NASA delays Artemis II to March after leaks bedevil testing

"The biggest problem was a liquid hydrogen leak. A leak in the interface that routes cryogenic propellant into the rocket's core stage delayed engineers as the team opted to stop the flow of liquid hydrogen in the hope that warming the interface would allow the seals to reseat. Eventually, the tanks in both the core stage and the interim cryogenic propulsion stage were filled, and the countdown could go ahead, but it was halted again at the five-minute mark when the ground sequencer automatically stopped proceedings due to a spike in the liquid hydrogen leak rate."

"Other challenges included retorquing a valve associated with the Orion crew module hatch and dealing with communication dropouts, which had been an ongoing issue in the weeks leading up to the WDR. Liquid hydrogen is a notoriously difficult fuel to work with, and NASA's first Artemis SLS launch suffered similar problems. Things appear to have gone more smoothly this time, but the leaks still ended up halting the countdown before the tanks could be pressurized and the vehicle switched to internal power."

"NASA did not confirm if the rocket will need to be rolled back to the Vehicle Assembly Building (VAB) or if the issues could be mitigated at the launch pad. However, having failed to reach the end of the WDR, a delay to the launch was inevitable, and the agency said the Artemis II crew would be released from quarantine. The purpose of the WDR is to run through all the steps required to launch the rocket without actually launching it. As such, reaching T-5 minutes and 15 seconds was a case of "so near and yet so far" for the team."

Recurring liquid hydrogen leaks during the Artemis II Wet Dress Rehearsal forced engineers to halt the test before completion and prompted NASA to push the launch to at least March 2026. Teams stopped and restarted cryogenic flow to warm interfaces and reseat seals; tanks in the core stage and the interim cryogenic propulsion stage were filled but the countdown stopped at T-5 minutes when a leak rate spiked and the ground sequencer halted proceedings. Additional issues included retorquing a valve on the Orion crew module hatch and persistent communication dropouts. The agency has not confirmed whether rollback to the VAB is required, and the crew will be released from quarantine.

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