By Jackie Wattles, CNN


By Jackie Wattles, CNN

(CNN) — SpaceX's Starship, the most powerful rocket ever built, was left grounded on its launch pad in South Texas on Monday morning because of a technical issue, delaying the vehicle's historic first launch attempt.

The massive Super Heavy rocket booster, which houses 33 engines, was expected to roar to life and vault the Starship spacecraft off its ground pad, which lies within SpaceX facilities on the coast of South Texas, sending the vehicle soaring out over the Gulf of Mexico.

But the launch was called off due to what the SpaceX broadcast said was a pressurization issue.

"A pressurant valve appears to be frozen, so unless it starts operating soon, no launch today," SpaceX CEO Elon Musk tweeted.

SpaceX could attempt the mission again in 48 hours.


The team continued to execute some launch operations and kept the countdown clock going in a practice run referred to as a "wet dress rehearsal," even after making the decision to wave off the launch attempt. They ultimately paused the countdown clock with 40 seconds left.

If the company were to move forward with liftoff, mission controllers would give the rocket a final "go" for launch at T-30 seconds, according to SpaceX principal integration engineer John Insprucker.

Starship's mission

When launch does occur, the Super Heavy booster is expected to expend its fuel about two and a half minutes after liftoff and separate from the Starship spacecraft, leaving the booster to be discarded in the ocean. The Starship will use its own engines, blazing for more than six minutes, to propel itself to nearly orbital speeds.

The vehicle will then complete nearly one full lap of the planet, reentering the Earth's atmosphere near Hawaii. It's expected to splash down off the coast about an hour and a half after liftoff.

The test flight comes after years of explosive tests, regulatory hurdles and public hyping from SpaceX CEO Elon Musk.

In the lead-up to Monday's liftoff, Musk sought to temper expectations, saying, "Success is not what should be expected...That would be insane."

He added that if the Super Heavy booster were to explode on the launch pad, it could melt the steel infrastructure surrounding it, and SpaceX would have to spend a few months rebuilding the launch site.

"If we get far enough away from launch pad before something goes wrong, then I think I would consider that to be a success," Musk said during a Twitter "Spaces" event on Sunday. "Just don't blow up the pad."

SpaceX officials are expected to provide an update in the coming hours regarding when the next launch attempt will take place.

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