WASHINGTON — Delays in the development of Orion’s European-built service module, and damage to a NASA facility from a tornado, are the key schedule risks for the first Space Launch System mission, agency officials said March 29.

The schedule for the launch of Exploration Mission 1 (EM-1), currently planned for late 2018, remains uncertain regardless of the technical issues as NASA studies the possibility of putting a crew on the flight, which would likely delay it by up to a year.

In a presentation to a meeting of the NASA Advisory Council’s Human Exploration and Operations Committee here, Bill Hill, deputy associate administrator for exploration systems development, said service module delays and damage to the Michoud Assembly Facility in New Orleans from a February tornado are running “kind of neck and neck” about being the biggest issue with the existing schedule for EM-1.

“The delivery of the European Service Module continues to be the critical path for Orion,” he said. The module, currently being built by Airbus in Bremen, Germany, is now scheduled for the fall of this year, but he said that could be delayed. “The delivery date continues to erode.”

Hill said an issue delaying the service module’s development is with unspecified subcontractors. “We’ve got some challenges with vendor-supplied units, and Airbus getting their vendors to deliver on time,” he said. “That’s delaying some of the actual delivery of the overall unit.”

Other elements of the development of the Orion spacecraft are going well, he said, although there have been adjustments to the schedule to accommodate delays in the delivery of the service module. Hill credited that to the experience building an Orion prototype for the Exploration Flight Test 1 mission, a December 2014 flight that put an Orion into Earth orbit for a five-hour mission.

Hill said NASA is still working out the effects on the EM-1 schedule from a Feb. 7 tornado that damaged several buildings at Michoud, including those involved in the assembly of the core stage of the SLS. “We were down for a while there, and still are recovering,” he said. In addition, he said a “snafu” after the tornado damaged a weld head in the assembly facility used to weld the SLS core stage components.

Hill said NASA is seeking supplemental funding to cover repair costs to several buildings at Michoud. “In the meantime, we’re expending SLS funds to do the repairs to get things done,” he said.

“I think we were really surprised by the amount of damage,” added Bill Gerstenmaier, NASA associate administrator for human exploration and operations. “This has been a major disruption to our overall schedule at Michoud.”

Repairing the damage and resuming work at Michoud has delayed the core stage by months, Hill said. “The tornado probably cost us two to three months,” he said. “We’re still evaluating that and seeing what the options are.”

He said NASA is working with Boeing, the prime contractor for the SLS core stage, to see how to recover at least some of the lost time. “Right now, the core stage is the critical path for EM-1.”

It’s unclear how much effect the service module and core stage issues would have on the overall schedule for EM-1, which had been planned for September to November 2018. Hill’s presentation omitted a schedule chart for the mission included in similar previous discussions, which he acknowledged was due to ongoing studies of the feasibility of flying a crew on the mission.

“We’re looking at maybe adjusting the launch date” to accommodate that, Hill said, making the mission’s schedule uncertain.

That study should be completed soon. Gerstenmaier told the committee March 28 that he hopes a final decision would be made by the time the administration releases its detailed fiscal year 2018 budget request in May. Putting a crew on EM-1, he said, “will require additional budget, and it will also require additional schedule.”