- Lift off from Kennedy Space Center between 13:33 and 15:33 BST
Artemis’ test flight to the moon was thought to be back on track after a suspected hydrogen leak was fixed, but new problems could set the mission back.
Engineers believe they have discovered a possible crack in a flange in the intertank area of the center stage. This is potentially very serious as it could indicate a fault in the thermal protection system.
Also, engine number three is still too hot for launch.
An issue with the rocket’s fuel had previously been fixed, although it was noted at the time that weather changes could still affect the timing of the launch.
Then Derrol Nail of Nasa Communications said: “Looking good so far.” However, it remains unclear whether these latest issues could derail the release.
The original launch time was set for 8.33am ET (1.33pm BST), with a two-hour window after which the rocket can lift off, but Nasa said: “It is expected that the timeline will slip.” NASA has stopped the countdown clock 40 minutes after launch as it continues to fix the engine cooling problem.
If Artemis 1 can’t launch today, the next windows will be September 2 and 5, although there are concerns that worsening weather could affect flights as Florida heads into hurricane season .
Follow the latest updates below.