By Jonathan Amos
Science reporter, BBC News
Industrial groups in Europe are about to look in detail at ideas for a new launch system to put humans in space.
The study will look at what could follow the Soyuz system
The meetings have been convened by the European Space Agency (Esa) under a development study that involves Russia - with Japan also eager to contribute.
The discussions at industrial level will formally start in July.
Europe is keen to see a crew transport system that is independent of the US Orion vehicle, which is set to replace the space shuttles in the next decade.
The new Crew Space Transportation System (CSTS) could be an updated and enhanced version of the venerable Russian Soyuz approach or an entirely new concept.
"We need two transportation systems; we cannot rely on only one," said Daniel Sacotte, Esa's director of Human Spaceflight, Microgravity and Exploration.
"We want to have parallel systems, to be cooperative; so that if one system has a failure, there is another one that allows space exploration to continue," he told BBC News.
Back to the future
The industrial partners on the project in Europe include EADS-Astrium (which leads the production of Ariane rockets and built the Columbus space station module) and Thales Alenia Space. For Russia, which will lead the study, Soyuz manufacturer RKK Energia will be involved.
The investigation hopes to provide some conclusions that can be taken before Europe's space ministers when they next meet in 2008.
The US is building the Orion vehicle to replace its shuttles
Esa has released about 18m euros for the work. If ministers approved further development of a CSTS, they would have to commit many hundreds of millions of euros more.
The Americans are returning to some of the Apollo heritage for their new Orion project - a flight capsule and service module launched on "single stick" rockets, in contrast to the spaceplane configuration used in their current shuttle system.
The purpose of the Esa-backed feasibility work is to find the most appropriate architecture for the CSTS. This will depend on the type of missions for which it will be used - flights in low-Earth orbit to the space station or to carry people to the Moon, and even beyond.
Russia's Soyuz experience is key, but Europe believes its recent efforts also bring important competencies to the project.
Mr Sacotte was speaking at Esa's technical facility, Estec, in Noordwijk, the Netherlands, from where Europe's Automated Transfer Vehicle (ATV) is about to be despatched to a spaceport for launch to the International Space Station (ISS).
The ATV - essentially a 20-tonne cargo ship - incorporates advanced automated rendezvous and docking systems that could be employed in some future CSTS.
"It will be a system with different components - one classical launcher probably, systems derived from the ATV. And if we want to go to the Moon, something that will have to be specific to that. We have in mind something very modular," Mr Sacotte said.
ATV - CARGO TRUCK
ATV will re-supply the ISS with up to 7,500kg of cargo
Deliveries will include science equipment, food and clothing
Large tanks can transport vital air, water and fuel supplies
ATV project's estimated cost is about 1.3bn euros (£0.9bn)
At least four craft will follow the maiden ATV - the Jules Verne, named after the author who wrote about fantastic journeys
EADS-Astrium has already had preliminary discussions with the Russians on the topic. Philippe Berthe, a systems engineer who works on advanced projects, told the BBC: "We would like for the ATV to be used as a source of know-how and experience for future European vehicles.
"It masters a lot of complex systems and sub-systems that must interact with each other. Once you develop something as complex as the ATV, you are very close to developing a human system.
"We would like to see, given the combined capabilities of Europe and Russia, if we could come up with a vehicle capable of performing a human mission for exploration to the Moon as a first step."
THE US ORION SHIP AND ARES LAUNCH SYSTEM
(1) The heavy-lift Ares 5 rocket blasts off from Earth carrying a lunar lander and a "departure stage"
(2) Several days later, astronauts launch on an Ares 1 rocket inside their Orion vehicle (CEV)
(3) The Orion docks with the lander and departure stage in Earth orbit and then heads to the Moon
(4) Having done its job of boosting the Orion and lunar lander on their way, the departure stage is jettisoned
(5) At the Moon, the astronauts leave the Orion and enter the lander for the trip to the lunar surface
(6) After exploring the lunar landscape for seven days, the crew blasts off in a portion of the lander
(7) In Moon orbit, they re-join the waiting robot-minded Orion and begin the journey back to Earth
(8) On the way, the service component of the Orion is jettisoned. This leaves just the crew capsule to enter the atmosphere
(9) A heatshield protects the capsule; parachutes bring it down on dry land, probably in California