Orlando ? NASA prepared the international space station for future expansion Thursday by successfully unfurling a new set of electricity-producing solar arrays.

The giant panels, carried to the outpost by shuttle Atlantis, eventually will double power production and get the station ready for two more modules slated for launch by the end of 2008.

After a delay caused by a software glitch, NASA extended the arrays during a painstaking, four-hour process early Thursday. The solar panels unfolded in accordionlike fashion, glistening gold and black against a backdrop of the planet.

When locked into place, the arrays spanned 240 feet from tip to tip.

“Big day for space station. Congratulations,” astronaut Pam Melroy radioed the shuttle crew from Mission Control in Houston.

NASA managers said they were thrilled with the successful deployment, which marks the start of an intense construction period at the outpost. The station, slated to get additional European and Japanese laboratory modules in the next two years, had been in a holding pattern since the Columbia accident of 2003.

The arrays already are producing power to charge their own batteries but none for the station itself. Some additional work must be carried out on the next shuttle mission – tentatively scheduled for December – before they are ready to generate electricity for the outpost.