VIDEO: Expedition 42-43 mission preview

Astronauts Barry “Butch” Wilmore and Terry Virts floated outside the International Space Station Wednesday for the second of three spacewalks to help ready the complex for dockings by commercial crew capsules. Back inside the station’s airlock, Virts reported a small amount of water in his space helmet, but officials said he was not in any danger.

A European supply freighter is set to undock from the International Space Station on Saturday, heading for a destructive dive into Earth’s atmosphere about 30 hours later after a power system failure forced the cancellation of an experiment to observe the dynamics of the re-entry of a large spacecraft.

Concern about a possible ammonia coolant leak Wednesday prompted astronauts on the International Space Station to evacuate the U.S. segment of the complex and shelter in the Russian portion of the outpost while flight controllers scrambled to untangle initially confusing telemetry.