SpaceX’s second test flight of their Starship rocket is being postponed to Saturday, Nov. 18, Elon Musk announced.

Musk made the announcement Thursday on his social media platform X, formerly known as Twitter.

“We need to replace a grid fin actuator, so launch is postponed to Saturday,” Musk posted.

The Federal Aviation Administration previously issued its launch license on Wednesday, noting that SpaceX has met safety, environmental and other requirements to launch again.

READ MORE: SpaceX will try again to launch its mega rocket into orbit after first attempt ended in an explosion

SpaceX announced that same day they were targeting a Friday morning launch. The SpaceX website says a 20-minute launch window for Starship's launch opens Saturday at 7 a.m. central.