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.

Now in the home stretch of a complex, multi-year upgrade, two space station astronauts floated outside the lab complex Thursday and pressed ahead with the third of four spacewalks the current crew is carrying out to complete the replacement of aging batteries in the station’s solar power system.

A three-person crew heading for the International Space Station took off Wednesday from the Baikonur Cosmodrome in Kazakhstan and arrived in orbit around nine minutes later, beginning a two-day pursuit of the research outpost.