September 20, 2011
While anchored to the foot restraint on the Canadarm2, astronaut Dave Williams, STS-118 mission specialist representing the Canadian Space Agency, participates in the mission's second planned session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 6-hour, 28-minute spacewalk, Williams and astronaut Rick Mastracchio (out of frame), mission specialist, removed a faulty control moment gyroscope (CMG-3) and installed a new CMG into the station's Z1 truss. The failed CMG will remain at its temporary stowage location on the station's exterior until it is returned to Earth on a later shuttle mission. The new gyroscope is one of four CMGs that are used to control the station's attitude in orbit.
Topics: Space, Spaceflight, Space exploration, Integrated Truss Structure, Richard Mastracchio, External Stowage Platform, Extra-vehicular activity, Control moment gyroscope, STS-118, International Space Station, Human spaceflight, Dave Williams, Astronaut