BY JUSTIN RAY

MONDAY, MARCH 24, 2008
2358 GMT (7:58 p.m. EDT)

Commanding of the latches on the 2B array of the Port 6 truss to engage has been reattempted, a NASA spokesman says. Undocking will occur about five minutes after the solar wing is locked in place.

2354 GMT (7:54 p.m. EDT)

The latching problem involves the arrays on the Port 6 truss on the far end of the station, Mission Control says. It could be 15 minutes before the latches can be locked.

2350 GMT (7:50 p.m. EDT)

It does appear undocking will be delayed at least a few minutes while station controllers work to get one of the solar wing gimbal assemblies locked.

2346 GMT (7:46 p.m. EDT)

Now 10 minutes from the scheduled undocking time. The shuttle crew is awaiting a final "go" for the departure to be radioed up from Mission Control. On the station-side, work is still underway to get one of the solar array beta gimbal assemblies latched for the undocking.

2220 GMT (6:20 p.m. EDT)

With hugs and handshakes, the Endeavour astronauts said farewell to their space station colleagues today, gathering one last time to mark the end of a marathon five-spacewalk assembly mission before floating back into the shuttle, closing hatches and preparing to undock.

European Space Agency astronaut Leopold Eyharts, launched to the station aboard the shuttle Atlantis in February to help activate ESA's new Columbus research module, departed with Endeavour's crew, leaving his replacement, Garrett Reisman, behind with Expedition 16 commander Peggy Whitson and flight engineer Yuri Malenchenko.

Read our full story.

2155 GMT (5:55 p.m. EDT)

The Endeavour astronauts bid farewell to their space station crewmates and then floated into the space shuttle around 5:15 p.m. in preparation for today's departure.

New station resident Garrett Reisman, with assistance by commander Peggy Whitson, pulled shut the hatch between the docking port and the Harmony module at 5:49 p.m. The hatch closure concluded 11 days, 16 hours and 21 minutes of joint operations between the Endeavour and station spacecraft.

1700 GMT (1:00 p.m. EDT)

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.

Read our full story.

SUNDAY, MARCH 23, 2008
1700 GMT (1:00 p.m. EDT)

With five spacewalks behind them, the Endeavour astronauts are enjoying a final few hours of off-duty time today before making preparations for undocking Monday evening. The joint shuttle-station crews will share an Easter meal later today before participating in a news conference to discuss the progress of the mission.

Read our full story.

0710 GMT (3:10 a.m. EDT)

Astronauts Bob Behnken and Mike Foreman staged a successful six-hour two-minute spacewalk Saturday, mounting the shuttle Endeavour's heat-shield inspection boom on the station, deploying an experiment package and carrying out a critical inspection of a stalled solar array positioning mechanism. It's still not clear what is causing internal contamination, but an impact from orbital debris does not appear to be the root cause.

Read our full story.

0236 GMT (10:36 p.m. EDT Sat.)

EVA ENDS. Repressurization of the Quest airlock module began at 10:36 p.m. EDT, marking the official end of today's spacewalk by Bob Behnken and Mike Foreman. It was the fifth and final spacewalk planned for Endeavour's STS-123 mission.

Tonight's EVA lasted 6 hours and 2 minutes. That brings the total time for the five spacewalks to 33 hours and 28 minutes.

0225 GMT (10:25 p.m. EDT Sat.)

Both spacewalkers are back inside the airlock.

0205 GMT (10:05 p.m. EDT Sat.)

The spacewalkers are doing tool inventories and progressing through their pre-airlock ingress activities as this EVA nears conclusion. All of the tasks planned for this evening have been accomplished.

0125 GMT (9:25 p.m. EDT Sat.)

Astronaut Bob Behnken successfully mounted an experiment package on the Columbus research module after initial attempts during a spacewalk last week were called off due to problems with an attachment fitting. Mike Foreman, meanwhile, was busy inspecting the space station's right-side solar alpha rotary joint, or SARJ. The SARJ uses a 10-foot-wide drive gear to turn outboard solar arrays to track the sun. But a problem of some sort has marred the right side bearing race ring and generated large amounts of metallic contamination.

Read our full story.

0120 GMT (9:20 p.m. EDT Sat.)

Mike Foreman now unbolting the fifth of the six SARJ covers slated for removal and inspections on this EVA. There hasn't been any major news from the joint inspections thus far tonight, though Foreman has been taking closeup photos for engineers to analyze.

0055 GMT (8:55 p.m. EDT Sat.)

While Foreman continues the SARJ inspections, Behnken has been given an extra task to complete for this EVA. He will be installing thermal covers on the strut pins protruding from the new Japanese logistics module. The pins were used to latch the module in Endeavour during launch.

0047 GMT (8:47 p.m. EDT Sat.)

Both MISSE cases have been opened by spacewalker Bob Behnken to expose the material samples contained in the packages to space.

0026 GMT (8:26 p.m. EDT Sat.)

The second experiment has been installed! Both MISSE 6A and 6B have been attached to the space station.

0017 GMT (8:17 p.m. EDT Sat.)

Behnken is unable to get the pins through the second MISSE attachment post, which is the problem experienced a few days ago on this particular bracket. He is going to use a hammer to lightly force the two pins into their holes to securely attach the experiment into place.

Foreman has completed photo-taking of the SARJ ring beneath the first cover. He is reinstalling that cover now.

0010 GMT (8:10 p.m. EDT Sat.)

The second MISSE package is being hauled up from the payload bay now. MISSE stands for the Materials International Space Station Experiment. These packages will expose various materials and coatings to the environment of low-Earth orbit for an extended duration of time. Scientists are looking at the effects of atomic oxygen, direct sunlight, radiation and temperature extremes on the test materials. Eventually, the cases will be retrieved and returned to the ground for analysis.

2356 GMT (7:56 p.m. EDT)

Behnken reports the first MISSE package has been installed and pinned in place. He will travel back to the payload bay and retrieve the second package, which will be mounted in the port that experienced the problem on the third EVA.

A graphic showing the experiment locations is posted here.

2345 GMT (7:45 p.m. EDT)

Down in the payload bay of space shuttle Endeavour, spacewalker Bob Behnken has retrieved the MISSE 6 materials exposure science experiment, a small suitcase-size package that he will carry up to a mounting plate on the station's Columbus laboratory. Attempts to install this experiment during the third spacewalk of Endeavour's flight weren't successful. Behnken will have various attachment options available tonight to secure the experiment in place.

Meanwhile, Mike Foreman has begun removing cover panels on the starboard-side space station truss rotary joint for inspections of the internal ring contamination.

2315 GMT (7:15 p.m. EDT)

Astronaut Garrett Reisman, operating the space station's robot arm, handed the shuttle Endeavour's 50-foot-long heat shield inspection boom to spacewalkers Bob Behnken and Mike Foreman, who plugged in keep-alive power and mounted it on the front of the station's solar power truss.

Read our full story.

2304 GMT (7:04 p.m. EDT)

Now two-and-a-half hours into today's EVA. With the boom installation work now completed, the two spacewalkers will be going their separate ways to accomplish different tasks. Astronaut Bob Behnken will try again to mount two science experiments to the Columbus lab's exterior, while Mike Foreman will head to the solar truss rotation joint on the station's starboard side for continued inspections of debris in that giant joint.

2250 GMT (6:50 p.m. EDT)

Foreman has slid a cover onto the end of the boom to shield the sensor package during this two-month storage in space. The shroud will guard against contamination and help with thermal protection.

2242 GMT (6:42 p.m. EDT)

Shuttle Endeavour's 50-foot-long heat shield inspection boom has been successfully installed onto the space station truss structure.

The boom will remain anchored there for the next two months until the crew of space shuttle Discovery arrives at the station in late May. The astronauts will use this boom to survey the shuttle's wings and nose cap to check for launch damage.

Unlike the previous shuttle missions that have included a boom in the payload bay, the Kibo science laboratory module being launched aboard Discovery is too large for the sensor platform to be carried as well.

2218 GMT (6:18 p.m. EDT)

The station arm has now moved the OBSS to the proper position for the spacewalkers to manually grab the boom for docking into the retention brackets.

2202 GMT (6:02 p.m. EDT)

A power check with the keep alive umbilical now attached to the OBSS confirms a good connection.

2200 GMT (6:00 p.m. EDT)

Astronaut Bob Behnken has plugged in the keep alive power cable to the Orbiter Boom Sensor System. This long cord running from the station to the OBSS will provide heater power to keep the boom's sensors and camera package warm and alive during the two-month storage on the station.

2142 GMT (5:42 p.m. EDT)

The station robot arm has moved the OBSS within just a few feet of the truss. The spacewalkers will reach out and connect the power extension cord.

2124 GMT (5:24 p.m. EDT)

The spacewalkers have bolted the keep alive umbilical equipment to the station truss. Now, they are working to mate connectors from the box to the station.

2120 GMT (5:20 p.m. EDT)

A graphic showing the OBSS' installation to the station is posted here.

2101 GMT (5:01 p.m. EDT)

The 50-foot-long Orbiter Boom Sensor System has been handed off from the shuttle arm to the space station's arm, which will maneuver the boom toward the truss for the spacewalkers to manually install onto brackets later tonight.

2035 GMT (4:35 p.m. EDT)

EVA BEGINS. The airlock has been depressurized and the outer hatchway to space has swung open. The spacewalkers switched their suits to internal battery at 4:34 p.m. EDT, marking the official start time for today's EVA by Bob Behnken and Mike Foreman.

2007 GMT (4:07 p.m. EDT)

Airlock depressurization is in progress.

1920 GMT (3:20 p.m. EDT)

Behnken and Foreman appear to be eager to get today's spacewalk underway. Both are suited in their EVA gear and Mission Control says the spacewalk preparations are running about 50 minutes ahead of schedule.

