This
story was updated at 9:45 p.m. EDT.
Two
spacewalking astronauts ventured outside the International Space Station
Saturday to set the stage for future construction and prime the outpost for
Japan's first space freighter.
Discovery
shuttle astronauts Steven Swanson and Joseph Acaba pushed through a packed list
of maintenance chores to ease the workload for future
spacewalkers. They started with a trek to the very edge of the station's
port side to loosen bolts the outpost's oldest solar array batteries.
An alarm
rang out as the spacewalkers completed the battery work, but flight controllers
said it meant the orbiting lab's attitude-controlling gyroscopes were
overwhelmed by the work on the end of the station's backbone-like truss, which
is longer
than a football field. Mission Control turned control of the station over
to the shuttle Discovery's thrusters.
"Nothing to
worry about," Mission Control told the spacewalkers.
Later,
an incorrectly stowed metal pin blocked the spacewalkers efforts to set up a
spare parts platform on the station's main truss. The swing-out cargo carrier
was one of two the astronauts hoped to prepare during the spacewalk, but
Mission Control told the spacewalkers to abandon both tasks and tie down the
half-deployed platform for the time being as time ran short.
"Great
job today," said astronaut Richard Arnold II, who choreographed the spacewalk
from inside Discovery. "Sorry for all the changes we threw at you."
Space
station flight director Kwatsi Alibaruho told reporters late Saturday that, despite the platform
glitch, the spacewalkers accomplished the critical chores on their excursion.
Saturday's
6 1/2-hour spacewalk began at 12:51 p.m. EDT (1651 GMT) as the linked space
station and shuttle Discovery flew 220 miles (354 km) above the South Pacific.
The excursion came one day after the astronauts unfurled the space station's last
pair of gleaming solar wings, with Mission Control lauding the work in the Discovery
crew's morning mail.
"[The station] now looks like the artist renderings that
we've been seeing for years," Mission Control wrote. "A day to celebrate!"
It was also
a big day for Acaba, a
former Florida schoolteacher, who made his spacewalking debut.
"Joe,
great seeing you outside," said Arnold, who is also a fellow
teacher-turned-astronaut.
"Thank
you," Acaba called back.
Upgrading space station
During
their orbital work, Swanson and Acaba installed a new global positioning
antenna on the outer hull of the station's Japanese-built Kibo laboratory. The
antenna is one of two that will aid the docking of Japan's first space
freighter when it arrives at the station later this year.
They
also performed the bulk of their planned maintenance on a cable panel, as well
as an infrared camera survey of the space station's radiators, one of which has
been damaged. But they ran out time to finish some of those tasks.
While
working on the station's portside solar array batteries, the spacewalkers
routinely checked to make sure no metal from their spacesuits was exposed as a
safeguard against the remote chance of electrical shocks. Mission managers said
the risk was small and within safety limits, but the extra measure were just a
precaution.
The
spacewalk was the second of three planned during Discovery's mission, with some
of the chores pulled from a planned fourth spacewalk that was later cut from
the flight due to launch delays.
"We
sure appreciate the work you did for our beautiful space station," station
skipper Michael Fincke told the spacewalkers. "You guys proved
flexibility is definitely key."
Mission
managers are now working to replan the third spacewalk on Monday and determine
whether the reattempt the spare parts platform set up work.
NASA
trimmed the spacewalk and a day from Discovery's now 13-day flight in order to
complete the shuttle flight before the arrival of a Russian Soyuz spacecraft
next week carrying new station crewmembers and an American space tourist.
Space urine recycler fix
While
the spacewalkers worked outside, astronauts inside the station tested repairs
to the outpost's urine processer. Astronauts replaced a broken
distillation assembly, which spins like a centrifuge to begin filtering
urine back into drinking water, on Friday.
"You
can see the same good spinning," Fincke told Mission Control during a dry
run of the device. "We could barely hear any change in noise, which is
much different than the last time we did this."
The
urine processor is part of a larger recycling system designed to convert
astronaut urine, sweat and condensation into pure drinking water that can be
used for drinking, food preparation, bathing and oxygen generation.
Saturday's
orbital work marked the 122nd spacewalk dedicated to space station construction
and maintenance. It was the fourth career spacewalk for Swanson, who now has 26
hours and 22 minutes of spacewalking time, and the first for Acaba. Swanson and
Arnold will perform the mission's third spacewalk on for Monday
Discovery
is due to leave the space station on Wednesday after eight days docked at the
space station. The shuttle is due to land on March 28.
SPACE.com
is providing continuous coverage of STS-119 with reporter Clara Moskowitz and
senior editor Tariq Malik in New York. Click here for mission
updates and SPACE.com's live NASA TV video feed.
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