As of about 6:30 p.m. this evening, the Shuttle trailed the station by about 230 statute miles and was closing in by about 184 miles with each 90-minute orbit of Earth. The final phase of rendezvous will begin when Atlantis reaches a point about eight nautical miles directly behind the station and fires its engines in a terminal phase initiation burn just before 10 p.m. Central.
The TI burn, as it is called, will put the Shuttle on a course directly toward the station during the next orbit of Earth. As Atlantis moves within about a half-mile of the station, Wilcutt will take over manual control of the Shuttle's approach, flying the Shuttle from controls in the aft cockpit. Atlantis will arrive at a point about 600 feet directly below the station about 11:28 p.m. Central, and Wilcutt then will begin a half-circle of the orbiting outpost. Atlantis will pass about 350 feet in front of the station and then move to a point about 250 feet directly above it about 11:55 p.m. Central.
Wilcutt will then begin to descend toward the station and, just before midnight Central, hold position at a point about 170 feet away. Wilcutt will maintain that distance for about 20 minutes to allow the station to move within range of Russian ground communications stations before continuing the approach. At 12:41 a.m., Wilcutt will hold position again briefly at a point about 30 feet from the station to verify the Shuttle and station docking mechanisms are precisely aligned. Docking is expected about 11 minutes later with the Shuttle contacting the station at a slow rate of about a tenth of a foot per second. At the time of docking, the ISS and Atlantis will be at 49.6 degrees North Latitude, 57.1 degrees East Longitude as they fly over Western Kazakhstan.
During the rendezvous, Altman will assist Wilcutt in controlling Atlantis' approach. Mastracchio and Malenchenko also will assist with the rendezvous and docking, with Burbank and Lu operating the Shuttle's docking mechanism.
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 planned 6½-hour space walk by Lu and Malenchenko.
Near the end of their work day, Atlantis's crew will get 4 hours of off duty time to relax before beginning a planned eight hour sleep period at 10:46 a.m. on Sunday.