A SpaceX Falcon 9 rocket is standing more than 20 stories tall on pad 40 at Cape Canaveral Space Force Station, ready for blastoff with the Turksat 5A communications satellite.

SpaceX’s next Falcon 9 rocket launch, using a previously-flown first stage booster, took a step closer to liftoff Thursday with a countdown rehearsal culminating in ignition of the launcher’s nine Merlin main engines in a hold-down firing at pad 39A at NASA’s Kennedy Space Center in Florida.

Two days after blasting off from Kazakhstan, three new crew members docked with the International Space Station early Saturday to begin nearly four months of scientific experiments and maintenance on the orbiting research outpost. The Soyuz spacecraft linked up with the space station’s Rassvet module at 12:06 a.m. EDT (0406 GMT).