NASA Repairs SLS Hydrogen Leak, Artemis II Moves Closer to Historic Crewed Moon Mission

NASA has cleared a major technical hurdle on the road to its first crewed Artemis Moon mission. Engineers have successfully repaired a hydrogen leak in the Space Launch System (SLS) rocket, allowing Artemis II to advance toward its next critical fueling test and a targeted March 2026 launch window.

The issue surfaced during a wet dress rehearsal on February 3, when sensors detected hydrogen gas concentrations above allowable limits near the rocket’s ground fueling interface. Hydrogen, known for its extremely small molecular size, has long posed challenges for launch systems worldwide.

🔧 Inside the Fix: How NASA Stopped the Hydrogen Leak

The leak was traced to the Tail Service Mast Umbilical (TSMU)—a three-story-tall structure that delivers liquid hydrogen from the mobile launcher into the SLS core stage.

What went wrong

• Elevated hydrogen levels near interface plates connecting ground fueling lines to the rocket

What NASA did

• Technicians accessed the TSMUs on the mobile launcher

• Interface plates were removed

• Two critical primary seals were replaced

What’s next

• Final reconnection of the interfaces is scheduled for Monday, February 9

• Additional testing at NASA’s Stennis Space Center will simulate the pressure and stress experienced during real fueling operations

NASA says data from these tests will confirm whether the new seals can withstand launch-day conditions.

⏱️ Countdown Strategy Adjusted for Next Wet Dress Rehearsal

Alongside hardware repairs, NASA has refined its operational plan to improve efficiency and reduce the risk of another scrub.

Key changes include:

• Orion hatch closed before the test begins

• No closeout crew deployed to the launch pad during this rehearsal

• An additional 60 minutes of built-in hold time, split into two 30-minute troubleshooting windows

These changes give engineers more flexibility to resolve minor issues without stopping the test entirely.

🌕 Artemis I vs Artemis II: What’s Different?

The Artemis II crew includes NASA astronauts Reid Wiseman, Victor Glover, Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen.

👩‍🚀 Crew Status: Training Shifts Into High Gear

While the SLS remains at Launch Complex 39B, the Artemis II crew has exited quarantine and resumed intensive training. NASA reports the astronauts are conducting day-by-day mission simulations, focusing on Orion’s avionics, navigation, and life-support systems.

The agency says the objective is to make spacecraft operations “second nature” before the crew leaves Earth orbit.

🗓️ Will Artemis II Launch in March 2026?

NASA remains cautious. A formal launch date will only be announced once:

• The upcoming wet dress rehearsal is completed successfully

• Data confirms the integrity of the newly installed hydrogen seals

If testing proceeds as planned, NASA could attempt the final fueling test within the next 10–14 days.

🔍 Bottom Line

The successful repair of the SLS hydrogen leak marks a critical step forward for Artemis II. If upcoming tests validate the fix, NASA will be one step closer to sending humans back toward the Moon—setting the stage for future lunar landings and eventual missions to Mars.