NASA has ruled out a March launch for its Artemis II mission after engineers detected a problem with helium flow in the Space Launch System rocket, dealing another setback to the United States’ first crewed lunar mission in more than half a century.
The space agency said the interruption, discovered during safety checks following a full rehearsal at the Kennedy Space Center in Florida, would likely delay the highly anticipated 10-day journey around the Moon and back.
Artemis II is intended to mark humanity’s furthest voyage into space and serve as a precursor to a planned lunar landing under Artemis III, currently scheduled for 2028.
NASA Administrator Jared Isaacman said the helium flow issue would “take the March launch window out of consideration,” noting that the disruption is treated as a serious technical matter because helium is essential for pressurizing fuel tanks, purging rocket engines and cooling systems.
Engineers first detected the interruption after a 50-hour fueling simulation that loaded approximately 730,000 gallons of propellant into the rocket.
The wet dress rehearsal, conducted under real launch conditions, had recently been completed after earlier attempts were cut short by technical problems, including a liquid hydrogen leak.
The towering Space Launch System rocket and Orion spacecraft will now be rolled back into the Vehicle Assembly Building for further inspection and repairs.
Isaacman said a faulty filter, valve or connection plate could be responsible and added that a full briefing would follow in the coming days.
The delay adds to a series of postponements that have affected the Artemis program since its inception.
The uncrewed Artemis I mission launched in November 2022 after multiple delays and two failed launch attempts.
NASA had surprised observers late last year by suggesting Artemis II could launch as early as February, an acceleration that followed a renewed push to return astronauts to the Moon.
The Artemis II crew includes three U.S. astronauts — Reid Wiseman, Victor Glover and Christina Koch — along with Canadian astronaut Jeremy Hansen.
If successful, the mission would lay the groundwork for Artemis III, which aims to return humans to the lunar surface for the first time since 1972.