SpaceX Starship launch is canceled

The launch of Starship — the SpaceX rocket that was to have been the largest ever — in Boca Chica, Texas was called off on Monday.

An issue with a pressure valve prevented the rocket taking off, but a “wet dress rehearsal” of the rocket went ahead, with engineers continuing to load propellant into the ship.

Elon Musk tweeted that “a pressurant valve” appeared to be frozen.

Musk had warned that the launch may not proceed as planned, telling a Twitter Spaces event that he’d “like to just set expectations low” that the rocket would depart. “If we get far enough away from the launch pad before something goes wrong, then I think I would consider that to be a success,” Musk added.

Designed by Elon Musk’s SpaceX, the rocket is the largest ever built, outpacing Saturn V, NASA’s Apollo Mission-era rocket.

The rocket measures 394 feet tall and can carry a payload of up to 150 tons. Starship was to complete one revolution around the Earth before falling into the Pacific Ocean near Hawaii 90 minutes later.

Starship is designed to carry as many as 100 passengers, SpaceX says. The intention is to eventually transport people on interplanetary missions: Specifically, Musk plans to send people to Mars. The ship will also be capable of sending gear and materials between Earth and a base on the Moon.

NASA is watching Starship closely, investing billions of dollars into its success. The U.S. space agency has contracted SpaceX to ferry astronauts to the Moon as part of its Artemis IV mission.