Without FAA approval, Starship will not be leaving the ground any time soon.
The FAA said: “While we recognize the importance of moving quickly to foster growth and innovation in commercial space, the FAA will not compromise its responsibility to protect public safety.
“We will approve the modification only after we are satisfied that SpaceX has taken the necessary steps to comply with regulatory requirements.”
Mr Musk responded to Thursday’s scrub with harsh criticism of the FAA.
He tweeted: “Unlike its aircraft division, which is fine, the FAA space division has a fundamentally broken regulatory structure.