all expendable. A joint industry paper given by French, German and Italian FLPP participants at the 2008 International Astronautical Congress in Glasgow, recommended a two-stage, all-liquid oxygen and hydrogen-fuelled rocket that uses two to six strap-on solid rocket boosters (SRBs) to increase its GTO payload capability from 3,000kg to 8,000kg.
And before EUCASS, parts of the French government - ESA's largest financial contributor - made public their joint proposal for an Ariane 6.
The French nuclear agency CEA, defence procurement agency DGA and CNES propose a rocket with an SRB-augmented GTO capability.
Above: These concepts were presented by CNES launcher director Michel Eymard at the 3rd European Conference for Aerospace Sciences
CNES launcher director Michel Eymard provided details at EUCASS. He showed a booster with a 3,000kg to 8,000kg GTO capability and higher reliability than Ariane 5, while being 40% cheaper to build and able to fly more often, with a shorter launch campaign and an ability to change mission in two weeks.
Speaking to Flight International at EUCASS, ESA sources said the logic behind Ariane 6 was a cheaper, more-often launched rocket that allowed spaceport fixed costs to be spread over more flights to reduce prices. The higher frequency of launches would meet commercial customers' preferences for having their own launch when they wanted it.
France's Ariane 6 proponents think those commercial payloads will not exceed 8,000kg, come 2025. But ESA's own Post-ECA programme expects payloads to get heavier in future.
This programme is developing the Ariane 5 Mid-Life Evolution, or ME, which uses the FLPP/Post-ECA upper-stage Vinci engine, to deliver 11,500kg to GTO.
More questions on future payload sizes and rockets will be raised in the much-delayed ESA study "Tomorrow's Bird", which aims to predict the likely payloads customers will want launched in the 2020s, when NGL will begin operating.
The study was originally due to be completed in 2007, but ESA has told Flight International that its contractor, EADS Astrium, has not finished it.
Whatever the final choice, at the Paris air show EADS Astrium chief executive Francois Auque sounded a cautious note, saying he does not expect an Ariane 5 replacement chosen in 2011 to be ready by NGL's notional in-service date of 2025.