The Endeavour astronauts are gearing up to undock from the international space station this evening to close out a marathon five-spacewalk assembly mission. A brief farewell ceremony is planned for 5:13 p.m., followed by hatch closure around 5:30 p.m. With shuttle pilot Gregory Johnson at the controls, Endeavour is scheduled to disconnect from the space station's forward docking port, pressurized mating adapter No. 2, at 7:56 p.m. After looping around the lab complex for a photo survey, Johnson will fire the shuttle's maneuvering jets to leave the area around 9:40 p.m.

"There are a number of key steps both vehicles have to go through to make sure the undocking goes smoothly," said space station Flight Director Bob Dempsey. "First of all, we have to maneuver the combined space station-orbiter vehicle to the undocking attitude, as it's called. Normally, when the orbiter's docked there, the PMA-2, or the pressurized mating adapter 2 (docking port) is flying in the direction the vehicle is going. When the orbiter is docked, we actually flip the vehicle 180 degrees around ... so the delicate thermal protection system on the orbiter, the tiles, are not into the wind, as we say, and vulnerable to debris strikes. So we fly with the shuttle sort of in the back with the belly sort of facing downwind.

"But we can't undock in that position. So we will flip the station around 180 degrees to get them in the right orientation. Then another thing we will do to get ready for the undock is we will park the KU antenna on the space station. We do that so we don't radiate the orbiter. ... And then we will begin a series of minor power downs. The reason we're doing that is, the next thing we have to do is configure the solar arrays on the space station, both the giant U.S. arrays and the Russian arrays, so that as the orbiter's undocking and it's firing its thrusters, that impinges material that can dirty up and push, do some structural damage, to the solar arrays. So we park those so they're kind of edge on to the thrusters so when the orbiter's backing away, we minimize the amount of impact to the solar arrays.

"So once we do all those things, we're in the undocking configuration," Dempsey said. "The shuttle will give the commands and back off from the space station. It'll move away slowly, we don't want to impart a big moment to the space station and push it very hard, cause it to tumble or anything like that. So it'll back off slowly and once the crew gets far enough away, they'll start some minor thruster firings, do it as gently as possible ... then they'll actually do a fly around."

Johnson will guide Endeavour through a full 360-degree loop, flying directly above, behind and below the station for a detailed photo survey.

"That's going to be a great thing for a pilot," Johnson told CBS News before launch. "Undocking is about the opposite of docking, you're leaving the space station at a pretty controlled rate. And then at the end of the undocking timeline, when we get about 300 to 400 feet away, then we start what's called a fly-around and that's where you take the orbiter and go 360 degrees all the way around the station, about 45 minutes of flying. You get to see angles of space station that aren't normally observed and just a great, exciting period for the whole crew."

When the shuttle is a safe distance away, station commander Peggy Whitson, flight engineer Yuri Malenchenko and newly arrived flight engineer Garrett Reisman will begin work to put the station back into its normal operating mode, putting the solar arrays back in sun-track and powering up systems that were shut down earlier. Because of ongoing problems with one of the station's solar array rotary joints, the S4 solar panels on the right side of the complex will remain locked in place.

Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision L of the NASA television schedule):

EDT........DD...HH...MM...EVENT

03/24/08
11:43 AM...13...09...15...Crew wakeup
02:58 PM...13...12...30...Spacesuits transferred to shuttle
04:13 PM...13...13...45...Oxygen system teardown
05:13 PM...13...14...45...Farewell ceremony
05:28 PM...13...15...00...Hatch closure
05:33 PM...13...15...05...Group B computer powerup
05:58 PM...13...15...30...Leak checks
06:39 PM...13...16...11...ISS maneuvers to undocking attitude
06:42 PM...13...16...14...Sunrise
06:43 PM...13...16...15...Centerline camera setup
07:09 PM...13...16...41...ISS in undocking attitude
07:13 PM...13...16...45...Noon
07:13 PM...13...16...45...Undocking timeline begins
07:21 PM...13...16...53...US solar arrays in undocking configuration
07:23 PM...13...16...55...PMA-2 departure config
07:44 PM...13...17...16...Sunset

