The International Space Station has received a new pair of giant solar energy panels that will double the amount of power to the outpost.  Spacewalking astronauts have begun the task of connecting them to the outpost.

The 17-ton girder holding the folded solar arrays arrived on the U.S. shuttle Atlantis Monday. On Tuesday, Canadian astronaut Steve MacLean used the station's robot arm to lower it into position so automated bolts could lock it into place.

Soon after, astronauts Joe Tanner and Heidemarie Stephanyshyn-Piper left Atlantis' hatch on a spacewalk to hook up cables and lines to supply power, cooling and data to the unit. They also removed bolts, thermal covers, and other items installed to protect it during the rigors of launch and travel to the station.

Their work produced another piece of space trash when a bolt Tanner was working on sprang loose and flew away before he could grab it. He expressed concern that it might get into the mechanism, but space station flight director John McCullough says it apparently floated into space safely away from the outpost.

"We're very confident it's not in the structure and it did go out," he said. "It doesn't have a large separation rate, it's not a big threat to anybody, and it's going in a direction that we don't have to worry about right now."

The work to make the solar wings operational continues with a second spacewalk on Wednesday (set to begin at 5:15 a.m. EDT). In an interview before Atlantis' launch Saturday, astronaut MacLean said that he and Dan Burbank will leave the orbiter to finish removing launch braces from a rotating joint that will automatically turn the solar panels toward the sun as the station orbits.

"What Dan and I will do will basically be to spend a lot of time around that solar array rotary joint making sure that it is ready so that that joint can move late on during the mission," he said.

The giant solar energy arrays are the first new equipment on the half-built space station since before the shuttle Columbia accident in 2003 halted construction missions. The arrays will power additional research laboratories and living quarters still to come.

When they are unfolded from their packing crates and fully unfurled Thursday, they will stretch nearly 80 meters.

Mission officials have taken steps to help prevent the solar blankets, which are made of thin mylar plastic, from sticking together during deployment the way another set did during installation six years ago. This is a particular worry, since they have been stuffed in their boxes since before the shuttle Columbia accident.

To overcome sticking, station flight controllers will aim the blankets at the sun to warm and relax them, unfurl them half way and warm them for 30 minutes more before the final extension. The unfolding mechanism will also use more force to separate the folds.