Two NASA astronauts are poised to step
outside the International
Space Station (ISS) later today to make what will be the first of a series
of spacewalks to overhaul the orbital laboratory's cooling system.
Clad in
U.S. spacesuits, ISS Expedition 14 commander
Michael Lopez-Alegria and flight
engineer Sunita Williams are expected to spend more than six hours outside switching
half of the cooling lines servicing the space station's Destiny
laboratory into their permanent configuration [video].
"I can tell
you that the crew is focused," said Derek Hassman, NASA's lead ISS flight
director for the extravehicular activity (EVA). "They're very well prepared."
The
spacewalk is due to begin at 10:00 a.m. EST (1500 GMT), with Lopez-Alegria in a
red-striped spacesuit while Williams dons an all-white suit. Russian
cosmonaut Mikhail Tyurin, a fellow Expedition 14 flight engineer, will help
his crewmates don and doff their spacesuits for today's EVA.
Because of
their staggered arrival to the ISS, Lopez-Alegria and Williams have not
rehearsed today's spacewalk together in its entirety since July 2006, said
Hassman. Lopez-Alegria launched
to the ISS in September while Williams arrived
during last month's STS-116
shuttle mission, but both have spent the last few weeks studying up and
practicing elements in simulations aboard the ISS, he added.
During
their primary tasks in today's spacewalk, Lopez-Alegria and Williams will work
at a site on the space station's central Z1 truss -- known as the "Rat's Nest" --
that serves as a sort of hub for electrical and thermal control lines [image].
"It's full of cables and
fluid lines, a really tight space full of all kinds of things that you can get
hung up on," NASA's lead Expedition 14 spacewalk officer Glenda Laws said of the
worksite.
Once there,
Lopez-Alegria and Williams will unplug one of two ammonia-fed cooling loops
from a temporary set up in 2001, when previous spacewalkers installed the
Destiny lab, and then reattach them into a permanent configuration on the space
station's backbone-like main truss.
Space shuttle astronauts
activated the station's primary cooling system in December during the STS-116
mission.
"You can
think of it as a continuation of the work that the [STS-116] crew did on their
mission," Hassman said of today's spacewalk and the next few EVAs.
Today's
spacewalk is the first of three aimed primarily at revamping the space station's
cooling system, a vital part of NASA's plan to complete assembly of the ISS by
2010.
An
additional Expedition 14 EVA is scheduled for Feb. 4 to complete the cooling
system work. A third is set for Feb. 8 to be followed by a fourth,
Russian-controlled spacewalk slated for Feb. 22 to complete the densest series
of EVAs planned for ISS astronauts without a visiting space shuttle crew.
The Expedition
14 spacewalkers are trained to perform emergency decontamination and clean up procedures
in the event a toxic ammonia leak akin to that which
occurred when the Destiny module's cooling lines were first installed during
NASA's STS-98
mission in 2001.
"That's a
contingency that we've worked and we've planned for," Hassman said. "We feel that
we're ready to address it if it does come."
Laws said
Lopez-Alegria and Williams do have a series of additional construction and maintenance
tasks on tap for today's spacewalk, as well as some spare chores should they
have extra time.
"We do
expect them to finish early," Laws said.
The first
of the upcoming four Expedition 14 spacewalks is scheduled begin at 10:00 am.
EST (1500 GMT) on Wednesday, Jan. 31 and will be broadcast live on NASA TV.
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