By Jonathan Amos
Science reporter, BBC News
At almost 20 tonnes, the ATV will be the biggest spacecraft Europe has ever flown when it launches in January.
The Automated Transfer Vehicle is part-goods lorry and part-tugboat.
Its primary function will be to keep the International Space Station (ISS) stocked up with food, water, fuel and experimental equipment.
It will also re-boost the outpost, which has a tendency to drift down from its 300km-plus altitude as it brushes through the top of the atmosphere.
But the ATV is also a huge statement of capability. The maiden voyage will announce that Europe now has some important new technical competencies to rival the very best in the space exploration business.
"This is the most complex vehicle we have ever developed in Europe," said Jean-Jacques Dordain, head of the European Space Agency (Esa).
"It demonstrates automatic rendezvous and docking - a key technology which currently only the Russians have, but with much smaller vehicles. You have to imagine the ATV as a 20-tonne truck. When it docks with a manned space station, it has to do it smoothly," he told BBC News.
The first ATV - dubbed "Jules Verne" - will launch atop a specially prepared Ariane 5 from Kourou in French Guiana.
The rocket will put the vehicle - the size of a double-decker bus - into a 230km-high (140 miles) orbit, underneath the space station. The ATV will then raise its height and edge closer and closer to the platform over a series of orbits.
Both ATV and station will be moving across the sky at some 27,000km/h (17,000mph) - but relative to each other, they will lock together at less than walking pace.
The ship's own computers will be in charge as an advanced form of GPS and, in the latter stages, optical sensors guide it into position on the end of the Russian Zvezda module.
"The ATV can transition from one - what we call - 'hold point' to another. The whole sequence is monitored and to move from one point to another, it expressly needs clearance from the permanent control centre in Toulouse," explained Nicolas Chamussy, the ATV programme manager at prime contractors EADS-Astrium Space Transportation.
"And an astronaut in the station always has the possibility to stop the vehicle or, in the case of certain contingencies, can command a retreat manoeuvre using a red button."
But once securely docked, the station crew can start to unpack.
"When the crew goes into the pressurised part of ATV, they will recognise the layout from the MPLMs (Multi-Purpose Logistics Module) - the cargo modules that shuttles currently take to the station to deliver food, clothing, equipment, tools, etc," explained Esa astronaut Jean-Francois Clervoy.
"They will see racks; there are shelves with white bags carrying the supplies you would expect - gifts even from their families such as DVDs and books."
The vehicle will make a controlled re-entry over the Pacific
New oxygen supplies brought up by the ATV are simply vented into the station; water is carried out in bags; fuel is piped across to Zvezda.
The ATV will stay at the station for six months. At intervals of 10 to 45 days, the vehicle's thrusters will be used to boost the platform's altitude.
Over time, the ISS crew will use the vehicle as a refuse skip, filling the cargo section with all their waste. After undocking, the ATV will destroy all this material - and itself - in a controlled re-entry over the Pacific Ocean.
Upwards and onwards
The ATV is not designed to be an astronaut flight vehicle - people will not launch in an ATV to go to the ISS or to the Moon as they might in a Soyuz capsule or in the forthcoming US Orion vehicle. But the fact that people can move around safely inside it demonstrates Europe has the necessary skills to make important components of an independent human transportation system should it want to go down that route.
That looks a real possibility for the future - a joint venture with the Russians and perhaps the Japanese. Meanwhile, engineers are already thinking about more immediate evolutions on the concept.
SPACE STATION CARGO TRUCKS
ATV (L) will re-supply the ISS with up to 7,500kg of cargo
Capacity is three times that of the Russian Progress craft (R)
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 - Jules Verne
Named after the author who wrote about fantastic journeys
On the design board now is a re-entry capsule. This would be jettisoned by a returning ATV prior to the vehicle's destruction in the atmosphere. The capsule would land safely any experimental items from the ISS that were required for further study in Earth labs.
There are even plans for an ATV with a more open architecture. Continuing the juggernaut analogy, this unpressurised vehicle would be akin to a flat-bed truck.
This overcomes the approximately 80cm-width (30 inches) restriction placed on ATV packages by its hatch.
If the vehicle was made with no side walls, larger station components such as batteries and gyros could be launched to the platform. Spacewalkers could then manoeuvre these bulkier items into place with the help of the platform's robotic arm.
The ATV is a payment in kind to the $100bn ISS project. Instead of having to pay cash to cover station running costs, Europe has bartered for itself this important re-supply responsibility.
ATV technology could eventually feed into a crew vehicle
And with the Columbus science module also soon to be in place, Europe can then begin to feel the ISS is starting to give some return on its huge cost.
"Once Columbus is up there, once we have a full crew of six - then we have the full capability to do science," explained Mr Dordain.
"To do real science, you have to repeat and repeat an experiment; and with Columbus and a full crew we will have continuous access. The priority will be to do science and no longer engineering as has been the case up until now."