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NASA engineers are moving ahead with repairs and additional checks on the Artemis II launch system after detecting elevated hydrogen levels during a recent fueling rehearsal, as the agency continues targeting a March launch window.

See our previous report on NASA’s hydrogen leak.

Following the wet dress rehearsal completed on Feb. 3, technicians replaced two seals near the tail service mast umbilical on the mobile launcher, where sensors recorded hydrogen concentrations above acceptable limits. The removed hardware is undergoing analysis to pinpoint the source of the leak and prevent a repeat during future operations.

After draining the Space Launch System’s cryogenic propellants, teams accessed the connection points between the rocket and ground equipment to inspect fueling interfaces and install new seals along two propellant lines.

The twin tail service masts, each standing roughly three stories high, deliver supercold fuel and power connections to the rocket’s core stage. During launch, these structures pivot away, and built-in quick-disconnect systems separate instantly to allow a clean liftoff.

Reassembly of the interfaces is expected to wrap up by Feb. 9. Additional testing is scheduled at NASA’s Stennis Space Center in Mississippi to examine how the hardware performs under operational stresses. Engineers are weighing further checks before the next rehearsal to confirm the fixes hold under fueling conditions.

NASA plans to adjust procedures for the upcoming wet dress rehearsal with a stronger focus on tanking operations. The Orion crew hatch will be sealed earlier than before, and the closeout team that normally assists astronauts at the pad will not take part in this round of testing. The crew access arm will remain extended, since prior demonstrations showed it can retract during the final countdown phase.

The agency has also built extra time into the timeline, adding 30 minutes to two planned countdown pauses before and after fueling. The change gives teams more room to troubleshoot and extends the rehearsal by about an hour without affecting launch-day activities.

Meanwhile, the Artemis II astronauts — Reid Wiseman, Victor Glover, Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen — continue training on Orion systems and mission procedures. Their sessions include simulations and reviews of daily flight objectives to maintain readiness.

NASA has not locked in an official launch date. Managers say a target will be set only after the next rehearsal concludes successfully and engineers assess the collected data.