07:56 PM...13...17...28...UNDOCKING

07:58 PM...13...17...30...ISS holds attitude
08:01 PM...13...17...33...Range: 50 feet; reselect -X jets
08:03 PM...13...17...35...Range 75 feet; low Z
08:13 PM...13...17...45...Sunrise
08:25 PM...13...17...57...Range: 400 feet; start fly around
08:34 PM...13...18...06...Range: 600 feet
08:36 PM...13...18...08...Shuttle directly above ISS
08:40 PM...13...18...12...ISS in TEA attitude
08:44 PM...13...18...16...Noon
08:48 PM...13...18...20...Shuttle directly behind ISS
08:59 PM...13...18...31...Shuttle directly below ISS
09:11 PM...13...18...43...Separation burn No. 1
09:15 PM...13...18...47...Sunset
09:39 PM...13...19...11...Separation burn No. 2
09:43 PM...13...19...15...Post undocking computer reconfig
09:45 PM...13...19...17...Sunrise
10:28 PM...13...20...00...Group B computer powerdown
10:28 PM...13...20...00...PMA-2 leak checks
10:30 PM...13...20...02...Mission status briefing on NASA TV
10:58 PM...13...20...30...ISS crew sleep begins
11:03 PM...13...20...35...EVA unpack and stow
11:03 PM...13...20...35...Undocking videoi replay
11:28 PM...13...21...00...Shuttle arm (SRMS) powerdown

03/25/08
02:58 AM...14...00...30...Crew sleep begins
03:00 AM...14...00...32...Daily video highlights reel on NASA TV

"The orbiter crew will be taking all kinds of high resolution photos of the space station and we can use that to check the configuration, make sure everything looks healthy. We will get some baseline photos of the JLP, the Japanese pressurized module that we just installed during this mission and then over time, we'll be able to compare those to other photos ... and just monitor over time. So it gives us a good opportunity to check out the space station."

Departing station crews normally carry out a detailed heat shield inspection just after undocking to make sure the orbiter's nose cap and wing leading edge panels were in good shape for re-entry. Endeavour's crew did that inspection Friday and stowed the shuttle's inspection boom on the station during a spacewalk Saturday so it will be available to the next station assembly crew. Because of interference issues with the Japanese Kibo research module scheduled for launch in May, there was not enough room to carry an inspection boom on that mission.

If all goes well, Johnson, commander Dominic Gorie, flight engineer Michael Foreman, Richard Linnehan, Robert Behnken, Japanese astronaut Takao Doi and returning European Space Agency astronaut Leopold Eyharts will pack up Tuesday and prepare the ship for landing Wednesday evening at the Kennedy Space Center.

Landing is targeted for 7:05:08 p.m. Wednesday and forecasters are calling for good weather, with scattered clouds at 3,500 feet and winds out of the north at eight knots, gusting to 12. A second landing opportunity is available one orbit later, at 8:39:06 p.m.

"I know we're still three days out from landing but the weather is looking pretty reasonable," astronaut Terry Virts radioed the shuttle Sunday evening. "For now it looks good. We'll keep our fingers crossed."

STS-123 deorbit and landing opportunities

ORBIT....SITE..TIG........LANDING

03/26/08

248......KSC...06:01 PM...07:05 PM (Nominal end of mission)
249......KSC...07:36 PM...08:39 PM
250......EDW...09:04 PM...10:06 PM
251......EDW...10:39 PM...11:41 PM

03/27/08

264......KSC...06:24 PM...07:27 PM (EOM + 1)
265......KSC...08:00 PM...09:02 PM
266......EDW...09:30 PM...10:32 PM
267......EDW...11:06 PM...12:08 AM

03/28/08

279......KSC...05:12 PM...06:15 PM (EOM + 2)
280......KSC...06:48 PM...07:50 PM
281......EDW...08:18 PM...09:21 PM
.........NOR...08:19 PM...09:22 PM
282......EDW...09:53 PM...10:56 PM
.........NOR...09:55 PM...10:57 PM
283......EDW...11:30 PM...12:31 AM

Additional coverage for subscribers:
VIDEO: NARRATED ANIMATION OF UNDOCKING AND FLYAROUND PLAY

VIDEO: THE FLIGHT DAY 14 HIGHLIGHTS MOVIE PLAY
VIDEO: ARIZONA AND COLORADO SEEN FROM SPACE AT NIGHT PLAY
VIDEO: NEW YORK CITY AND BOSTON SEEN FROM SPACE AT NIGHT PLAY
VIDEO: BEAUTIFUL MOONSET SEEN FROM THE STATION PLAY
VIDEO: SUNDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: JOINT SHUTTLE AND STATION CREW NEWS CONFERENCE PLAY

