Watch the moment Nasa Moon rocket achieves lift-off, makes history

NASA's new moon rocket blasted off on its debut flight with three test dummies aboard early Wednesday, bringing the U.S. a big step closer to putting astronauts back on the lunar surface for the first time since the end of the Apollo program 50 years ago.

If all goes well during the three-week, make-or-break shakedown flight, the rocket will propel an empty crew capsule into a wide orbit around the moon, and then the capsule will return to Earth with a splashdown in the Pacific in December.

Nasa managed to plug a leak late Tuesday night while fuelling its new moon rocket for a middle-of-the-night launch, its third try to put an empty capsule around the moon for the first time in 50 years. The launch took place successfully with three test dummies aboard.

Hydrogen fuel sprouted from a valve on the launch pad — a different location than leaks during previous launch attempts. Two technicians and a safety official rushed into the blast zone to tighten the valve, with emergency rescue workers on standby.

The quick repair fixed the leak, allowing hydrogen to resume flowing into the rocket. But then a Space Force radar tracking site went down because of a bad ethernet switch, leading to yet another scramble. The problems pushed the launch into the wee hours of Wednesday, as the countdown clocks held at the 10-minute mark.

The rocket was gassed up with nearly 1 million gallons (3.7 million litres) of super-cold hydrogen and oxygen, when the latest leak occurred.

Nasa last sent astronauts to the moon in December 1972, closing out the Apollo programme.