CAPE CANAVERAL, Florida, January 10, 2026 — NASA has postponed the crewed Artemis II mission for the second time, pushing the launch from April 2026 to no earlier than September 2026 due to a persistent helium leak in the Space Launch System (SLS) mobile launcher.
The agency announced the delay Monday after engineers identified a leak in the mobile launcher’s gaseous helium system during final preparations for the uncrewed Artemis I test flight’s follow-up.
The helium is used to pressurize propellant tanks and purge lines during fueling. Despite extensive inspections and repairs, the leak has proven difficult to fully isolate without major disassembly of the 380-foot-tall mobile launcher.
NASA Administrator Bill Nelson stated: “Safety is our top priority. We will not fly until we are confident the system is ready.” The agency emphasized that the delay allows time for a thorough fix and additional testing, including a full wet dress rehearsal with the Orion spacecraft and SLS rocket stack.
The Artemis II mission will send four astronauts—Commander Reid Wiseman, Pilot Victor Glover, Mission Specialist Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen—on a 10-day lunar flyby, the first crewed flight beyond low Earth orbit since Apollo 17 in 1972. The crew has been training since 2023 and remains ready to adjust to the new timeline.
The previous delay, announced in late 2025, shifted the mission from late 2025 to April 2026 due to ongoing issues with the Orion heat shield and life support systems. This latest postponement keeps the Artemis III lunar landing targeted for no earlier than mid-2027, though officials acknowledge the schedule remains fluid.
NASA and prime contractor Boeing are working around the clock on repairs to the mobile launcher, which serves as the launch pad and transport platform for SLS.
A parallel effort is underway to prepare the backup mobile launcher for future missions. The agency plans to provide a detailed update on the repair timeline and new launch window in the coming weeks.
