In preparation for that linkup, the crew spent today readying a variety of tools and equipment needed to support the rendezvous and docking, as well as equipment that will be used during Monday morning's scheduled space walk.
With the assistance of crew mate Dan Burbank, spacewalkers Ed Lu and Yuri Malenchenko checked out the suits they will wear during their planned 6 ½ hour long space walk Monday. Burbank will act as the in-cabin choreographer for that space walk. Also today, Commander Terry Wilcutt and Pilot Scott Altman verified the operation of navigational aids that will be used during the final phases of Sunday's rendezvous and docking.
Mission Specialist Rick Mastracchio powered up the Shuttle's robot arm, verifying its operation and conducting a photographic survey of the payload bay. Cosmonaut Boris Morukov tended to experiments and photography and television-related activities.
Atlantis is scheduled to begin the final phase of rendezvous about 10 p.m. tonight, closing in toward the early Sunday docking. At present, Atlantis is approximately 1600 miles behind and slightly below the ISS, closing the distance between them by approximately 172 miles with each orbit of the Earth.
Today, flight controllers reported that one of Atlantis' two onboard star trackers is not operating properly and has been powered off. The star trackers can be used as one method of updating navigation information aboard Atlantis. The failure of the star tracker, a device located on the left side of Atlantis' nose that looks upward, will have no significant impact on the planned rendezvous and docking. The remaining star tracker can be used to perform the needed functions.
Once docked the astronauts and cosmonauts will briefly open the hatch between Atlantis and the mating adapter on ISS to gather an air sample. The hatch will then be closed in preparation for Monday morning's space walk.
Monday evening, the crew will open 12 hatches throughout the length of the 143-foot long station and the attached Progress supply vehicle to begin transferring equipment and hardware.
The crew will begin a seven hour sleep period at 10:46 a.m. today. They will be awakened at 5:46 p.m. to begin the final rendezvous and docking.