STARBASE: A frozen valve forced a postponement on Monday of the first test flight of SpaceX’s Starship, the most powerful rocket ever built, designed to send astronauts to the Moon, Mars and beyond.

Liftoff of the gigantic 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 continued 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.

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 (1320 GMT) from Starbase, the SpaceX spaceport in Boca Chica, Texas.