— Astronauts Steve MacLean and Jeff Williams moved the station’s robotic arm on Thursday from inside the station (Image: NASA TV)
The International Space Station spread its second pair of wings on Thursday after the newly attached solar arrays deployed successfully.
The orange arrays were part of the P3/P4 truss segment that the space shuttle Atlantis delivered to the ISS this week. They measure 73 metres (240 feet) from tip to tip and were unfurled from the P4 section of the truss, which acts as a support structure for the station's power and cooling systems.
Watch a video of the solar array deployment.
The station's first set of solar arrays were installed in 2000. During that deployment, some elements of the arrays stuck together while they were being unfolded. When they were pulled apart, they began to shake in a way that caused two tension cables to come off their reels forcing astronauts to fix them on one of their spacewalks.
This time, NASA deployed the arrays halfway and allowed the Sun to warm them up to reduce their stickiness. The arrays still shook somewhat but, this time, NASA kept their cables fairly tight so they would not come loose.
Tests showed that the solar arrays were working properly after they were deployed. Initially, however, they will provide only enough power for their own batteries and will not send power to the rest of the station until the next shuttle mission, currently scheduled for December.
Once that happens, they will double the station's power. That will allow more modules to be added to the station, including the European Space Agency's Columbus module, currently scheduled for a 2007 delivery.
"Power supply is one of the important prerequisites for that," European Space Agency astronaut Thomas Reiter told CNN from the space station on Thursday.
The astronauts and ground control got a little bit behind schedule before the arrays were deployed when a joint that will eventually allow the solar arrays to rotate and track the Sun did not work as expected late on Wednesday. Ground controllers traced it to a software problem and quickly fixed it.
Besides a couple of bolts floating away and a stuck bolt during a spacewalk, this mission has gone fairly smoothly, according to NASA managers. "I couldn't ask for a better restart for assembly," says NASA's ISS programme manager Mike Suffredini.
This is the first ISS construction mission since 2002. The shuttle fleet was grounded following the Columbia accident and the first two post-Columbia shuttle missions were devoted to testing new safety procedures and hardware and delivering supplies to the ISS.
On Friday, astronauts Joe Tanner and Heidemarie Stefanyshyn-Piper will embark on the mission's third spacewalk. One of their main tasks will be to replace a spare S-band antenna on the station's S1 truss. They also plan to deploy a new radiator on the P4 truss segment and add a heat shield for a Ku-band antenna on the station.
They will also unhook a tether that looks like it might be interfere with the railcar that allows the station's robotic arm to work the length of the truss. The railcar will move to the end of the new P3 truss after Friday's spacewalk.
And Tanner will climb up the structure supporting the station's other US solar array to retrieve an experiment that exposes materials to space.
If there is time, they may install an external wireless antenna on the Destiny laboratory and use an infrared video camera to look for damage on the orbiter's wings. The shuttle's heat shield has already been declared safe for landing, so this inspection will serve only as another test of this camera.