When will Artemis II launch?

Preparations are complete and on schedule. Contrary to outdated theories that countdown preparations are absent, the SLS rocket rolled out to Launch Complex 39B on March 19, 2026. The four-person crew arrived at Kennedy Space Center on March 27, and the official countdown is scheduled to begin on March 30 for an April 1 launch attempt. The physical reality of the rocket on the pad with the crew on-site strongly supports an imminent launch. The weather forecast is highly cooperative for the primary launch window. Meteorologists currently project only a 20% chance of rain for Cape Canaveral on April 1, with temperatures comfortably in the 70s—well above the strict 41°F 24-hour average minimum that would trigger a weather scrub. Backup days on April 3 and 4 also show highly favorable conditions with only a 15% chance of rain, giving NASA multiple clean looks at the sky. Recent hardware interventions have addressed known vulnerabilities. Following a wet dress rehearsal in February 2026, NASA rolled the rocket back to the Vehicle Assembly Building to replace a problematic seal in the quick disconnect and the liquid oxygen line. By proactively fixing the helium and oxygen seals that interrupted the February tests, the risk of a hydrogen leak scrub—the primary culprit for Artemis I delays—has been materially reduced for this launch attempt.

The Space Launch System has a demonstrated history of scrubbing due to propellant management issues. Artemis I, the only previous flight of this rocket architecture, scrubbed its first two launch attempts in August and September 2022 due to engine bleed and liquid hydrogen leaks, ultimately taking 2.5 months to get off the pad. Liquid hydrogen is notoriously difficult to manage, and a single sensor anomaly during the April 1 tanking process will halt the countdown. The market's resolution window is extremely tight. The market requires a launch *before* April 5, meaning April 4 is the absolute last valid day. If the April 1 attempt scrubs, the standard 48-hour recycle time required to replenish and manage SLS propellants means the next attempt wouldn't occur until April 3 or 4. A single significant technical scrub leaves NASA with zero margin for error before the market deadline expires. As the first crewed mission beyond low Earth orbit in over 50 years, NASA's safety margins will be absolute. Unlike uncrewed tests where some minor risks might be accepted to gather flight data, any off-nominal reading in the Orion life support, hatch pressurization, or launch abort systems will result in an immediate scrub. The threshold for a "No Go" call from the Mission Management Team is lower on Artemis II than on any NASA mission in recent history.