WATCH LIVE: NASA spacewalk

Astronauts Jeff Williams and Kate Rubins venture outside the lab complex Friday for a long-awaited spacewalk to attach a new docking mechanism, the first of two that will be used by U.S. crew ferry ships being built by Boeing and SpaceX to carry astronauts to and from the outpost, ending NASA’s sole reliance on Russian Soyuz spacecraft.The Boeing-built International Docking Adapter, or IDA, was delivered to the station in July aboard a SpaceX Dragon cargo ship. Williams and Rubins plan to