NASA's giant moon rocket begins test flight

NASA's gigantic Space Launch System moon rocket, topped by an uncrewed astronaut capsule, has begun an hours-long crawl to its launch pad this week ahead of its debut test flight.

On August 29, the 322 foot 98 metre tall rocket is expected to embark on its first mission to space, without any people.

It will be a crucial, long-delayed demonstration trip to the moon for NASA's Artemis program, the United States' multi billion dollar effort to return humans to the lunar surface as a practice for future missions to Mars.

The Space Launch System, the development of which has been led by Boeing, emerged from its assembly building at NASA's Kennedy Space Center in Florida about noon today AEST and began a six-kilometer trek to its launch pad.

Its transit will take approximately 11 hours and will take less than 1.6 kilometres per hour.

The astronaut capsule, built by Lockheed Martin Corp., will be NASA's Orion space capsule.

The capsule was designed to separate from the rocket in space, to bring humans to the moon, and to rendezvous with a separate spacecraft that would take the astronauts to the lunar surface.

The Orion capsule will sit empty at the Space Launch System for the August 29 mission, called Artemis 1, while it orbits the moon.

The rocket is scheduled to return to Earth for an ocean splashdown 42 days later.