Video: Expedition 50 spacewalk highlights

Space station commander Chris Cassidy and Robert Behnken floated back outside Tuesday for their fourth spacewalk in less than a month, completing preparations for future upgrades including the eventual installation of an airlock that will allow commercial experiments to be moved into and out of vacuum as required.

Armed with a knife, scissors and other cutting tools, cosmonauts Oleg Kononenko and Sergey Prokopyev went outside the International Space Station on Dec. 11 to slice into the thermal insulation of a Soyuz spaceship and inspect the site of a repaired air leak that briefly caused a minor drop in air pressure in the research outpost earlier this year.

Two astronauts floated outside the International Space Station early Friday for the first of four planned spacewalks to wrap up a complex multi-year job to replace 48 aging batteries in the lab’s solar power system with 24 more powerful lithium-ion units.