VIDEO: THE FLIGHT DAY 13 HIGHLIGHTS MOVIE PLAY
VIDEO: SUNDAY MORNING'S MISSION STATUS BRIEFING PLAY
VIDEO: CONCLUSION OF MISSION'S FINAL SPACEWALK PLAY
VIDEO: HELMET-CAM SURVEY OF DEPLOYED EXPERIMENTS PLAY
VIDEO: SECOND EXPERIMENT PACKAGE RETRIEVED FROM SHUTTLE PLAY
VIDEO: MATERIALS EXPOSURE EXPERIMENT INSTALLED ON ISS PLAY
VIDEO: FURTHER EXAMINATION OF STATION'S ROTARY JOINT PLAY
VIDEO: PROTECTIVE COVER PLACED OVER BOOM SENSOR PACKAGE PLAY
VIDEO: HEAT SHIELD INSPECTION BOOM MOUNTED ON THE STATION PLAY
VIDEO: BOOM MOVED FOR SPACEWALKERS TO MANUALLY STOW PLAY
VIDEO: GOOD CONNECTION CONFIRMED FOR BOOM UMBILICAL PLAY
VIDEO: CRITICAL UMBILICAL FOR BOOM INSTALLED ON STATION PLAY
VIDEO: INSPECTION BOOM HANDED OFF BETWEEN ROBOT ARM PLAY
VIDEO: ASTRONAUTS EXIT AIRLOCK TO BEGIN EVA NO. 5 PLAY
VIDEO: NARRATED ANIMATION OF BOOM ATTACHMENT TO ISS PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 5 PLAY

VIDEO: THE FLIGHT DAY 12 HIGHLIGHTS MOVIE PLAY
VIDEO: FRIDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: SCIENCE GLOVEBOX FACILITY MOVED INTO COLUMBUS LAB PLAY
VIDEO: INSPECTION BOOM SURVEYS SHUTTLE WINGS AND NOSE PLAY
VIDEO: NARRATED ANIMATION OF LATE INSPECTION PROCESS PLAY

VIDEO: THE FLIGHT DAY 11 HIGHLIGHTS MOVIE PLAY
VIDEO: FRIDAY MORNING'S MISSION STATUS BRIEFING PLAY
VIDEO: BEHNKEN GIVES ANOTHER SHOT AT STUCK CONNECTOR PLAY
VIDEO: TILE SAMPLES AND DISPENSER STOWED IN PAYLOAD BAY PLAY
VIDEO: CLOSEUP VIEW OF THE 'REPAIRED' SHUTTLE TILES PLAY
VIDEO: SPACE SHUTTLE TILE REPAIR DEMONSTRATION - PART 2 PLAY
VIDEO: SPACE SHUTTLE TILE REPAIR DEMONSTRATION - PART 1 PLAY
VIDEO: TILE REPAIR DRY RUN PRACTICE WITH THE DISPENSER PLAY
VIDEO: SPACEWALKERS SET UP WORKSITE FOR TILE REPAIR TEST PLAY
VIDEO: FOREMAN FIGHTS WITH STUCK POWER CONNECTOR PLAY
VIDEO: ASTRONAUTS EGRESS AIRLOCK FOR EVA NO. 4 PLAY
VIDEO: TILE REPAIR DEMONSTRATION PREVIEW PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 4 PLAY
VIDEO: NARRATED ANIMATION OF FUTURE DEXTRE WORK PLAY
VIDEO: NARRATED ANIMATION OF JAPAN'S SECTION OF ISS PLAY

VIDEO: LAUNCH VIDEO FROM COCKPIT CAMERA W/INTERCOM PLAY

VIDEO: THE FLIGHT DAY 10 HIGHLIGHTS MOVIE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: CREW MEDIA INTERVIEWS WEDNESDAY NIGHT PLAY
VIDEO: JAPANESE VIP CALL TO STATION PLAY

VIDEO: THE FLIGHT DAY 9 HIGHLIGHTS MOVIE PLAY
VIDEO: TUESDAY NIGHT'S MISSION STATUS BRIEFING PLAY
VIDEO: LAUNCH CARRIER PALLET RETURNED TO SHUTTLE PLAY
VIDEO: DEXTRE ROBOT ATTACHED TO DESTINY LAB MODULE PLAY
VIDEO: NARRATED ANIMATION OF DEXTRE'S RELOCATION PLAY

