Live coverage: Falcon 9 disintegrates after launch

The four astronauts will spend three to five days in a free-flier Dragon mission that will see them orbit over the north and south poles. The crew arrived in Florida on Monday for their final week of quarantine before launch.

Ground crews plan to load the final cargo into SpaceX’s Dragon supply ship Saturday after the capsule’s Falcon 9 rocket booster briefly fired up on the launch pad at Cape Canaveral for a flight readiness check.

SpaceX engineers ran through a customary prelaunch countdown test Saturday and fired the Falcon 9 rocket’s nine Merlin main engines at Cape Canaveral ahead of liftoff Monday with 2.2 tons of supplies and experiments for the International Space Station.