The shuttle Discovery closed in on the international space station early Saturday, on course for a docking around 2:16 p.m. The terminal phase of the rendezvous begins at 11:33 a.m. when commander Steven Lindsey and pilot Eric Boe fire the shuttle's maneuvering rockets to begin moving in from a point about 9.2 miles behind the space station.

Credit: Spaceflight Now/NASA

A few minutes after 1 p.m., Discovery will briefly halt its approach about 600 feet directly below the space station. At that point, Lindsey will oversee a computer-assisted 360-degree back flip maneuver, exposing the shuttle's belly and critical heat-shield tiles to the crew aboard the station.

Expedition 26 flight engineers Catherine "Cady" Coleman and Paolo Nespoli will film the maneuver, using 400 mm and 800 mm telephoto lenses respectively, to capture high-resolution photographs of Discovery's heat shield tiles. The images will be downlinked to analysts in mission control at the Johnson Space Center for detailed evaluation.

During Discovery's launching Thursday, several pieces of foam insulation fell away from the ship's external tank, including some that appeared to contact the shuttle's heat shield. The foam shedding occurred well after the first two minutes and 15 seconds of flight when the dense lower atmosphere can cause debris to hit with a high relative velocity. Engineers do not believe the foam lost Thursday caused any significant damage, but the photos shot during final approach Saturday will be carefully scrutinized to make sure, and to look for anything else that might need attention.

It will take about 10 minutes to complete the rendezvous pitch maneuver. After that, Lindsey will guide Discovery in an arc up to a point about 300 feet directly in front of the space station with the shuttle's nose pointed toward deep space and its open payload bay facing the front end of the lab complex. From there, Lindsey will carefully guide Discovery in to a docking at pressurize mating adapter No. 2 on the front end of the station's Harmony module. It will be Discovery's 13th and final docking with the International Space Station.

After the docking mechanism locks the two spacecraft together, hatches will be opened shortly after 3:30 p.m. and the station crew -- Expedition 26 commander Scott Kelly, Alexander Kaleri, Oleg Skripochka, Dmitry Kondratyev, Coleman and Nespoli -- will welcome Lindsey, Boe and their shuttle crewmates -- Al Drew, Stephen Bowen, Michael Barratt and Nicole Stott -- aboard.

After a mandatory safety briefing, the shuttle astronauts will get to work transferring spacesuits and other gear to the station. Barratt and Stott, operating the station's robot arm, plan to pull a cargo pallet out of Discovery's cargo bay just before 5 p.m. The pallet, known as external logistics carrier No. 4, is loaded with a spare set of radiator panels for the station's ammonia cooling system.

ELC-4 will be mounted on the underside of the station's right-side solar power truss. To get it there, Barratt and Stott will hand it off to the shuttle's robot arm, operated by Boe and Drew. The station arm then will be repositioned, inchworm fashion, moving from the Harmony module to its mobile base work station. When the move is complete, the shuttle arm will hand ELC-4 back to the station arm and the pallet will be mounted on the solar power truss for future use as needed.

A mission status briefing is planned for 4:30 p.m. The crew will go to bed shortly before 11 p.m.

Here is an updated timeline of the crew's activities for flight day three (in EST and mission elapsed time; includes rev. C of the NASA TV schedule and an updated rendezvous timeline):

DATE/EST...DD...HH...MM...SS...EVENT

02/26
06:53 AM...01...14...00...00...STS/ISS crew wakeup
08:18 AM...01...15...25...00...Group B computer powerup
08:33 AM...01...15...40...00...Rendezvous timeline begins
08:38 AM...01...15...45...00...ISS daily planning conference
09:17 AM...01...16...24...00...NH rendeavous rocket firing
09:56 AM...01...17...03...00...NC-4 rendezvous rocket firing
11:33 AM...01...18...40...00...Ti rendezvous rocket firing
12:05 PM...01...19...11...36...ISS maneuver to docking attitude
12:07 PM...01...19...13...57...Range = 33000 ft
12:09 PM...01...19...16...02...Service module lights on
12:09 PM...01...19...16...02...Sunset
12:10 PM...01...19...16...36...ISS in docking attitude
12:13 PM...01...19...20...00...Spacesuits removed from airlock
12:32 PM...01...19...38...36...Range = 10000 ft
12:40 PM...01...19...47...16...Range = 5000 ft
12:43 PM...01...19...50...00...Begin approach timeline
12:45 PM...01...19...51...36...US solar arrays feathered
12:45 PM...01...19...51...53...Service module lights off
12:45 PM...01...19...51...53...Sunrise
12:46 PM...01...19...52...45...Range = 3000 ft
12:50 PM...01...19...56...54...MC4 rendezvous rocket firing
12:54 PM...01...20...00...54...Range = 1500 ft
12:59 PM...01...20...05...54...Range = 1000 ft
01:02 PM...01...20...08...54...KU radar to LO (800 ft)
01:03 PM...01...20...09...54...Shuttle directly below ISS (725 ft)
01:08 PM...01...20...15...06...Range = 600 ft
01:13 PM...01...20...19...46...Noon
01:15 PM...01...20...21...36...ATV solar arrays feathered
01:15 PM...01...20...21...46...Shuttle pitch maneuver start window open
01:15 PM...01...20...21...47...Start pitch maneuver
01:20 PM...01...20...26...36...ISS to proximity operations mode
01:21 PM...01...20...27...54...Pitch maneuver photo window close
01:23 PM...01...20...29...47...End pitch maneuver
01:25 PM...01...20...31...36...ISS Ku radar mask enabled
01:25 PM...01...20...32...23...Begin move to front of ISS (575 ft)
01:29 PM...01...20...36...19...Pitch maneuver start window close
01:31 PM...01...20...37...36...Russian solar arrays feathered
01:37 PM...01...20...43...53...Shuttle directly in front of ISS
01:38 PM...01...20...44...43...Range = 300 ft
01:41 PM...01...20...47...38...Sunset
01:42 PM...01...20...48...53...Range = 250 ft
01:46 PM...01...20...53...03...Range = 200 ft
01:48 PM...01...20...55...33...Range = 170 ft
01:50 PM...01...20...57...13...Range = 150 ft
01:54 PM...01...21...01...23...Range = 100 ft
01:57 PM...01...21...04...23...Range = 75 ft
02:01 PM...01...21...08...33...Range = 50 ft
02:05 PM...01...21...11...53...Range = 30 ft (start stationkeeping)
02:10 PM...01...21...16...53...End stationkeeping; push to dock
02:14 PM...01...21...21...13...Range = 10 ft