1725 GMT (1:25 p.m. EDT)

Astronauts Bob Behnken and Mike Foreman are preparing for a fifth and final spacewalk, a six-and-a-half hour excursion this evening to mount the shuttle Endeavour's 50-foot-long heat shield inspection boom on the space station for use by the next station assembly crew. The astronauts also plan to install an experiment package they were unable to attach earlier and inspect the station's right-side solar array rotary joint in an ongoing effort to determine what might be causing internal interference and contamination.

Read our full story.

0125 GMT (9:25 p.m. EDT Fri.)

The port wing observations as part of the late-inspections on STS-123 were completed, ironically, at 0123 GMT tonight.

This inspection of Endeavour's wings and nose cap to look for space debris hits normally occurs after a undocks from the station. But because the next shuttle mission, STS-124, will launch the massive Kibo science laboratory and the heat shield inspection boom won't fit in Discovery's payload bay, the Endeavour astronauts will leave their boom on the station. The Saturday evening spacewalk will mount the boom on the station's truss structure.

Meanwhile, space station crewmates Peggy Whitson and Garrett Reisman have transferred two large science facilities from the U.S. Destiny laboratory module to the European Space Agency's Columbus lab. The vibration-isolated Express 3 experiment rack and the microgravity science glovebox were pulled out of their previous locations and manually pushed to the new module.

0030 GMT (8:30 p.m. EDT Fri.)

Using the Orbiter Boom Sensor System attached to the end of Endeavour's robotic arm, the astronauts have completed the nose cap survey this evening. Earlier, the starboard wing's RCC panels were inspected. Still to come tonight is the port wing checks.

FRIDAY, MARCH 21, 2008
2009 GMT (4:09 p.m. EDT)

Inspections of the starboard wing's leading edge panels have begun.

1845 GMT (2:45 p.m. EDT)

The Endeavour astronauts are peforming a final heat shield inspection today before mounting the shuttle's inspection boom on the space station's solar power truss Saturday for use by the next station assembly crew. Shuttle crews normally carry out so-called "late inspections" after undocking from the station.

Read our full story.

0915 GMT (5:15 a.m. EDT)

With the shuttle Endeavour's mission entering the home stretch, shuttle Discovery remains on track for blastoff May 25 to ferry a huge Japanese laboratory module to the space station. But subsequent near-term flights, including a high-profile mission to service the Hubble Space Telescope, could be delayed, sources say, because of ongoing external tank production issues.

Read our full story.

0900 GMT (5:00 a.m. EDT)

Our post-spacewalk story has been updated after today's status briefing.

0455 GMT (12:55 a.m. EDT)

Astronaut Bob "Bam Bam" Behnken and Michael "Dr. Goo" Foreman wrapped up a six-hour 24-minutes spacewalk early today, successfully replacing a faulty circuit breaker and testing a promising heat-shield repair technique. The tile repair demonstration went smoothly and while a complete assessment will require detailed post-landing analysis, the astronauts were pleased with the initial results.

Read our full story.

0430 GMT (12:30 a.m. EDT)

EVA ENDS. Repressurization of the Quest airlock module began at 12:28 a.m. EDT, marking the official end of today's spacewalk by Bob Behnken and Mike Foreman.

The EVA lasted 6 hours and 24 minutes. That brings the total time for the four spacewalks conducted thus far during Endeavour's mission to 27 hours and 26 minutes.

This was the second EVA for both Behnken and Foreman. They will head outside again on Saturday night for EVA No. 5.

0359 GMT (11:59 p.m. EDT Thurs.)

Efforts by Behnken to release the stuck electrical cable have been unsuccessful. Both spacewalkers are about to begin tool inventories and head back to the airlock to wrap up this EVA.

0331 GMT (11:31 p.m. EDT Thurs.)

Astronaut Bob Behnken is making his way over to the Z1 truss to try reconfiguring some electrical cables associated with powering the station control gyros. Early in tonight's spacewalk, Mike Foreman was unable to get a stubborn connect freed from a patch panel. Behnken is going to give another shot.

0322 GMT (11:22 p.m. EDT Thurs.)

A thermal mitten covering one of the hands of the Canadian Dextre robot has been moved by spacewalker Mike Foreman.

0316 GMT (11:16 p.m. EDT Thurs.)

The eight launch lock on the port-side berthing port of Harmony have been released by spacewalker Mike Foreman. The Japanese Kibo science laboratory will be attached to this port during the next shuttle mission, STS-124.

0306 GMT (11:06 p.m. EDT Thurs.)

The tile samples and the repair tools have been stored in compartments down in space shuttle Endeavour's payload bay for the trip back to Earth.

A couple of extra tasks remaining for the spacewalk involves releasing some launch locks on one of the Harmony module's berthing ports and removing a thermal cover from one of Dextre's hands.

0225 GMT (10:25 p.m. EDT Thurs.)

Astronaut Mike Foreman earned some of the more unusual kudos in spacewalking history this evening during tests of a new heat shield repair technique. Filling deliberately damaged tiles with a thick pink toothpaste-like material, "Mr. Goo" was praised his skill as a "tile and grout specialist," a "brain surgeon" and a "Rembrandt" for his deft work.

Read our full story.

0205 GMT (10:05 p.m. EDT Thurs.)

Just past the four-hour mark in the EVA. The spacewalkers are stowing their tools and cleaning up the tile repair worksite before heading off to the remaining tasks in tonight's EVA.

0135 GMT (9:35 p.m. EDT Thurs.)

The sample box has been closed. All 10 samples were "repaired" during tonight's test. The samples will be returned to Earth aboard Endeavour for extensive research to determine how the repair material and techniques performed.

0127 GMT (9:27 p.m. EDT Thurs.)

Foreman is giving the samples some final smoothing with the brush. This demonstration has gone very well.

0120 GMT (9:20 p.m. EDT Thurs.)

A photo showing a large repair sample conducted on the ground is posted here.

You can see a photo here showing a ground repair sample that was later cut in half, revealing the internal bubbling. Tonight's in-space test will determine how these bubbles evolve in microgravity.

0107 GMT (9:07 p.m. EDT Thurs.)

These last four samples are patterned after actual tile damage seen previously on the shuttle and from ice-impact testing conducted on the ground.

0102 GMT (9:02 p.m. EDT Thurs.)

The first six samples are nearly complete. Foreman just performed a purge of the dispenser gun to get fresh tile repair material into the device before moving on to fill the final four samples.

0053 GMT (8:53 p.m. EDT Thurs.)

Now a third layer is being applied. Foreman is filling the material performance sample, the two density samples, the two adhesion samples and the multi-step sample, as depicted in this graphic of the box.

0042 GMT (8:42 p.m. EDT Thurs.)

A second layer of material has been dispensed into the six samples Foreman is working with right now.

0037 GMT (8:37 p.m. EDT Thurs.)

With several of the samples filled with the first layer of repair material, spacewalker Mike Foreman is using a small brush tool to press and smooth the material before it cures and hardens.

0035 GMT (8:35 p.m. EDT Thurs.)

A graphic of the box showing the tiles and samples to be filled with the repair material is posted here.

0030 GMT (8:30 p.m. EDT Thurs.)

The long-awaited tile repair demonstration test has begun. Foreman just pulled the trigger on the dispenser gun to start flowing the thick, putty-like repair material into the first tile sample.

A photo of the Tile Repair Ablator Dispenser (T-RAD) gun device is posted here.

0025 GMT (8:25 p.m. EDT Thurs.)

Foreman has been testing the gun by shooting some of the repair material into a container. The tile repair sample repairs will begin shortly.

0004 GMT (8:04 p.m. EDT Thurs.)

Working alongside is Behnken, who is operating the controls and pressurized the repair gun.

THURSDAY, MARCH 20, 2008
2357 GMT (7:57 p.m. EDT)

With the tile sample box now open, Foreman is doing a dry run with the repair gun to practice motions and such.

2340 GMT (7:40 p.m. EDT)

The spacewalkers are getting set to begin the tile repair demonstration on the Earth-facing hull of the Destiny laboratory module. A box of samples will be filled with the repair material over the next couple of hours, then stowed in the shuttle payload bay for return to Earth.

2330 GMT (7:30 p.m. EDT)

Astronaut Bob Behnken replaced a faulty space station circuit breaker today but fellow spacewalker Mike Foreman was unable to disconnect an electrical cable as part of a patch panel reconfiguration. As a result, flight controllers were not immediately able to switch one of the station's four stabilizing gyroscopes back to its own power supply as planned.

Read our full story.

2258 GMT (6:58 p.m. EDT)

Spacewalker Bob Behnken has successfully removed and replaced the failed circuit breaker. Mike Foreman, meanwhile, has been fighting with a stubborn electrical connector at the patch panel he is trying to reconfigure. Mission Control just radioed the crew, saying it was time to give up and move on with the spacewalk timeline.

2240 GMT (6:40 p.m. EDT)

The first item on the agenda is to replace the faulty circuit breaker, known as a remote power control module, or RPCM. As it now stands, two of the station's four control moment gyroscopes, or CMGs, are tied to a single RPCM. By replacing the faulty unit, the astronauts will restore lost redundancy.

Behnken will change out the circuit breaker in the central S0 solar array truss segment while Foreman moves to the Z1 truss atop the central Unity module to reconfigure an electrical patch panel.

2205 GMT (6:05 p.m. EDT)

EVA BEGINS. The airlock has been depressurized and the outer hatchway to space has swung open. The spacewalkers switched their suits to internal battery at 6:04 p.m. EDT, marking the official start time for tonight's EVA by Bob Behnken and Mike Foreman.

