Their goal was to prepare the PMA-2 docking adapter for relocation to the newly installed Harmony Module. Harmony will be relocated at a later date from the Unity Node to the forward end of the Destiny laboratory.

This is the first of three spacewalks to prepare for delivery of the long-awaited European science module, Columbus.

The Discovery shuttle just returned to Earth on Wednesday after delivering the Italian-made Harmony module that is crucial to attaching the next European space module, the Columbus laboratory.

Columbus will be stowed aboard the Atlantis shuttle when it launches December 6, part of a dizzying schedule of shuttle flights being made in a rush to double capacity on the space station by 2010, when NASA's ageing shuttle fleet is set to retire.

The Discovery crew however left Harmony parked at a temporary location on the space station, and now the job of the space station residents is to put it in its proper place before Columbus arrives in December.

Whitson, who was dressed in a white suit with red stripes, and Malencho, who wore an all white costume, have conducted a six hours spacewalk.

The two spent early Friday morning disconnecting and stowing cables, removing a light on one of the station’s transport carts and taking a cover off the Harmony node’s Common Berthing Mechanism, or CBM. On Monday, the Pressurized Mating Adapter 2 (PMA-2) will be moved from the Destiny lab and attached to Harmony’s CBM.

The spacewalkers also removed a base-band signal processor that will later be refurbished and a remote power controller module that will be replaced. They then transferred tools in preparation for upcoming spacewalks.

After Columbus' delivery in December, two more shuttle flights will deliver parts of Japanese and other European science labs to the orbiting research station.