Nasa has fixed a problem with defective equipment on a new rocket designed to take astronauts to the Moon.
The National Aeronautics and Space Administration has prepared the giant Space Launch System (SLS) for its maiden flight scheduled for March.
Last month, it identified a fault with a built-in motor controller.
But the component has now been replaced and all four engine controllers did well in testing last week.
They act as the "brain" for each of the powerful RS-25 engines, which help drive SLS into orbit, communicate with the rocket to provide precision control of the engine and diagnose any problems.
At the end of last year, some electronics on the motor four controller could not turn on consistently during a test.
But last week, all controllers were turned on and functioned as expected, while engineers reviewed their steps in further testing.
The SLS is housed in the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida.
When the Orion spacecraft is stacked on top, the entire system stands 98m (322ft) high - taller than the Statue of Liberty.
This version of the SLS will generate as much as 8,800,000 lb (39.1 meganewtons) of pressure.
This is 15% more than the powerful Saturn V launcher that brought people to the Moon in the 1960s and 70s.
This SLS is being prepared for a mission called Artemis-1, which will see the rocket launch NASA's Orion spacecraft towards the Moon.
The mission is intended to test SLS and Orion systems ahead of the first manned launch in 2024.
The culmination of the test for the Artemis-1 hardware is the wet dress rehearsal, in which the SLS is rolled out to the launch pad at Kennedy and filled with its cryogenic (cold) liquid propellants.
The mission known as Artemis-3 will see the first humans land on the moon's surface since the Apollo 17 mission in 1972.
It could be launched in 2025 if all goes well.
The crew members who will land on the Moon as part of this mission have not yet been announced, but Nasa is training a select pool of astronauts to fly the Orion spacecraft.
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