Nasa cancels launch of moon mission after engine trouble

The blast-off of the first US rocket in 50 years capable of carrying humans to the moon was called off on Monday morning after last-minute problems with an engine cooling system.

The 322ft-tall Space Launch System rocket had been due to lift off from launch pad 39B at Florida's Kennedy Space Center, the same site that witnessed the launch of Apollo 17, the last US mission to the moon.

The launch, set for 8.33am local time, was put on hold and then scrapped after Nasa assessed a number of last-minute problems, including with one of the hydrogen "bleed" lines used to cool the engines before ignition.

Nasa sought to paint the delay as part of the usual teething problems for a new rocket.

"Launch controllers were continuing to evaluate why a bleed test to get the RS-25 engines on the bottom of the core stage to the proper temperature range for lift-off was not successful," Nasa said.

The first flight of the rocket is set to open a new era in human space exploration as the US races China to put astronauts back on the lunar surface.

Monday's mission was due to carry an unmanned Orion capsule on a six-week test flight around the moon, a prelude to its first human mission in 2024 and a moon landing in 2025.

The moon missions are the first step in Nasa's Artemis programme, which was set up with the eventual goal of carrying astronauts to Mars and beyond.

China, which has landed three robotic craft on the moon, has said it is planning to build a lunar base with Russia, and has invited other countries to join the project.