This
story was updated at 7:22 p.m. EDT.
Astronauts
aboard the docked shuttle Discovery and International Space Station began a tough
two-day task Wednesday that will ultimately add a new pair of solar wings to
complete the station's power grid.
The
10-astronaut crew of the linked
shuttle and station gingerly plucked the nearly 16-ton addition for the
orbiting lab out of Discovery's payload bay in order to move into position for
its final installation during a Thursday spacewalk
"We are
looking forward to today, getting that [truss] on its way," said Discovery
astronaut Steve Swanson, who will help bolt down the massive girder in
tomorrow's spacewalk.
The
station's new Starboard-6
(S6) truss is a 45-foot (nearly 14-meter) long girder destined for the
right side of the space station's backbone-like main truss. It weighs 31,000
pounds (14,061 kg) and is the final piece of the station's 11-segment truss,
which will span more than 300 feet (91 meters) from end-to-end when complete -
longer than an American football field.
Two
wing-like solar arrays, each 115 feet (35 meters) long, are folded away like
oversized maps in boxes on the end of the $298 million segment. Discovery
astronauts plan to install
the array-laden girder in Thursday's spacewalk and unfurl them as early as
Friday.
The solar
wings are the fourth, and last, set of U.S. solar arrays for the space station's
power grid, which will generate enough electricity to power 42 average sized
homes, NASA has said.
"It's going
to give us all sorts of power to get us to do the kind of science the space
station was designed for," shuttle flight director Paul Dye told reporters late
Tuesday.
Discovery's
crew initially planned to unfurl the new solar wings on Sunday, but mission
managers said they might move it up to Friday if the astronauts did not need to
perform an extra heat shield inspection that day.
So far,
images from a Tuesday photo survey revealed only one relatively minor dinged
heat-resistant tile of note on Discovery's underbelly and mission managers
decided to forgo the extra inspection. Mission Control radioed the news up the
shuttle astronauts late Wednesday.
"That's absolutely
great news," shuttle commander Lee Archambault replied.
Slow and
steady
Astronauts
had to take great care moving
the massive new girder, which required the use of robotic arms aboard the
space station and Discovery. At times, the 16-ton truss was just inches away
from the space shuttle, with little room for error.
"It can
swing a little bit, so we've got to be really careful about that," Discovery
astronaut John Phillips said in an interview before the shuttle's Sunday
evening launch. "I wouldn't say that we have to wiggle it out, but we're not
just picking it straight up. It's kind of a big deal."
The orbital
extraction went smoothly, with Phillips and Discovery astronaut Sandra Magnus
using the station's Canadarm2 robotic arm to latch onto the starboard-side
truss and ease it out of the shuttle's cargo bay. They handed the segment off
to Discovery's robotic arm, and moved their own station appendage into position
to take back the massive girder and park it overnight.
The move
began at about 11:38 a.m. EDT (1538 GMT) and lasted more than six hours.
Space
station commander Michael Fincke radioed down to Mission Control that cameras
inside the space station were available to watch the astronauts move the
outpost's newest addition.
"We want to
share the great adventure with you all," Fincke said.
Dye said
every move must be controlled perfectly to avoid breaking the robotic arms,
losing control of the massive girder at the end of the outstretched limbs, or
overtaxing the space station's attitude control system.
"Obviously
we want to make sure that we don't bump into anything," Dye said.
Shuttle
pilot Dominic "Tony" Antonelli and mission specialist Joseph Acaba will control
Discovery's robotic arm during the move. Acaba, a teacher-turned-astronaut, and
fellow educator astronaut Richard Arnold II are also due to discuss
their spaceflight with the Channel One educational channel later today.
Discovery's
seven-astronaut crew is in the midst of a 13-day mission to deliver the new
solar arrays and swap out one member of the station's Expedition 18 crew.
Japanese astronaut Koichi Wakata, who launched aboard Discovery, replaced
Magnus as a station flight engineer late Tuesday. Magnus will return home
aboard the shuttle when it lands on March 28.
NASA cut a
day and a spacewalk from the mission, which was initially slated to include
four spacewalks and run 14 days, in order to complete the construction flight
before the arrival of a previously scheduled Russian Soyuz flight bearing a new
station crew and an American space tourist.
Dye told
reporters that mission managers continue to rework the mission plan for
Discovery's crew, including moving tasks from the canceled spacewalk into the
flight's third excursion.
"I think
you're going to see non-stop action, especially on the station," Dye said.
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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