EVA ENDS. Today's spacewalk concluded at 1923 GMT (2:23 p.m. EST) with the start of repressurization of the Quest airlock. The EVA lasted 7 hours and 30 minutes.

Hopkins and Mastracchio will get out of their spacesuits once pressure in the airlock is equalized with the space station's atmosphere. The crew plans to take the day off on Christmas Day.

Later this evening, mission control will pressurize the fresh ammonia pump module and activate it for a thorough checkout before integrating it with the space station's coolant loop A, allowing the space station's non-essential systems -- some of which were shut down following the loss of full cooling Dec. 11 -- to be powered back up.

Officials are hopeful the orbiting complex will be back up to full capability by the end of the week.

With the hatch closed, the astronauts will wait inside the airlock a few extra minutes before beginning repressurization. This is a cautionary procedure to ensure any ammonia residue on their spacesuits does not enter the lab's cabin.

Hopkins and Mastracchio are back in the Quest airlock and about to close the hatch after collecting and stowing tools the used today. The end of this EVA will be marked when repressurization of the airlock begins.

NASA spokesperson Rob Navias says flight controllers believe the space station crew will complete all of the required pump replacement tasks on this spacewalk, eliminating the need for a third EVA in the next few days.

There is a previously scheduled spacewalk by Russian cosmonauts Oleg Kotov and Sergey Ryazanskiy on Friday.

NASA reports the new pump module is "alive and well" after a good start-up test commanded from mission control in Houston.

"Houston, you've got yourself a new pump module," one of the astronauts just radioed mission control. The spacewalkers have completed connecting five electrical cables to power the pump module.

While ground controllers work on opening up the final valves in the ammonia lines, the astronauts are gearing up to connect five electrical cables to power the new pump module.

All four ammonia lines have been connected to the pump module.

The third ammonia line has now been latched on to the pump module.

Now passing the five-hour mark in this EVA.

The astronauts say they no longer see any ammonia around them, and they are pressing on with connection of the third ammonia line to the new pump module.

The astronauts still see ammonia flakes and report some of the material came in contact with their suits.

After struggling more than a half-hour with closing a valve between the M3 ammonia line and the jumper box, the astronauts appear to have finally succeeded. The spacewalkers did report some ammonia flakes leaking out of the quick-disconnect.

"Nice work, guys," said astronaut Doug Wheelock from mission control. "The valve is closed, standby."

Mission control has given instructions for the astronauts to try several options at freeing this troublesome ammonia line from the jumper box. They have tried adding and reducing torque, and the astronauts have retrieved several different tools, but nothing has worked so far.

The spacewalkers are having some trouble disconnecting the M3 ammonia line from a jumper box, which was used to cycle the fluid through the space station's coolant loop A after the faulty pump module was removed during Saturday's spacewalk.

Hopkins is in charge of disconnecting the ammonia lines from the jumper box and reconnecting the lines to the newly-installed pump module.

Hopkins has connected a second ammonia line.

The first of the four ammonia lines has been hooked up to the fresh pump module.

The pump module has been vented of pressurized nitrogen, clearing the way for attachment of the four ammonia connectors.

In a change of plans, NASA is directing the astronauts to proceed with fluid connections before hooking up electrical cables to the pump module.

There are four ammonia lines leading to the pump module. Three of the connectors are 1.5 inches in diameter, and the fourth line is a half-inch in diameter.

Mastracchio is venting the pump module before ammonia is cleared to flow into the fresh unit.

Hopkins has driven four bolts to firmly attach the spare pump in position. Next up is the connecting of electrical cables to route power to the pump module.

Japanese astronaut Koichi Wakata, at the controls of the robot arm, has positioned Hopkins with the pump module in the correct position to begin bolting the spare in place.

Hopkins is positioning the pump module at the S1 truss after a spectacular ride on the robotic arm from the pump's storage platform.

The astronauts will soon begin driving four bolts to connect the pump to its new home.

After loosening and removing four bolts, the astronauts have removed the spare pump module from its mounting platform on the S3 truss. Astronaut Mike Hopkins, standing on the end of the robot arm, is holding the refrigerator-sized pump while robotics operator Koichi Wakata maneuvers him into position to install the spare module on the S1 truss.

