Inspections of the reinforced carbon-carbon wing leading edge panels on the right wing have been completed. The crew is returning the boom to its cradle in the payload bay.

Observations of the port wing are now underway aboard shuttle Discovery. This is the third and final part of the inspections for today.

The right wing was scanned using the laser and camera package of the Orbiter Boom Sensor System. The crew has swung the boom in position to inspect Discovery's nose cap next.

Inspections of Discovery's starboard wing have begun.

The early weather forecast for Saturday afternoon's planned landing at the Kennedy Space Center in Florida predicts generally favorable conditions.

At the landing time, the forecast is calling for scattered clouds at 5,000 feet, seven miles of visibility, a southerly wind from 170 degrees of 13 peaking to 21 knots, equating to a 5-knot crosswind and a 20-knot head/tailwind at the runway.

But the outlook for the backup landing opportunity on Sunday indicates crosswinds, low clouds and the chance of rain and thunderstorms could prohibit the shuttle's return.

Sunday's forecast includes clouds at 3,000 feet possibly forming a ceiling and a broken deck of clouds at 8,000 feet, seven miles of visibility and a westerly wind from 260 degrees of 13 peaking to 21 knots, equating to a 20-knot crosswind and a 5-knot head/tailwind at the runway.

The alternate landing site at Edwards Air Force Base in California looks ideal on Saturday, but has crosswind concerns on Sunday.

Favorable weather is forecast for both KSC and Edwards on Monday.

The Discovery astronauts have picked up the Orbiter Boom Sensor System with the shuttle's robot arm for today's series of heat shield inspections. The survey is similar to the inspections performed the day after launch. Today's results will be compared with the earlier data to ensure the orbiter's wing leading edge panels and nose cap are free of any space debris impacts that could have occurred during the mission.

Updates on today's launch of the Soyuz rocket with the Expedition 19 space station crew can be seen here.

As the shuttle Discovery slowly continued its separation from the international space station, Russian engineers readied a Soyuz rocket for blastoff today from the Baikonur Cosmodrome in Kazakhstan to ferry two fresh crew members and a wealthy space tourist to the outpost.

The shuttle crew plans to unlimber the ship's robot arm later this morning for a post-undocking inspection of the ship's reinforced carbon carbon nose cap and wing leading edge panels. The inspection is designed to spot any impact damage that might have occurred since an identical inspection was carried out the day after launch. The astronauts plan to pack Friday for the trip home.

Read our full story.

The shuttle is quickly departing the immediate vicinity of the space station following separation burn No. 2 at 5:37 p.m. EDT.

Discovery is due home at the Kennedy Space Center on Saturday afternoon. Before that, the crew will spend tomorrow inspecting the orbiter's heat shield one more time and Friday will feature the standard pre-landing checks of shuttle systems.

Saturday's two landing opportunities on back-to-back orbits would lead to touchdown at either 1:43 p.m. and 3:19 p.m. EDT.

The shuttle just performed the first of two separation engine firings, as Discovery moves back out in front of the station to complete a full loop flyaround. Once at a point well above the station, the final burn is scheduled.

Discovery is directly beneath the station now, continuing its circle around the complex.

The shuttle and station are flying over Houston, home of the Mission Control Center.

The shuttle now is directly behind the station in terms of the direction of travel of the two spacecraft around the Earth. This is a point known as the -V bar.

Discovery is reaching a point directly above the space station.

The flyaround started with the shuttle in front of the station. It takes Discovery to a point directly above the complex, then behind it, looping below and back out in front. After climbing above the station for a second time, the final separation engine firing will be performed. This burn will send Discovery away from the vicinity of the station.

Pilot Tony Antonelli has begun flying Discovery in a one-lap flyaround of the station.

With pilot Dominic "Tony" Antonelli at the controls, the shuttle Discovery undocked from the international space station today at 3:53 p.m. as the two spacecraft sailed 220 miles above the Indian Ocean to close out a challenging three-spacewalk assembly mission.

Read our full story.

Discovery is now 250 feet from the station.

Discovery continues to back away from the station. The shuttle is headed to a point about 400 feet away where it will fire thrusters to begin an arc above the station.

UNDOCKING! Shuttle Discovery and the international space station are parting company after 7 days, 22 hours and 33 minutes of being linked together high above Earth.

The shuttle delivered the final solar array power module, attaching the 15.5-ton truss and unfurling its giant wings that completed the space station's power grid and doubled the amount of electricity available for international science aboard the outpost.

With the addition of the Starboard 6 structure, the station is 336 feet long from the left end of the truss backbone to the right. The complex weighs 669,291 pounds, and now is 81 percent complete, as measured by mass.

