NASA has delayed the launch of its Artemis II mission, pushing the first crewed flight of the Space Launch System and Orion spacecraft to March 2026 at the earliest after engineers encountered technical issues during a critical prelaunch test.
The agency said the decision followed problems uncovered during a “wet dress rehearsal” at Kennedy Space Center in Florida, an hours-long simulation designed to replicate launch day conditions. During the test, engineers detected liquid hydrogen leaks near the base of the Space Launch System rocket, forcing NASA to halt the countdown just minutes before a planned simulated liftoff.
As a result, NASA said it will skip its February launch window, which had been scheduled to run through February 11, and instead target early March to allow teams time to review data and conduct another rehearsal. The agency said potential launch opportunities are available between March 6 and March 9, with an additional window on March 11 and further options in April if needed.
Artemis II is a milestone mission for NASA. It will be the first crewed flight of the agency’s Artemis program and the first time astronauts fly aboard the Space Launch System rocket and Orion capsule. The mission is designed to send four astronauts on a multi-day journey around the Moon, paving the way for a future lunar landing later in the decade.
During the rehearsal, NASA loaded the rocket with more than 700,000 gallons of cryogenic propellant and proceeded through the launch countdown as it would occur on launch day. Engineers paused the operation multiple times to assess hydrogen leaks, which returned in the final minutes of the test. Automated systems ultimately stopped the countdown after sensors recorded a spike in leak rates.
In addition to the hydrogen issue, NASA said engineers are reviewing audio problems that affected communication channels used by ground teams during the rehearsal.
NASA Administrator Jared Isaacman said the delay, while disappointing, reflects the agency’s cautious approach. “With more than three years between SLS launches, we fully anticipated encountering challenges,” Isaacman said in a social media post. He emphasized that wet dress rehearsals are intended to reveal issues before flight to reduce risk on launch day.
The four crew members assigned to Artemis II—NASA astronauts Reid Wiseman, Christina Koch, and Victor Glover, along with Canadian astronaut Jeremy Hansen—had been scheduled to travel to Florida this week after entering preflight quarantine in Houston. NASA said the crew will now be released from quarantine and will resume the process roughly two weeks before the next targeted launch date.
The delay echoes challenges faced during the uncrewed Artemis I mission, which also experienced hydrogen leaks during testing and was ultimately delayed by several months before launching successfully in late 2022.
With astronauts aboard for the first time, NASA officials stressed that safety remains the overriding priority.