2143 GMT (5:43 p.m. EDT)

Depressurization of the Quest airlock down to 5.0 psi has occurred for a round of standard leak checks. Once these are completed, the pressure will be taken to vacuum in preparation for the start of tonight's spacewalk.

1900 GMT (3:00 p.m. EDT)

Astronauts Bob Behnken and Mike Foreman are gearing up for a six-and-a-half-hour spacewalk today to replace a faulty space station circuit breaker and to test a new heat shield repair technique that represents one of NASA's final post-Columbia safety upgrades.

Read our full story.

WEDNESDAY, MARCH 19, 2008

Midway through a grueling 16-day mission, the Endeavour astronauts and their space station counterparts enjoyed a second half-day off Wednesday, taking a call from Japan's prime minister and fielding questions from reporters before gearing up for a fourth spacewalk Thursday. In an interview with CBS News, station commander Peggy Whitson said the time off was a welcome break.

Read our full story.

TUESDAY, MARCH 18, 2008

The Spacelab pallet that carried to orbit the pieces of Canada's Dextre handyman robot was successfully returned to the payload bay of space shuttle Endeavour this evening, latching down at 11:54 p.m. EDT for its eventual ride back to Earth.

The Dextre robot was assembled during the first three spacewalks of Endeavour's mission, then freed from the pallet early Tuesday morning. After hanging on the space station's arm during the day while the astronauts slept, Dextre was maneuvered to the grapple fixture on Earth-facing side of the U.S. Destiny laboratory a couple of hours ago. It will remain there for the near-term.

Read our full story.

2030 GMT (4:30 p.m. EDT)

The Endeavour astronauts are gearing up for a busy day of work to move the Canadian Space Agency's Dextre robot to its new home on the space station's Destiny lab module. The robot's construction pallet, meanwhile, will be moved back to the shuttle's payload bay for return to Earth.

Read our full story.

0830 GMT (4:30 a.m. EDT)

Astronauts Richard Linnehan and Robert Behnken wrapped up a six-hour 53 minute spacewalk early today, completing assembly of a 3,400-pound Canadian maintenance robot and moving critical spare parts from the shuttle Endeavour to the space station.

"This really was the kind of spacewalk that, when it's all done, you just want to throw your hands up in the air and howl at the moon," said Zeb Scoville, lead spacewalk officer for Endeavour's mission. "It really was a great day for us. There were a few challenges we had along the way, but I consider this a real huge success for the EVA team, for the assembly of (the robot), getting all the (spares) transferred, is just a monumental feat by the robotics team and the EVA team together."

The only problem of any significance cropped up late in the spacewalk when two suitcase-size experiment packages designed to expose a variety of materials and coatings to the space environment could not be installed on the station's hull as planned because of problems getting the first package firmly locked in place.

Read our full story.

0608 GMT (2:08 a.m. EDT)

Astronauts Rick Linnehan and Bob Behnken wrapped up a six-hour 53 minute spacewalk early today, completing assembly of a Canadian maintenance robot and moving spare parts from the shuttle Endeavour to the space station. Two suitcase-size experiment packages designed to expose a variety of materials and coatings to the space environment could not be installed on the station's hull as planned because of problems getting the first package firmly locked in place.

Read our full story.

0600 GMT (2:00 a.m. EDT)

The EVA duration has been revised by a minute to 6 hours, 53 minutes. The total EVA time for STS-123 now stands at 21 hours and 2 minutes.

0549 GMT (1:49 a.m. EDT)

EVA ENDS. Repressurization of the Quest airlock module is underway, marking the official end of today's spacewalk by Rick Linnehan and Bob Behnken.

The EVA lasted 6 hours and 54 minutes. That brings the total time for the three spacewalks conducted thus far during Endeavour's mission to 21 hours and 3 minutes.

This was the third and final EVA for Linnehan during STS-123 and just the first for Behnken who will perform EVA Nos. 4 and 5 with fellow astronaut Mike Foreman in the coming days.

0448 GMT (12:48 a.m. EDT)

MISSE has been put back into its launch carrier on the sidewall of shuttle Endeavour's payload bay. Attempts to install the experiment package into a socket on the outside of the station's Columbus module were unsuccessful. Mission Control told spacewalker Bob Behnken to return the experiment to the shuttle.

Meanwhile, Rick Linnehan has placed the second of the two spare direct current switching units on the station stowage deck outside the Quest airlock module. This will complete the last major task for tonight's spacewalk.

Both astronauts will begin the cleanup tasks of putting away equipment and doing an inventory of tools before heading back inside to conclude this third EVA of the STS-123 mission.

0423 GMT (12:23 a.m. EDT)

Efforts to install the MISSE payload have been unsuccessful. It is going to be returned to the shuttle bay. Behnken reported he was unable to engage the pin to hold the suitcase-size package to the station bracket. Some metal shavings in the attachment fitting were noted by the spacewalker.

0410 GMT (12:10 a.m. EDT)

Linnehan is once again down in the payload bay to grab the second DCSU electical box for relocation to the station. Behnken is working to install MISSE 6 but is experiencing disfficulty getting the pins installed.

0342 GMT (11:42 p.m. EDT Mon.)

Spacewalker Bob Behnken has picked up the MISSE 6 science package in the payload bay to be carried up to the station for deployment. Meanwhile, Rick Linnehan is moving the first of two spare electronic boxes, called direct current switching units, or DCSUs, from the shuttle to an external storage platform on the station.

0310 GMT (11:10 p.m. EDT Mon.)

The spare station arm yaw joint has been delivered to the external stowage platform.

Still to come during the spacewalk, two spare electrical units and the MISSE 6 experiment launched on the shuttle will be moved to the station.

0239 GMT (10:39 p.m. EDT Mon.)

The arm has maneuvered Linnehan back to the payload bay to pick up a spare yaw joint that will be transferred from the shuttle to an external parts deck on the station. The joint was launched on Endeavour as part of a strategy to stockpile spare parts on the station for use when needed.

0222 GMT (10:22 p.m. EDT Mon.)

Rick Linnehan is connecting the mounting plate to one of the Columbus lab module's outboard external brackets. A materials exposure science package, called MISSE 6, will be installed on this plate later in tonight's spacewalk.

0208 GMT (10:08 p.m. EDT Mon.)

Bob Behnken just attached a camera package to Dextre, completing the complex assembly work on the robot that has occurred during all three spacewalks staged on Endeavour's mission thus far.

0151 GMT (9:51 p.m. EDT Mon.)

Now passing the three-hour mark in the EVA as Linnehan rides the arm down to the payload bay to retrieve a 200-pound mounting plate that will be installed on the station's Columbus module to house an external science experiment. Meanwhile, Behnken is adjusting thermal covers on Dextre and cleaning up the Spacelab carrier pallet for its eventual return to the shuttle payload bay.

0130 GMT (9:30 p.m. EDT Mon.)

Another piece of equipment -- a tool holder assembly -- has been attached below Dextre's right arm.

0116 GMT (9:16 p.m. EDT Mon.)

The tool platform has been successfully installed on Dextre, a task that required some extra effort by the spacewalkers. Their battery-powered tool couldn't engage the bolts, forcing the crew to manually ratchet the fasteners.

0045 GMT (8:45 p.m. EDT Mon.)

Riding on the end of the station's arm, astronaut Rick Linnehan has carried the Orbital Replacement Unit Tool Platform device from one side of the Dextre pallet to the other for attachment to the robot. A graphic illustrating Dextre is available here. The device being installed right now is labeled the OTP.

Mission Control says the spacewalkers have fallen about 30 minutes behind the EVA timeline.

0005 GMT (8:05 p.m. EDT Mon.)

A little more than an hour into the spacewalk, the crew is busy at the Spacelab pallet that has housed Dextre for launch. They are working to release the final pieces of equipment from the carrier for installation onto the robot.

2310 GMT (7:10 p.m. EDT)

Read our update story on the start of the spacewalk.

2252 GMT (6:52 p.m. EDT)

EVA BEGINS. The airlock has been depressurized and the outer hatchway to space has swung open. The spacewalkers switched their suits to internal battery at 6:51 p.m. EDT, marking the official start time for tonight's EVA by Rick Linnehan and Bob Behnken.

2220 GMT (6:20 p.m. EDT)

Depressurization of the Quest airlock has begun as preparations run ahead of schedule for this evening's spacewalk, the third of shuttle Endeavour's STS-123 mission to the space station.

2000 GMT (4:00 p.m. EDT)

Astronauts Richard Linnehan and Robert Behnken are gearing up for a planned six-and-a-half-hour spacewalk this evening to complete assembly of a Canadian maintenance robot and to move spare parts and an experiment package from the shuttle Endeavour to the international space station.

Read our full story.

SUNDAY, MARCH 16, 2008

The Canadian Space Agency's $209 million space station robot, Dextre, was subjected to joint-by-joint brake tests today to make sure the gangly mechanical handyman's 11-foot-long arms are working properly. All but one of the joints passed the first round of tests and managers said the one that didn't was only slightly out of limits and not a major concern.

Read our full story.

2015 GMT (4:15 p.m. EDT)

The Endeavour astronauts, well ahead of schedule in their space station assembly mission, face a busy day of work stowing equipment needed for the next shuttle mission and testing a Canadian maintenance robot nearing completion after two spacewalks.

Read our full story.

0658 GMT (2:58 a.m. EDT)

EVA ENDS. Repressurization of the Quest airlock module began at 2:57 a.m. EDT, marking the official end of today's spacewalk by Rick Linnehan and Mike Foreman.

The EVA lasted 7 hours and 8 minutes. That brings the total time for the two spacewalks conducted thus far during Endeavour's mission to 14 hours and 9 minutes.

0600 GMT (2:00 a.m. EDT)

Just past the six-hour mark in tonight's spacewalk. The crew is wrapping up its work on Dextre for this EVA and preparing to start the tool cleanup before heading back to the airlock.

