Walheim and Schlegel stepped outside the International Space Station's Quest airlock at 8:27 a.m. CST, and during the next six hours and 45 minutes they worked to replace a nitrogen tank used to pressurize the station's ammonia cooling system. Once the tank was replaced, Walheim, mounted on the station's robotic arm, maneuvered the spent tank into Atlantis' payload bay for return.
Once the task was completed, Walheim and Schlegel made some minor repairs to the Destiny laboratory's debris shield and worked on some tasks in advance of the third and final spacewalk of the mission, which will take place on Friday.
While Walheim and Schlegel were finishing up their tasks 210 miles above the earth, mission managers on the ground decided to extend Atlantis' mission by one extra day to continue activation of the new Columbus laboratory. They also cleared the shuttle's thermal protection system for re-entry based on inspections completed thus far. Additional inspections are scheduled following Atlantis' departure from the station.
Atlantis is now scheduled to land at 8:06 a.m. CST on Wednesday, Feb. 20.