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

NASA delayed its highly anticipated Artemis II lunar fly-around mission to April after a new problem emerged with the Space Launch System rocket. The flow of helium to the rocket's upper stage was interrupted overnight, officials said Saturday, just one day after the space agency had targeted March 6 for the mission.

April is now the earliest that the four Artemis II astronauts could fly to the moon. Solid helium flow is essential for purging the engines and pressurizing the fuel tanks.

Administrator Jared Isaacman said a bad filter, valve or connection plate could be to blame for the stalled helium flow. Regardless of the cause, he said, the only way to access the area and fix the problem is to return the 322-foot (98-meter) rocket to its hangar for repairs.

"We will begin preparations for rollback, and this will take the March launch window out of consideration," Isaacman said via X. NASA's next opportunities would be at the beginning or end of April.

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. A second fueling test on Thursday revealed hardly any leakage, giving managers the confidence to aim for a March liftoff. The four astronauts went into their two-week quarantine Friday evening, mandatory for avoiding germs.

Everything worked fine with the rocket's helium system during both dress rehearsals, Isaacman said. The "unexpected development" cropped up later in routine testing that kept engineers up all night assessing the situation.

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.

NASA announced Friday it's revamping its Artemis moon exploration program to make it more like the fast-paced Apollo program half a century ago, adding an extra practice flight before attempting a high-risk lunar landing with a crew in two years. The overhaul in the flight lineup came just two days after NASA's new moon rocket returned to its hangar for more repairs.

Artemis II, a lunar fly-around by four astronauts, is off until at least April because of rocket problems. The follow-up mission, Artemis III, had been targeting a landing near the moon's south pole by another pair of astronauts in about three years. But with long gaps between flights and concern growing over the readiness of a lunar lander and moonwalking suits, Isaacman announced that mission would instead focus on launching a lunar lander into orbit around Earth in 2027 for docking practice by astronauts flying in an Orion capsule.

The new plan calls for a moon landing — potentially even two moon landings — by astronauts in 2028.

"Everybody agrees. This is the only way forward," Isaacman said.

Another three-year gap was looming between Artemis II and the moon landing by astronauts as originally envisioned, Isaacman said. Isaacman stressed that "it should be incredibly obvious" that three years between flights is unacceptable. He'd like to get it down to one year or even less.

During NASA's storied Apollo program, he said, astronauts' first flight to the moon was followed by two more missions before the first lunar landing. What's more, he added, the Apollo moonshots followed one another in quick succession, just as the earlier Projects Mercury and Gemini had rapid flight rates, sometimes coming just a few months apart. Twenty-four Apollo astronauts flew to the moon from 1968 through 1972, with 12 of them landing.

"No one at NASA forgot their history books. They knew how to do this," Isaacman said. "Now we're putting it in action."

To pick up the pace and reduce risk, NASA will standardize its Space Launch System rockets moving forward, Isaacman said. These are the massive rockets that will launch astronauts to the moon aboard Orion capsules. At the same time, SpaceX and Blue Origin are speeding up their work on the landers needed to get the astronauts from lunar orbit down to the surface.

Isaacman said next year will see an Orion crew rendezvousing in orbit around Earth with SpaceX's Starship, Blue Origin's Blue Moon or both landers. It's similar to the methodical approach that worked so well during Apollo in the late 1960s, he noted.

"We should be getting back to basics and doing what we know works," he said.

The Aerospace Safety Advisory Panel recommended this week that NASA revise its objectives for Artemis III "given the demanding mission goals." It's urgent the space agency do that, the panel said, if the United States hopes to safely return astronauts to the moon. Isaacman said the revised Artemis flight plan addresses the panel's concerns and is supported by industry and the Trump administration.

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.