Hydrogen Leak Disrupts NASA’s Lunar Mission Rehearsal

Fueling test of Space Launch System halted as engineers assess impact on Artemis timeline

February 3, 2026: NASA’s preparations for its next crewed mission around the Moon hit a snag after a hydrogen leak was detected during a crucial fueling rehearsal of the Space Launch System (SLS) rocket at Kennedy Space Center. The all-day test, designed to mirror the final stages of a real launch countdown, is considered a decisive milestone for setting the mission’s launch date. The leak emerged while teams were loading super-cold liquid hydrogen and oxygen into the 322-foot rocket, forcing officials to pause operations midway through the high-stakes procedure.

The rehearsal involved transferring more than 700,000 gallons of propellant into the rocket’s tanks and holding it under launch-like conditions. Sensors flagged elevated hydrogen levels near the lower section of the vehicle after only about half of the core stage had been filled, prompting a safety halt. Engineers turned to mitigation techniques refined during the SLS rocket’s uncrewed debut three years ago, which was also plagued by hydrogen leaks before eventually lifting off successfully. NASA teams are now evaluating whether the rehearsal can continue and how the issue may affect launch readiness.

Meanwhile, the four astronauts assigned to the mission—three Americans and one Canadian—monitored developments remotely from Johnson Space Center in Houston while remaining in pre-launch quarantine. The outcome of this rehearsal will play a key role in determining when NASA can attempt its first human lunar fly-around in more than 50 years. The mission is a central step in the Artemis programme, aimed at restoring human presence around the Moon and paving the way for future landings and deeper space exploration.