By Jonathan Amos
Science reporter, BBC News, Bremen
There is no guarantee the vehicle will be built - even just an unmanned version
Europe has taken the first step towards building its own manned spaceship.
The European Space Agency has asked industry to work out the requirements of the craft and its likely cost.
Known as the Advanced Re-Entry Vehicle, it would be developed in phases - first as an unmanned vessel to carry cargo, and then as an astronaut crew ship.
At the moment, Europe has no independent capability to transport humans into space and must hitch rides on American or Russian systems.
Tuesday's announcement is just the start of a very long process, and there is no guarantee either ARV variant will be built.
ARV BASIC REQUIREMENTS
Takes the best from Esa's ATV
Incorporates a conical capsule
Diameter will be about 4.4m
Able to return science samples
Crewed version to have 4 seats
Esa member states will want to see industry's report before approving any development on the spaceship.
Even then, it is possible only the robotic version will make it off the drawing board. Assuming progress is smooth, a first flight of the unmanned spacecraft could come as soon as 2016; the astronaut version could fly in perhaps 2025.
The ARV "phase A" study was launched here in Bremen, a major centre for EADS Astrium.
Europe's largest space company will lead a consortium working on the project.
A 21m-euro contract agreeing the scope of the research was signed by Esa's director of human spaceflight, Simonetta Di Pippo, and Dr Michael Menking, Astrium's head of orbital systems and space exploration.
The ARV would essentially be an upgraded version of Europe's highly successful unmanned space freighter, known by another acronym - ATV (Automated Transfer Vehicle).
This 20-tonne vessel flew a maiden voyage to the International Space Station (ISS) last year.
The robotic truck has sophisticated automatic rendezvous and docking technology - it can find its own way to the ISS and attach itself without any human intervention.
What it cannot do, however, is return to Earth at high speed through the atmosphere. At present, it simply burns to destruction.
An ARV would have that survivability. This would be a significant asset for the space station which, when the US space shuttle retires next year, will have no means of getting heavy cargo - including science experiments - back to Earth.
Esa believes the unmanned ARV upgrade to its ATV could cost something in the order of 1.5bn euros.
ADVANCED RE-ENTRY VEHICLE - MISSION PROFILE
The ARV would launch on an Ariane 5 rocket from Kourou, French Guiana
The Mk I would only carry cargo, and qualify systems for human flight
Four European astronauts could travel safely inside the Mk II ARV
The new vehicle would incorporate a conical capsule. Its structure would be much stronger than the current cargo module on the ATV, and, significantly, it would have special protection to get it through the intense heat of re-entry, and a parachute system to slow the final descent.
Even though an unmanned cargo ARV is the initial target, designers would always be mindful of the potential to carry astronauts, said Cristian Bank, the head of crew transport at Astrium.
EUROPE'S RE-ENTRY HERITAGE
Human transport studied before
Hermes shuttle (T) never flew
Esa-Nasa X-38 (B) was cancelled
Know-how will now pass to ARV
"The loads which are imposed on the vehicle [must] not exceed the loads which are acceptable to astronauts, even if in the first instance we transport only cargo and we could exceed those loads," he explained.
"We shouldn't [do that] in order to ensure that whatever the mission looks like afterwards, it still allows astronauts to survive the flight."
Putting the necessary systems inside the unmanned ARV capsule so it can carry astronauts would cost many hundreds of millions of euros more.
"There're a lot of discussions on that, and I wouldn't like to give a figure; but it's one of the objectives of the Phase A that any decision taken by the member states can be based on a solid estimate," said Marco Caporicci, Esa's head of transportation and re-entry systems division.
Attention would also need to be paid to the safety systems on its launch rocket, an Ariane 5; and to establishing the ground infrastructure to support the vehicle in flight and retrieve it from a splashdown in the Atlantic, probably near the Azores.
But by designing the cargo ARV with the human version in mind, Esa believes substantial economies can be found.
"If we go ahead with a configuration which is also taking into account the manned version, this will allow us to reduce drastically the overall cost of the capsules," Mrs Di Pippo told BBC News.
The next major Esa ministerial council will take place in 2011. The member states will have received the results of the new study by then and should be in a position to decide a future course.
At the contract signing ceremony, a call was made to the ISS to speak to Esa astronaut Frank De Winne.
The Belgian is set to become the first European commander of the platform after a crew rotation in a few weeks' time.
Asked about the ARV, he said: "If you want to bring humans back to Earth, you first need to do a number demonstration flights and a cargo vehicle can very well serve for these demonstration flights.
"I hope that in the near future, Esa and the member states will make the decision to go into a full development of the ARV."
The manned ARV would require modifications to the Ariane 5 rocket
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