Starship is scheduled to blast off for the first time on Monday, but SpaceX CEO Elon Musk warned people not to get their hopes up for a successful launch.
During a Twitter Spaces session on Sunday, Musk said there was a high chance SpaceX would abort and postpone the launch from its Starbase facility near Brownsville, Texas.
His biggest concern was that a "fireball" incident could melt the launchpad if one of the engines failed. Musk said such an incident would melt the steel and destroy the area where the rocket took off. He said this would be a "very bad day."
Musk said it would take SpaceX several months to rebuild the launchpad if Starship exploded and melted it.
He previously said in an interview at a Morgan Stanley conference in March that if this rocket — made up of Ship 24 and Booster 7 — were to explode, other Starships could be waiting in the wings.
Any other problem that doesn't damage the launchpad post-launch is considered a win, he added.
"I'd like to set expectations low," he said. "If we get far enough away from the launchpad before something goes wrong, I think I would consider that a success. Just don't blow up the launchpad."
Launching the enormous Starship is an engineering feat
The billionaire said Starship, which is set to fly to the moon and Mars, is a "very complicated, gigantic rocket" and the largest space vehicle ever made.
"It may take us a few kicks of the can here before we reach orbit," he said.
A failed launch on Monday doesn't mean it would be the end for Starship. Speaking to Insider in February, Olivier de Weck, a professor of aeronautics, said: "Let's keep in mind that this is just one test out of hundreds. And if anything, SpaceX has shown us that they learn a lot from failures."
The Federal Aviation Administration on Friday gave SpaceX a launch license to fly Starship to orbit. Following the license, SpaceX tweeted it was projecting to launch Starship as soon as Monday.
But Musk has previously been skeptical about Starship launching successfully for the first time.
During an interview at the Morgan Stanley Conference in March, Musk said Starship had "a 50% chance of reaching orbit" but added that he was "guaranteeing excitement" and it wouldn't be boring.
Musk said in March, however, that even if Ship 24 didn't make it, the prospect of another Starship successfully launching within the year was substantially higher, at about 80%.
