Crew Dragon astronauts Douglas Hurley and Robert Behnken thanked their space station crewmates for a productive two-month visit, readied their SpaceX capsule for departure and stood by for a final “go” from flight controllers to undock Saturday night, setting up a Gulf of Mexico splashdown Sunday afternoon.

Fueled segments of the solid rocket boosters that will lift off on the first flight of NASA’s Space Launch System have arrived at the Kennedy Space Center in Florida, but officials will hold off on stacking the boosters until the SLS core stage completes a crucial test-firing later this year.

Four days after a Soyuz ferry craft brought three space station fliers down to a frigid landing in Kazakhstan, three fresh crew members are poised for launch early Tuesday from the Baikonur Cosmodrome to boost the lab’s crew back to six.