SUBMITTED BY ARTHUR N1ORC - AMSAT A/C #31468

*Mastracchio, Williams Install New Station CMG *

Rick Mastracchio removes failed CMGImage above: Astronaut Rick Mastracchio holds the failed control moment gyro shortly after its removal from the Z1 truss. Image: NASA TV

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STS-118’s second spacewalk is now in the history books. Mission Specialists Dave Williams and Rick Mastracchio successfully installed a new control moment gyroscope (CMG) onto the International Space Station’s Z1 truss during the excursion, which ended at 6 p.m. EDT.

The new CMG replaces a faulty gyroscope, which was removed during the first half of the spacewalk. The new gyroscope is one of four CMGs that are used to control the station’s attitude in orbit.

Before concluding the 6-hour, 28-minute excursion, the orbital duo relocated the faulty CMG to external stowage platform-2, where it will stay until it is returned to Earth on a future shuttle mission.

Mission Specialist Tracy Caldwell served as the spacewalk coordinator, and STS-118 Pilot Charles Hobaugh and Expedition 15 Flight Engineer Clay Anderson operated the station’s robotic arm.

The next spacewalk is scheduled to take place Wednesday. Mastracchio and Anderson will team up to prepare the station’s Port 6 truss for relocation during STS-120. A fourth spacewalk was added to the schedule when STS-118 was extended by three days.

In other activities, crew members continued cargo transfers between Endeavour and the station. Experts on the ground continued to analyze imagery collected Sunday during the STS-118 crew’s focused inspection of five areas of concern on the Endeavour’s heat shield.