SAN DIEGO — Adapting the European Space Agency’s Automated Transfer Vehicle (ATV) into a service module for NASA’s Orion deep-space capsule is threatening to push the craft’s first mission to lunar space beyond its notional December 2017 launch date, a NASA official said here.

ESA officials said in May that ATV prime contractor Airbus Defence and Space was back on track to deliver Orion’s service module in time for a late-2017 launch without having to resort to double- and triple-shifts to get the job done. ESA’s assurances followed a May 19 preliminary design review where Airbus officials showed they had resolved the module’s excess weight. With the module’s critical design review slated for late 2015, Airbus’ head of orbital systems and space exploration, Bart Reijnen, said in an interview at the time that the overall schedule remained challenging.

Mark Geyer, NASA’s Orion program manager, told SpaceNews here Aug. 5 at the American Institute of Aeronautics and Astronautics’ Space 2014 conference that timely delivery of Europe’s ATV-based service module remains a concern.

“We’re struggling to make December 2017, and I have a lot of challenges to make that date,” Geyer said. “They’re finalizing their contract in September with Airbus, and they have challenges on the schedule that we are negotiating with them on what that means for me. If they show up a little later than I planned, is there something they can do at the Cape? Can they travel some work to the Cape so they can get it to me earlier? That’s what we’re talking about now, and we’re going to finalize their delivery date probably by the end of this month.”

An uncrewed Orion — with a U.S.-built service module — is due to launch Dec. 4 from Cape Canaveral Air Force Station, Florida, aboard a Delta 4 Heavy rocket to check out the capsule’s heat shields and avionics during the course of two orbits and a high-speed re-entry. Europe’s service module is not needed until Orion’s next flight, a planned December 2017 launch, known as Exploration Mission 1, that would take another uncrewed Orion to a distant lunar retrograde orbit using the capsule’s intended carrier rocket, the heavy-lift Space Launch System.

Todd May, NASA’s SLS program manager, said during an Aug. 5 panel discussion here that the heavy-lift rocket is on track for a December 2017 launch.

Whether Orion will be ready remains an open question. In addition to the schedule challenges at ESA and Airbus, NASA and Orion prime contractor Lockheed Martin Space Systems of Denver have been dealing with schedule challenges of their own.

Orion’s heat shield, being made by Lockheed subcontractor Textron Industries of Providence, Rhode Island, came out of the factory with cracks and had to be recured. In addition, welds on the complex plumbing for Orion’s propulsion system “took us longer than we expected,” Geyer said. NASA and Lockheed teams also had to take time to repair the crew module’s pressure vessel, which cracked during proof tests at the Kennedy Space Center in 2012.

On top of all that, the two-week partial government shutdown last October kept the Orion team locked out of the Kennedy Space Center, Geyer noted. The delays pushed Orion’s upcoming debut from September to December, which in turn delayed the date Lockheed and NASA engineers could begin working on the craft bound for lunar space.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.