NASA may not launch its Artemis 2 moon mission just a few weeks from now after all.
After overnight data showed an interruption in helium flow in the SLS interim cryogenic propulsion stage, teams are troubleshooting and preparing for a likely rollback of Artemis II to the VAB at @NASAKennedy. This will almost assuredly impact the March launch window. @NASA will…February 21, 2026
“This will almost assuredly impact the March launch window,” Isaacman said.
That window is relatively short. It runs from March 6 through March 9, with another opportunity on March 11. If Artemis 2 can’t hit any of those dates, NASA will have to wait at least three additional weeks: The next window features target launch dates of April 1, April 3-6 and April 30.
“A rollback would mean NASA will not launch Artemis 2 in the March launch window,” NASA officials wrote in a blog post on Saturday. “However, the quick preparations enable NASA to potentially preserve the April launch window if a rollback is required, pending the outcome of data findings, repair efforts, and how the schedule comes to fruition in the coming days and weeks.”
Saturday’s news was something of a surprise. It came just a day after NASA announced that it was targeting March 6 for the launch of Artemis 2, the first crewed mission beyond low Earth orbit since the end of the Apollo era. Artemis 2 will send three NASA astronauts and one Canadian on a roughly 10-day trip around the moon and back to Earth in a Orion capsule.
The agency made the March 6 call after reviewing data from Artemis 2’s second wet dress rehearsal (WDR), a two-day-long practice run of the major operations leading up to launch.
The WDR wrapped up on Thursday (Feb. 19) with a successful fueling of both SLS stages. This was a big milestone for the Artemis 2 team, which had to terminate the mission’s first WDR early on Feb. 2 due to a leak of liquid hydrogen (LH2) propellant.
LH2 leaks plagued Artemis 1, delaying the launch of that ultimately successful uncrewed moon mission multiple times back in 2022. But NASA seems to now have the issue under control.
During a press conference on Friday, Artemis 2 team members said there were just a couple of big boxes left to check before giving the mission a green light to launch.
One was the completion of the flight readiness review, which was expected to take place late this coming week. The other was the installation of two “contingency pad access” trusses on the SLS’ mobile launch tower, which will allow teams to check Artemis 2’s flight termination system on the pad.
Those trusses were installed on Friday, NASA officials wrote in Saturday’s blog post. But they’ll probably be removed soon.
“Teams are actively reviewing data, and taking steps to enable rollback positions for NASA to address the issue as soon as possible while engineers determine the best path forward,” officials wrote in the update.
“In order to protect for troubleshooting options at both Pad B and the VAB, teams are making preparations to remove the pad access platforms installed yesterday, which have wind-driven constraints and cannot be removed during high winds, which are forecasted for tomorrow,” they added.
Proper helium flow is vital to the proper functioning of the SLS upper stage; it pressurizes the LH2 and liquid oxygen propellant tanks and helps maintain “the proper environmental conditions” for engine operation, according to the blog post. The flow issue was not seen during the WDR.
Editor’s note: This story was updated at 2:15 p.m. ET on Feb. 21 with additional details from NASA’s blog post, which itself was updated.
