The pair, destined to become members of the Expedition Two crew aboard the station later in the mission, began the 17th station assembly space walk at 11:12 p.m. CST Saturday. Inside Discovery, Paul Richards choreographed their activities and served as liaison with Mission Control.
The space walkers were delayed early in their excursion when a portable foot restraint attachment device became untethered, and Voss had to retrieve a spare from its storage location on the outside of the station's Unity module.
Helms and Voss successfully prepared Pressurized Mating Adapter-3 for repositioning from Unity's Earth-facing berth to its port-side berth to make room for Leonardo, the Italian Space Agency-built Multipurpose Logistics Module. They disconnected eight cables and removed an Early Communications System antenna from the left-side Common Berthing Mechanism so that shuttle robotic arm operator Andy Thomas could put the mating adapter in its place, freeing up the Earth-facing berthing port for Leonardo.
The space walkers also removed a Lab Cradle Assembly from the cargo bay and installed it on the side of the Destiny laboratory module, where it will form the base for station robotic arm to be launched on STS-100 in mid-April. Because of the early delay, they were instructed to defer power and data cable connections for the cradle until Monday's scheduled space walk by Richards and Thomas. Voss and Helms also installed a cable tray to Destiny for later use by the station's robot arm.
The pair reentered Discovery's airlock early Sunday and waited for Thomas to maneuver the docking port to its new location, but remained at the ready to assist if needed. After Commander Jim Wetherbee drove the Common Berthing Mechanism latches home and secured the docking port at 7:43 a.m., the airlock was repressurized, ending the space walk at 8:08 a.m. Sunday after 8 hours 56 minutes, making it the longest space walk in Shuttle history. The space walk brings the total exterior construction time on the station to 117 hours 39 minutes over the course of 17 space walks, and the total EVA time in Shuttle program history to 386 hours, 15 minutes over 61 separate space walks.
Meanwhile aboard the station, Expedition Two Commander Yury Usachev began a handover of duties from Expedition One Commander Bill Shepherd, with Flight Engineer Sergei Krikalev also still on board. The hatches between Discovery and the International Space Station are to be reopened shortly after 8 p.m. Sunday, as the crew begins the fifth day of the mission.
Both crews are scheduled to begin an eight-hour sleep period at 9:42 a.m. central time, awakening at 5:42 p.m. Discovery and the station are in excellent condition in an orbit of about 235 statute miles.