Nasa is aiming for a 1 April launch for the first crewed mission around the Moon in more than 50 years.
The launch window opens at 18:24 local time on Wednesday (22:24 GMT) and lasts for two hours.
The Artemis II mission, which will last about 10 days, will take its astronauts further into space than anyone has been before.
It aims to set the stage for an eventual human landing on the lunar surface for the first time since the Apollo missions of the 1960s and 70s.
If the 1 April launch has to be delayed, because of bad weather or technical issues, Nasa’s next possible dates are 2, 3, 4, 5, 6 and 30 April 2026.
In December 2025, the space agency set a deadline to launch Artemis II before the end of that month.
A potential February launch was ruled out after a pre‑flight test – known as a wet dress rehearsal – was cut short when hydrogen rocket fuel leaked from a connection linking the launch tower to the rocket.
