SLS core stage rollout
The core stage of the first Space Launch System rocket is moved to its transport barge, in the background, for shipment to the Stennis Space Center, where it will undergo tests. Credit: NASA

HONOLULU — The first core stage for NASA’s Space Launch System finally rolled out of its factory Jan. 8, ready to be shipped to a NASA center for a key series of tests in the coming months.

The core stage of the SLS rolled out of the Michoud Assembly Facility in New Orleans, accompanied by workers who helped build the stage as well as a band. The stage was moved about two kilometers to a barge, which will later transport it to the Stennis Space Center in Mississippi.

NASA unveiled the stage during an “Artemis Day” event at Michoud Dec. 9. At the time, the agency expected to have the stage ready to ship to Stennis by the end of December. “We said we’d finish the core stage just before the end of the year, and today, it’s really less than two weeks from the date we’d said we’d be done,” NASA Deputy Administrator Jim Morhard said in a media teleconference, congratulating NASA and Boeing workers. “This is something they said they were going to do, and they kept their word.”

The SLS core stage, though, is two years, not two weeks, behind schedule, something John Shannon, Boeing vice president and SLS program manager, acknowledged in the call.

“When we came out of the critical design review in ’15, we expected to have the rocket built really by the end of ’17. We’re about two years late, and Boeing complete owns that,” he said. That two-year slip, he said, was caused in part by challenges using friction stir welding to manufacture the stage as well as underestimating the complexity of building the engine section, which houses the four RS-25 engines.

Once the core stage arrives at Stennis, it will be installed on a test stand there for months of tests. The most important of those tests will be a “wet dress rehearsal” where the stage is loaded with liquid oxygen and hydrogen propellants, followed by a static-fire test called the Green Run where the stage’s RS-25 engines are fired for about eight minutes, the length of time they’re used on an actual launch.

How long all those tests take will depend on whether there are any technical issues that arise during the tests, as well as weather than can delay activities on the outdoor test stand. “The range would be between July and August if everything goes perfectly, to an October timeframe if we deal with what would normally be typical weather or typical damage,” Shannon said.

Some of that post-test refurbishment work, which would include inspections of the stage and any needed repairs of thermal protection on the stage, may take place after the stage is shipped from Stennis to the Kennedy Space Center. One reason for that, Shannon said, is that the work could be done indoors inside the Vehicle Assembly Building at KSC.

NASA has not set a new date for when that core stage will launch as part of the Artemis 1 mission, an uncrewed test flight of the Orion spacecraft. NASA Administrator Jim Bridenstine said at the Artemis Day event last month that the mission would likely take place some time in 2021, but would let Doug Loverro, the new associate administrator for human exploration and operations, set that date.

Loverro said in a Dec. 10 interview that he had established a “baseline assessment team” to examine the state of the program. “I want to understand who all owns this program and how they connect together. Where do we stand right now? What are the individual technical issues that we need to solve?” he said. “Following that review we will get into a huddle and we will all figure out what the right date is for Artemis 1.”

Even if Artemis 1 slips to well into 2021, Bridenstine said it won’t necessarily have a domino effect on future missions, including the Artemis 2 crewed test flight and the Artemis 3 lunar landing mission in 2024.

“A lot of people seem to believe that, if Artemis 1 slips, then Artemis 3 isn’t going to make it in 2024, and that is simply not accurate,” Bridenstine said in that same Dec. 10 interview. “Artemis 2 is an independent mission from Artemis 1, and if we needed to we could push Artemis 1 back and still make Artemis 2 go on schedule to make Artemis 3 successful.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...