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| Image above: Astronaut Rick Mastracchio holds the
failed control moment gyro shortly after its removal from the Z1 truss.
Image: NASA TV |
STS-118 spacewalkers Dave Williams and Rick Mastracchio, KC5ZTE,
are rolling along with the replacement of a faulty attitude control device
on the International Space Station.
They have removed the faulty device, called a control moment gyro (CMG),
from the Z1 truss. The Z1 houses four CMGs that are used to maintain the
station orientation in space.
The next step is the installation of the new gyro, which traveled to
the station in Space Shuttle Endeavour’s payload bay. The failed
CMG will remain at its temporary stowage location on the station’s
exterior before it returns to Earth on a later shuttle mission.
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, KD5PLA,
are operating the station’s robotic arm. The spacewalk is timelined
to wrap up at 6:02 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.
Managers Add Three Days to Shuttle Mission
Mission managers decided Sunday to extend the STS-118 mission by three
days. The decision came after the successful operation of the new Station-to-Shuttle
Power Transfer System (SSPTS).
Endeavour is now scheduled to undock from the International Space Station
on Aug. 20 and land Aug. 22. In addition to the extra time at the orbital
outpost, managers added a fourth spacewalk that is scheduled to take place
Aug. 17.
The SSPTS reroutes power from the space station to the shuttle during
docked operations, allowing the orbiter to conserve materials needed to
generate power and spend more time in space.
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