Built by Boeing, the pump module has a mass of about 780 pounds and measures 5-and-a-half feet long, 4 feet wide and 3 feet high.

Now passing the two-hour mark in this spacewalk.

With electrical connections demated, the spare pump module is about to be pulled out of its stowage location for the transfer to the S1 truss segment for installation into the space station's coolant system.

Mission control reports the astronauts are a few minutes behind the timeline so far this morning, but there are plenty of consumables in both spacesuits and NASA is optimistic Hopkins and Mastracchio will complete all their tasks.

Hopkins has attached himself to the end of the space station's 58-foot robotic arm and Mastracchio has completed removal of dust caps on the spare pump module's four ammonia quick-disconnect lines.

Mastracchio will soon unbolt the pump module from its external stowage platform and Hopkins will unhook five electrical connectors.

The spacewalkers are at the external stowage platform on the S3 truss segment and are removing thermal covers on the spare pump module. The astronauts will also disconnect five electrical cables and remove tape and velcro from hand rails on the refrigerator-sized pump module.

Hopkins and Mastracchio is moving to a work site on the starboard S3 truss segment, where the spare pump module is stored on an external platform. The first step to remove the pump is to open up thermal insulation covering the device and take off protective covers from the pump module's fluid lines.

EVA BEGINS. The spacewalk officially began at 6:53 a.m. EST (1153 GMT) with the switching of the spacesuits to internal battery power.

This spacewalk is the eighth in the career of astronaut Rick Mastracchio, following three excursions each on the STS-118 and STS-131 space shuttle missions and Saturday's spacewalk. It's the second EVA for Hopkins.

This is the 176th spacewalk devoted to space station assembly and maintenance.

Hopkins is the lead spacewalker for this EVA, wearing the all-white suit. Mastracchio is wearing the suit with red stripes.

Both astronauts also have helmet-mounted cameras. Mastracchio's view will have the no. 20 in the corner of the screen, and the camera on Hopkins' spacesuit is denoted by the no. 18.

Hopkins and Mastracchio have already opened the hatch of the airlock and will soon head outside.

After an early morning suiting up inside their spacesuits, astronauts Rick Mastracchio and Mike Hopkins have floated inside the Quest airlock's crew lock, which is now being depressurized.

Astronauts Rick Mastracchio and Mike Hopkins are gearing up for a Christmas Eve spacewalk, their second in four days to complete an urgent cooling system repair job, installing a spare 780-pound ammonia pump module on the right side of the International Space Station's main power truss.

Read our full story.

NASA says the next spacewalk to finish the replacement of a faulty ammonia pump module outside the International Space Station is now scheduled for Tuesday, a day later than previously planned.

The spacewalk will begin at 7:10 a.m. EST (1210 GMT).

Astronauts Rick Mastracchio and Mike Hopkins returned to the International Space Station's airlock Saturday to wrap up a successful five-hour 28-minute spacewalk, the first of at least two excursions needed to repair a critical coolant loop.

Read our full story.

EVA ENDS. Today's spacewalk officially ended with repressurization of the airlock at 12:29 p.m. EST. The EVA was clocked at 5 hours, 28 minutes.

After cleaning up their work area, Mastracchio and Hopkins are back in the Quest airlock. The spacewalk will officially end when the airlock starts repressurizing.

With the failed pump now on a temporary platform, lead spacewalker Rick Mastracchio says he would prefer to end the EVA soon and not continue with work to prepare the spare module for its move on Monday.

Mission control discussed the possibility of Hopkins heading over to the fresh pump module to prepare the spare for its removal from a storage platform, but lead spacewalker Rick Mastracchio suggested concluding the EVA once he gets the failed pump positioned in a temporary location.

Standing on the robot arm, Mastracchio has pulled the pump module partway out of the truss. The astronauts will attach a grapple bar to the pump to help place it in a temporary stowage location.

All four bolts holding the pump module to the space station have been unscrewed.

Using an electric screwdriver built for spaceflight, the astronauts are working on unbolting the pump module now.

With extra time available, the focus of the spacewalk has turned back to the failed pump module. Mastracchio says he has disconnected the five electrical cables leading to the module, and Hopkins has retrieved a grapple bar to help attach the pump to a firm structure once it is pulled out of its housing on the S1 truss.

