Hydrogen Leak Halts Countdown

NASA's long-awaited Artemis II crewed Moon mission has hit another fueling snag. During a wet dress rehearsal that began on January 31, a hydrogen leak was detected at an umbilical plate connecting the launch pad's fuel line to the base of the SLS rocket's first stage. The leak first appeared when the hydrogen tank was approximately 55% full, and despite brief pauses, it persisted as the tank reached 77% capacity.

The automated Ground Launch Sequencer ultimately stopped the clock for good at T-minus 5 minutes and 15 seconds when it detected an increase in hydrogen gas concentrations beyond allowable limits.

Repairs and a New Timeline

Since the February 3 test concluded, technicians have accessed the tail service mast umbilical on the mobile launcher and replaced two seals in the area where elevated gas levels were detected. Engineers are now reviewing options to verify the repair work before conducting a second wet dress rehearsal.

As a result of the incomplete test, NASA scrubbed the February 8-11 launch window and is now targeting five opportunities in March, beginning March 6 and ending March 11. The Artemis II crew, who had entered quarantine in Houston on January 21, has been released and will re-enter quarantine approximately two weeks before the next targeted launch date.

A Familiar Problem

Hydrogen leaks have plagued the SLS program before. The uncrewed Artemis I mission in 2022 was delayed six months due to similar hydrogen leaks identified during its first wet dress rehearsal. With more than three years between SLS launches, some degradation of seals and interfaces is expected.

NASA Administrator Jared Isaacman acknowledged the challenge directly: "With more than three years between SLS launches, we fully anticipated encountering challenges. That is precisely why we conduct a wet dress rehearsal. These tests are designed to surface issues before flight and set up launch day with the highest probability of success."

What Comes Next

NASA plans to complete a second wet dress rehearsal after repairs are verified before proceeding to a March launch attempt. Artemis II will carry four astronauts on a flyby of the Moon, the first crewed mission beyond low Earth orbit since Apollo 17 in 1972. The stakes for getting the fueling right could not be higher.

This article is based on reporting by Ars Technica. Read the original article.