VIDEO: THE FLIGHT DAY 8 HIGHLIGHTS MOVIE PLAY
VIDEO: TUESDAY MORNING'S MISSION STATUS BRIEFING PLAY
VIDEO: DEXTRE ROBOT FREED FROM LAUNCH PALLET PLAY
VIDEO: SECOND SPARE DCSU BOX PLACED ON THE STATION PLAY
VIDEO: SPACEWALKER UNABLE TO INSTALL MISSE EXPERIMENT PLAY
VIDEO: FIRST SPARE DCSU BOX PLACED ON THE STATION PLAY
VIDEO: SPARE YAW JOINT FOR STATION ARM TRANSFERRED PLAY
VIDEO: MOUNTING PLATE ATTACHED TO COLUMBUS PLAY
VIDEO: DEXTRE ROBOT FITTED WITH TOOL HOLDER PLAY
VIDEO: TOOL PLATFORM ATTACHED TO DEXTRE PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 3 PLAY

VIDEO: LEFT-HAND BOOSTER CAMERA LOOKING UPWARD PLAY
VIDEO: LEFT-HAND BOOSTER CAMERA LOOKING INBOARD PLAY
VIDEO: LEFT-HAND BOOSTER CAMERA LOOKING DOWNWARD PLAY
VIDEO: RIGHT-HAND BOOSTER CAMERA LOOKING UPWARD PLAY

VIDEO: THE FLIGHT DAY 7 HIGHLIGHTS MOVIE PLAY
VIDEO: DEXTRE MOVES ARMS FOR BRAKE TESTS PLAY
VIDEO: CREW MEDIA INTERVIEWS SUNDAY NIGHT PLAY
VIDEO: SUNDAY NIGHT'S MISSION STATUS BRIEFING PLAY

VIDEO: THE FLIGHT DAY 6 HIGHLIGHTS MOVIE PLAY
VIDEO: SUNDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SECOND ARM ATTACHED TO DEXTRE ROBOT PLAY
VIDEO: FIRST ARM ATTACHED TO THE DEXTRE ROBOT PLAY
VIDEO: SPACEWALKERS HELP DEXTRE DO A SIT-UP PLAY
VIDEO: SECOND DEXTRE ARM PULLED FROM LAUNCH CARRIER PLAY
VIDEO: FIRST ARM REMOVED FROM PALLET WITH FORCE PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 2 PLAY

VIDEO: THE FLIGHT DAY 5 HIGHLIGHTS MOVIE PLAY
VIDEO: SATURDAY MORNING MEDIA INTERVIEWS PLAY
VIDEO: STATION ARM GRAPPLES DEXTRE TO PROVIDE POWER PLAY
VIDEO: CEREMONY AT JAPANESE MODULE HATCH OPENING PLAY
VIDEO: SATURDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: FRIDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY

VIDEO: THURSDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: THE FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: NEW MODULE CONNECTED TO THE STATION PLAY
VIDEO: JAPANESE MODULE UNBERTHED FROM SHUTTLE PLAY
VIDEO: SPACEWALKER START ASSEMBLING DEXTRE ROBOT PLAY
VIDEO: JAPANESE MODULE PREPPED FOR UNBERTHING PLAY
VIDEO: HARMONY DOCKING PORT PREPPED PLAY
VIDEO: SPACEWALK NO. 1 BEGINS PLAY
VIDEO: NARRATED ANIMATION PREVIEWING JAPANESE JLP MODULE PLAY
VIDEO: NARRATED ANIMATION PREVIEWING MODULE MOVE PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 1 PLAY
VIDEO: THURSDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY

VIDEO: THE FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: DEXTRE PALLET MOVED FROM SHUTTLE TO STATION PLAY
VIDEO: NARRATED ANIMATION PREVIEWING DEXTRE ROBOT PLAY
VIDEO: NARRATED ANIMATION PREVIEWING PALLET MOVE PLAY
VIDEO: THURSDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SHUTTLE CREW WELCOMED ABOARD STATION PLAY
VIDEO: DOCKING REPLAY FROM OTHER TRUSS CAMERA PLAY
VIDEO: SHUTTLE ENDEAVOUR DOCKS TO SPACE STATION PLAY
VIDEO: ENDEAVOUR PERFORMS THE 360-DEGREE BACKFLIP PLAY
VIDEO: VIEWS OF THE SHUTTLE APPROACHING FROM BELOW PLAY
VIDEO: NARRATED ANIMATION OF PREVIEWING THE DOCKING PLAY
VIDEO: UPDATE FROM MISSION MANAGEMENT TEAM PLAY

