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STORY: NASA's huge, next-generation rocket has finally blasted off for the moon in an unmanned test flight that not only paves the way for a return of astronauts to the lunar surface, but signals a major change in direction for NASA itself.

But Artemis I first had some drama before its launch from Cape Canaveral. There were problems for hours, including a crew of technicians who are being heralded as heroes for carrying out a repair inside the rocket's blast zone.

NASA administrator and former senator Bill Nelson, shortly after liftoff:

"Why are we going back? (...) We're going back to the moon, not just for the sake of going to the moon, but to learn to live, to develop, to learn how to live on the moon in order to prepare to send humans all the way to Mars. The moon is just a few days away. Mars is months and months away."

Artemis I will send its capsule, called Orion, within 60 miles of the lunar surface in a mission that will last 25 days, before returning for a water landing back on Earth.

The eventual goal of the Artemis program is to get astronauts back to the moon by the end of decade and use it as a stepping stone for a Mars mission.

Artemis I is also being accompanied by a small satellite that will park itself in orbit around the moon, testing the location for a future space station, also planned this decade.

This is a big switch for NASA, which after the end Apollo missions back in the 70s largely focused its manned spaceflight program on what's called "low-Earth orbit" missions, such as the space shuttle and International Space Station.

Artemis has been in development for over a decade, with years of delays and cost overruns, and evolved from other moon and Mars projects that went through revisions and cancelations during the Bush and Obama administrations.

This was the third attempt to launch Artemis I, after 10 weeks of technical issues and hurricanes.