Following the installation of the P3/P4 Truss to the ISS by the Canadarm2, Tanner and Stefanyshyn-Piper began their spacewalk to activate the truss at 09:17 UTC.
During the EVA they installed power and data cables between the P1 & P3/P4 trusses, released the P3/P4 truss' launch restraints and a number of other tasks to configure the truss for upcoming activities.
The spacewalk was so successful that the astronauts carried out a number of tasks scheduled for later EVAs, with the eventual completion of the EVA at 15:43 UTC.
A bolt, spring and washer assembly from a launch lock was lost during these extra activities and floated off into space.

Following the completion of the EVA, the station's crew began preparing for Day 5's spacewalk, with astronauts Burbank and MacLean entering the Quest Airlock for their "camp out" at 18:40 UTC, ready for the scheduled 09:15 UTC EVA.
Following the installation of the P3/P4 Truss to the ISS by the Canadarm2, Tanner and Stefanyshyn-Piper began their spacewalk to activate the truss at 09:17 UTC. During the EVA they installed power and data cables between the P1 & P3/P4 trusses, released the P3/P4 truss' launch restraints and a number of other tasks to configure the truss for upcoming activities. The spacewalk was so successful that the astronauts carried out a number of tasks scheduled for later EVAs, with the eventual completion of the EVA at 15:43 UTC. A bolt, spring and washer assembly from a launch lock was lost during these extra activities and floated off into space.
Following the completion of the EVA, the station's crew began preparing for Day 5's spacewalk, with astronauts Burbank and MacLean entering the Quest Airlock for their "camp out" at 18:40 UTC, ready for the scheduled 09:15 UTC EVA.
STS-115