NASA Releases Artemis II Moon Mission Launch Countdown
NASA announced the detailed launch countdown for Artemis II, the agency’s first crewed flight of the Artemis program, set for liftoff on 17 January 2026 from Launch Complex 39B at Kennedy Space Center, Florida. The mission will carry NASA astronauts Reid Wiseman, Victor Glover, Christina Koch and Canadian Space Agency astronaut Jeremy Hansen on a lunar flyby. A two‑day pre‑launch sequence will be managed by the Kennedy Space Center launch team and supporting personnel nationwide. The countdown schedule was released alongside images of the crawler‑transporter moving the Space Launch System (SLS) rocket and Orion spacecraft from the Vehicle Assembly Building to the mobile launcher at Pad 39B.
The countdown begins with “L‑Minus” timing at 49 hours 50 minutes before launch, during which the launch crew assembles at their stations and the clock starts. Liquid oxygen and liquid hydrogen loading for the core stage and the Interim Cryogenic Propulsion Stage (ICPS) commence between L‑42 hours and L‑40 hours, followed by power‑up of Orion and the four RS‑25 engines. Battery charging for Orion and the core stage occurs from L‑33 hours to L‑24 hours, after which the ICPS is powered up for launch at L‑20 hours. Non‑essential personnel vacate the pad at L‑15 hours, and a series of nitrogen inerting, ground launch sequencer activation and built‑in holds shape the “T‑Minus” timeline. Cryogenic chill‑down, slow and fast fills of LOX and LH2, and vent‑relief tests progress through the L‑9 hour to L‑6 hour window, leading to crew weather briefings, white‑room access, and final hatch closures. The terminal count incorporates a 30‑minute hold, a 1‑hour 10‑minute hold, and multiple short holds that can be extended or recycled depending on launch‑window constraints, with the automated launch sequencer assuming control at T‑10 seconds and RS‑25 engine start at T‑6.36 seconds.
Artemis II will validate the integrated SLS‑Orion system and the launch‑pad operations that support NASA’s goal of establishing a sustainable human presence on the Moon. Successful execution of the countdown and launch will inform subsequent Artemis missions, including the crewed lunar landing planned for Artemis III, and will contribute to the agency’s longer‑term objective of crewed exploration of Mars.
