SpaceX Crew Dragon launch preparations in full swing with pre-dawn test firing

Just five hours after a Russian Soyuz capsule brought three space station flyers back to Earth in Kazakhstan, SpaceX test fired the first stage engines of a Falcon 9 rocket in Florida early Saturday to clear the way for Thursday's planned launch of another four station-bound astronauts.

The Falcon 9, carrying a Crew Dragon commercial astronaut ferry ship, was hauled atop the historic 39A launch pad on Friday, a few hours before the rocket's three-man, one-woman crew arrived at the Kennedy Space Center to begin final launch preparations. Following the same timeline that will be in place Thursday, SpaceX engineers loaded the booster with supercold liquid oxygen and RP-1 kerosene rocket fuel and briefly fired up nine first stage Merlin engines at 6:11 a.m. EDT. The "static fire" test is intended to validate prelaunch procedures and verify the readiness of the rocket.