This story was updated at 3:09 a.m. EDT.
Two spacewalking astronauts tackled
a tough coolant tank swap at the International Space Station late Thursday, one
that required them to move hefty components as massive as small cars.
Astronauts Danny Olivas and Christer
Fuglesang spent about 6 1/2 hours working outside the space station to install
the new tank full of ammonia coolant and stow
an old one aboard their shuttle Discovery.
The spacewalk occurred as a large
piece of space
junk - part of a 3-year-old European rocket - headed toward the station and
shuttle, but the derelict object posed no
collision risk at all to the two spacecraft and their crews, NASA officials
said. The orbital debris is expected to make its closest approach to the
station and shuttle Friday morning.
Minor spacesuit glitches delayed Thursday
night's spacewalk by nearly an hour, but the astronauts made up for lost time
and eventually got well ahead of schedule. They began the planned 6 1/2-hour
spacewalk at 6:12 p.m. EDT (2212 GMT) as the station and shuttle flew 225 miles
(362 km) above China.
"That was a beautiful sunrise,"
Olivas said at one point. "It was incredible."
New tank for station
Olivas and Fuglesang swiftly tackled
their main orbital chore to install a 1,700-pound (772-kg) tank full of toxic
ammonia coolant to the space station's port side.
Olivas and different crewmate
removed an old ammonia tank from the station in a Tuesday spacewalk.
That tank had been on the station since 2002 and is nearly empty. It weighs about 1,300 pounds
(589 kg).
"If you can almost picture someone handing around a Mini Cooper car between the two of them, it's about the similar weight and mass of the tank they were handing between each other," said Zeb Scoville, lead spacewalk officer for Discovery's mission.
The tanks are vital components of
the space station's cooling system. They are also huge: each about 5 feet long,
7 feet wide and 4 feet tall (1.5 m by 2.1 m by 1.2 m).
"It takes a lot of concentration to
keep this thing still," Olivas said as he held the old tank.
Olivas and Fuglesang packed the
empty tank in Discovery's payload bay so it can be returned to Earth for an
overhaul. Fuglesang, a Swedish
astronaut representing the European Space Agency, spent much of the
spacewalk on the space station's robotic arm, moving the ammonia tanks and
enjoying the view.
"Thanks for a long, nice ride," he told
crewmate Kevin Ford, who controlled the arm from inside the station.
The spacewalkers were so far ahead
of schedule - nearly a full hour - that Mission Control gave them some extra
maintenance chores before letting them back inside the International Space
Station. They installed some lens covers on station video cameras among other
tasks.
While the spacewalkers worked
outside, the 11 astronauts inside the station moved new cargo delivered by
Discovery into the orbiting lab.
Thursday's spacewalk was the 132nd
dedicated to space station construction or maintenance and the fourth career
excursions for both Olivas and Fuglesang.
It was the second of three
spacewalks on tap during Discovery's 13-day mission, which is delivering
nearly 8 tons of supplies and science equipment to the space station, as well
as a treadmill named after comedian Stephen Colbert.
The next spacewalk is set for Saturday.
All 13 astronauts aboard the space station and Discovery are expected to take
some time off on Friday.
SPACE.com is providing complete
coverage of Discovery's STS-128 mission to the International Space Station with
Managing Editor Tariq Malik and Staff Writer Clara Moskowitz in New York. Click here for shuttle mission
updates and a link to NASA TV.
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