NASA has cancelled the launch of its Artemis 1 moon rocket after discovering a leak - the second time in less than a week the launch has failed to go ahead.
NASA engineers insisted that the launch director call off the planned lift-off.
The rocket was initially supposed to launch on Monday 29 but was aborted due to a hydrogen leak.
Early on Saturday, NASA said: "During tanking of the Artemis I mission, a leak developed in the supply side of the eight-inch quick disconnect while attempting to transfer fuel to the rock. "Attempts to fix it so far have been unsuccessful."
This most recent scrapped attempt to launch was called off after repeated attempts by engineers to fix a leak of super-cooled liquid hydrogen propellant that was being pumped into the vehicle's core-stage fuel tanks.
As well as failing to fix the leak, the problems resulted in mission managers falling behind in the countdown, leaving too little time to complete pre-launch preparations before lift-off.
No immediate confirmation of when the re-launch will be attempted has been announced, however, it is likely that NASA will schedule another launch for Monday or Tuesday.
The goal of the Artemis programme is to land humans back on the surface of the moon for the first time in more than 50 years since the last Apollo mission - NASA is planning on establishing a base on the moon as it looks to the future for a manned mission to Mars.
If the five-week moon flight succeeds, NASA hopes to fly astronauts around the moon in 2024 with the goal of landing humans back there in 2025.