A few minutes ago, Mastracchio reported his feet were getting cold but is otherwise in good shape to continue on with the removal of the faulty pump module from its location on the S1 truss today.

And Hopkins is topping off his spacesuit with oxygen to ensure he is able to continue the spacewalk and take care of the pump removal task today. Mission control expects the EVA will now run more than 7 hours.

The astronauts will now turn to configuring the spare pump module, which is located on External Stowage Platform no. 3 on the outboard starboard truss, for its move to replace the old pump. This involves disconnecting five electrical cables, opening up thermal insulation and removing tape and velcro from hand rails.

Mission control in Houston says the spacewalk is running far enough ahead of schedule to allow the astronauts to remove the pump module with the failed flow control valve and place it on a temporary attach point. This task was originally scheduled for Monday's spacewalk.

NASA penciled in three spacewalks to complete the pump replacement, but officials were hopeful the work could be finished in two EVAs.

Mastracchio has demated the other two ammonia connectors from the pump module, reporting a few more ammonia flakes in the process. The astronauts will add thermal insulation to the ammonia lines before moving on to prepare the spare pump module for removal from its stowage location, an activity planned for Monday's spacewalk.

NASA says the spacewalkers are about one hour ahead of the timeline.

Hopkins has reconnected the ammonia lines to the jumper. Next up is the installation of a thermal cover over the jumper box.

After disconnecting the second line, Mastracchio reported some "small flakes" coming from the connector. This is not unexpected. NASA is reserving time at the end of the spacewalk for a "bakeout" using sunlight to cleanse the astronauts' spacesuits of toxic ammonia residue before going back inside the space station.

Mastracchio has removed the first ammonia line from the pump module.

Mastracchio and Hopkins are ready to begin disconnecting four fluid lines from the pump module on the starboard truss.

Mastracchio is standing on the end of the robot arm and will close ammonia valves in each line before manually demating quick-disconnect interfaces on each ammonia line. The spacewalkers will initially remove two of the four quick-disconnects before installing a "jumper box" to keep the ammonia loop from over pressurizing and ensure the fluid stays in a liquid phase as temperatures fluctuate during each of the space station's day and night passes.

Once the jumper is hooked up, the astronauts will remove the other two ammonia lines and unplug five electrical cables leading to the pump module.

For a summary of today's tasks, including a comprehensive timeline of the spacewalk, read our updated preview story.

Mastracchio is preparing to latch himself on to the end of the space station's 58-foot robot arm, while Hopkins is working on removing insulation covering the pump module to be disconnected later in the EVA.

NASA reports the spacewalkers are running about a half-hour ahead of the timeline.

An initial check of the astronauts' helment absorption pads shows no moisture build-up, meaning there has so far been no recurrence of the water leak that plagued a spacewalk in July.

Mastracchio has retrieved a foot restraint and is preparing to mount it on the station's robot arm.

The first task for the spacewalkers is for Hopkins to retrieve a jumper to be used later in the EVA to bypass ammonia around the pump module once the astronauts disconnect its fluid and electrical lines.

Mastracchio is getting a foot restraint to configure the space station's 58-foot robot arm for later activities.

The spacewalkers will then move out to the work site on the S1 starboard truss to begin work to remove the pump module, which is about the size of a refrigerator and weighs 780 pounds on Earth. The pump modules are built by Boeing and measure 5-and-a-half feet long, 4 feet wide and 3 feet high.

EVA BEGINS. The spacewalk officially began at 7:01 a.m. EST (1201 GMT) with the switching of the spacesuits to internal battery power.

This spacewalk is the seventh in the career of astronaut Rick Mastracchio, following three excursions each on the STS-118 and STS-131 space shuttle missions. It's the first EVA for Hopkins.

This is the 175th spacewalk devoted to space station assembly and maintenance.

Mastracchio is the lead spacewalker for this EVA, wearing the suit with the red stripes. Hopkins is wearing the all-white suit.

Both astronauts also have helmet-mounted cameras. Mastracchio's view will have the no. 20 in the corner of the screen, and the camera on Hopkins' spacesuit is denoted by the no. 18.