Five minutes from undocking. The steering jets on Discovery are inhibited for the period of physical undocking from the station. The separation occurs when large springs push the two craft apart. Once the shuttle is a couple feet away from the station and the docking devices are clear of one another, pilot Tony Antonelli will fire Discovery's thrusters to continue the movement away.

Both the shuttle and station flight control teams report all systems on the respective spacecraft are ready for the undocking at 3:53 p.m.

The Orbiter Docking System on Discovery has been powered up for the shuttle's release from the space station.

The shuttle/station complex has been reoriented to the proper attitude for undocking.

The official time of hatch closure between the space station and Discovery was noted at 1:59 p.m. EDT.

Closing out a busy assembly mission, the Discovery astronauts, accompanied by outgoing station flight engineer Sandra Magnus, said farewell to the international space station's three-man crew today and floated out of the lab complex for the last time to rig the shuttle for undocking at 3:53 p.m.

Read our full story.

The astronauts have said their farewells and now the seven shuttle crew members have floated over to Discovery in preparation to close the hatchway.

The joint crews are finishing up the transfer of samples to the shuttle for the ride back to Earth. A farewell ceremony and the closing of hatches between Discovery and the station are scheduled to occur later this hour.

The Discovery astronauts prepared for undocking today, working through a busy timeline of packing and experiment sample transfers from the space station to the shuttle. After a final joint meal with their space station colleagues, the combined crews will hold a brief farewell ceremony around 1 p.m. before closing hatches for the shuttle's departure at 3:53 p.m. EDT.

Read our full story.

The astronauts are awake now, ready to begin Flight Day 11.

This is undocking day for space shuttle Discovery. The final transfer of stuff between the shuttle and station will be completed this morning, including the move of science samples from laboratory freezers to Discovery for return to Earth. Hatches between the two spacecraft will be closed around 1 p.m. EDT, leading to the departure of Discovery at 3:53 p.m. EDT.

The shuttle will make a one-lap flyaround of the station, then fire its maneuvering thrusters around 5:36 p.m. to open up a large separation distance from the outpost.

After taking a phone call from President Barack Obama, the Discovery astronauts and their space station colleagues transferred spacesuits and equipment back to the shuttle and took the afternoon off before a busy day Wednesday completing final transfers and undocking from the international lab complex.

Read our full story.

President Barack Obama, hosting school kids and members of Congress, called the crews of the shuttle Discovery and the international space station today, quizzing the astronauts about life in space and offering congratulations for a successful station assembly mission.

Read our full story.

Discovery astronauts have been awakened to begin Flight Day 10.

The failure to fully deploy an external cargo carrier mechanism during the Discovery crew's final spacewalk Monday will have no immediate impact on space station assembly, the flight director said. The jammed carrier, intended to support pallets carrying spare parts and other equipment for downstream use, may be repaired by the station crew or astronauts on an upcoming assembly flight.

Read our full story.

See our update story on EVA's ending.

EVA ENDS. Repressurization of the Quest airlock module is underway, marking the official end of today's spacewalk by Ricky Arnold and Joe Acaba at 6:04 p.m. EDT.

The EVA lasted 6 hours and 27 minutes. That brings the total time for the three spacewalks conducted during Discovery's mission to 19 hours and 4 minutes.

For Arnold, today was the second spacewalk in his career. He logged 12 hours and 34 minutes of EVA time on spacewalks No. 1 and No. 3 of the STS-119 mission.

For Acaba, his EVA scorecard now reads 12 hours and 57 minutes on spacewalks No. 2 and No. 3.

Cleanup tasks and putting away tools are the focuses right now for the crew.

Spacewalker Ricky Arnold has concluded the Canadarm2 grapple snare wire and bearing greasing and maintenance work. Joe Acaba has been releasing some clamps on truss umbilicals.

Ricky Arnold is starting some maintenance on the free end of the station's robot arm. Joe Acaba is working to adjust the clearance for one of the CETA carts.

Passing the four-and-a-half-hour mark of today's EVA. The astronauts have moved onward to other odds and ends on NASA's spacewalking to-do list outside the space station.

The securing work is just about complete. Tethers have been used to restrain the fixture from moving.

Once finished on the Port 3 truss a short time from now, the spacewalkers will proceed to the other tasks left on today's schedule, including adding lubrication to the station's robot arm grappling mechanism and configuring umbilicals in the station's thermal control system.

Mission Control has cancelled deployment of a similar payload attachment device on the other side of the station on today's spacewalk.

