NASA Scrubs Artemis II Wet Dress Rehearsal After Hydrogen Leak; February Launch Now Unlikely

Photo Credit: NASA/Jim Ross

Kennedy Space Center, FL — (February 3, 2026)

A critical pre-launch test for NASA’s Artemis II crewed lunar flyby mission was abruptly halted today after engineers first detected a liquid hydrogen leak earlier in the countdown, during which the final stages of the “wet dress rehearsal” countdown at Launch Complex 39B caused the terminal count to halt at T-5 Minutes and 15 Seconds. The scrub effectively removes the remaining February launch window for the mission, NASA confirmed.

The wet dress rehearsal — a full-countdown simulation that loads real cryogenic propellants into the Space Launch System (SLS) rocket and validates launch procedures — was progressing into its terminal count when the leak occurred at approximately T-5 minutes, 15 seconds. Teams opted to terminate the rehearsal and begin draining the rocket after hydrogen concentrations at a tail service mast umbilical exceeded allowable limits.

Hydrogen, the rocket’s primary fuel, is notoriously difficult to contain due to its small molecular size. Even minor leaks require immediate response to ensure personnel safety and hardware integrity. Similar leak-related issues have occurred in prior tall-rocket preflight tests, underscoring the complexity of fueling operations at the scale required for Artemis missions.

NASA engineers are now securing the vehicle and assessing the cause of the leak before determining a path forward. The agency has not announced a revised plan for completing the wet dress rehearsal or a new target launch date, but the remaining February opportunities have effectively closed, given the time required for troubleshooting and corrective work.

Artemis II is the first crewed mission in NASA’s Artemis program, designed to send astronauts around the Moon and back. The flight will carry four astronauts — NASA’s Reid Wiseman, Victor Glover, Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen — on a roughly 10-day free-return trajectory.

A NASA news conference is scheduled for tomorrow, during which agency officials are expected to provide additional details on the leak, discuss what steps will be taken next, and outline new timelines for completing pre-launch testing.

Until then, Artemis II teams will be analyzing data from today’s wet dress rehearsal and determining whether the hydrogen leak can be addressed at the pad or requires more extensive corrective work. NASA has stressed that safety remains the top priority as the agency prepares for its most ambitious human spaceflight mission since the Apollo era.

This is a developing story. Updates will be made in a separate news article after tomorrow’s press conference.