NASA will forego a February launch for its Artemis II mission after engineers ran into leaks, cold-weather delays, and equipment problems during a key fueling test that ended early Tuesday morning.
The fuel-loading problems were reminiscent of the challenges the space agency faced in 2022 when it attempted to launch Artemis I, the uncrewed maiden voyage of the program.
The decision pushes the earliest possible launch to March and underscores the technical challenges facing Artemis II, NASA's first crewed lunar mission in more than 50 years and a critical step in the effort to return humans to the moon and possibly Mars. The mission will send four astronauts -- Commander Reid Wiseman, pilot Victor Glover, Christina Hammock Koch, and Jeremy Hansen -- on a 10-day journey around the moon without landing, testing the Orion spaceship's life-support systems. It's a key test flight before NASA puts boots on the lunar surface in Artemis III.
NASA concluded a so-called wet dress rehearsal that simulated launch countdown operations by loading 700,000 gallons of super-cold fuel into the 322-foot Space Launch System rocket, sending a team to the pad to complete closeout work on the capsule, and then safely draining propellant out of the rocket. The test is designed to expose problems before liftoff.
"Safety remains our top priority, for our astronauts, our workforce, our systems, and the public," said NASA administrator Jared Isaacman in a post on X. "We will only launch when we believe we are ready to undertake this historic mission."
Engineers encountered several issues over the two-day countdown simulation that began Jan. 31 in Cape Canaveral, Florida, NASA said. The agency will review data from the rehearsal and conduct another fueling test before setting an official launch date.
Passing on the February launch window means the Artemis II astronauts will leave quarantine and not travel to Kennedy Space Center this week as planned. The crew has been waiting in Houston at Johnson Space Center since Jan. 21.
NASA said the astronauts will return for quarantine about two weeks before the next targeted launch opportunity. With February ruled out, the next window opens March 6 and continues through March 9, with one extra opportunity on March 11.
Cold weather at the launchpad slowed operations almost immediately, delaying the start of propellant loading while teams worked to warm hardware connections.
During tanking on Feb. 2, engineers spent several hours troubleshooting a liquid hydrogen leak where propellant feeds into the rocket's core stage. Teams paused the flow of hydrogen, allowed the hardware to warm up to refit the seal, and adjusted flow rates.
Despite the delay, engineers ultimately filled all the tanks. A five-person team then went to the launchpad to complete Orion closeout operations as if the astronauts were there and boarding the ship.
The test ended prematurely with about five minutes remaining in the countdown. The ground launch sequencer automatically stopped after sensors detected a spike in the hydrogen leak.
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Liquid hydrogen has been NASA's fuel of choice for decades because it has the lowest molecular weight. That's ideal for keeping the tanks as light as possible. It also helps that hydrogen burns with extreme intensity.
But the reason why hydrogen leaks seem to always stymie launches is that those little molecules are hard to wrangle, seeping out of any tiny crevice or crack. The super-cold temperature of the fuel can cause the rocket materials to contract and shrink, leaving minuscule gaps for the propellant to escape.
NASA reported several other problems during the test. A valve linked to pressurization of the Orion hatch required retightening after a recent replacement. Final checkouts took longer than expected. Cold temperatures disrupted multiple cameras and other equipment, which would have required extra attention if that had happened on launch day.
Engineers also experienced intermittent audio communication dropouts across ground teams, an issue they have been working on for weeks apparently.
"Getting this mission right means returning to the Moon to stay," Isaacman said, "and a future to Artemis 100 and beyond."