Astronauts Rick Mastracchio and Mike Hopkins are suited up and have entered the Quest airlock, which is now depressurizing ahead of the start of today's contingency spacewalk to begin repairing the International Space Station's broken coolant system.

The spacewalk is the first using U.S. spacesuits since water filled the helmet of astronaut Luca Parmitano in July. Engineers narrowed the likely cause to contamination in a filter inside the suit, allowing water to back up into the system and leak into Parmitano's helmet.

But NASA isn't sure what caused the contamination. Astronauts replaced components inside Parmitano's suit, which Hopkins will use on today's spacewalk, and officials are sure the suit is pristine.

The goal of the series of spacewalks is to replace a refrigerator-sized pump module on the space station's starboard-side truss. A flow control valve inside the pump module malfunctioned last week, preventing the station's computer from properly regulating the temperature of ammonia coolant flowing through the lab's external coolant system's loop A.

The ammonia is now too cold to flow through a heat exchanger on the space station's Node 2 module, where ammonia collects heat from a water loop coursing through the outpost's pressurized modules to dissipate heat from electronics and other electrical systems.

Read more details in a preview story.

Welcome aboard! The newest residents have floated into the International Space Station from their Soyuz capsule for the formal ceremony. Also participating via a live communications linkup are the VIPs gathered back at Baikonur still.

For the first time since October 2009, nine people are aboard the space station without a space shuttle present. And it marks the most people inside the complex since 10 people lived and worked at the station during the last space shuttle mission in July 2011.

The outpost's current crew is comprised of four Russians, three Americans, a European astronaut and a Japanese astronaut.

Three of the astronauts - Fyodor Yurchikhin, Karen Nyberg and Luca Parmitano - will return to Earth late Sunday night, U.S. time, to wrap up a five-month stay on the space station.

The docking probe on the front of Soyuz has retracted, allowing the hooks and latches to close and form a seal between the capsule and station. Pressure and leak checks will be performed over the next orbit before the hatchway is opened for the crew to enter into the station in a couple of hours.

The docking occurred as the two spacecraft flew above Germany just 6 hours and 14 minutes since liftoff, completing the Soyuz's third speedy sprint from launch to docking in the International Space Station program.

Over the next few minutes, the Soyuz docking probe will retract to allow hooks and latches to bring the spacecraft to a firm seal with the station. Hatches between the two vehicles will be opened around 7:40 a.m. EST (1240 GMT).

DOCKING! The Soyuz TMA-11M spacecraft has docked to the Rassvet module of the space station, delivering Russian cosmonaut Mikhail Tyurin, NASA flight engineer Rick Mastracchio and Japanese astronaut Koichi Wakata to the international outpost for their 198-day mission.

The Olympic torch has also been delivered for a quick four-day stay to celebrate the upcoming 2014 Winter Games in Sochi, Russia.

Range is now 29 feet. A steady, stable approach using Soyuz's automated rendezvous system continues.

Soyuz is now about 150 feet from the Poisk docking module and closing at 0.4 mph. The station and Soyuz are passing over the North Atlantic Ocean.

Inside 200 feet and closing. The crew has activated the Soyuz floodlight to better illuminate the Rassvet docking port.

The Russian flight control team has given approval for the final approach to commence.

The Soyuz completed the flyaround to align with the docking port. It's now in the stationkeeping hold 200 meters, or about 656 feet, away from the complex about while controllers verify all is in readiness for final approach.

The flyaround has begun. Soyuz is flying itself around the international outpost to get into the approach corridor leading to the Rassvet module's Earth-facing docking port.

Live views from the space station show spectacular imagery of the Soyuz spacecraft firing thrusters to slow its approach to the complex. Range is now 650 meters, or about 2,132 feet.

The Soyuz reports they can see the International Space Station. Range is now 2 kilometers, or about 1.2 miles.

Range between the Soyuz TMA-11M spacecraft and the space station is now about 15 kilometers, or 9 miles.

The Soyuz is now in its automated rendezvous sequence, and the Kurs rendezvous radar system has been activated and is providing good data to the spacecraft's guidance computer.

The International Space Station has also maneuvered into its docking attitude.