When elbow grease wasn't enough, spacewalkers Joe Acaba and Ricky Arnold retrieved a hammer from the space station's airlock and whacked a jammed locking pin to get it out of the way and free an external cargo carrier for full deployment. But with the adjustable diameter pin, or ADP, finally out of the way, the carrier mechanism still failed to extend properly.

Read our update story.

Mission Control just told the astronauts that engineers are going to need to study this deployment problem further. So the spacewalkers will tie down the structure in a safe configuration until further attempts can be made by a future crew.

Pushing together, the spacewalkers can't budge the payload structure any further toward the deployment position.

Ricky Arnold and Joe Acaba made their way out to the Port 3 truss to resume work to fully deploy an external cargo attachment fitting. However, their efforts haven't paid off yet.

The device seemed stuck and wouldn't move into the proper position during the last EVA on Saturday.

The spacewalkers have worked together to install the cart to its new location on the other side of the Mobile Transporter. This was done to clear the cart out of the way for future work by the mobile robot arm transporter.

The spacewalkers have worked together to install the cart to its new location on the other side of the Mobile Transporter. This was done to clear the cart out of the way for future work by the mobile robot arm transporter.

Perched on the end of the space station's robot arm, spacewalker Joe Acaba has pulled the Crew and Equipment Translation Aid (CETA) cart off the station rail tracks. He will hold the cart in his hands while the arm swings him from the station's port side of the Mobile Transporter over to the starboard side for re-installation.

Shuttle Atlantis has arrived inside the Vehicle Assembly Building, completing a key milestone in preparations for its mid-May launch to the Hubble Space Telescope.

Over the next 24 hours, Atlantis will be hoisted upright to point its nose skyward, gently maneuvered high into the rafters of the 52-story building and then lowered into the assembly bay for attachment to the shuttle's awaiting external fuel tank and twin solid rocket boosters already put together atop the mobile launching platform.

Once Atlantis is bolted to the tank, the combined shuttle system will undergo several days of testing before rollout to pad 39A next Monday.

Atlantis is slated for launch May 12 at 1:11 p.m. EDT on the long-awaited mission to repair and upgrade NASA's original Great Observatory, the Hubble telescope.

Atlantis is making the turn into the VAB now.

At Kennedy Space Center, space shuttle Atlantis has emerged from its processing hangar. Mounted atop a 76-wheel transporter, the shuttle is taking a quarter-mile trip to the cavernous Vehicle Assembly Building. The move was delayed from earlier this morning due to rainy weather at the Florida spaceport.

Both spacewalkers have egressed the airlock as this six-and-a-half-hour EVA gets underway.

EVA BEGINS. The spacewalkers switched their suits to internal battery power at 11:37 a.m. EDT, marking the official start time for today's EVA by Ricky Arnold and Joe Acaba.

Depressurization has been completed and the airlock's outer hatch was just opened.

Down at the Kennedy Space Center, meanwhile, ground crews are starting to move the space shuttle Atlantis out of its hangar. The orbiter is being transported to the Vehicle Assembly Building for attachment to an external fuel tank and twin solid rocket boosters.

Atlantis will be rolled out to launch pad 39A next Monday to begin preparations for liftoff May 12 to service the Hubble Space Telescope.

Airlock depressurization has started in preparation for today's EVA.

The two former school teachers are getting suited up for today's spacewalk outside space station.

Astronauts Richard Arnold and Joseph Acaba, both former school teachers, are preparing to venture back outside the international space station today for a planned six-and-a-half-hour spacewalk. The primary objectives are to complete the deployment of an external cargo mounting mechanism; to extend another cargo carrier on the far side of the station's solar power truss; to lubricate the grappler on the station's robot arm; to reconfigure a wiring patch panel; and to reposition an equipment cart.

Read our preview story.

The Flight Day 9 wakeup call has been uplinked from Mission Control to the shuttle Discovery astronauts. Former teachers Ricky Arnold and Joe Acaba will conduct the third and final spacewalk of the mission later today. The EVA is slated to begin around 11:45 a.m. EDT.

After a lot of troubleshooting and replacement parts, the urine processor in the station's water recycling system started a "wet" test a few minutes ago. So far, the unit is running smoothly and quietly, commander Mike Fincke reports.

Discovery commander Lee Archambault maneuvered the shuttle-space station "stack" today to avoid multiple close encounters with a piece of Chinese space junk that could have posed a threat during a third and final spacewalk Monday. Space station commander Mike Fincke, meanwhile, made solid progress with lab's urine recycling system and resumed testing late in the day after resolving a snag earlier in the day.

Read today's wrap-up story.

