Nasa’s Artemis 1 Moon rocket launch was due to launch on August 29 – but was been postponed due to a problem with one of the engines.
The flight is the first in Nasa’s Artemis programme and will be uncrewed this time.
The rocket had been due to take off from the Kennedy Space Centre in Cape Canaveral, Florida, during a two-hour window after 1.33pm BST, but was called off by the launch director moments before.
The Artemis 1 mission will see the first launch of the new 322ft tall Space Launch System (SLS) rocket, which the agency says is the world’s most powerful rocket to date.
It will take the Orion capsule, powered by the Airbus-built European Service Module (ESM), into the moon’s orbit.
You can watch the launch on Nasa’s Youtube channel.