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The launch of Nasa's most-powerful ever rocket has been delayed due to a tropical storm which could become a hurricane.

The Artemis I Moon rocket has been delayed twice already because of a fault and a fuel leak but was expected to launch from the Kennedy Space Center, in Florida, on Tuesday.

However, the approaching tropical storm Ian has meant the un-crewed test flight has been postponed for a third time.

Eventually, Nasa wants to use the rocket, known as the Space Launch System (SLS), to send astronauts and equipment back to the Moon for the first time in more than 50 years.

Failed attempts

The first launch failed at the end of August due to technical glitches, while a second attempt at the start of September had to be stopped because of a fuel leak.

Engineers found there was a dent in the fuel line which carries liquid hydrogen - the fuel - between the rocket and the mobile launcher.

Hydrogen is very flammable which means if there is still a leak, there's a huge risk of the rocket catching fire and exploding.

Tropical storm Ian

With a third launch now cancelled, Nasa will decide whether the rocket can remain on the launch pad as the storm rolls in.

The hurricane centre, which looks at the storm's path has predicted that it will move just south of Jamaica, over western Cuba and into Florida.

The entire state is expected to be hit by the bad weather and that includes the launch site at Nasa's Kennedy Space Center.

Following the forecast, the space agency decided on Saturday to cancel Tuesday's blast off and has instead prepared the rocket - which is slightly taller than Big Ben's tower - for a possible return to its hangar.

If the rocket has to be shielded from the weather, it will miss the current launch window, which ends on 4 October.