Station commander Mike Fincke continues to fill the water regeneration system with urine in hopes of processing the first samples. Despite problems earlier today, the crew replaced a filter assembly and was given approval from Houston to try processing a sample again.

Shuttle commander Lee Archambault used Discovery's steering jets today to re-orient the shuttle-space station "stack" and in so doing, slightly lower their altitude. The maneuver was ordered to reduce the odds of a potential close encounter, or conjunction, with a 4-inch-long piece of Chinese rocket debris.

Read our full story.

Space station commander Mike Fincke has been asked by Houston to replace the Recycle Filter Tank Assembly in the water regeneration system. A flow rate problem earlier today prevent a urine processing test from being performed.

The space shuttle commander, Lee Archambault, is preparing for a maneuver of the combined Discovery/station complex into a different orbital orientation because of a possible space debris concern. Space trackers are watching a piece of debris with an "erratic orbit" that makes it a potential threat, NASA says. The new orientation will produce a slight change in the station's orbit and ease worries about the debris.

A critical test run using the space station's presumably repaired urine processor system was called off today when the lab crew ran into problems loading the system with stored urine. After several hours of troubleshooting, mission control told station commander Mike Fincke to close the water recovery system rack and call it a day.

Read our full story.

Mission Control has called off today's planned sample-taking test using the Urine Processor Assembly. The astronauts had installed a replacement Distillation Assembly earlier in Discovery's mission and hoped to make the first sample today. However, ground controllers noted the flow rate in one of the valves was lower than expected. Further troubleshooting is planned before a sample is processed through the system.

The equipment is part of the station's water recycling gear that was delivered on the last shuttle flight in November.

Meanwhile, the astronauts are getting set for a private conference with teams on the ground working up new plans for tomorrow's spacewalk. The teams are developing options to free a misconfigured pin that is stuck in the external cargo storage fixture, which is preventing the device was being fully deployed.

The Discovery astronauts are enjoying a half-day off today before gearing up for a replanned third and final spacewalk Monday. The space station astronauts, meanwhile, plan to begin testing the lab's repaired urine processing system.

Read our morning story.

After getting an extra 30 minutes of sleep, the wakeup call to begin Flight Day 8 was just sounded for the Discovery crew. The astronauts will enjoy some off duty time today, then later tonight begin preparations for Monday's third and final spacewalk of the mission.

Engineers are studying options for freeing a jammed locking pin, part of a clamp that apparently was installed backwards by a spacewalker today in the topsy-turvy world of microgravity. The backward clamp prevented a stowed space station cargo carrier from fully deploying and locking into place.

Read our full story.

EVA ENDS. Repressurization of the Quest airlock module began at 7:21 p.m. EDT, marking the official end of today's spacewalk by Steve Swanson and Joe Acaba.

The EVA lasted 6 hours and 30 minutes. That brings the total time for the two spacewalks conducted thus far during Discovery's mission to the space station to 12 hours and 37 minutes.

The third and final spacewalk for the Discovery crew is planned for Monday. Acaba will be joined by Ricky Arnold for that excursion.

Both spacewalkers are back inside the airlock.

Swanson has secured the attachment fixture using tethers. He'll now head back to the airlock to wrap up today's EVA.

Because of his limited spacesuit consumables remaining, Joe Acaba is hanging out at the airlock. Steve Swanson will be heading to the Port 3 truss where he will take two or three tethers, hooked together, to tie down and cinch the partially deployed cargo attachment fixture. Swanson has a little more than an hour of suit consumables left.

Swanson was trying to swap around umbilicals to route power to one of the space station's control moment gyros via a different circuit breaker. However, he wasn't able to get one of the cables to disengage from the receptacle.

Acaba is finishing the radiator survey and will return the equipment to the airlock. Meanwhile, Swanson has been dispatched to get started on the Z1 truss work as the EVA clock passes five-and-a-half hours.

The big-picture plans just radioed up from Mission Control will have Acaba head over to the Z1 truss to complete some work on an umbilical patch panel. Swanson will return to the P3 truss and get the external stowage fixture in a good configuration to leave partially deployed. The spacewalkers ran into a problem with a stuck pin and couldn't finish the deployment task earlier today.

After Acaba imaged one side of the radiators, Mission Control is rotating the structure so the spacewalker can photograph the other side.

Spacewalker Joe Acaba is performing his photographic survey of the starboard and port radiators of the international space station. The top surface on one of those panels recently peeled up, so engineers have asked for an inspection of all the radiators. Acaba is equipped with a regular camera and a special infrared camera.

Spacewalker Steve Swanson is atop the logistics module of the Japanese Kibo laboratory installing a Global Positioning System navigation antenna. It's the second of two such antennas that will be used by the H-2 Transfer Vehicle, an unmanned cargo-carrying spacecraft slated for its first mission to the space station in September.

