Astronauts Replace Nitrogen Tank on International Space Station

In this image, courtesy of NASA, astronaut Hans Schlegel works on the International Space Station earlier this week. In the darkness of space , European Space Agency astronaut Hans Schlegel participates in the mission’s second spacewalk as construction and maintenance continue on the International Space Station. During the six-hour, 45-minute spacewalk, Schlegel and NASA astronaut Rex Walheim (out of frame) worked to replace a nitrogen tank used to pressurize the station’s ammonia cooling system.