Video: Expedition 50 spacewalk highlights

Astronauts Jeff Williams and Kate Rubins ventured 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.

Two Russian cosmonauts stepped outside the International Space Station Wednesday, sent birthday greetings to former cosmonaut Alexey Leonov, the first man to walk in space, and then carried out a full slate of maintenance work.

For the second time in less than a week, astronauts will leave their quarters inside the International Space Station on Thursday to outfit a relocated docking adapter to eventually receive Boeing and SpaceX commercial crew capsules.