Multiple defects in hardware and software have been found in Europe’s unmanned space tug and will delay the launch of the 20,000-kilogram vehicle to the international space station by at least a year to May 2007, according to European government and industry officials.

European Space Agency (ESA) governments have been informed of the problems but for the moment will not need to pay the cost overruns associated with the delay of the Automated Transfer Vehicle (ATV).

Because of earlier difficulties with the program, ESA governments insisted on a firm, fixed-price contract for the ATV with prime contractor EADS Space Transportation. It is that company, and its long list of component suppliers, that will bear the cost of the latest series of glitches.

“The customer and the contractor are very much in the same boat on this thing,” said Alan Thirkettle, head of development for ESA’s directorate of human spaceflight, microgravity and exploration.

EADS Space Transportation leads a team including Alcatel Alenia Space that is building the first ATV, called Jules Verne, under a contract that has been renegotiated on at least two occasions and was valued at about 975 million euros ($1.17 billion) when signed in 2004. Before then, ATV work was performed under a cost-reimbursement scheme.

The same industrial team is building six more ATVs to service the international space station under a separate contract valued at 835 million euros.

The ATV often is referred to as the most complicated orbital machine ever attempted in Europe. The roller-coaster ride in production of the Jules Verne prototype would appear to confirm that characterization.

“We are building something with all the characteristics of a human spaceflight vehicle, plus all the technical requirements of a satellite, in a machine that has to find its own way to a given point in space,” Thirkettle said Oct. 5 in an interview confirming the latest round of ATV problems.

EADS Space Transportation spokesman Remi Roland did not respond to requests for comment on the ATV. Other industry officials said the ATV difficulties are due at least in part to repeated changes in customer specifications, whether ordered by ESA, or NASA as space station general manager, or the Russian space agency, Roskosmos, whose Zvezda space station module will be the docking point for the ATV.

But these industry officials also said the ATV contracting team has suffered from corporate reorganizations and personnel changes that have complicated an already-difficult engineering endeavor.

One European government official was highly critical of EADS Space Transportation for bungling the ATV project.

Thirkettle declined to be that harsh. “I am convinced that the prime contractor is now making a major effort,” he said. “Up to several months ago they perhaps were trying to get to the end of the program before the loose ends were tied up. We weren’t particularly impressed. They are now fully engaged. [ATV] is a major effort that neither they nor we can afford to see fail.”

Thirkettle and industry officials said the Jules Verne ATV, originally scheduled for launch in 2004, was undergoing final preparation for a May 2006 flight at ESA’s Estec technology center in Noordwijk, Netherlands, this summer when bad news struck from several angles.

At that time, the agency was coping with a revised set of flight-safety and operational demands ordered by NASA and Roskosmos. “They were fairly fundamental changes to our flight application software, which is 1.5 million lines of code,” Thirkettle said. “But we had to bite the bullet and accept it.”

While updating the software, ESA officials discovered that the ATV flight simulator — racks of electronics that simulate each phase of the ATV mission — was incapable of doing its job.

The ATV is designed to carry more than 9,000 kilograms of water, fuel and other supplies to the station following its launch atop an Ariane 5 rocket. It stays docked to the station for up to several months to be loaded with garbage before being undocked and sent on a course to re-enter and burn up in the Earth’s atmosphere. Also among its many functions is to use its on-board engines to raise the station’s orbit on regular occasions.

It is Europe’s first rendezvous and docking vehicle, and is designed to approach the station, then back off in the event of difficulty and remain near the station until ordered to approach again.

At around the same time as the simulator defects were disclosed, ESA managers learned that activators in the ATV’s attitude control system also were defective. No bigger than a cigarette and deeply buried in the completed ATV, all 48 of them had to be removed and replaced.

“The good news is that we found the actuator problem before it found us,” Thirkettle said. “Every little engine on the ATV has these valves.”

To top it off, the drive mechanisms on the Jules Verne ATV’s solar arrays also were found to need replacing, Thirkettle said.

At that point, ESA officials were facing a six-month delay to the ATV’s planned May 2006 launch. But keeping to that revised schedule would have meant ordering the contracting team and ESA’s own ATV managers to work double shifts and weekends.

“We determined that this is not the best way to keep teams motivated, and we have set a schedule that includes sufficient margins and would permit us to launch around March 2007,” Thirkettle said. “Given the fact that we also want to launch after a planned Soyuz [manned flight] to the station that spring, we are now targeting a May 2007 launch.”

Peter B. de Selding was the Paris bureau chief for SpaceNews.