After a mechanical issue forced a halt to the countdown, SpaceX postponed the Starship's first test flight for Thursday. 

A planned liftoff, that was set for Monday morning, of the giant rocket was called off less than 10 minutes ahead of the scheduled launch because of a pressurization issue in the first-stage booster, SpaceX said.

The private space company resumed with the countdown in what it called a "wet dress rehearsal," stopping the clock with 10 seconds to go, just before the massive engines on the booster were to have been ignited.

Commenting on the unsuccessful test flight, SpaceX founder Elon Musk said a frozen pressure valve forced a scrub of the launch, which had been planned for 8:20 am Central Time (13:20 GMT) from Starbase, the SpaceX spaceport in Boca Chica, Texas.

"Learned a lot today, now offloading propellant, retrying in a few days," Musk tweeted.

Before announcing Thursday as the new liftoff date, SpaceX had previously stated that the first flight will be postponed for at least 48 hours in order to recycle the liquid methane and liquid oxygen that power the rocket. 

The new launch window opens Thursday at 8:28 am Central Time (13:28 GMT) and will last 62 minutes, as per SpaceX.

Here's what you need to know

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.

Approximately three minutes after launch, if everything goes as planned, the rocket will separate from Starship and splash down in the Gulf of Mexico.

The six-engined Starship will continue to ascend to a height of close to 150 miles before making a nearly complete rotation of the planet and splashing down in the Pacific Ocean roughly 90 minutes after launch.

'Objective is to establish bases on the Moon and Mars'

SpaceX held a successful test-firing of the 33 Raptor engines on the first-stage booster of Starship back in February. During the test-firing, also known as a static fire, the rocket was attached to the ground to stop it from taking off.

In November 2024, NASA will send astronauts to the moon on its own, using the Space Launch System (SLS), a hefty rocket that has been in development for more than ten years that has more than twice as much thrust as the Saturn V rockets used to launch the Apollo astronauts to the Moon, and produces 17 million pounds of thrust.

In the future, SpaceX plans to launch a Starship into orbit, refuel it with another Starship, and then send it on its way to Mars or beyond. Musk said the goal is to make Starship reusable and bring down the price to a few million dollars per flight.

"In the long run -- long run meaning, I don't know, two or three years -- we should achieve full and rapid reusability," he said. The eventual objective is to establish bases on the Moon and Mars and put humans on the "path to being a multi-planet civilization," Musk said.

"We are at this brief moment in civilization where it is possible to become a multi-planet species," he said. "That's our goal. I think we've got a chance."

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