Atlantis brings a new airlock to the station. It will enable station crewmembers to conduct spacewalks from the station, using either Russian or U.S. spacesuits.
The hatch separating the Atlantis crew, Lindsey, Pilot Charles Hobaugh, and mission specialists Mike Gernhardt, Janet Kavandi and James Reilly, from Expedition Two crewmembers Yury Usachev, Jim Voss and Susan Helms was opened at midnight. After a safety briefing by Expedition Two Commander Usachev, both crews began an hour-long review of procedures for the first of three spacewalks of the STS-104 mission.
The spacewalk, by Gernhardt and Reilly, is to begin about 9:10 p.m. Saturday and last more than seven hours. Focus of the spacewalk is the berthing of the airlock, named Quest. Two subsequent spacewalks by Gernhardt and Reilly will attach high-pressure Oxygen and Nitrogen tanks to the airlock.
After the hour-long meeting on the spacewalk, robotic arms on both the station and Atlantis were put through a rehearsal of procedures to be used during removal of the airlock from the shuttle's cargo bay and its attachment to the station. Helms took the station's 58-foot-long robotic arm, Canadarm2, through a dry run of the berthing of the new airlock to the starboard docking port of the station's Unity node. Aboard Atlantis, Kavandi powered up the shuttle's robotic arm and practiced its spacewalk activities.
Early Saturday Gernhardt and Reilly checked the batteries of their spacesuits and found no evidence of potassium hydroxide leakage that was seen Friday as they checked a spare spacesuit. The battery was replaced and the suit cleaned. Managers decided to postpone temporarily the planned transfer of that suit to the station while they study the situation.
Hatches between Atlantis and the station were closed at 4:45 a.m. and the pressure in the shuttle's cabin reduced to 10.2 pounds per square inch in preparation for the first spacewalk.