Dramatic Spacewalk in Progress

Image of Expedition 24 Flight Engineers Doug Wheelock (foreground) and Tracy Caldwell Dyson working on the International Space Station's S1 Truss during the first of two spacewalks to replace a failed ammonia pump module. Credit: NASA TV A pair of space station astronauts ventured out on an urgent spacewalk this morning to restore a crucial cooling system - one of the most challenging repairs ever attempted at the orbiting lab. According to NASA, Expedition 24 Flight Engineers Doug Wheelock...