NASA on ‘aggressive’ schedule to complete SLS repairs for April launch

WASHINGTON — NASA has about three weeks to complete repairs to the Space Launch System’s upper stage to make the next launch window for the Artemis 2 mission in early April.

NASA announced Feb. 21 that it would roll back the SLS and Orion spacecraft from Launch Complex 39B to the Vehicle Assembly Building after helium flow in the Interim Cryogenic Propulsion Stage, or ICPS, was interrupted. The rollback took place Feb. 25.

“While we have the ability to access the boosters and the core stage out at the pad,” said Lori Glaze, acting associate administrator for the Exploration Systems Development Mission Directorate, at a Feb. 27 briefing, “we do not have the ability to access the interior of the upper stage at the pad, so that’s what required us to roll back to the Vehicle Assembly Building.”

At the briefing, which focused primarily on broader Artemis architecture changes, NASA provided few details about what may have interrupted helium flow in the stage. NASA Administrator Jared Isaacman said Feb. 21 that the problem could have been caused by the final filter between ground and vehicle systems, a quick-disconnect umbilical interface or a failed check valve inside the stage. The check valve caused a similar issue during Artemis 1, but Isaacman noted NASA took steps after that mission to prevent a recurrence.

In a Feb. 26 update, NASA said it had narrowed the potential causes to a seal in the quick-disconnect or a check valve.

“The team has worked to streamline a plan for the work inside the VAB to give us the very best possible chance at a launch in the early April launch period,” Glaze said. That window runs from April 1 to 6.

The components suspected of causing the helium flow issue will be removed and inspected. “We hope to get down to the root cause of that and make changes, not just to the hardware but to our operational procedures, so that we don’t encounter the same issue again when we roll back out to the pad,” she said.

Additional maintenance is planned while the vehicle is in the VAB. That includes replacing and retesting batteries in the rocket’s flight termination system and giving closeout crews another opportunity to rehearse procedures for preparing the Orion spacecraft for launch. Some items loaded into Orion will “time out” because of the delay and will be replaced, she said.

Glaze also said workers will replace a seal in an umbilical that transfers liquid oxygen into the SLS core stage. Similar seals in liquid hydrogen lines were replaced after leaks during a wet dress rehearsal in early February, although NASA had not reported issues with liquid oxygen leaks.

During the briefing, NASA did not provide a detailed schedule for completing the work. Glaze said the agency would need “at least a week and a half or so” of work at the pad before being ready to launch. That suggests Artemis 2 would need to return to the pad in about three weeks to support an April 1 launch.

Another NASA official described the timeline as aggressive.

“The teams do have an aggressive schedule,” said Casey Swails, NASA deputy associate administrator, in a speech at the ASCENDxTexas conference Feb. 25. “They have an aggressive schedule to get back in there, understand what’s going on and make fixes so we can get out to the pad as quickly as possible and hopefully preserve the April launch window.”

If Artemis 2 cannot launch in early April, the next opportunity opens April 30. NASA has not disclosed additional details about that opportunity or later launch windows.