0510 GMT (1:10 a.m. EDT)

The second arm has been connected to Dextre and the spacewalkers have gone to work securing it in place.

0500 GMT (1:00 a.m. EDT)

After falling behind schedule, astronauts Richard Linnehan and Michael Foreman have successfully attached the first of two 11-foot-long, seven-joint arms to the Dextre maintenance robot being assembled at the internaional space station.

Read our full story.

0450 GMT (12:50 a.m. EDT)

The first arm has been installed on the Dextre robot by spacewalkers Rick Linnehan and Mike Foreman. Next they'll be attaching the second arm, which has been waiting on a temporary location on the pallet for the past couple of hours.

0420 GMT (12:20 a.m. EDT)

Dextre's main body is being raised up in the Spacelab pallet in preparation for attachment of its two arms by the spacewalkers tonight. The first arm is temporarily stowed on the pallet while Foreman holds the second arm.

0353 GMT (11:53 p.m. EDT Sat.)

Releasing the second arm has gone considerably smoother than the first.

0340 GMT (11:40 p.m. EDT Sat.)

The spacewalkers are working on Dextre's second arm now. Releasing the fasteners on the arm is going to require a pry bar, just like the first arm a little while ago, Linnehan says.

0305 GMT (11:05 p.m. EDT Sat.)

Resorting to brute force and a pry bar, spacewalkers Rick Linnehan and Mike Foreman fell nearly an hour behind schedule tonight forcing two tight expansion bolts out of their receptacles. With grunts and heavy breathing, Linnehan finally forced the bolts out, releasing the first of two 775-pound mechanical arms.

Read our full story.

0255 GMT (10:55 p.m. EDT Sat.)

The first of Dextre's two 11-foot arms has been connected to a temporarily stowage position. The spacewalkers now must free some bolts and an umbilical between the robot's main body and the carrier pallet, then install the second arm.

0230 GMT (10:30 p.m. EDT Sat.)

The spacewalkers have found themselves about 50 minutes behind the EVA timeline due to difficulty releasing stubborn fasteners holding Dextre's first arm to the launch pallet. After giving some brute force, the crew finally got the arm freed for its upcoming attachment to Dextre's main body.

0010 GMT (8:10 p.m. EDT Sat.)

Running 34 minutes ahead of schedule, astronauts Richard Linnehan and Michael Foreman switched their spacesuits to battery power at 7:49 p.m., kicking off a planned seven-hour spacewalk to attach two 11-foot-long arms to a Canadian maintenance robot being assembled at the international space station.

Read our full story.

SATURDAY, MARCH 15, 2008
2350 GMT (7:50 p.m. EDT)

EVA BEGINS. The airlock has been depressurized and the outer hatchway to space has swung open. The spacewalkers switched their suits to internal battery at 7:48 p.m. EDT, marking the official start time for tonight's EVA by Rick Linnehan and Mike Foreman.

2320 GMT (7:20 p.m. EDT)

Depressurization of the station's Quest airlock module has begun for tonight's EVA. Dressed in their spacewalking spacesuits and ready to head outside, Linnehan and Foreman are running a half-hour ahead of the day's timeline.

2020 GMT (4:20 p.m. EDT)

Rick Linnehan and Mike Foreman are suiting up for a planned seven-hour spacewalk this evening to attach two 11-foot-long arms with gripper-like hands to the torso of a 12-foot-tall Canadian maintenance robot being assembled on the international space station.

Read our preview story.

1930 GMT (3:30 p.m. EDT)

The shuttle and station astronauts have been awakened to begin preparations for tonight's spacewalk that will continue assembly of the Dextre robot. The seven-hour EVA by Rick Linnehan and Mike Foreman is slated to begin at 8:23 p.m. EDT.

FRIDAY, MARCH 14, 2008

Here is our coverage from Flight Day 5 of Endeavour's mission:

• Day's preview story
• Crew enters new module
• Dextre comes alive

THURSDAY, MARCH 13, 2008

Astronauts Rick Linnehan and Garrett Reisman completed a 7-hour, 1-minute spacewalk overnight that prepare the Japanese logistics module for attachment to the space station and began assembly of a Canadian robot known as Dextre. The shuttle's arm mounted the new module to the station at 4:06 a.m.

Here is our coverage from Flight Day 4 of Endeavour's mission:

• Day's preview story
• EVA No. 1 begins
• Module prepped for move
• JLP unberthed from shuttle
• Software doesn't fix Dextre glitch

WEDNESDAY, MARCH 12, 2008
1030 GMT (6:30 a.m. EDT)

A high-tech Canadian robot, launched disassembled on large pallet, was moved from the Endeavour to a work site on the station early today. An initial attempt to route power to the pallet was not successful, but power is not required for the robot's initial assembly and the astronauts were told to press ahead with preparations for a spacewalk Thursday night.

Read our full story.

0745 GMT (3:45 a.m. EDT)

Our docking story has been updated with hatch opening and mission status briefing details.

0537 GMT (1:37 a.m. EDT)

HATCHES OPEN. The hatchway between Endeavour and the space station has been opened and the shuttle crew is being welcomed aboard the outpost now.

0420 GMT (12:20 a.m. EDT)

The shuttle Endeavour glided to a gentle docking with the space station as the two spacecraft sailed 212 miles above Malaysia at five miles per second. With commander Dominic Gorie at the controls, the shuttle's docking system engaged its counterpart on the front of the lab complex at 11:49 p.m. EDT to wrap up a two-day orbital chase that began with Endeavour's sky-lighting blastoff early Tuesday.

Read our full story.

0403 GMT (12:03 a.m. EDT)

The docking ring between the two craft has been retracted into the shuttle's Orbiter Docking System, pulling the station to a tight mating. And the hooks and latches have driven shut to firmly connect the two spacecraft.

Pressure and leak checks will be performed by the crews before the hatchway is opened.

0349 GMT (11:49 p.m. EDT Wed.)

CONTACT AND CAPTURE! Endeavour has arrived at the space station carrying the first Japanese module for the complex and Canada's two-armed Dextre servicing robot.

The relative motions of the shuttle and station will be allowed to damp out over the next few minutes by the spring-loaded docking system. Later, the hooks and latches will be closed to firmly join the two craft and Endeavour' Orbiter Docking System docking ring will be retracted to form a tight seal.

The opening of hatches between the station and shuttle is expected in about 90 minutes. That will be followed by a welcoming ceremony and safety briefing.

0349 GMT (11:49 p.m. EDT Wed.)

The distance to docking is now 5 feet.

0347 GMT (11:47 p.m. EDT Wed.)

Less than 15 feet separating the shuttle from the station. Endeavour' thrusters are programmed to fire in a post-contact maneuver to force the two docking ports together. That procedure is being armed.

0344 GMT (11:44 p.m. EDT Wed.)

About 25 feet to go. Endeavour is closing at less than one-tenth of a foot per second.

0342 GMT (11:42 p.m. EDT Wed.)

The final approach beginning. The alignment between docking ports on Atlantis and the space station is acceptable and no "fly out" maneuver by the shuttle is necessary.

0341 GMT (11:41 p.m. EDT Wed.)

The shuttle has closed to within 35 feet of the space station.

0336 GMT (11:36 p.m. EDT Wed.)

Endeavour and the station are 60 feet apart.

0328 GMT (11:28 p.m. EDT Wed.)

About 105 feet left to go.

0325 GMT (11:25 p.m. EDT Wed.)

The spacecraft are seeing the first light of an the orbital sunrise.

0320 GMT (11:20 p.m. EDT Wed.)

Mission Control estimates docking time will be roughly 11:45 p.m. based on the shuttle's approach rate.

0315 GMT (11:15 p.m. EDT Wed.)

About 200 feet separate the shuttle and station. Endeavour is closing at about two-tenths of a foot per second.

0307 GMT (11:07 p.m. EDT Wed.)

Now about 275 feet from docking.

0259 GMT (10:59 p.m. EDT Wed.)

The shuttle's crew has been given a "go" for docking.

0258 GMT (10:58 p.m. EDT Wed.)

The shuttle is reaching the point directly in front of the station along the imaginary line called the velocity vector, or +V bar. Endeavour is 372 feet from the station.

0240 GMT (10:40 p.m. EDT Wed.)

Endeavour is marking the arc from the point beneath the station to a point in front of the complex to align with the docking port on the Harmony module. Docking is about 45 minutes away.

0234 GMT (10:34 p.m. EDT Wed.)

The pitch maneuver has been completed. Endeavour is back in the orientation where it started, with the payload bay looking up at the station as the craft fly over the Pacific.

0232 GMT (10:32 p.m. EDT Wed.)

The main engine nozzles of Endeavour are facing the station now as the shuttle points its tail upward.

0230 GMT (10:30 p.m. EDT Wed.)

This 360-degree, nose-first pirouette by Endeavour gives the station crew about 100 seconds of quality photography time to snap detailed pictures of the orbiter's black tiles in the search for any launch impact damage.

0229 GMT (10:29 p.m. EDT Wed.)

The formal photo-taking period has started for the Expedition 16 crew, now that the shuttle has rotated its underside in view of the station complex.

0228 GMT (10:28 p.m. EDT Wed.)

Endeavour is nose-up facing the station as the two craft fly more than 200 miles above Australia.

0226 GMT (10:26 p.m. EDT Wed.)

The rendezvous pitch maneuver -- the 360-degree flip -- is beginning. The shuttle is the under the control of commander Dom Gorie, who is flying the ship from the aft flight deck.

As the shuttle's underside rotates into view, the station's crew will photograph Endeavour's belly with handheld digital cameras equipped with 400- and 800-millimeter lenses.

