NASA will not slingshot a spacecraft around the moon this week following two previous called-off launch attempts, officials confirmed at a news conference Saturday evening.

That means the team will likely haul the gigantic, 322-foot Space Launch System rocket back to its hangar, the Vehicle Assembly Building, and perhaps take another shot at the moon in October. The U.S. space agency is bumping up against a launch blackout period and can't conflict with a SpaceX flight carrying astronauts to the International Space Station in a few weeks.

Another obstacle for Artemis I: The flight termination system — explosives that destroy the rocket if it veers off course — needs to be retested after 25 days, though NASA may ask the spaceport for an extension on its certification so it can try to launch sooner.

"Unless we get a waiver, it is a rollback scenario," said Mike Sarafin, Artemis mission manager.

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Mission leaders are weighing various options and will announce next steps in about a week. Engineers and technicians may perform some work at the platform before the rocket leaves the launchpad.

Launch director Charlie Blackwell-Thompson canceled the second launch attempt a little after 11 a.m. on Saturday, after the team discovered a large fuel leak that engineers couldn't stop. The liquid hydrogen seeping out was two or three times the permissible level, Sarafin said. When high concentrations of hydrogen are mixed in the air, there is a high risk for flammability.

"It was pretty clear that we weren't going to be able to work our way through it like we did on Monday, in terms of managing the leak," he said.

NASA is still investigating the cause of the leak. One possibility the team will look into is whether an accidental overpressurization of the fuel line earlier in the morning could have been the culprit.

During the initial launch attempt on Monday, Aug. 29, the team unexpectedly encountered a smaller-by-comparison liquid hydrogen leak, an engine that appeared not to be chilling down properly, and bad weather. Later NASA investigated the engine issue and felt certain the problem was an inaccurate sensor, not inadequately cooled fuel. That confidence led the team to proceed with another try on Saturday.

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Artemis I is expected to be the first deep spaceflight of a capsule built for astronauts in about 50 years. Orion will travel 1.3 million miles, including a 40,000-mile swing past the moon, on a looping journey to test various orbits. No humans will be aboard the test flight, but a successful mission will clear the way for astronauts to use the vehicles to go to the moon and perhaps eventually Mars.

Mission managers stressed that scrubbed launches are common. They emphasized that the Space Shuttle had 20.

"I'm sure there's going to be a question of are we confident, and I actually love that question because it's like, 'Are you confident you're going to get out of bed this time?'" said Jim Free, associate administrator of exploration systems development.

"We don't just say, 'Hey, we hope this is going to work.' The confidence to do another launch attempt today was borne out of the fact that we understood, the hydrogen leaks that we had on Monday. Those are different from the leaks that we had today."