Photos: Atlas 5 rocket soars from West Coast

When the countdown hit zero last Friday and the engines powering a previously flown Falcon 9 first stage roared to life for takeoff, the four astronauts strapped into a SpaceX Crew Dragon some 21 stories up started laughing.

The U.S. Air Force’s ninth Global Positioning System (GPS) 2F satellite, GPS 2F-9, is encapsulated in the Delta 4 rocket’s four-meter-diameter nose cone at a processing facility and then moved to the launch pad at Complex 37 for mating to its booster inside the mobile service tower.

These narrated videos show the pre-launch preparations that readied the United Launch Alliance Atlas 5 rocket and the Orbital ATK Cygnus commercial cargo-delivery spacecraft for flight and rolling to Complex 41 for liftoff to the International Space Station.