VIDEO: THE FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: ANIMATION OF THE HEAT SHIELD INSPECTIONS PLAY
VIDEO: NARRATED TOUR OF ENDEAVOUR'S PAYLOAD BAY PLAY

VIDEO: THE FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: THE FULL LAUNCH EXPERIENCE PLAY
VIDEO: SHUTTLE ENDEAVOUR BLASTS OFF! PLAY
VIDEO: THE POST-LAUNCH NEWS CONFERENCE PLAY
VIDEO: HIGHLIGHTS FROM ENDEAVOUR'S LAUNCH CAMPAIGN PLAY
VIDEO: HIGHLIGHTS OF THE PAYLOADS' LAUNCH CAMPAIGN PLAY

VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: PAD FRONT PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY
VIDEO: LAUNCH REPLAY: UCS-23 WIDESCREEN PLAY
VIDEO: LAUNCH REPLAY: CAMERA 009 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 049 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 050 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 051 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 054 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 061 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 063 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 070 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 071 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY

VIDEO: FINAL PRE-LAUNCH POLLS GIVE "GO" FOR LIFTOFF PLAY
VIDEO: ENDEAVOUR'S CREW MODULE CLOSED FOR FLIGHT PLAY
VIDEO: ASTRONAUT DOI CLIMBS INTO HIS SEAT PLAY
VIDEO: PILOT JOHNSON CLIMBS INTO HIS SEAT PLAY
VIDEO: ASTRONAUT REISMAN CLIMBS INTO HIS SEAT PLAY
VIDEO: COMMANDER GORIE CLIMBS INTO HIS SEAT PLAY
VIDEO: ASTRONAUTS ARRIVE AT LAUNCH PAD 39A PLAY
VIDEO: CREW DEPARTS QUARTERS FOR LAUNCH PAD PLAY
VIDEO: ASTRONAUTS DON SPACESUITS FOR LAUNCH PLAY
VIDEO: TIME-LAPSE MOVIE OF SUNSET OVER PAD 39A PLAY
VIDEO: MORNING PREPARATIONS AT LAUNCH PAD 39A PLAY
VIDEO: PAD GANTRY RETRACTED FOR LAUNCH PLAY

VIDEO: OVERVIEW BRIEFING ON CANADA'S DEXTRE ROBOT PLAY
VIDEO: OVERVIEW BRIEFING ON JAPAN'S KIBO FACILITIES PLAY
VIDEO: SUNDAY'S COUNTDOWN STATUS BRIEFING PLAY
VIDEO: SATURDAY'S COUNTDOWN STATUS BRIEFING PLAY
VIDEO: CREW ARRIVES AT KENNEDY SPACE CENTER FOR LAUNCH PLAY
VIDEO: FRIDAY'S COUNTDOWN STATUS AND WEATHER BRIEFING PLAY

VIDEO: STS-123 ASTRONAUT BIOGRAPHY MOVIE PLAY
VIDEO: NARRATED SHORT FILM PREVIEW ENDEAVOUR'S FLIGHT PLAY

VIDEO: STS-123 MISSION OVERVIEW BRIEFING PLAY
VIDEO: BRIEFING ON THE SPACEWALKS PLAY
VIDEO: CREW'S PRE-FLIGHT BRIEFING PLAY
VIDEO: SHUTTLE AND ISS PROGRAM UPDATE PLAY

VIDEO: CREW INTERVIEW: COMMANDER DOM GORIE PLAY
VIDEO: CREW INTERVIEW: PILOT GREG JOHNSON PLAY
VIDEO: CREW INTERVIEW: MS1 BOB BEHNKEN PLAY
VIDEO: CREW INTERVIEW: MS2 MIKE FOREMAN PLAY
VIDEO: CREW INTERVIEW: MS3 TAKAO DOI PLAY
VIDEO: CREW INTERVIEW: MS4 RICK LINNEHAN PLAY

VIDEO: FLIGHT READINESS REVIEW NEWS BRIEFING PLAY
VIDEO: TCDT TRAINING HIGHLIGHTS PLAY
VIDEO: PRESS CHAT WITH CREW AT LAUNCH PAD PLAY
VIDEO: CREW ARRIVES AT KSC FOR PRACTICE COUNT PLAY
VIDEO: ENDEAVOUR ARRIVES AT PAD 39A PLAY | XL SIZE
VIDEO: SHUTTLE ROLLS TO THE VAB PLAY | XL SIZE
MORE: STS-123 VIDEO COVERAGE
SUBSCRIBE NOW