Construction continues on the International Space Station. Astronaut Rick Mastracchio of the space shuttle Endeavour participates in STS-118's first planned session of extravehicular activity (EVA). During the 6-hour, 17-minute spacewalk Mastracchio and Canadian Space Agency's Dave Williams (out of frame) attached the Starboard 5 segment of the station's truss and retracted the forward heat-rejecting radiator from the station's Port 6 truss.