An update story on the spacewalk has been posted here.

Mission Control has advised the spacewalkers it's time to give up on these efforts to finish the external cargo carrier deploy today. Engineers on the ground will have to come up with some other options for clearing the stuck pin.

The spacewalkers will press ahead with their next planned tasks -- collecting infrared images of a damaged radiator panel and installing a Global Positioning System antenna on the Japanese segment of the space station.

Try as they may, even attempting to use a rachet to help pry out the stuck pin, the spacewalkers cannot move that pin.

An update story on the spacewalk has been posted here.

The spacewalkers are fighting with a pin that has delayed completion of this task.

Meanwhile, the crew members inside the space station have activated the newly installed distillation assembly unit in the water generation system to begin critical testing.

Now passing the three-hour mark into today's EVA, the crew is reaffixing the truss braces temporarily removed to deploy the cargo attachment fitting.

Having moved brace beams out of the way, the spacewalkers rotated a carrier attachment device out of the interior of the Port 3 truss. This fixture will be available to hold future external hardware on the space station's truss backbone.

A similar device on the Starboard 3 truss will be deployed by the spacewalkers later today.

The work on the Port 6 truss has been completed already. The spacewalkers will be moving inboard a bit to the P3 truss for deployment of an attach fitting for future external equipment.

The spacewalkers made their way out to the Port 6 truss, the first power module launched to the space station back in 2000. Its batteries will be replaced by the next shuttle crew in June, so today's first task for the spacewalkers is to loosen the torque on bolts to ensure no problems will be experienced by the STS-127 crew a couple months from now.

"What the crew will do is, they'll go out to that worksite and break the torque on those batteries and install some foot restraints and pre-stage some tools that they'll use to save the crew of the next mission some time when they go to do the complex operations to replace those batteries. So we're going to do that get-ahead task," said lead flight director Kwatsi Alibaruho.

Both spacewalkers have egressed the airlock. Swanson is making his fourth EVA, while Acaba is on his first. They'll be gathering up a pair of foot restraint platforms, then head for the Port 6 truss on the far left side of the station to begin the battery replacement prep work.

EVA BEGINS. The spacewalkers switched their suits to internal battery power at 12:51 p.m. EDT, marking the official start time for today's EVA by Steve Swanson and Joe Acaba.

Depressurization has been completed and the airlock's outer hatch was just opened.

Airlock depressurization has started in preparation for today's EVA.

The spacewalkers are being moved into the compartment of the airlock that will be depressurized a short time from now.

The suitup process is underway in the Quest airlock module for Joe Acaba and Steve Swanson. Today's EVA is scheduled to start around 12:45 p.m. EDT, although the crew could get ahead of the timeline.

Astronauts Joseph Acaba and Steven Swanson are preparing for a revised six-and-a-half-hour spacewalk today. The major goals of the excursion, the second of three planned for the shuttle Discovery's mission, are to prepare a set of solar array batteries for replacement in June; to deploy storage platforms on the international space station's solar power truss; to install a GPS navigation system antenna on a Japanese module; and to photograph two sets of radiator panels with an infrared camera. Insulation on one radiator panel has pulled away and engineers want to assess the health of the system.

Read our preview story.

Houston has awakened the astronauts for Flight Day 7. Today will feature the second spacewalk of Discovery's mission.

NASA managers, thrilled at the successful deployment of a fourth and final set of solar arrays on the international space station today, approved a revised flight plan that will delay hatch closure and the shuttle Discovery's undocking slightly to improve the odds of getting critical experiment samples back to Earth in case of weather wave-offs that might delay the orbiter's return.

Read our full story.

Read our solar array story here.

The international space station's new solar arrays have been successfully deployed, stretching some 240 feet from tip to tip. The new wings, each with their 32,800 solar cells, will provide enough power-generating capacity to double the electricity available for space station science operations, from 15 to 30 kilowatts.

The deployment has resumed after the half-hour warming.

As the crew inspects the array, a couple of the map-like folds in the blanket are popped inside out. However, Mission Control says that shouldn't be a problem as the blanket continues to extend.

A good extension to 49 percent has been confirmed by the astronauts controlling today's activities in orbit. The deploy sequence will be stopped at this point for about 30 minutes to let the solar array warm up before extending the rest of the way.

The array is about one-third deployed.

The 3B solar wing of the space station's new power truss is beginning to extend outward to the 49 percent mark.

The international space station is flying 220 miles over the Pacific Ocean in orbital darkness. Once the complex moves back into sunlight about 10 minutes from now, the second array deployment opportunity will open.

