SpaceX postpones launch to switch astronauts at the International Space Station.

SpaceX had to delay a mission to the International Space Station because of a problem with the launch pad. This mission is important because it will bring new astronauts to replace two who have been in space for a long time.

Butch Wilmore and Suni Williams have been living on the space station for nine months and are ready to come back to Earth. The new crew was supposed to launch on a SpaceX rocket, but there was an issue with the system that helps the rocket lift off.

Engineers were worried about a part called the hydraulic system, which helps move the rocket's arms. These arms hold the rocket in place and need to move out of the way for a safe launch.

The astronauts were already sitting in their capsule, waiting to launch, when the decision to delay was made. SpaceX now plans to try launching the mission again on Friday at the earliest.

The new crew includes astronauts from the United States, Japan, and Russia. They will take over the work on the space station from Wilmore and Williams, who had to stay longer than planned due to problems with a different spacecraft.