Astronauts Begin Space Construction Job

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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