NASA Delays Artemis II Moon Mission to April After Helium Flow Problem

NASA delayed the Artemis II astronaut moon mission to April after a helium flow problem emerged in the rocket's upper stage, officials announced Saturday. The setback came just one day after the space agency had targeted March 6 for the historic flight, humanity's first crewed mission to the moon in more than half a century.

Overnight, the flow of helium to the rocket's upper stage was interrupted. Solid helium flow is essential for purging the engines and pressurizing the fuel tanks. The administrator said a bad filter, valve or connection plate could be to blame for the stalled helium flow. Regardless of the cause, the only way to access the area and fix the problem is to return the 322-foot rocket to its hangar for repairs.

NASA is targeting 9 a.m. on Wednesday, Feb. 25, 2026, for the move to the Vehicle Assembly Building at Kennedy Space Center in Cape Canaveral. The space agency's crawler-transporter, a tank-like vehicle the size of a baseball infield, will carry the Space Launch System, the Orion spaceship, and the mobile launcher. The stacked mega moon rocket weighs some 18 million pounds.

The interrupted helium flow is confined to the SLS rocket's interim cryogenic propulsion stage. This upper stage is essential for placing the Orion crew capsule into the proper high-altitude orbit around Earth for checkout, following liftoff. After that, it's supposed to separate from Orion and serve as a target for the astronauts inside the capsule, allowing them to practice docking techniques for future moon missions.

Everything worked fine with the rocket's helium system during both dress rehearsals. The "unexpected development" cropped up later in routine testing that kept engineers up all night assessing the situation. This helium issue has nothing to do with the hydrogen fuel leaks that marred a countdown dress rehearsal of the Space Launch System rocket earlier this month and forced a repeat test.

Once back in the hangar, teams will begin installing platforms to access an area of the rocket's upper stage where NASA recently discovered the helium flow problem. Prior to the rollback, mission managers had said they were looking at several potential causes, including a connection point between the ground equipment and the rocket, a valve in the upper stage, and a filter in the helium line.

Artemis II is a 10-day lunar flyby, testing the new Orion spaceship with humans aboard. Four astronauts — Commander Reid Wiseman, Victor Glover, Christina Hammock Koch, and Jeremy Hansen — will be along for the ride. It's NASA's first crewed mission beyond Earth orbit since 1972. The four astronauts went into their two-week quarantine Friday evening, mandatory for avoiding germs.

If teams can address the problem quickly, an April launch might be possible. The opportunities for the month include April 1, April 3 through 6, and April 30. Other dates are likely available in May, but NASA hasn't made any launch window information beyond April available to the public.

While the rocket is in the Vehicle Assembly Building, teams will replace batteries, including those in the flight termination system, a mandatory safeguard that destroys the rocket if it veers off course or critically malfunctions during launch.

The test flight sets the stage for a lunar landing during the next mission, Artemis III. The purpose of the Artemis program is to establish a long-term human presence on the moon before trying to survive on Mars. During NASA's Apollo program, 24 astronauts flew to the moon from 1968 through 1972. The new Artemis program has completed only one flight so far, a lunar-orbiting mission without a crew in 2022. That first test flight was also plagued by hydrogen fuel leaks before blasting off, as well as a helium issue similar to the one that arose Saturday.