STS-123 MCC Status
Report #21
(21 March 2008) Astronauts Bob Behnken
and Mike Foreman completed the fourth spacewalk of Endeavour's STS-123 mission
early today.
The duration of the spacewalk was 6 hours 24
minutes, and it was the 108th spacewalk in support of the construction of the
International Space Station.
Behnken and Foreman replaced an electrical
circuit box called a Remote Power Controller Module (RPCM) on the station's
truss. One of the goals of the task was to restore redundant power to control
moment gyroscope (CMG) 2, but the astronauts were unable to remove one of the
connectors from the Z1 truss. CMG-2 will continue to operate on its primary
RPCM until that connector is removed.
The major focus of today's
spacewalk was a demonstration of the Tile Repair Ablator Dispenser - a
caulk-gun-like device - and the application of a substance called Shuttle Tile
Ablator-54 (STA-54) into intentionally damaged heat shield tiles. The
astronauts applied the STA-54 into various moulds, including a few that were
created to resemble damage seen on previous shuttle missions and damaged tiles
from prior flights. The test samples will be returned to Earth to undergo
extensive testing on how STA-54 performs in both a microgravity and vacuum
environment.
Behnken and Foreman also removed a cover from Dextre, the
station's new robotic attachment, and some of the launch locks that were still
attached to the Harmony module. Those locks were removed in preparation for the
arrival of the pressurised Japanese Kibo laboratory aboard Discovery in
May.
Mission managers on the ground are continuing to assess what is
believed to be a software error involving the shoulder roll joint of Dextre.
The shoulder joint had been working properly yesterday, but commands detected
errors as the teams worked through power-up procedures. Both of Dextre's arms
are currently stowed in their proper position.
The next STS-123 status
report will be issued after crew wake-up at 12:28 p.m., or earlier if events
warrant.
(source: NASA)
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