The planned crewed flyby of the Moon has been postponed again due to technical issues that required the Space Launch System (SLS) rocket to be returned to the assembly building for repairs.

The Artemis II mission’s March launch window was ruled out because of problems with helium supply to the SLS rocket’s interim cryogenic stage. Both the rocket and the Orion spacecraft will be sent back to the Kennedy Space Center’s assembly facility in Florida to address the malfunctions, canceling the previously scheduled launch date of March 6.

The anomaly occurred overnight during a routine pressure-raising operation. Although the helium supply systems—essential for engine purging and maintaining pressure in the liquid hydrogen and oxygen tanks—had functioned properly in recent tests, the team unexpectedly lost helium flow to the rocket. Thanks to the ground-based purging system, the spacecraft remains in a safe configuration. Possible causes of the malfunction include failure of the final filter, the quick-disconnect interface, or the onboard check valve. A similar issue was recorded during the uncrewed Artemis I mission, which launched in November 2022 after its own series of delays.

The Artemis II mission is planned to last 10 days and will include three American astronauts and one Canadian. This will be the first crewed lunar flyby in over 50 years. The program has already faced several postponements, including a liquid hydrogen leak in early February that prematurely ended one of the tests.

Launched during Donald Trump’s first presidential term, the Artemis program is seen as a crucial step toward establishing a permanent lunar base and paving the way for future crewed missions to Mars. A detailed technical briefing on the next steps is expected later this week.