The Soyuz spacecraft is nearing the space station for the final phase of rendezvous and docking. You can watch live NASA Television coverage right here on this page.

A Russian Soyuz booster roared to life late Wednesday and rocketed away from Kazakhstan carrying a crew of three and an Olympic torch bound for the International Space Station, the centerpiece of an out-of-this-world photo op to herald the 2014 Winter Games in Sochi, Russia.

Read our full story.

Russian cosmonaut Mikhail Tyurin, NASA flight engineer Rick Mastracchio and Japanese astronaut Koichi Wakata have arrived in orbit following a good launch aboard the Soyuz TMA-11M spacecraft from the Baikonur Cosmodrome.

The solar arrays have been unfurled aboard the spacecraft to generate electricity, and the first major orbit-adjustment maneuver is planned for 11:56 p.m. EST (0416 GMT) to begin raising the capsule's altitude to match that of the space station.

A second "delta velocity" burn is set for 12:44 a.m. EST (0544 GMT), followed by several more firings over the next few hours to set up for rendezvous and docking.

The 7.9-ton capsule's automated rendezvous sequence, guided by its Kurs radar system, will commence a couple of hours before docking.

The Soyuz should be in position to start a flyaround maneuver at about 5:06 a.m. EST (1006 GMT) to line up with the docking port on the space station's Rassvet module. Soyuz commander Mikhail Tyurin will be standing by to take over manual flying of the spacecraft if required. Final approach will begin about 10 minutes before docking, which is scheduled for 5:31 a.m. EST (1031 GMT).

The docking should occur a mere 6 hours and 17 minutes after liftoff.

The craft is completing a programmed sequence to deploy the power-generating solar arrays, as well as antennas for navigational and communication systems.

T+plus 9 minutes. CAPSULE SEPARATION! The Soyuz spacecraft is flying free after the upper stage finished its engine firing and then separated away. The capsule is in pursuit of the International Space Station for a planned docking at 5:31 a.m. EST (1031 GMT).

T+plus 8 minutes. About a minute remains in the propulsion by the upper stage. The motor consumes kerosene and liquid oxygen just like the Soyuz rocket's other powerplants.

T+plus 7 minutes. The four-nozzle engine of the upper stage continues to burn to put the spacecraft into orbit.

T+plus 6 minutes. Soyuz's upper stage is firing to propel the spacecraft into a stable orbital perch around Earth on the six-hour, four-orbit trek to catch the International Space Station.

T+plus 5 minutes. The core stage of the Soyuz rocket has shut down and separated at an altitude of approximately 105 miles, leaving the upper stage to complete the job of injecting the Soyuz capsule into orbit.

T+plus 4 minutes. The core motor continues to fire on its propellant mixture of kerosene fuel and supercold liquid oxygen.

T+plus 3 minutes. The safety escape tower and launch shroud have been jettisoned from the atop the Soyuz capsule.

T+plus 2 minutes, 10 seconds. The four strap-on boosters clustered around the Soyuz rocket's main stage have burned out and separated. The core engine continues to fire as Soyuz streaks into space at more than 3,300 mph.

T+plus 60 seconds. Good performance one minute into this ascent for the Soyuz rocket and its three-person crew from the Kazakh launch base. NASA flight engineer Rick Mastracchio is strapped into the left-hand seat serving as co-pilot, veteran cosmonaut Mikhail Tyurin is in the center seat for his role as the Soyuz commander and Japanese astronaut Koichi Wakata is riding in the right-hand seat.

T+plus 20 seconds. The Soyuz rocket has maneuvered on course for a rendezvous with the space station six hours from now. The station currently is flying 260 miles over southern Russia.

LIFTOFF! Liftoff of the Expedition 38 crew en route to the International Space Station for docking in six hours!

T-minus 40 seconds. The first umbilical arm has separated from Soyuz. The second will retract in the next few seconds.

T-minus 1 minute and counting. The Soyuz has been placed on internal power.

T-minus 2 minutes and counting. Rocket propellant tank pressurization is underway. The vehicle's onboard measurement system is activated. Oxidizer and fuel drain and safety valves of the launch vehicle have been closed.

T-minus 4 minutes and counting. The nitrogen purge of the combustion chambers of side and central engine pods of the rocket is being performed in preparation for ignition.

