SpaceX launched a reduced two-man crew on a flight to the International Space Station Saturday, along with supplies and a pair of empty seats for two Starliner astronauts waiting to hitch a ride home in February after an unexpected eight-and-a-half-month stay in orbit.

The U.S. military’s next GPS navigation satellite moved to a SpaceX launch facility late Thursday at Cape Canaveral, ready for attachment with a Falcon 9 rocket for liftoff June 30 to take the place of an aging GPS spacecraft launched from Florida’s Space Coast more than 20 years ago.

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.