NASA has rolled the Space Launch System (SLS) rocket for the crewed Artemis II mission off the launchpad and back into its hangar after new technical problems prevented another launch attempt.
The SLS was moved to the pad in late January 2026 for a mission that will carry four astronauts on a lunar flyby. The original launch window opened February 6, 2026, but repeated delays now push any realistic liftoff into April or later.
A cold snap in February delayed a critical “wet” dress rehearsal — a full fueling test that loads roughly 700,000 gallons (about 2.6 million liters) of liquid hydrogen and liquid oxygen into the rocket. When engineers eventually attempted the test it was halted because of hydrogen leaks, a class of problem that also grounded Artemis I in 2022. After repairs to fuel connections, NASA ran a retest on February 20 and cleared the hydrogen leaks, setting a tentative earliest target of March 6.
Subsequently, technicians discovered a separate issue with helium flow. Helium is used to pressurize the upper-stage propellant tanks, and the anomaly cannot be fully corrected while the vehicle is on the launchpad. Because of that constraint, mission managers chose to roll the rocket back to the hangar for further troubleshooting and repairs.
Artemis II has seen repeated schedule slips. After the uncrewed Artemis I flight in 2022 revealed erosion on Orion’s heat shield during re-entry, NASA carried out an extensive investigation to ensure crew safety. The crewed Artemis II flight was initially planned for 2023, then moved to September 2025, and later into 2026.
The four-person crew — Christina Koch, Victor Glover, Jeremy Hansen, and Reid Wiseman — will not board Orion until the hydrogen leak and helium flow problems are fully resolved.
Moon launch windows are tightly constrained and calculated to the minute. Artemis II must be released into a high Earth orbit for system checks, achieve the correct alignment for the trans-lunar injection burn, maintain sufficient sunlight for the European Service Module’s solar arrays (no more than about 90 minutes of darkness), and ensure a safe return trajectory. Current April opportunities include April 1, 3, 4, 5, and 6, but those dates depend on successful troubleshooting and a clean test campaign.