Astronauts aboard the International Space Station and the visiting shuttle Discovery tumbled into a spanking new room on Saturday, the first addition to the orbital outpost in six years.

The chamber, called Harmony, is a six-sided vestibule that will anchor the docking ports for new science laboratories that are scheduled to begin arriving in December.

“It’s beautiful … bright, shiny. It’s as clean as can be, perfect shape,” flight director Rick LaBrode told reporters after Harmony’s hatch was opened for the first time in orbit.

Installing the Harmony module was one of the top priorities for the shuttle Discovery crew, which arrived at the station on Thursday for a 10-day construction mission.

Astronauts used a robotic crane to hoist the school-bus-sized module out of Discovery’s cargo bay so spacewalking crewmates could bolt it into position on Friday.

The second of five spacewalks planned during Discovery’s mission is scheduled for Sunday when an 18-tonne section of the station’s frame will be prepared for relocation. The move of the solar power tower to the far end of the station’s backbone is scheduled during the third spacewalk on Tuesday.

PREPARING FOR COLUMBUS

After the shuttle’s departure, station crewmembers will continue preparing the complex for the arrival of Europe’s Columbus module around December 8.

In addition to outfitting the new module with gear and removing about 700 bolts that secured it for launching in the shuttle, Harmony must be moved to its permanent position at the end of the U.S. Destiny laboratory before the next shuttle flight arrives with Columbus.

Discovery is currently docked where Harmony will be located.

Donning masks and goggles to protect themselves from floating debris, station commander Peggy Whitson and Discovery crewmember Paolo Nespoli, with the Italian space agency, were the first to slip inside the new room, which was built in Italy for NASA.

“It is a pleasure to be here in this very beautiful piece of hardware,” Nespoli said.

“We want to acknowledge and christen the Harmony module,” Whitson said. “We think Harmony is a very good name for this module because it represents the culmination of a lot of international partner work.”

Whitson, the station’s first female commander, received a necklace with a Harmony charm from Discovery commander Pamela Melroy.

Harmony adds 2,600 cubic feet (74 cubic metres) of space to the station, which measured 15,000 cubic feet (425 cubic metres) before its arrival.

NASA plans to finish the $100 billion (49 billion pound) station by 2010 when the shuttle fleet is set to be retired.

Discovery is due back at the Kennedy Space Centre in Florida on November 6.