By Jonathan Amos

Science reporter, BBC News



The last fuelling procedure begins on Friday morning

The Automated Transfer Vehicle (ATV) will be lofted in the 22 February to 8-9 March timeframe, European Space Agency (Esa) officials say.

The 20-tonne vessel will then attach itself to the international outpost during one of two windows; in early March, or in late March to early April.

ATV is the biggest, most sophisticated spacecraft Europe has attempted to fly.

Its preparation at the Kourou spaceport in French Guiana is very nearly complete.

This Friday, engineers will start the final stage of fuelling, adding 2.7 tonnes of oxidiser to the ship's propellant system.

Once this is done, and major headway has been made on the final 200 or so items on an "open work list", the ATV will be moved out of Kourou's giant S5 integration halls and taken to the Baf (Final Assembly Building) where it will be mated with its Ariane 5 launcher.

SPACE STATION CARGO TRUCKS Mission Guide: Jules Verne ATV (l) will resupply 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

ATV flight animation

"Since October, we have lost just three days in the planning. We have some 200 actions still to do, but these are normal; I don't see major issues," he told BBC News.

Last week, at a general designers' review in Moscow, the Russians (one of the major partners in the space station project) gave their formal approval for the mission to proceed. A similar meeting will be held in the US this week at which the Americans are also expected to sign off ATV.

A gathering of space agency officials on 6 February will then begin the process of narrowing the launch window to a specific date. Much will depend on what happens to the shuttle Atlantis.

It is scheduled to fly to the International Space Station on 7 February. If it is held on the ground because of bad weather or further technical problems, the ATV launch date may start to creep to the back of its window.

But when ATV lifts off is probably not so important as when it arrives. It cannot dock when the shuttle is present or in flight - not least because the two vehicles both make use of the US Tracking and Data Relay Satellite System.

"We have built ATV to be almost independent of a lot of the other operations," explained John Ellwood, Esa's ATV mission manager.

There are about 200 - mostly simple - tasks still to perform

"We then go to the space station and we have the option of immediately docking if conditions are right or we could loiter. We have a strategy where we go to a point 2,000km in front of the space station and just wait there."

The best times to dock are 15-19 March and 30 March to 5 April. These are periods when the station's alignment to the Sun will give astronauts a clear view of the ATV's approach; cameras will not be blinded by bright light.

Once attached, the ATV - dubbed Jules Verne for its first flight - will stay on-station until August, after which it will be commanded to undock and ditch itself in the Pacific.

Preparation work on the second ATV, likely to fly in 2010, has already begun.

Jonathan.Amos-INTERNET@bbc.co.uk