The 800mm images should provide one-inch resolution for examination of landing gear door and external tank umbilical door seals. The 400mm will yield three-inch resolution.

After completing the RPM maneuver, Endeavour will fly directly ahead of the space station with the shuttle's nose facing deep space and its cargo bay pointed at the lab complex. Then Gorie will guide the spacecraft to a docking with a pressurized mating adapter attached to the Harmony connecting module.

0220 GMT (10:20 p.m. EDT Wed.)

Endeavour has reached a point 600 feet directly beneath the station. The shuttle will hold this position until the RPM flip occurs a few minutes from now.

0205 GMT (10:05 p.m. EDT Wed.)

The shuttle is about 1,400 feet below the station. Mission Control has given the "go" for the upcoming rendezvous pitch maneuver.

0155 GMT (9:55 p.m. EDT Wed.)

Distance between the shuttle and station is less than 4,000 feet now. Endeavour has completed a couple of available mid-course correction burns during this approach to the station.

0100 GMT (9:00 p.m. EDT Wed.)

Space shuttle Endeavour is 50,000 feet away from the station and closing in for tonight's docking. Endeavour has performed the Terminal Initiation burn, which puts the shuttle on a trajectory to directly intercept the orbiting station over the next orbit and a half. This burn is the latest in a series of maneuvers performed by Endeavour during its two days of chasing the station since launch Tuesday.

Docking is anticipated at 11:25 p.m. EDT.

WEDNESDAY, MARCH 12, 2008
2020 GMT (4:20 p.m. EDT)

The Endeavour astronauts are closing in on the international space station today, on track for a docking around 11:25 p.m. EDT to kick off a five-spacewalk assembly mission.

Read our full story.

0755 GMT (3:55 a.m. EDT)

The astronauts unlimbered the shuttle's robot arm and inspected the ship's nose cap and wing leading edge panels with a laser scanner on the end of a 50-foot-long boom. The areas of the orbiter that experience the most extreme heating during re-entry appeared in good shape to the untrained eye, including the nose section where launch imagery indicates a possible bird or debris strike about 10 seconds after liftoff.

Read our full story.

TUESDAY, MARCH 11, 2008
1000 GMT (6:00 a.m. EDT)

Our launch story has been updated with cooling system problem details and initial debris report.

0839 GMT (4:39 a.m. EDT)

One piece of debris was spotted during the launch, passing by but not striking the right wing of Endeavour about 83 seconds into the flight, CAPCOM Jim Dutton just told the Endeavour crew.

0830 GMT (4:30 a.m. EDT)

An attempt by the crew to switch the flash evaporator cooling system back to its primary controller did not work. The system went to the backup controller during launch.

0829 GMT (4:29 a.m. EDT)

Mission Control just gave the astronauts a "go" for on-orbit operations following today's journey to space.

0827 GMT (4:27 a.m. EDT)

Both 60-foot-long payload bay doors have been opened.

0824 GMT (4:24 a.m. EDT)

Payload bay door opening is underway. The starboard door has swung out and latches have been released on the port door.

0741 GMT (3:41 a.m. EDT)

Two issues seen during this morning's ascent are deemed "minor" by Mission Management Team chairman LeRoy Cain and shouldn't affect the flight of Endeavour.

The flash evaporator cooling system switched to its backup controller. It is something that has been seen during previous launches and should be no impact to the mission, Cain said. The cooling system worked, albeit with less redundancy. Troubleshooting will be performed after the payload bay doors are opened in hopes of restoring the primary system for later use.

Also, there was a failure of a card in an electronics box, causing the loss of instrumentation data for a few of the shuttle's left-side steering thrusters. Cain said the thrusters probably wouldn't be used during the mission given the loss of insight by this box issue, but would be no impact to mission either.

0738 GMT (3:38 a.m. EDT)

The space shuttle Endeavour, carrying a crew of seven, a Japanese space station module and a high-tech Canadian robot with 11-foot-long arms, vaulted into orbit early today, lighting up the pre-dawn sky for miles around as it knifed through low clouds and rocketed away on a 16-day space station assembly mission.

Read our full story.

0708 GMT (3:08 a.m. EDT)

T+plus 40 minutes. The twin Orbital Maneuvering System engines on the tail of Endeavour have been fired successfully to propel the shuttle the rest of the way to orbit. The burn occurred over the Indian Ocean.

0707 GMT (3:07 a.m. EDT)

T+plus 38 minutes, 50 seconds. The maneuvering engines have ignited for the orbit raising burn.

0659 GMT (2:59 a.m. EDT)

T+plus 31 minutes. The two flapper doors on the belly of Endeavour are being commanded to swing shut to shield the umbilicals that had connected to the external fuel tank.

0644 GMT (2:44 a.m. EDT)

T+plus 16 minutes, 40 seconds. The three Auxiliary Power Units have been shut down as planned.

0638 GMT (2:38 a.m. EDT)

T+plus 10 minutes. An issue with reaction control system thrusters and the shuttle's flash evaporator cooling system switching from primary to backup were radioed to the crew during ascent. Standing by for additional details.

0637 GMT (2:37 a.m. EDT)

T+plus 9 minutes, 38 seconds. It was a nominal MECO. A quick boost from the Orbital Maneuvering System engines is not required to reach the planned preliminary sub-orbital trajectory.

0637 GMT (2:37 a.m. EDT)

T+plus 8 minutes, 47 seconds. The emptied external tank has been jettisoned from the belly of space shuttle Endeavour. The tank will fall back into the atmosphere where it will burn up harmlessly.

0636 GMT (2:36 a.m. EDT)

T+plus 8 minutes, 34 seconds. MECO. Main Engine Cutoff confirmed! Endeavour has reached orbit carrying the first module for Japan's Kibo science laboratory facilities and Canada's Dextre robot arm device.

0635 GMT (2:35 a.m. EDT)

T+plus 7 minutes, 40 seconds. The main engines are beginning to throttle down to ensure the shuttle does not experience forces greater than 3 g's as it continues to accelerate prior to engine shutdown.

0635 GMT (2:35 a.m. EDT)

T+plus 7 minutes, 4 seconds. Single engine press 104. The shuttle can reach orbit on the power from a single main engine should two fail at this point. But all three continue to fire properly.

0634 GMT (2:34 a.m. EDT)

T+plus 6 minutes, 14 seconds. "Press to MECO" Endeavour can now achieve a safe orbit on two engines. All three remain in good shape.

0634 GMT (2:34 a.m. EDT)

T+plus 6 minutes. The shuttle has started rolling to a heads-up position to improve communications with the TDRS satellite network.

0633 GMT (2:33 a.m. EDT)

T+plus 5 minutes, 35 seconds. Endeavour is 294 miles northeast of the launch pad at an altitude of 67 miles.

0633 GMT (2:33 a.m. EDT)

T+plus 5 minutes, 6 seconds. "Press to ATO". Endeavour can reach an orbit, albeit a low orbit, on two engines should one shut down now. But all three powerplants are still running just fine.

0632 GMT (2:32 a.m. EDT)

T+plus 4 minutes, 30 seconds. Endeavour will be tripling its speed in the next four minutes to reach orbital velocity of 17,500 mph.

0632 GMT (2:32 a.m. EDT)

T+plus 4 minutes. Negative return. The shuttle has passed the point where Endeavour could turn around and make an emergency landing at Kennedy Space Center in the event of a main engine problem. Landing sites in France and Spain are now available to Endeavour in the unlikely event an abort occurs during the remainder of today's launch.

0631 GMT (2:31 a.m. EDT)

T+plus 3 minutes, 45 seconds. Endeavour is nearing 300,000 feet in altitude, 115 miles downrange from the launch pad.

0631 GMT (2:31 a.m. EDT)

T+plus 3 minutes. Commander Dom Gorie just received the "Two-engine TAL" call from CAPCOM Jim Dutton in Mission Control. The call means Endeavour can now reach a Transatlantic Abort Landing site if one main engine fails. However, all three engines continue to burn normally.

0630 GMT (2:30 a.m. EDT)

T+plus 2 minutes, 45 seconds. The twin Orbital Maneuvering System engines on the ship's tail have ignited to provide an extra boost in thrust in addition to Endeavour's three main engines.

0630 GMT (2:30 a.m. EDT)

T+plus 2 minutes, 20 seconds. Guidance is converging as programmed. Endeavour's engine nozzles are swiveling to steer the ship toward a precise point for main engine cutoff about six minutes from now.

0630 GMT (2:30 a.m. EDT)

T+plus 2 minutes, 10 seconds. Mission Control confirms a good jettison of the solid rocket boosters has occurred. The spent boosters will parachute into the Atlantic Ocean for retrieval. Endeavour continues its nighttime streak toward space on the power generated by the three liquid-fueled main engines.

0629 GMT (2:29 a.m. EDT)

T+plus 1 minute, 45 seconds. Standing by for burn out and separation of the twin solid rockets. Commander Dom Gorie and pilot Greg Johnson are joined on the flight deck by mission specialists Bob Behnken and Mike Foreman. Rick Linnehan, Japanese astronauts Takao Doi and station-bound Garrett Reisman are seated down on the middeck.

0629 GMT (2:29 a.m. EDT)

T+plus 90 seconds. The space shuttle now weighs just half of what it did at liftoff. The solid rocket boosters are burning 11,000 pounds of propellant every second. The main engines are guzzling a half-ton of liquid fuel per second from the external tank.

0629 GMT (2:29 a.m. EDT)

T+plus 80 seconds. Endeavour is 51,000 feet in altitude, 11 miles downrange from the launch pad.

0629 GMT (2:29 a.m. EDT)

T+plus 70 seconds. Endeavour's three main engines have revved up to their 104 percent power setting. And Mission Control has given the "go at throttle up" call.

