February 3, 2026, 7:22 AM EST. NASA's Space Launch System (SLS) underwent a hydrogen leak during a late-stage wet dress rehearsal atop pad 39B, but engineers continued fueling. About 750,000 gallons of supercold LOX and hydrogen were pumped into the rocket as the test moved toward a simulated launch. The leak appeared at the tail service mast umbilical interface when the first stage was about 55% full, triggering a pause, then a resumed fill in replenishment mode. NASA later said the liquid hydrogen concentration at the umbilical remained within acceptable limits. The countdown, scheduled for 9 p.m. EST, stretched past the T-minus milestone as teams weighed an overnight review. A Sunday launch hinges on post-test analysis and weather; NASA has three February launch days before a potential March slip, tied to the Artemis mission.
