Washington - With sunlight glowing golden across its expanse, the fourth and final pair of solar panels finished unfolding at the space station Friday, clinching a huge milestone for the orbiter. In a final visual inspection, NASA officials said there was "good tension ... and performance" in the deployment of the panel's two sections to a full 80 metres.
The process, controlled remotely from inside the docked Discovery shuttle, took more than two hours and finished at 1717 GMT.
"We are very happy," one of the astronauts from the Discovery shuttle mission said during the live webcast. NASA control in Houston, Texas, suggested the ten members of the shuttle and station crew should "celebrate."
The final installation was years in the making, as NASA shut down for more than two years after the 2003 Columbia disaster, in order to reconfigure safety procedures.
It wasn't really until 2006 that shuttles were able to resume their heavy lifting to the station, carrying up the huge truss and the four pairs of solar panels needed to expand the power supply.
When finally plugged into the station's electricity grid, the four pairs of solar collectors will provide 120 KW of usable electricity - enough to allow six astronauts, instead of the current three, to live at the station at any one time.
By May, the station is slated to be at its new full occupancy of six astronauts.
The panel was attached to the station Thursday during a spacewalk by Discovery astronauts, but needed to be unfolded from its transport and storage blankets, where the sections sometimes stick to each other.
To ease the process, NASA paused the actions midway to allow it to "warm in the sun" and gradually un-stick.
The next spacewalk is slated for 1643 GMT Saturday, to continue external work on the outside of the station. The final spacewalk is slated for Monday.
In an all-time first for the space station, an astronaut from Japan - Koichi Wakata - moved in to take up residence. He will replace US astronaut Sandra Magnus, who will join the Discovery crew for the flight back to Earth, with landing slated for March 28.
The shuttle launched Sunday after weeks of delays to inspect and study the hydrogen fuel valves and a later leak in a fuel vent.
After a final ten missions to finish station construction, the ageing shuttles, workhorses for more than two decades, are to be mothballed by late 2010. NASA is developing a new spacecraft that is expected to return to the moon, using it as a base for further space exploration.
When the shuttle programme closes down, only the smaller Russian Soyuz spacecraft will be available for ferrying astronauts to and from the station. The Russians also operate unmanned cargo craft, called Progress, to deliver supplies to and remove garbage from the station.
