NASA’S ARTEMIS 1 moon rocket launch has been called off due to an engine conditioning issue.

The uncrewed 322-foot Space Launch System (SLS) rocket had been due to take off from the Kennedy Space Centre in Cape Canaveral, Florida, during a two-hour window after 1.33pm Irish time, but was called off by the launch director moments before.

Teams had been working on an engine bleed on engine 3 of the rocket and were trying to figure out a troubleshooting plan, but the space agency said the issue couldn’t be remedied and the launch attempt was scrubbed.

The next available launch date for the mission will be on Friday 2 September, but a decision has not yet been made on whether it will go ahead.

A liquid hydrogen leak earlier interrupted Nasa’s preparations for the new moon rocket launch. Similar fuel leaks hindered Nasa’s countdown tests in April and June.

A “crack” was also identified on the thermal protection system material on one of the rocket’s connection joints.

Speaking on the space agency’s live feed, spokesperson Derrol Nail said: “The issue that came up was an engine lead that couldn’t be remedied, but the rocket is currently in a stable configuration.

The launch of #Artemis I is no longer happening today as teams work through an issue with an engine bleed. Teams will continue to gather data, and we will keep you posted on the timing of the next launch attempt. https://t.co/tQ0lp6Ruhv pic.twitter.com/u6Uiim2mom

— NASA (@NASA) August 29, 2022

“Engineers are now working on a plan to continue gathering data about this particular engine and the bleed that didn’t work out,” he said.

In an update posted online, Nasa said: “The launch director halted today’s Artemis I launch attempt at approximately 8.34 am EDT. The Space Launch System rocket and Orion spacecraft remain in a safe and stable configuration.

“Launch controllers were continuing to evaluate why a bleed test to get the RS-25 engines on the bottom of the core stage to the proper temperature range for liftoff was not successful, and ran out of time in the two-hour launch window. Engineers are continuing to gather additional data.”

Nasa’s most powerful rocket yet had been set to blast off on the maiden voyage of a mission to take humans back to the moon, and eventually to MArs.

Tens of thousands of people had gathered along the beaches of Florida to watch the launch, including US Vice President Kamala Harris.

Hotels around Cape Canaveral were booked solid with between 100,000 and 200,000 spectators expected to attend the launch.

The capsule is set to orbit the moon to see if the vessel is safe for people in the near future. At some point Artemis will see a woman and a person of color walk on the moon for the first time.

“This mission goes with a lot of hopes and dreams of a lot of people. And we now are the Artemis generation,” Nasa administrator Bill Nelson said Saturday.

The massive orange-and-white rocket has been sitting on the space center’s Launch Complex 39B for a week.

Its fuel tanks were to be filled overnight Sunday into Monday with more than three million liters of liquid hydrogen and oxygen.

For the first time a woman – Charlie Blackwell-Thompson – is set to give the final green light for liftoff. Women now account for 30% of the staff in the control room; there was just one back with Apollo 11.

The Orion capsule will orbit around the moon, coming within 100 kilometers at its closest approach and then firing its engines to get to a distance 40,000 miles beyond, a record for a spacecraft rated to carry humans.

Temperatures half as hot as the Sun

One of the primary objectives of the mission is to test the capsule’s heat shield, which at 16 feet in diameter is the largest ever built.

On its return to the Earth’s atmosphere, the heat shield will have to withstand a speed of 25,000 miles per hour and a temperature of 2,760 degrees Celsius. That is half as hot as the Sun.

Taking the place of people for now, dummies fitted with sensors will take the place of crew members, recording acceleration, vibration and radiation levels.

It will deploy small satellites to study the lunar surface.

A complete failure would be devastating for a program that is costing $4.1 billion per launch and is already running years behind schedule.

The next mission, Artemis 2, will take astronauts into orbit around the moon without landing on its surface. The crew of Artemis 3 is to land on the moon in 2025 at the earliest.

While the Apollo astronauts who walked on the moon were exclusively white men, the Artemis program plans to include the first woman and person of color.

And since humans have already visited the moon, Artemis has its sights set on another lofty goal – an eventual crewed mission to Mars.

The Artemis program is to establish a lasting human presence on the moon with an orbiting space station known as Gateway and a base on the surface.

Gateway would serve as a staging and refueling station for a voyage to Mars that would take a minimum of several months.

© AFP 2022, additional reporting from Jane Moore and the Press Association