0629 GMT (2:29 a.m. EDT)

T+plus 60 seconds. All systems are looking good one minute into the flight. Endeavour is traveling on a northeastward trajectory toward orbit, its speed already in excess of 1,000 miles per hour as the main engines and twin solid rockets generate nearly 7 million pounds of thrust.

0628 GMT (2:28 a.m. EDT)

T+plus 35 seconds. Endeavour's three liquid-fueled main engines are easing back to two-thirds throttle to reduce the aerodynamic stresses on the vehicle as it powers through the dense lower atmosphere and breaks the sound barrier.

0628 GMT (2:28 a.m. EDT)

T+plus 20 seconds. Endeavour has maneuvered on the proper heading to rendezvous with the space station tomorrow night to deliver the first Japanese module to the complex and Canada's two-armed Dextre servicing robot.

0628:14 GMT (2:28:14 a.m. EDT)

T-minus 10 seconds, go for main engine start, fuel valves are opening, engine ignition, 3, 2, 1 and LIFTOFF! Liftoff of Endeavour on the 25th space shuttle construction flight to the International Space Station!

0627:43 GMT (2:27:43 a.m. EDT)

T-minus 31 seconds. AUTO SEQUENCE START! The handoff has occurred from the Ground Launch Sequencer to the space shuttle. Endeavour's computers now controlling.

In the next few seconds, the solid rocket booster hydraulic steering system will be started, the orbiter's body flap and speed brake moved to their launch positions, the firing chain armed. Main engine ignition begins at T-minus 6.6 seconds.

0627:14 GMT (2:27:14 a.m. EDT)

T-minus 1 minute. Computers are verifying that the main engines are ready for ignition. Sound suppression water system is armed. The system will activate at T-minus 16 seconds to suppress the sound produced at launch. And the residual hydrogen burn ignitors are armed. They will be fired at T-minus 10 seconds to burn off hydrogen gas from beneath the main engine nozzles.

Shortly, the external tank strut heaters will be turned off; Endeavour will transition to internal power; the liquid oxygen and liquid hydrogen outboard fill and drain valves will be closed; the payload bay vent doors will be positioned for the launch; and the gaseous oxygen vent arm will be verified fully retracted.

0626:44 GMT (2:26:44 a.m. EDT)

Now 90 seconds from launch. All remains "go" for liftoff of Endeavour and the seven-man crew at 2:28 a.m.

0626:14 GMT (2:20:14 a.m. EDT)

T-minus 2 minutes. The astronauts are being instructed to close and lock the visors on their launch and entry helmets.

At T-minus 1 minute, 57 seconds the replenishment to the flight load of liquid hydrogen in the external tank will be terminated and tank pressurization will begin.

0625:44 GMT (2:25:44 a.m. EDT)

T-minus 2 minutes, 30 seconds. The external tank liquid oxygen vent valve has been closed and pressurization of the LOX tank has started.

Endeavour's power-producing fuel cells are transfering to internal reactants. The units will begin providing all electricity for the mission beginning at T-50 seconds.

And pilot Greg Johnson has been asked to clear the caution and warning memory system aboard Endeavour. He will verify no unexpected errors in the system.

In the next few seconds, the gaseous oxygen vent hood will be removed from atop the external tank. Verification that the swing arm is fully retracted will be made by the ground launch sequencer at the T-minus 37 second mark.

0625:14 GMT (2:25:14 a.m. EDT)

T-minus 3 minutes. Orbiter steering check is now complete; the main engine nozzles are in their start positions.

0624:44 GMT (2:24:44 a.m. EDT)

T-minus 3 minutes, 30 seconds. The main engine nozzles now being moved through a computer controlled test pattern to demonstrate their readiness to support guidance control during launch today.

0624:14 GMT (2:24:14 a.m. EDT)

T-minus 4 minutes. Activation of the APUs is complete. The three units are up and running normally.

And the final helium purge sequence is underway in the main propulsion system. This procedure readies fuel system valves for engine start. In the next few seconds, the aerosurfaces of Endeavour will be run through a pre-planned mobility test to ensure readiness for launch. This is also a dress rehearsal for flight of the orbiter's hydraulic systems.

0623:14 GMT (2:23:14 a.m. EDT)

T-minus 5 minutes. The "go" has been given for for Auxiliary Power Unit start. Pilot Greg Johnson is now flipping three switches in Endeavour's cockpit to start each of the three APU's. The units, located in the aft compartment of Endeavour, provide the pressure needed to power the hydraulic systems of the shuttle. The units will be used during the launch and landing phases of the mission for such events as moving the orbiter's aerosurfaces, gimbaling the main engine nozzles and deploying the landing gear.

Over the course of the next minute, the orbiter's heaters will be configured for launch by commander Dom Gorie, the fuel valve heaters on the main engines will be turned off in preparation for engine ignition at T-6.6 seconds and the external tank and solid rocket booster safe and arm devices will be armed.

0622:44 GMT (2:22:44 a.m. EDT)

T-minus 5 minutes, 30 seconds. APU pre-start is complete and the units are ready for activation. The orbiters flight data recorders have gone into the record mode to collect measurements of shuttle systems performance during flight.

0622:14 GMT (2:22:14 a.m. EDT)

T-minus 6 minutes. Pilot Greg Johnson has been asked by the orbiter test conductor to pre-start the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation after the countdown passes T-minus 5 minutes.

0620:44 GMT (2:20:44 a.m. EDT)

T-minus 7 minutes, 30 seconds. The Ground Launch Sequencer has started pulling the orbiter access arm away from the crew hatch on the port side of the vehicle. The arm was the passage way for the astronauts to board Endeavour a few hours ago. The arm can be re-extended very quickly should the need arise later in the countdown.

0620:14 GMT (2:20:14 a.m. EDT)

T-minus 8 minutes and counting. Pilot Greg Johnson has flipped the switches in the cockpit of Endeavour to directly connect the three onboard fuel cells with the essential power buses. Also, the stored program commands have been issued to the orbiter.

0619:14 GMT (2:19:14 a.m. EDT)

T-minus 9 minutes and counting! The Ground Launch Sequencer has been initiated. The computer program is located in a console in the Firing Room of the Complex 39 Launch Control Center. The GLS is the master of events through liftoff. During the last 9 minutes of the countdown, the computer will monitor as many as a thousand different systems and measurements to ensure that they do not fall out of any pre-determine red-line limits. At T-minus 31 seconds, the GLS will hand off to the onboard computers of Endeavour to complete their own automatic sequence of events through the final half minute of the countdown.

0615 GMT (2:15 a.m. EDT)

NASA launch director Mike Leinbach has conducted his poll and given approval to resume the countdown for liftoff at 2:28 a.m. this morning!

"It should be interesting for you to punch through the clouds tonight," Leinbach radioed commander Dom Gorie.

"You've just made a lot of people smile around the world, and you've got seven smiling faces here on Endeavour," Gorie said.

0614 GMT (2:14 a.m. EDT)

The final readiness poll by the NASA test director Steve Payne confirms there are no technical issues being addressed. The Range also reports "go" on the local weather. And Mission Control says that the abort landing site weather is acceptable, too.

0609 GMT (2:09 a.m. EDT)

Ten minutes are remaining in this built-in hold. Final readiness polls will be conducted over the next few minutes.

0607 GMT (2:07 a.m. EDT)

Weather conditions here at the Cape remain stable and "go" for launch. The clouds over the launch site are between 6,300 and 6,500 feet.

0558 GMT (1:58 a.m. EDT)

Now 30 minutes from Endeavour's launch on an eight-and-a-half minute trek to space. At main engine cutoff, Endeavour will be flying on a suborbital trajectory with a high point of 136 statute miles and low point of 36 nautical miles. A half-hour later, the twin orbital maneuvering engines will be fired to place the shuttle into a 140 by 98 mile orbit.

0550 GMT (1:50 a.m. EDT)

The International Space Station is orbiting 220 miles above Earth. At launch, it will be south of Perth, Australia. Liftoff is timed to place Endeavour on course to dock with the station at 11:20 p.m. EDT on Wednesday night.

0539 GMT (1:39 a.m. EDT)

Weather continues to be acceptable for the launch both here at the Kennedy Space Center and the primary abort landing site across the Atlantic in Zaragoza, Spain.

0534 GMT (1:34 a.m. EDT)

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 45-minute, 14-second built-in hold. Today's launch remains set for 2:28:14 a.m. EDT.

0532 GMT (1:32 a.m. EDT)

Mission Control in Houston has loaded Endeavour's onboard computers with the proper guidance parameters based on the projected launch time.

0531 GMT (1:31 a.m. EDT)

The Main Propulsion System helium system is being reconfigured by pilot Greg Johnson. Soon the gaseous nitrogen purge to the aft skirts of the solid rocket boosters will be started.

0528 GMT (1:28 a.m. EDT)

Now one hour away from launch of Endeavour.

Pilot Greg Johnson is configuring the displays inside Endeavour's cockpit for launch while commander Dom Gorie enables the abort steering instrumentation.

0523 GMT (1:23 a.m. EDT)

T-minus 20 minutes and counting. The countdown has resumed after a 10-minute hold. Clocks will tick down for the next 11 minutes to T-minus 9 minutes where the final planned hold is scheduled to occur. The hold length will be adjusted to synch up with today's preferred launch time of 2:28:14 a.m.

Endeavour's onboard computers are now transitioning to the Major Mode-101 program, the primary ascent software. Also, engineers are dumping the Primary Avionics Software System (PASS) onboard computers. The data that is dumped from each of PASS computers is compared to verify that the proper software is loaded aboard for launch.

