Takeoff was slated for Wednesday evening from Kennedy Space Center in Florida, but the company waived off the launch attempt because of an issue with the launchpad’s ground system. The problem stemmed from a hydraulics system used to control one of two clamps that hold on to the upper portion of the rocket as it sits vertically on the ground pad before launch.

SpaceX launch scheduled for Wednesday will carry replacement crew for astronauts who have been stuck on the International Space Station since their troubled Starliner mission.