HOUSTON - Astronauts aboard NASA's shuttle
Discovery will take a few hours off Monday after some delicate robotic arm work
to move a massive girder outside the International Space Station (ISS), while
engineers on Earth study contamination in one of the orbital laboratory's solar
array-turning joints.
Working together
with the station's Expedition 16 crew, Discovery's STS-120 astronauts were handing
off the 17.5-ton Port 6 (P6) solar array truss segment between their two
spacecraft's robotic arms to position it for installation on the port edge of
the orbital laboratory's main truss during a Tuesday spacewalk.
Reattaching
the port side girder and unfurling its two wing-like solar arrays successfully is
even more vital after a spacewalker discovered what appeared to be metal
shavings inside a 10-foot (three-meter) wide joint designed to rotate
the space station's starboard solar arrays like a paddlewheel to track the Sun.
ISS
Expedition 16 commander Peggy Whitson tested samples of the shavings early
Monday, finding them to be magnetic.
"It's
definitely ferrous," Whitson told Mission Control.
Expedition
16 flight engineer Daniel Tani collected the samples from inside the station's
starboard Solar Alpha Rotary Joint (SARJ) during
a Sunday spacewalk. Astronauts installed the joint at the ISS last June,
but over the last 50 days it has exhibited slight current spikes and vibrations
suggesting added friction as it rotated its solar arrays.
ISS flight
controllers have parked the station's starboard solar arrays in a fixed
position that should generate adequate power while Discovery remains docked at
the space station through Nov. 4. Mission managers also plan to send astronaut
Scott Parazynski out to a similar solar array-turning joint on the space
station's port side, which has been working properly since its September 2006 installation,
during Tuesday's spacewalk.
Mike
Suffredini, NASA's ISS program manager, said that inspecting the port joint
will give engineers a baseline against which they can measure the starboard
joint's contamination. If Tuesday's P6 solar array relocation goes as planned
and the starboard solar wing can be adjusted in optimum Sun-catching
positions periodically, the station will be in a good power configuration to
support the planned December arrival of the European Space Agency's Columbus laboratory, he added.
But a
definitive plan to either clean up the starboard joint contamination or conduct
lengthy repairs using spare parts already in orbit will have to wait until
after Discovery's current
STS-120 construction flight, which NASA has called its most ambitious to
date. In addition to moving the seven-year-old P6 truss from its central
mast-like perch atop the ISS to the station's port side, Discovery's crew has
also swapped out one Expedition 16 crewmember and delivered the new
connecting node Harmony to the orbital laboratory.
"For this
mission, we don't really think we'll be able to have time to come up with a plan
to do any serious troubleshooting," ISS flight director Heather Rarick said
late Sunday. "We'll probably do some more inspections though, so we are leaving
some of our options open to get some more inspection time."
Astronauts aboard
Discovery and the ISS also watched early Monday as flight controllers on Earth commanded
a pair of starboard radiators to unfold and join a third one already deployed
from the station's Starboard 1 (S1) truss. Shuttle commander Pamela Melroy, who
helped install the S1 truss on a previous spaceflight, said the girder looked
great "with all its flags flying."
NASA roused
Discovery's crew with the song "One by One" performed by Wynton Marsalis and
selected for Discovery astronaut Stephanie Wilson, the crew's lead robotic arm
operator.
"Space is
certainly a special to be," Wilson said. "I'd like to thank my parents, Barbara
and Gene, for that song. I love them very much and I couldn't do this mission,
or anything that I've done in my life, without their love and their support."
Wilson, a Boston native, received some welcome news from Mission Control when she learned her
beloved Red Sox won the World Series Sunday night.
"Woooo!"
she exclaimed. "That's great news!"
NASA is broadcasting
Discovery's STS-120 mission operations live on NASA TV. Click here for mission updates
and NASA TV from SPACE.com.
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