0513 GMT (1:13 a.m. EDT)

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch is scheduled for 2:28 a.m. EDT. Everything is going smoothly with the countdown and current weather conditions are acceptable. There are low-level clouds over the Cape but they are not violating the any of the weather rules right now.

During this built-in hold, all computer programs in Firing Room 4 of the Complex 39 Launch Control Center will be verified to ensure that the proper programs are available for the countdown; the landing convoy status will be verified and the landing sites will be checked to support an abort landing during launch today; the Inertial Measurement Unit preflight alignment will be verified completed; and preparations are made to transition the orbiter onboard computers to Major Mode 101 upon coming out of the hold. This configures the computer memory to a terminal countdown configuration.

A short time ago, commander Dom Gorie pressurized the gaseous nitrogen system for Endeavour's Orbital Maneuvering System engines and pilot Greg Johnson activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

0456 GMT (12:56 a.m. EDT)

The official launch window this morning opens at 2:23:18 a.m. and closes at 2:33:05 a.m. EDT. Liftoff is targeted to occur in the middle of the window at 2:28:14 a.m. EDT.

0454 GMT (12:54 a.m. EDT)

The ground pyro initiator controllers (PICs) are scheduled to be powered up around this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.

The shuttle's two Master Events Controllers are being tested. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

0433 GMT (12:33 a.m. EDT)

Now passing the T-minus 1 hour mark in the countdown. Two scheduled holds are planned at T-minus 20 minutes and T-minus 9 minutes, leading to the target liftoff time of 2:28:14 a.m. EDT.

The final pre-flight alignment of Endeavour's guidance system inertial measurement units is underway.

0428 GMT (12:28 a.m. EDT)

Just two hours remain until the planned liftoff time.

0427 GMT (12:27 a.m. EDT)

The shuttle's crew compartment hatch is confirmed to be closed and latched for flight.

0418 GMT (12:18 a.m. EDT)

And now Endeavour's crew module hatch is swinging shut for launch.

0415 GMT (12:15 a.m. EDT)

The "go" has been given to close Endeavour's hatch.

0403 GMT (12:03 a.m. EDT)

T-minus 90 minutes and counting. Countdown clocks continue to tick down to T-minus 20 minutes where the next hold is planned. Countdown activities remain on track for liftoff at 2:28 a.m. There are no technical issues being worked and weather continues to be acceptable.

At this point in the count, the Ground Launch Sequencer software that will control the final nine minutes of the countdown has been initialized. Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first stage of flight.

0346 GMT (11:46 p.m. EDT Mon.)

The final crewmember just boarded Endeavour. Mike Foreman serves as mission specialist No. 2 and the flight engineer on STS-123. He will ride in the flight deck's aft-center seat.

Read his biography here.

0335 GMT (11:35 p.m. EDT Mon.)

Japanese astronaut Takao Doi serves as mission specialist No. 3 on Endeavour's STS-123 flight. He just entered the orbiter to take the center seat on the middeck.

Read his biography here.

0334 GMT (11:34 p.m. EDT Mon.)

Rookie astronaut Bob Behnken is mission specialist No. 1 for Endeavour. He is climbing to the flight deck's aft-right seat.

Read his biography here.

0328 GMT (11:28 p.m. EDT Mon.)

Three hours and counting until liftoff time.

0324 GMT (11:24 p.m. EDT Mon.)

Rick Linnehan just entered the orbiter to take the middeck's left seat. The veteran of two Spacelab missions in 1996 and 1998, plus the most recent Hubble Space Telescope servicing flight in 2002, is mission specialist No. 4 for STS-123.

Read his biography here.

0322 GMT (11:22 p.m. EDT Mon.)

Greg Johnson, an Air Force colonel and the rookie astronaut pilot of Endeavour, is making his way to the flight deck's front-right seat.

Read his biography here.

0313 GMT (11:13 p.m. EDT Mon.)

Station-bound crewmember Garrett Reisman, a rookie NASA astronaut, has boarded Endeavour to take the middeck's right-side seat. He will move aboard the station for an extended stay as part of the Expedition crew, replacing European astronaut Leopold Eyharts.

Read his biography here.

0309 GMT (11:09 p.m. EDT Mon.)

Commander Dom Gorie is the first astronaut to board the shuttle. He is taking the forward-left seat on the flight deck.

The retired Navy captain has flown three previous shuttle missions -- as pilot of STS-91 to the Russian space station Mir in 1998 and the STS-99 shuttle radar mapping mission in 2000 and commander of STS-108 to the International Space Station in 2001. Read his biography here.

0256 GMT (10:56 p.m. EDT Mon.)

Endeavour's crew arrived at launch pad 39A at 10:56 p.m. The AstroVan came to a stop on the pad surface near the Fixed Service Structure tower elevator that will take the seven-man crew to the 195-foot level to begin boarding the shuttle.

0249 GMT (10:49 p.m. EDT Mon.)

The AstroVan is passing the 52-story Vehicle Assembly Building where Endeavour was attached to its external tank and solid rocket boosters and the adjacent Launch Control Center.

The Press Site is located across the street, and reporters went outside to watch at the passing convoy. This is a launch day tradition to say farewell and good luck to the astronaut crews.

0239 GMT (10:39 p.m. EDT Mon.)

Commander Dom Gorie, the crew includes pilot Greg Johnson, mission specialists Bob Behnken, Mike Foreman, Takao Doi, Rick Linnehan and station-bound crewmember Garrett Reisman just departed the Kennedy Space Center crew quarters to board the AstroVan for the 20-minute ride from the Industrial Area to launch pad 39A on the edge of the Atlantic Ocean.

0233 GMT (10:33 p.m. EDT Mon.)

T-minus 3 hours and counting. The countdown clocks are ticking again after the planned two-and-a-half hour built-in hold. Clocks will proceed to T-minus 20 minutes when the next hold is scheduled. A final hold occurs at the T-minus 9 minute mark to synch up with the 2:28 a.m. EDT launch time.

0212 GMT (10:12 p.m. EDT Mon.)

The crew has donned the day-glow orange launch and entry partial pressure spacesuits. After final adjustments and pressure checks, the astronauts will depart the suitup room and take the elevator down to the ground level of the Operations and Checkout Building to board the AstroVan for the trip to launch pad 39A around 10:38 p.m.

0158 GMT (9:58 p.m. EDT Mon.)

Commander Dom Gorie, pilot Greg Johnson and flight engineer Mike Foreman have received a weather briefing on expected conditions at the Kennedy Space Center and the primary abort landing sites. Weather is not expected to be a constraint to launching on time tonight. Meanwhile, the rest of the crew is moving into the suitup room to start donning their suits.

Schedules call for the seven astronauts to depart crew quarters at 10:38 p.m. for the trip out to the launch pad for boarding the shuttle tonight.

0135 GMT (9:35 p.m. EDT Mon.)

All continues go well in the countdown for the 2:28 a.m. EDT launch of Endeavour. The launch team is not working any issues of significance and the weather forecast still predicts a 90 percent chance of acceptable conditions for the liftoff.

0045 GMT (8:45 p.m. EDT Mon.)

The Final Inspection Team is performing its observations of Endeavour this evening.

The team is responsible for checking the shuttle and launch pad one last time prior to liftoff. The team is comprised of engineers and safety officials from NASA, United Space Alliance and tank-builder Lockheed Martin. At the conclusion of their two-hour tour-of-duty, the team will have walked up and down the entire fixed service structure and mobile launcher platform.

The team is on the lookout for any abnormal ice or frost build-up on the vehicle and integrity of the external tank foam insulation.

The team uses a portable infrared scanner that gathers temperature measurements on the surface area of the shuttle and can spot leaks. The scanner will be used to obtain temperature data on the external tank, solid rocket boosters, space shuttle orbiter, main engines and launch pad structures. The scanner can also spot leaks of the cryogenic propellants, and due to its ability to detect distinct temperature differences, can spot any dangerous hydrogen fuel that is burning. The team member also is responsible for photo documentation.

The team wears the highly visible day-glow orange coveralls that are anti-static and flame resistant. Each member also has a self-contained emergency breathing unit that holds about 10 minutes of air.

0010 GMT (8:10 p.m. EDT Mon.)

FUELING COMPLETED. The external fuel tank has been pumped full with a half-million gallons of supercold liquid oxygen and liquid hydrogen. The three-hour fueling process started at 5:04 p.m. with the chilldown conditioning and was completed at 8:05 p.m.

But given the cryogenic nature of the oxidizer and propellant, the supplies naturally boil away. So the tanks are continuously topped off until the final minutes of the countdown in a procedure called "stable replenishment."

With the hazardous tanking operation completed, the Orbiter Closeout Crew and Final Inspection Team have been given the OK to go out to the pad to perform their jobs. The closeout crew will ready Endeavour's crew module for the astronauts' ingress in a couple of hours; and the inspection team will give the entire vehicle a check for any ice formation following fueling.

0003 GMT (8:03 p.m. EDT Mon.)

T-minus 3 hours and holding. The countdown has entered the next planned hold. This pause will last two-and-a-half hours.

MONDAY, MARCH 10, 2008
2320 GMT (7:20 p.m. EDT)

The three-hour loading of the external tank is in the final phases now. All has gone well during this evening's fueling of Endeavour, NASA says.

2250 GMT (6:50 p.m. EDT)

The schedule for Endeavour's seven astronauts tonight began with their wakeup call at 5:30 p.m., breakfast at 6 p.m. and final medical exams at 6:30 p.m.

They'll gather in the crew quarters dining room at 8:55 p.m. for the traditional pre-launch photo, then receive a weather briefing at 9:58 p.m., begin suiting up at 10:08 p.m. and head for the launch pad at 10:38 p.m.

