NASA canceled the launch of its powerful new moon rocket on its maiden flight with three test dummies on board Monday after encountering a cascade of last-minute problems culminating in unexplained problems involving an engine.

The next launch attempt won’t be until Friday at the earliest and could be delayed until mid-September or later.

The mission will be the first flight of NASA’s Project Artemis, a quest to put astronauts back on the moon for the first time since the Apollo program ended 50 years ago.

As precious minutes passed Monday morning, NASA repeatedly shut down and restarted refueling of the Space Launch System rocket due to a leak of high-explosive hydrogen, ultimately managing to reduce the seepage to acceptable levels. The leak happened at the same location that saw seepage during a dress rehearsal in the spring.

Refueling was already nearly an hour late due to thunderstorms off Kennedy Space Center in Florida.

Then NASA encountered further problems when it was unable to properly cool one of the rocket’s four main engines, officials said. Engineers continued to work to identify the source of the problem after the announcement of the launch delay.

“It’s a very complicated machine, a very complicated system, and all of these things have to work, and you don’t want to light the candle until it’s ready to go,” the NASA administrator said. , Bill Nelson.

Referring to launch delays, he said: “It’s just part of the space business and it’s part, in particular, of a test flight.”

The rocket was to lift off on a flight to propel a crew capsule into orbit around the moon. The six-week mission was to end with the capsule returning to Earth during a dive in the Pacific in October.

The 322-foot (98-meter) spacecraft is the most powerful rocket NASA has ever built, even surpassing the Saturn V that took Apollo astronauts to the moon.

Mannequins inside the Orion capsule were fitted with sensors to measure vibrations, cosmic radiation and other conditions during the shakedown flight, intended to test the spacecraft and push it to its limits in a way which would never be attempted if humans were on board.

As for when NASA might make another liftoff attempt, launch commentator Derrol Nail said engineers were still analyzing the engine problem and “we have to wait to see what comes out of their test data.”

Although no one was on board, thousands of people lined the coast to watch the rocket take off. Vice President Kamala Harris and Apollo 10 astronaut Tom Stafford were among the VIPs who arrived.

Assuming the shakedown flight goes well, astronauts will board for the second Artemis mission and fly around the moon and back as soon as 2024. A two-person lunar landing could follow by the end of 2025.

The problems seen Monday were reminiscent of the era of NASA’s space shuttle, when hydrogen leaks interrupted countdowns and delayed a series of launches in 1990.

Later that morning, NASA officials also spotted what they feared was a crack or other flaw in the main stage – the big orange fuel tank with four main engines on it – but said more. late that it appeared to be just a buildup of frost in a crevice of the foam insulation.

Launch director Charlie Blackwell-Thompson and his team also had to deal with a communication problem involving the Orion capsule.

Engineers raced to figure out an 11-minute delay in communication lines between launch control and Orion that occurred Sunday night. Although the issue was resolved Monday morning, NASA needed to know why it happened before committing to a launch.

Regardless of all the technical problems, the thunderstorms would have ultimately prevented a takeoff. Dark clouds gathered over the launch site as soon as Blackwell-Thompson interrupted the countdown, thunder echoing off the coast.