NASA's Artemis I mega-moon rocket launch has been cancelled again following a fuel leak "too complex" to fix in time.

The unmanned spacecraft was due to set off for the moon yesterday evening, but instead had to be brought back into the hangar for repairs.

It is thought that the leak likely won't be fixed in a few days either.

Artemis I spacecraft. Image: NASA Space Launch System

Artemis Mission Manager Mike Sarafin said of the failed attempt: "This is an incredibly hard business."

"We're gonna fly when we're ready."

"As part of this initial test flight, we're learning the vehicle, we're learning how to operate the vehicle."

"And we are learning all of the things required to get us ready to fly."

Second try

Artemis I is the first part of a plan to get man back on the moon, with no person having landed there since 1972.

The unmanned flight's been called off at the last minute twice now, with the spacecraft brought back into the hangar for repairs.

A liquid hydrogen leak foiled its first launch attempt on Monday just minutes before liftoff.

The spacecraft is carrying one male and two female mannequins fitted with sensors to measure radiation levels and other stresses human astronauts will face.

Main image shows Artemis I Prelaunch. Picture by: NASA/Flickr