The first of two giant solar wings has been successfully deployed from the space station's new Starboard 6 truss. The array has unfurled its full length of 115 feet.

Extension of the second solar array is expected to begin around 12:30 p.m. EDT.

Unfurling of the solar array has resumed, headed for full extension.

It's been a good deploy to this point, commander Lee Archambault says.

The 1B power-generating solar array on the S6 truss has been extended to the 49 percent mark. The deployment has paused at this point for a half-hour to let the panels warm up before proceeding to a full 100 percent.

Deployment of the first solar array is underway. The astronauts aboard the space station are in control of the commanding to the deploy mechanism.

The team will be awaiting S-band telemetry communications to be established between the station and Houston before the array deployment starts. That's expected in a few minute.

Preparations for deploying the solar arrays are being completed now. The astronauts are gathering together in the Destiny laboratory to review the procedures one more time before they begin commanding the wing deploys.

The Discovery astronauts and their three space station counterparts plan to carefully extend a newly attached set of solar arrays today in a critical operation that will complete the station's U.S. power system after eight years of construction.

Read our full story.

It's wakeup time for the astronauts as Flight Day 6 begins.

Initial work to deploy the two new solar wings began overnight aboard the international space station. Mission Control commanded the array blanket boxes to open slightly, allowing the stowed panels to decompress. One array will be unfurled to 49 percent, then to 100 percent length beginning just before 11 a.m. EDT today. Extension of the other wing should follow around 12:30 p.m., on the subsequent orbit.

EVA ENDS. Repressurization of the Quest airlock module began at 7:23 p.m. EDT, marking the official end of today's spacewalk by Steve Swanson and Ricky Arnold. The EVA lasted 6 hours and 7 minutes. It was the first of three spacewalks planned for Discovery's construction mission to the international space station.

The outer hatch has been closed and locked.

The spacewalking duo has climbed into the airlock and will soon close the hatch to complete this successful first EVA of Discovery's STS-119 flight.

Another story on the progress of today's spacewalk is posted here.

Nearing the six-hour mark of the EVA. The spacewalkers have done inventories of their tool and equipment. They're heading for the airlock now.

The heat-dissipating radiator has been extended from the station's new power truss.

The radiator has begun to unfold via commanding from Mission Control in Houston.

Mission Control just told the crew that deployment of the radiator on the S6 truss is coming up shortly.

The spacewalkers have accomplished all of the primary tasks for today's EVA.

No-longer-needed thermal coverings on exterior electronic equipment of the Starboard 6 truss have been removed and tossed overboard by the spacewalkers. The four shrouds will fall from orbit and burn up in the atmosphere.

All four blanket boxes have been unstowed in preparation for the solar wings to be unfurled from those containers as early as tomorrow.

The second Beta Gimbal Assembly has been pushed out of its launch orientation. The folded up boxes containing the solar array wings will be rotated out of their stowed positions now.

The two spacewalkers had to join forces to get one of the Beta Gimbal Assemblies unstowed and latched in its operational position. The BGA enables the solar arrays to rotate and track the sun as the space station orbits the Earth.

Now Swanson is working to release restraints holding one of the Beta Gimbal Assembly canisters in the launch configuration. Arnold is finishing up with the Solar Array Blanket Box lock removals.

The crew reports Swanson has finished the radiator work. The long panel is scheduled to be deployed by remote control a little later today.

Swanson has released a half-dozen cinches holding the folded up radiator on the S6 truss. Next, he'll unfasten a pair of winch and pin assemblies.

Mission Control says activation of the Starboard 6 truss is going well. Ground controllers are working through steps to begin the new element to life.

Meanwhile, spacewalkers Steve Swanson and Ricky Arnold continue their work to release various restraints and locks that were in place for the S6's launch into space aboard shuttle Discovery.

A story on the progress of today's spacewalk is posted here.

With the cabling routed and connected, the spacewalkers are pressing ahead with their next tasks. Steve Swanson will be releasing cinches and winches holding the stowed radiator on the S6 truss. Ricky Arnold will be freeing launch restraints on the boxes containing the solar array blankets.

Now passing two hours, 30 minutes into today's EVA. The power and data umbilical connections are being made by the spacewalkers now.

The station's robot arm has ungrappled S6 following today's installation.

Spacewalker Steve Swanson is beginning work to run umbilical cables between the S6 truss and the space station.

All four bolts on the corners of the S6 truss have been torqued down. The $300 million power module is a permanent part of the international space station.

And with that, the operators can detach the robot arm from its grip on the truss.

