HOUSTON -- Two shuttle astronauts are poised to step
outside the International
Space Station (ISS) later today in an extra spacewalk aimed at furling a
finicky solar array.
Discovery's
STS-116 spacewalkers Robert
Curbeam and Christer
Fuglesang are due to start climbing the space station at 2:17 p.m. EST
(1917 GMT) to reach the peak of its mast-like
Port 6 (P6) truss which harbors the troublesome solar wing.
"I have a
pretty good feeling that we've got a good chance of success," Curbeam told the Associated
Press TV Sunday in an interview broadcast on NASA TV.
With
Curbeam perched at the tip of the station's robotic arm and Fuglesang floating
free, the duo plan to poke and prod a partially-furled
solar array until its two "blankets" are tucked neatly away in their storage
boxes. NASA flight controllers hope the singular task will require little or
none of the strong-arm shaking performed
in a Saturday spacewalk [image].
"We are
going to try it with a little more finesse," said Tricia Mack, NASA's lead extravehicular
activity (EVA) officer for Discovery's
STS-116 mission, in a status briefing Sunday.
Curbeam
will serve as a solar array surgeon of sorts, with Fuglesang handing him pliers,
a scraper or a hooked tool--some rigged together and all wrapped in translucent
orange Kapton tape--as needed to alternately poke on hinges or tug on guide
wires to loose snares during the folding process [image].
Astronauts inside the ISS and
Discovery will issue the commands that remotely retract the 115-foot (35-meter)
solar wing. Shuttle pilot William
Oefelein will choreograph today's spacewalk while his crewmates Joan
Higginbotham and Sunita
Williams wield the ISS robotic arm.
"We really
want the entire array in the blanket box at the end of this EVA," Mack said,
adding that a spaceworthy scraper tool wrapped in tape is expected to be the
tool of choice to free the guide wires [image].
Today's
spacewalk, which is slated to run no longer than six and one half hours but may
take less than five, will be the fourth of Discovery's STS-116 spaceflight. Mission managers added it to the schedule late Saturday during a previous EVA in order to
fold the P6 array without impacting later ISS or shuttle missions.
Solar
array shakes and folds
The beleaguered
ISS solar array extends over the station's port side and is one of two atop the
P6 truss that must be retracted before the massive segment can be moved to its
final location next year.
Discovery
and ISS astronauts attempted
to furl the six-year-old array last week, but encountered folding problems when
guide wires jammed as they passed through grommets along some metal hinges of
the 115-foot (35-meter) solar wing's individual panels [image].
At just over half-folded, the array was stowed enough to allow a pair of newer solar
wings on the port side the station to rotate and track the Sun.
"Right now,
we're in a pretty good configuration and we're getting good power," Higginbotham
told television reporters Sunday, adding that the extra spacewalk added a
welcome extra day in space for herself and her crewmates. "So if the solar
array is not fully retracted, we're still good. But of course, we'd all like to
get it fully retracted."
NASA mission managers were also concerned
that future maneuvers, such as spacecraft engine firings to boost the space
station's orbit from vehicles at certain docking ports, could damage or even
break the solar array's mast in its half-furled configuration [image].
A
spacewalking first
Curbeam
will make a bit of NASA history today as he sets a new space agency record for
the most spacewalks performed by a single astronaut during shuttle mission.
"Well, I
didn't know it was a record, but I feel great," Curbeam told television
reporters Sunday. "I'll just have to treat it like any other spacewalk."
A veteran
spaceflyer with six EVAs and three shuttle missions under his belt, Curbeam has
served as the chief STS-116 spacewalker. He lead each of the three mission's
spacewalks to first install
the new Port 5 (P5) truss segment on the space station's port side, and
then rewire
the orbital laboratory's power grid and ultimately shake
its finicky P6 solar array.
"Beamer is
a pretty cool customer, I'm sure he'll be ready for tomorrow's EVA," Mack said
Sunday, referring to Curbeam by his nickname.
Today's
spacewalk will also mark the third for Fuglesang, a European Space Agency
astronaut and Sweden's first spaceflyer, who is making his first spaceflight
during the STS-116 mission.
Mack said
that before the solar array spacewalking tasks, the P6 truss extending above
the ISS was the only region of the space station Curbeam was not slated to
visit. Over the course of three spacewalks, Curbeam ascended the ranks to move
from 22nd to 13th on the list of most spacewalking time.
"He is just
a machine," Mack said. "He is an EVA machine."
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