SpaceX's Falcon 9 rocket blasted off shortly after 1 a.m. Saturday from the Kennedy Space Center in Florida, carrying four astronauts

The replacements for NASA’s two stuck astronauts launched to the International Space Station on Friday night, paving the way for the pair’s return after nine long months. Butch Wilmore and Suni Williams need SpaceX to get this relief team to the space station before they can check out.

The Falcon 9 rocket is carrying four astronauts who will replace Wilmore and Williams, both of whom are veteran NASA astronauts and retired U.S. Navy test pilots and were the first to fly Boeing's faulty Starliner capsule to the ISS in June.