The S6 truss hookup work continues to go smoothly.

The capture claw has been closed around a bar on the base of S6. Next, the spacewalkers will engage a series of bolts to firmly mate the S5 and S6 trusses together and attach grounding straps.

The robot arm has been limped while the capture claw pulls S6 to its new home on the outer starboard side of the space station.

Ricky Arnold is closing a claw-like device on the S5 truss to capture the new Starboard 6 module to its permanent location on the space station.

The arm is in motion once again, now driving the S6 truss to the installation position against the S5 structure.

The spacewalkers are providing some alignment advice to the arm operators working inside the Destiny laboratory of the international space station before the S6 truss moves the final inches.

The arm operators are moving S6 to the next waypoint, just two inches from attachment.

The robot arm has been paused again for a clearance check.

Spacewalkers Steve Swanson and Ricky Arnold are giving visual reports to robot arm operators John Phillips and Koichi Wakata as the S6 truss is maneuvered into position for attachment. The arm controllers do not have any good camera views to do this truss installation job alone, making the spacewalkers' calls on alignment most crucial.

After completing an inspection of the Starboard 5 truss where the new S6 truss will be connected, the spacewalkers have given a "go" for the robot arm to move the payload to within 8 inches.

The spacewalkers are climbing to the far end of the station where the S6 truss will be attached this afternoon. The station's robot arm has the truss poised to move the final few feet to the installation spot.

EVA BEGINS. The spacewalkers switched their suits to internal battery power at 1:16 p.m. EDT, marking the official start time for today's EVA by Steve Swanson and Ricky Arnold.

Depressurization has been completed and the Quest airlock's outer hatch leading to space just swung open.

Airlock depressurization is underway.

Dressed in their spacewalking suits, Steve Swanson and Ricky Arnold have gone into the section of the airlock that will be depressurized a short time from now.

Space station resident Koichi Wakata reports the robot arm has placed the Starboard 6 truss about five feet away from its installation point. The actual attachment of the truss will occur once the spacewalkers get out there to assist.

Final steps in the suitup process are being completed in the Quest module now. The spacewalkers are being outfitted with the SAFER backpacks that would enable an untethered astronaut to fly back to the station.

Perched on the end of the space station's robot arm, the Starboard 6 payload is en route from the overnight parking location to the pre-install position on the far end of the truss structure.

The spacewalkers are beginning to climb into their spacesuits for today's excursion outside the space station.

Astronauts Steven Swanson and Richard Arnold are gearing up for a planned six-and-a-half-hour spacewalk today to attach the last solar array truss unit to the international space station.

Meanwhile, mission managers may look to bring Discovery back to Earth a day earlier than currently planned.

Read our morning story.

The big day of space shuttle Discovery's construction mission to the international space station has begun. Houston woke up the astronauts a moment ago to start Flight Day 5.

The mission's primary payload -- the Starboard 6 solar array truss -- will be installed onto the station and readied for activation today during a six-and-a-half-hour spacewalk. The EVA gets underway around 1 p.m. EDT.

If all goes well with today's work, the giant power-generating wings can be unfurled from the truss tomorrow to complete the station's electrical grid.

A $300 million, 31,000-pound solar array truss segment was plucked from the shuttle Discovery's cargo bay today, handed off, re-grappled and moved to an overnight park position near the right end of the international space station's main power truss for installation Thursday during a planned six-and-a-half-hour spacewalk.

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More high definition video has been posted, included a dramatic view of the space station during yesterday's backflip by the shuttle. Our Spaceflight Now Plus subscribers can view the videos here.

Analysts have determined that no focused inspections of the shuttle's heat shield will be required during a block of time in the astronauts' schedule on Friday. That means deployment of the solar array wings on the new Starboard 6 truss can be moved up to that Friday time slot instead of waiting until Sunday.

NASA says Discovery came through its launch to orbit in great shape.

The fourth and final solar array truss segment is now in the hands of the space station. The station arm has grappled the Starboard 6 truss again, taking the handoff from the shuttle after moving down the rail system to the proper position for tomorrow's installation of the new truss onto the S5 element.

Just before the grappling, the astronauts had to open and close the arm's latching mechanism because the internal snares were out of place. This is a known condition that spacewalkers plan to remedy by applying new lubricant.

Today's delicate robotics between the Canadian-built space shuttle and station arms have gone well. A little after 11 a.m. EDT tomorrow, the station arm will maneuver S6 into the pre-install position. The actual attachment of the truss to the station's backbone will occur during the afternoon spacewalk.

The mobile transporter railcar that moves the space station's robot arm up and down the truss backbone is in motion. The arm is being repositioned on the starboard side of the truss where it will receive the S6 truss payload in a handoff from the shuttle arm later today.

