WASHINGTON
-- Two NASA astronauts kicked off
the first of four tightly-packed
spacewalks outside the International Space
Station (ISS) Wednesday by carefully overhauling
part of the orbital laboratory's cooling system despite the last-minute find of
a few toxic ammonia flakes.
ISS
Expedition 14 commander Michael
Lopez-Alegria and flight engineer Sunita
Williams successfully switched four liquid ammonia coolant lines from a
temporary set up to their permanent configuration during almost eight hours of
spacewalking work high above the Earth
[image].
The work
was slow and demanding, but paid off as Lopez-Alegria and Williams activating
the new cooling loop near the midpoint of the seven-hour, 55-minute spacewalk [video].
The only
hint of leaking ammonia occurred near the end of the spacewalk, when Williams
reported about four small "flakes" of frozen, yet toxic, ammonia drifting out
of a fluid line cap during a completely different task.
"Whoa,"
Williams said, adding that the coolant did not appear to contaminate her Lopez-Alegria's
spacesuit. "I am pretty positive that it didn't get in any contact with his
spacesuit."
Ammonia
contamination has been a concern since
2001, when a cloud of frozen ammonia flakes bloomed around NASA astronaut Robert
Curbeam as he too handled
ISS cooling system lines.
"At very
low levels it could be an irritant," Derek Hassman, NASA's lead Expedition 14
flight director in a post-spacewalk briefing, of ammonia coolant, adding that
higher levels could have more serious effects. "It can have a significant
impact on the crew's respiratory function."
But unlike the
2001 incident, where contamination was known and required extreme cleanup
measures, today's ammonia sighting fell under "suspected contamination" and
called for only minor preventative steps, NASA
officials said, adding that all tests were negative for ammonia contamination.
"We didn't
introduce any ammonia into the airlock or into the habitable region of the
space station," Hassman said.
Lopez-Alegria
later described the flakes as rectangular and narrow, adding that a bit of
plastic he saw earlier in the cooling line work may indeed have been bit of
frozen ammonia.
The
spacewalk, Lopez-Alegria's seventh career extravehicular activity (EVA), marked
the first of an unprecedented three excursions in nine days (and four overall
in the coming month) for an ISS crew. It is the most densely packed series of
spacewalks to date for space station astronauts outside of a visiting space shuttle mission.
The EVA
marked Williams' second career spacewalk.
Wrangling
cooling lines
The
spacewalk began at 10:14 a.m. EST (1514 GMT) as the ISS passed 220 miles (354
kilometers) over the South Atlantic. Expedition 14 flight engineer Mikhail
Tyurin, who remained inside the ISS during the spacewalk, helped his
crewmates don and doff their spacesuits and watched over the station's systems
[image].
"Beautiful,"
said Lopez-Alegria as he and Williams began their spacewalk. "Looks like just a
little bit of a circular storm down there."
During
their cooling system overhaul, Lopez-Alegria and Williams rerouted ammonia
cooling lines from their temporary track through the space station's mast-like
Port 6 truss into a final setup that runs through a series of heat
exchangers in the outpost's U.S.
Destiny laboratory [image].
"It was
worth it taking our time," Lopez-Alegria said. "We ran into a few things, but
it's all good."
The work is
vital to prepare the station's power and cooling systems to handle future
international laboratories. It also helps to ready the station's Port 6 truss
for its relocation to the edge of the orbital lab's port truss segment in a September
shuttle mission.
The
astronauts primarily handled the station's Loop A cooling lines, which
transport heat away from the Destiny module's environmental control systems and
experiment hardware. But it was hard work, especially on the astronauts' hands.
NASA commentator Rob Navias likened the activity to working on your car engine
while clad in a snowsuit and gloved hands.
"My hands
are toast," Lopez-Alegria said near the spacewalk's end.
The
station's Loop B cooling system, which oversees station payloads and flight
avionics, will be reconfigured in a mirror image of today's spacewalk set for
Feb. 4.
In addition
to their cooling system work outside the ISS, the Expedition 14 astronauts also
primed a pair of cables to help transfer power between the ISS and NASA
shuttles during future missions. They also secured a defunct ISS radiator -- no
longer needed after today's cooling system overhaul -- and stripped one of two
fluid lines from an unneeded ammonia coolant reservoir [image].
Lopez-Alegria
and Williams ultimately ran out of time and were unable to complete a laundry
list of extra chores set aside for them, but they or future spacewalkers will
have the opportunity.
Glenda
Laws, NASA's lead Expedition 14 spacewalk officer, said the extra tasks --
known as get aheads -- could be added to one or both of the next ISS
spacewalks, but completing the cooling system overhaul remains a priority.
Wednesday's
spacewalk marked the 78th EVA dedicated to ISS assembly, the 50th
staged from the orbital laboratory itself, and the 30th to begin at
the outpost's U.S. Quest airlock.
The
spacewalk also pushed Lopez-Alegria to the rank of fourth all-time spacewalker
(up from 13th), with a total EVA time of 47 hours and 31 minutes.
Williams, for her part, is now the second all-time female spacewalker with 15
hours and 26 minutes.
The second
of the upcoming four Expedition 14 spacewalks is scheduled begin at 8:30 am. EST
(1330 GMT) on Sunday, Feb. 4, and will be broadcast live on NASA TV.
advertisement
