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 spacewalkers Dave Williams and Rick Mastracchio installed a new control moment gyroscope (CMG) into the International Space Station’s Z1 truss. They will secure the faulty CMG and equipment before wrapping up the excursion.

The new CMG replaced a faulty gyroscope, which was removed during the first half of the spacewalk. The failed gyro will remain at its temporary stowage location on the station’s exterior before 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.

The excursion began 11:32 a.m. EDT. Mission Specialist Tracy Caldwell is serving as the spacewalk coordinator, and STS-118 Pilot Charles Hobaugh and Expedition 15 Flight Engineer Clay Anderson are operating the station’s robotic arm. The spacewalk is scheduled to wrap up about 6 p.m.

Meanwhile, crew members are transferring cargo between Endeavour and the station. Experts on the ground continue to analyze imagery collected Sunday during the STS-118 crew’s focused inspection of five areas of concern on the Endeavour’s heat shield.