The Starboard 6 truss has been lifted above Discovery's payload bay by the space station's robot arm. Now, the shuttle's arm has been locked to another grapple fixture on the truss. The station's arm can release its grip and begin relocating itself to the starboard side of the rail tracks.

The space station's robot arm has reached down into space shuttle Discovery's payload bay and grappled the Starboard 6 solar power truss. The arm will slowly lift the 15.5-ton truss out of the bay in a little while.

Once the truss is unberthed, Discovery's arm will latch onto the payload and the station arm will let go. The shuttle arm can't perform the initial hoisting task because of clearance issues with the Japanese laboratory module just above the port-side of Discovery.

Discovery's 50-foot arm will maneuver the truss out over the starboard side of the shuttle. In the meantime, the station arm will travel on its railcar from the port-side to the starboard-side of the outpost's truss backbone. Once repositioned, the station arm will take back the S6 payload from the shuttle arm and place it into a thermally-acceptable orientation for overnight parking.

The station arm will install the S6 truss tomorrow with help by spacewalking astronauts.

Our morning story can be seen here.

The musical wakeup call in the form of Johnny Cash's "Walk the Line" has been beamed up to the astronauts for the start of Flight Day 4 of shuttle Discovery's mission. Today's primary activity will be the complex robotic operation to hoist the Starboard 6 truss out of Discovery's payload bay, which is work that will involve both the station and shuttle arms. The truss gets installed during tomorrow's spacewalk.

Last night, Koichi Wakata officially moved from the shuttle to the space station, becoming the first Japanese astronaut to serve as a long-duration resident crew member aboard the outpost. He replaced Sandy Magnus, who will return to Earth on Discovery.

With hugs, smiles and handshakes,the crew of the international space station welcomed shuttle commander Lee Archambault and his six crewmates aboard late today after a picture-perfect docking over western Australia.

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CONTACT AND CAPTURE! Discovery has arrived at the space station to deliver the $300 million Starboard 6 solar array truss, the fourth and final power module for the international outpost. The 15.5-ton girder will be connected to the station's backbone by spacewalking astronauts during the mission.

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 Discovery's 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.

Now 10 feet separating the shuttle from the station. Discovery's thrusters are programmed to fire in a post-contact maneuver to force the two docking ports together. That procedure is being armed.

Discovery is closing at about 0.1 feet per second.

The alignment now looks good between docking ports on Discovery and the space station. The final approach covering the last 30 feet to docking is beginning.

The shuttle crew reports the alignment is about two degrees off in roll. The astronauts will correct the roll before continuing into docking.

Now 60 feet left to go.

About 90 feet separate the shuttle and station.

Now about 125 feet from docking.

Discovery is 212 feet from the station. Mission Control projects docking will occur about 10 minutes later than advertised.

The shuttle has reached the point 300 feet directly in front of the station along the imaginary line called the velocity vector, or +V bar.

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

Discovery 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.

"The orbiter looked clean, very nice," station commander Mike Fincke reports.

The pitch maneuver has been completed. Discovery is back in the orientation where it started, with the payload bay looking up at the station.

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

This 360-degree, nose-first pirouette by Discovery 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.

The formal photo-taking period has started for the Expedition 18 crew, now that the shuttle has rotated its underside in view of the station complex.

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

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

As the shuttle's underside rotates into view, the station's crew will photograph Discovery'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, Discovery 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 Archambault will guide the spacecraft to a docking with a pressurized mating adapter attached to the Harmony connecting module.

The shuttle backflip has been delayed because of communications problem with the station crew.

Another of the mid-course correction burns has been completed by the shuttle to fine-tune its path to the station. Discovery is about 1,700 feet below the station.

Discovery just completed one of the available mid-course correction burns during this approach to the station. The shuttle is less than 5,000 feet away.

Just two miles separate the shuttle and station now.

Distance between Discovery and the space station is 37,000 feet. The shuttle remains on course for docking.

The shuttle has performed the Terminal Initiation burn using the Orbital Maneuvering System. This 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 Discovery during its two days of chasing the station since launch Sunday night.

Docking is anticipated at 5:13 p.m. EST.

The crew is getting into the official rendezvous timeline now. The final phase of the two-day trek to the space station begins at 2:34 p.m. EDT with the Terminal Initiation maneuver.

This morning's wakeup call was just beamed from Mission Control to the shuttle Discovery crew to begin Flight Day 3 of the mission. This day will see the shuttle rendezvous with the space station for docking a little after 5 p.m. EDT.

Read our morning story here.