SpaceX scrubbed the launch of a relief crew on Wednesday night, delaying the handoff for NASA astronauts who have been awaiting a return trip to Earth.

NASA and SpaceX anticipate astronauts Williams, Wilmore, Nick Hague, and Aleksandr Gorbunov will depart the space station Wednesday. Williams previously spoke last month to NASA about what it will feel like physically when that space flight comes to an end.