SpaceX plans to attempt for a second time on Thursday to carry out the first test flight of Starship, which is described as the most powerful rocket built, and was manufactured to send astronauts to outer space to the moon and beyond.

A planned liftoff was aborted on Monday, less than 10 minutes ahead of the scheduled launch, because of a pressurization issue in the first-stage booster.

SpaceX announced that the new window for liftoff from Starbase, the SpaceX spaceport in Boca Chica, Texas, opens on Thursday at 8:28 am Central Time (13:28 GMT) and lasts for about an hour.

Elon Musk, the founder of SpaceX, has sought to downplay expectations for the risky inaugural test flight, casting some doubt on whether the launch will take place on Thursday.

He tweeted late Tuesday that "the team is working around the clock on many issues," Musk tweeted late Tuesday. "Maybe 4/20, maybe not."

For the first time since the Apollo program ended in 1972, NASA has chosen the Starship spacecraft to ferry astronauts to the Moon in late 2025 (a mission known as Artemis III).

Starship includes a 50-meter tall spacecraft crafted to carry crew and cargo that sits atop a 230-foot tall first-stage Super Heavy booster rocket. The spaceship and the Super Heavy rocket, collectively known as Starship, have never taken off together, despite the spacecraft's several sub-orbital test flights on its own.

The 33 massive Raptor engines on the first-stage booster were successfully tested by SpaceX in February, and the integrated test flight will evaluate their combined performance.

The launch on Monday was canceled due to a frozen pressure valve on the Super Heavy booster, and SpaceX had to postpone for another attempt in order to recycle the liquid methane and liquid oxygen that powers the rocket.

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Musk had warned ahead of the launch that delays and technical issues were likely. "It's a very risky flight," he said. "It's the first launch of a very complicated, gigantic rocket. 

"There's a million ways this rocket could fail," Musk said. "We're going to be very careful and if we see anything that gives us concern, we'll postpone."