NASA is moving the Space Launch System (SLS) rocket, slated to carry four astronauts on a flyby of the moon, off the launchpad and back into its hangar after new technical issues prevented another launch attempt.
The mission, Artemis II, was rolled to the pad in late January 2026 and faced multiple postponements. Its original launch window opened on February 6, 2026; after several delays the mission will not launch before April.
Cold weather in February delayed a critical “wet” rehearsal — a full fueling test that pumps about 700,000 gallons (2.6 million liters) of liquid hydrogen and oxygen into the SLS tanks. When the test was eventually attempted, it was halted due to hydrogen leaks, a type of problem that also grounded Artemis I in 2022. After repairs to fuel connections, NASA retested on February 20 and resolved the hydrogen leaks, setting a new target of March 6 at the earliest.
However, a later issue with helium flow — which pressurizes the liquid hydrogen and oxygen tanks in the rocket’s upper stage — was discovered. Because those helium flow problems cannot be corrected while the rocket is on the launchpad, NASA decided to roll the vehicle back to the hangar for further work.
Artemis II has experienced repeated delays. After the uncrewed Artemis I mission in 2022 revealed erosion on Orion’s heat shield during re-entry, NASA conducted an extensive investigation to ensure astronaut safety. The crewed Artemis II flight, originally planned for 2023, was pushed to September 2025 and then into 2026.
The flight’s crew — Christina Koch, Victor Glover, Jeremy Hansen, and Reid Wiseman — will wait to board Orion until the leak and helium issues are fully resolved.
Moon launch windows are tightly constrained and often calculated to the minute. For Artemis II, windows must allow Orion to be released into a high Earth orbit for system checks, ensure correct alignment for the trans-lunar burn, provide sufficient sunlight (no more than 90 minutes of darkness) to power the European Service Module’s solar arrays, and allow a safe trajectory back to Earth. NASA’s April opportunities currently include April 1, 3, 4, 5, and 6.
Edited by: Zulfikar Abbany