Two astronauts hooked up the new 300-foot panels during a spacewalk Monday, and during the night engineers at Mission Control began remotely unfolding the array from its storage box. The movement was to continue slowly throughout the day to let the panels warm gradually in the sunlight and prevent them from sticking together.
The shuttle astronauts arrived at the station on Sunday and have been granted an extra couple of days in orbit to allow time to fix a thermal blanket near the shuttle's tail that peeled back during its launch.
Experts don't believe the gap would pose any threat to the astronauts, though it could allow damage to the shuttle during its re-entry into Earth's atmosphere.
This photo provided by NASA shows the International Space
Station's Russian cosmonaut Oleg V. Kotov, as he participates
in a session of extravehicular activity (EVA)
Wednesday June 6, 2007.
After the array was moved into place on the station's girder-like backbone by the station's robotic arm, astronauts James Reilly and Danny Olivas removed locks and restraints on the new segment.
The start of their spacewalk was delayed by more than an hour because the four spinning gyroscopes that keep the space station properly positioned became overloaded; Atlantis was used to help control the station's orientation until the gyroscopes were able to take over again.
On Wednesday, an older solar array will be folded up into a box so it can be moved during a later shuttle mission. The retraction of that array will allow the newly installed pair of panels to rotate, following the direction of the sun.
Engineers at Johnson Space Center in Houston were already were practicing techniques the astronauts might use to repair the thermal blanket.
"It was a 100 percent consensus that the unknowns of the engineering analysis and the potential damage ... under the blanket was unacceptable and we should go in and fix it if we could," said John Shannon, chairman of the mission management team.
The thermal blankets are used to protect the shuttle from searing heat during re-entry into Earth's atmosphere. Engineers didn't think the intense heat generated by re-entry could burn through the graphite structure underneath it and jeopardize the spacecraft, but they worried it might cause some damage that would require repairs on the ground.
With three additional shuttle flights to the space station planned this year, NASA can't afford delays.
The repair to the thermal blanket, covering a 4-by-6-inch area over an engine pod, likely will involve an astronaut attached to the end of the shuttle's robotic arm and boom reaching the shuttle's tail area. No decision has been made on whether it will be made during a previously planned third spacewalk or if a fourth, extra spacewalk will be added.
The rest of the shuttle appeared to be in fine shape, Shannon said.
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