02:16 PM...01...21...22...53...DOCKING

02:16 PM...01...21...23...28...Sunrise
02:33 PM...01...21...40...00...Leak checks
03:03 PM...01...22...10...00...Group B computer powerdown
03:03 PM...01...22...10...00...Docking system prepped for ingress
03:33 PM...01...22...40...00...Hatch open
03:58 PM...01...23...05...00...Docking video playback
04:18 PM...01...23...25...00...Welcome aboard!
04:23 PM...01...23...30...00...Safety briefing
04:30 PM...01...23...37...00...Mission status/MMT briefing on NTV
04:53 PM...02...00...00...00...Station arm (SSRMS) unberths cargo pallet (ELC)
04:53 PM...02...00...00...00...EVA suits, equipment moved to ISS
05:53 PM...02...01...00...00...SSRMS hands ELC to shuttle arm (SRMS)
06:08 PM...02...01...15...00...SSRMS ungrapples ELC
06:38 PM...02...01...45...00...SSRMS walks off to MBS
07:08 PM...02...02...15...00...SRMS hands ELC back to SSRMS
07:48 PM...02...02...55...00...SSRMS ELC install
07:53 PM...02...03...00...00...ISS evening planning conference
08:33 PM...02...03...40...00...ELC-4 install
10:23 PM...02...05...30...00...ISS crew sleep begins
10:53 PM...02...06...00...00...STS crew sleep begins

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Additional coverage for subscribers:
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VIDEO: NARRATED PREVIEW OF THE DOCKING PLAY | HI-DEF
VIDEO: GUIDED TOUR OF SHUTTLE'S PAYLOAD BAY PLAY | HI-DEF

VIDEO: FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
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VIDEO: NARRATED PREVIEW OF FLIGHT DAY 2 ACTIVITIES PLAY | HI-DEF

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VIDEO: LAUNCH REPLAY: PAD CAMERA 070 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD CAMERA 071 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: UCS-23 TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PLAYALINDA BEACH PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD FRONT CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: WEST TOWER CAMERA PLAY | HI-DEF

VIDEO: ASTRONAUTS LEAVE CREW QUARTERS PLAY | HI-DEF
VIDEO: CREW FINISHES GETTING SUITED UP PLAY | HI-DEF

VIDEO: LOOK BACK AT THE LAUNCH DELAYS PLAY | HI-DEF
VIDEO: NARRATED REVIEW OF SHUTTLE'S PREPARATIONS PLAY | HI-DEF
VIDEO: NARRATED REVIEW OF PAYLOADS' PREPARATIONS PLAY | HI-DEF

VIDEO: TIME-LAPSE OF PAD GANTRY ROLLBACK PLAY
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VIDEO: SETTING UP ACCESS PLATFORMS AROUND TANK PLAY | HI-DEF

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VIDEO: INSTALLING DOUBLERS OVER STRINGERS PLAY | HI-DEF
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VIDEO: DOUBLERS TO BEEF UP CRACKED BEAMS PLAY | HI-DEF
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VIDEO: OPENING UP TANK'S ENTRANCE DOOR PLAY | HI-DEF
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VIDEO: BROKEN FOAM REMOVED FROM THE TANK PLAY | HI-DEF
VIDEO: VENT ARM LETS GO FROM LEAKY GUCP PLAY | HI-DEF
VIDEO: DISCOVERY AWAITS REPAIRS TO TANK PROBLEMS PLAY | HI-DEF

VIDEO: INFORMATIVE DESCRIPTION OF TANK CRACK PROBLEM PLAY
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VIDEO: STS-133 MISSION PREVIEW MOVIE PLAY | HI-DEF
VIDEO: SHUTTLE DISCOVERY CREW BIOGRAPHIES PLAY | HI-DEF
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VIDEO: SPACE STATION CREW BIOGRAPHIES PLAY | HI-DEF

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VIDEO: ASTRONAUTS VISIT THEIR SPACECRAFT PLAY | HI-DEF
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VIDEO: EXTERNAL FUEL TANK UNLOADED FROM BARGE PLAY | HI-DEF
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VIDEO: POST-FLIGHT DESERVICING: OMS POD PLAY | HI-DEF
VIDEO: POST-FLIGHT DESERVICING: OBSS BOOM PLAY | HI-DEF
VIDEO: POST-FLIGHT DESERVICING: ENGINES PLAY | HI-DEF
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