2215 GMT (6:15 p.m. EDT)

The liquid hydrogen low-level engine cutoff sensors in the bottom of the external tank have undergone initial testing today after they were submerged by propellant during the first hour of fueling. The launch team sent commands to test the health of the sensors and a NASA spokesman says the expected readings were received from the sensors, indicating all four are working properly.

2200 GMT (6:00 p.m. EDT)

Filling of the space shuttle's external fuel tank takes about three hours to complete, and keeping the tank fully loaded continues until just minutes before liftoff time.

The process starts with the chilldown thermal conditioning of the system, followed by a slow-fill mode and then the fast-fill mode. The tank then enters a stable replenishment mode that ensures the liquid hydrogen and liquid oxygen supplies are topped off through the final minutes of the countdown.

The cryogenics are pumped from storage spheres at the pad, through feed lines to the mobile launcher platform, into Endeavour's aft compartment and finally into the external fuel tank.

There are two tanks inside the shuttle's external fuel tank. The liquid oxygen tank occupies the top third of the bullet-shaped tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit. The liquid hydrogen tank is contained in the bottom two-thirds of the external tank. It holds 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit.

2114 GMT (5:14 p.m. EDT)

FUELING UNDERWAY. The filling of space shuttle Endeavour's external fuel tank with a half-million gallons of supercold propellants has begun at launch pad 39A.

The tanking operation commenced with the chilldown thermal conditioning process at 5:04 p.m.

2103 GMT (5:03 p.m. EDT)

The Mission Management Team has given a "go" to begin fueling space shuttle Endeavour for tonight's launch. Engineers in Firing Room 4 will start the three-hour fueling process shortly.

The coundown has just resumed ticking after the two-hour planned hold at the T-minus 6 hour mark. The next scheduled hold occurs at T-minus 3 hours.

Liftoff is targeted for precisely 2:28:14 a.m. EDT.

1730 GMT (1:30 p.m. EDT)

The weather forecast for tonight's launch remains excellent with a 90 percent chance of acceptable conditions for the 2:28 a.m. EDT liftoff time.

"Today partly cloudy skies and northeasterly winds will prevail for the daylight hours. Overnight Monday and into launch time on Tuesday, generally favorable weather conditions will continue with a slight chance of a low cloud ceiling moving onshore over Kennedy Space Center during the launch countdown. Our primary concern for launch time is a low cloud ceiling," the weather team reported this morning.

The launch time outlook calls for scattered stratocumulus clouds at 3,000 feet, scattered altocumulus clouds at 8,000 feet and broken cirrus clouds at 25,000 feet, good visibility, northeasterly winds from 060 degrees at 8 peaking to 12 knots and a temperature of 63 degrees F.

Should the launch be delayed for any reason, the odds of good weather on Wednesday morning are 70 percent and fall to 60 percent on Thursday morning.

"On Wednesday and Thursday, an upper level feature is forecast to move into Florida increasing the chance of low cloud ceilings and possible precipitation."

1545 GMT (11:45 a.m. EDT)

Rollback of a protective gantry from the shuttle Endeavour was delayed today while engineers replaced a suspect cockpit audio cable that will be used by flight engineer Mike Foreman during the climb to space early Tuesday. Tower rollback was delayed about three hours, but by 9 a.m., the huge gantry was in its launch position and engineers said the snag would not have any impact on the remainder of Endeavour's countdown.

Read our full story.

1245 GMT (8:45 a.m. EDT)

The rotating service structure just moved away from the space shuttle, exposing Endeavour at pad 39A on a day in which the spacecraft will be fueled for Tuesday's 2:28 a.m. EDT blastoff.

Work this morning include activating the orbiter's inertial measurement units and power-generating fuel cells, plus checking all of the switches in Endeavour's cockpit to ensure they are in the correct positions for launch.

At 10:03 a.m. EDT, countdown clocks will resume ticking following the half-day hold at the T-minus 11 hour mark. The count will proceed down to the T-minus 6 hour point where a two-hour begins at 3:03 p.m. EDT. During that pause this afternoon, the launch team will verify all systems are ready to begin loading a half-million gallons of supercold rocket fuel in the shuttle's external tank.

The three-hour fueling process is scheduled to commence at 5:03 p.m. EDT, pending a final "go" from the Mission Management Team's afternoon meeting to review the status of the count and the latest weather outlook.

The seven astronauts will be awakened at 5:30 p.m. to begin their launch day routine, leading to suitup at 10:08 p.m., departure from crew quarters at 10:38 p.m. and arrival at the launch pad shortly after 11 p.m. to start strapping aboard the shuttle.

SUNDAY, MARCH 9, 2008
1400 GMT (10:00 a.m. EDT)

Engineers pumped liquid oxygen and hydrogen into the shuttle Endeavour's fuel cell system early today in preparation for launch Tuesday on a space station assembly mission. There are no technical problems of any significance launch complex 39A and forecasters say the weather is behaving as expected with a 90 percent chance of acceptable conditions at launch time.

Read our full story.

1250 GMT (8:50 a.m. EDT)

Space shuttle Endeavour's fuel cell storage tanks were successfully filled with the liquid hydrogen and liquid oxygen reactants overnight as standard work continues at pad 39A for Tuesday's scheduled 2:28 a.m. EDT liftoff.

The fuel cells use cryogenic reactants to generate power and drinking water during the shuttle's mission. The cryogenics were loaded into storage spheres located beneath the payload bay.

Today's planned activities include final tests of the three main engines, functional checks of the orbiter's star trackers, activating the inertial measurement units, thoroughly testing the communications network, loading the last items into the crew module, filling of the launch pad's sound suppression system water tank and installing film in pad cameras.

Countdown clocks will enter the lengthy T-minus 11 hour planned hold period at 8 p.m. EDT tonight. The built-in hold will last 14 hours and 3 minutes.

The giant gantry-like rotating service structure is scheduled for retracting from around Endeavour at 6 a.m. tomorrow, marking a key milestone to ready the shuttle and launch pad for Monday evening's fueling of the external tank.

The weather outlook for Tuesday morning's launch attempt remains excellent with a 90 percent chance of acceptable conditions.

SATURDAY, MARCH 8, 2008
1700 GMT (12:00 p.m. EST)

The shuttle Endeavour's countdown is ticking smoothly through its initial stages, with engineers checking out the ship's avionics systems and gearing up to pump liquid oxygen and hydrogen aboard early Sunday to power the orbiter's electricity generating fuel cells.

Read our full story.

1200 GMT (7:00 a.m. EST)

Delayed by heavy rain, the shuttle Endeavour's crew arrived at the Kennedy Space Center early Saturday for the start of the countdown to launch Tuesday on a 16-day space station assembly mission. Commander Dom Gorie, standing with his crewmates on the rain-soaked shuttle runway, spoke briefly to waiting reporters.

Read our full story.

0808 GMT (3:08 a.m. EST)

Inside Firing Room 4, countdown clocks have started ticking toward Tuesday's planned liftoff of the space shuttle Endeavour.

Launch team members gathered for the "call to stations" at 2:30 a.m. EST, and then the three-day countdown commenced at 3 a.m. as scheduled.

Clocks read T-minus 43 hours and counting. But a series of holds are timed throughout the next few days, leading to Thursday's targeted liftoff time of 2:28 a.m. EDT.

The early portion of the count involves buttoning up launch pad equipment and removing platforms inside the shuttle's crew module, reviewing flight software stored in Endeavour's mass memory units, loading backup software into the general purpose computers and testing navigation systems.

0645 GMT (1:45 a.m. EST)

"Good evening. Thank you all for coming out and welcoming us here in this wonderful weather we've got. I think while we get the weather done with today, we're going to have a nice shot at launching here this week," commander Dom Gorie said from rainy Kennedy Space Center following the crew's arrival today.

"But we all just wanted to convey how excited we are to be here for launch week. We've got a great training team that got us ready. We've got multiple shifts of folks at Mission Control waiting to run this 16-day mission with us. And we've got a very, very ambitious flight schedule."

"But with a great orbiter waiting for us, and this great crew, we're going to have a great mission. Thank you very much. You all have a nice evening."

0625 GMT (1:25 a.m. EST)

A heavy, drenching rain at the Kennedy Space Center greeted space shuttle Endeavour's astronauts overnight as the seven-man crew arrived from Houston to begin final preparations for Tuesday's blastoff.

The crew's trip from their main training base at the Johnson Space Center was delayed Friday night due to the stormy weather across the southern U.S. They finally arrived around 1:22 a.m. EST.

Meanwhile at the Launch Control Center, the countdown remains set to begin at 3 a.m. this morning.

FRIDAY, MARCH 7, 2008
2120 GMT (4:20 p.m. EST)

Arrival of shuttle Endeavour's astronauts is being delayed from 9 p.m. tonight until 1 a.m. EST or possibly later due to bad weather.

1645 GMT (11:45 a.m. EST)

The shuttle Endeavour's seven-member crew flies to Florida this evening to prepare for a sky lighting night launch early Tuesday on a quick-turnaround space station assembly mission. The countdown is scheduled to begin at 3 a.m. EST Saturday and forecasters are predicting a 90 percent chance of good weather for launch, targeted at 2:28:12 a.m. EDT Tuesday.

NASA has two opportunities to launch Endeavour, on March 11 and 12, before standing down to make way for the March 15 launch of an Air Force Delta 2 rocket carrying a Global Positioning System navigation satellite. Shuttles and unmanned rockets launched from the nearby Cape Canaveral Air Force Station share tracking, imagery and self-destruct systems.

"Because of turnaround constraints between one launch and the next, we would attempt launches on the 11th and 12th and then stand down, let the Delta rocket play through - it has two attempts if it needs it - and then we could re-attempt, the earliest would be on the 17th, late in the evening," said NASA Test Director Steve Payne. "After that, we'd have opportunities through March 22 if we needed them."

Read our full story.