T-minus 5 minutes and counting. Soyuz has switched to onboard control, the ground measurement system and the capsule commander's controls are being activated.

T-minus 6 minutes. The automatic program for final launch operations is being initiated. And the launch key has been inserted in the bunker for liftoff.

See our Facebook page for images of the countdown and launch!

T-minus 9 minutes and counting. The crew has closed its helmet visors.

T-minus 10 minutes. The crew inside the Soyuz capsule are starting recorders to collect data during launch.

T-minus 14 minutes and counting. The Soyuz telemetry systems are being activated. They will relay real-time data back to Earth during today's launch.

T-minus 17 minutes. Now in the launch count, realignment of the Soyuz rocket's trajectory control system and checks of internal batteries should be complete. The Soyuz telemetry system will soon be activated and monitoring of Soyuz's thermal control system also will begin.

T-minus 20 minutes and counting. The three-stage Soyuz rocket will insert the 15,700-pound space capsule into a 143 by 118 mile orbit, inclined 51.6 degrees to the equator, according to NASA.

T-minus 22 minutes and counting. At the time of launch, the International Space Station will be flying 260 miles over southern Russia just north of the border with Mongolia. When the Soyuz TMA-11M spacecraft deploys from the Soyuz rocket's third stage, the space station will be flying 2,600 miles ahead of the Soyuz.

The space station will fly almost directly overhead the Baikonur Cosmodrome about five-and-a-half minutes before launch.

The capsule will close that distance over the next six hours, with docking to the space station's Rassvet module scheduled for 5:31 a.m. EST (1031 GMT).

T-minus 24 minutes. The crew is completing leak checks of the Sokol launch spacesuits at this point in the countdown.

T-minus 27 minutes and counting. The emergency escape system is being armed. The system would be employed if a major malfunction occurs, propelling the Soyuz capsule off the top of the rocket to safety.

T-minus 40 minutes and counting. The two-piece service structure which enclosed the Soyuz rocket is being retracted to a horizontal position. The towers protected the rocket and provided workers and the Soyuz crew with access to the spacecraft since the rocket arrived at the launch pad at sunrise Tuesday.

Several other umbilical arms connecting the rocket to the ground will be retracted at various times later in the countdown.

T-minus 55 minutes and counting. Soyuz TMA-11M commander Mikhail Tyurin, NASA flight engineer Rick Mastracchio and veteran Japanese astronaut Koichi Wakata were awakened about eight hours ago to begin launch day activities.

They signed the doors at crew quarters and received religious blessings before boarding a bus that took the three crewmates the 25-mile distance into the cosmodrome. They donned their white Sokol launch and entry suits, met with officials from their respective space agencies and then headed for the pad. Crowds of well-wishers gathered to wave goodbye as the crew reached the rocket. An elevator took the trio up to the capsule-level of the tower to begin climbing aboard the cramped spacecraft.

T-minus 59 minutes. Live streaming video coverage of today's rocket flight to orbit begins now.

T-minus 90 minutes. The Soyuz rocket is fueled, the crew has traveled to the launch pad and the countdown is progressing toward liftoff of the space station's Expedition 38 crew from the Baikonur Cosmodrome at 11:14 p.m. EST (0414 GMT).

Live launch coverage and commentary begins in the stream at 10:15 p.m. EST.

Engineers are readying a Russian Soyuz spacecraft for launch late Wednesday to ferry three crew members to the International Space Station, along with an Olympic torch that will be featured in a weekend spacewalk photo op as a dramatic prelude to the 2014 Winter Games in Sochi, Russia.

Read our full story.

Adorned with colorful artwork celebrating the 2014 Olympic Games, a Soyuz rocket rode a specially-built railroad car to a launch pad in Kazakhstan on Tuesday in one of the final steps before liftoff of a new three-man crew for the International Space Station.

Technicians propped up the Soyuz rocket on the launch pad after its short sunrise rail journey.

Russian cosmonaut Mikhail Tyurin, NASA flight engineer Rick Mastracchio and Japanese astronaut Koichi Wakata will climb inside the Soyuz TMA-11M capsule atop the Soyuz rocket for launch at 0414 GMT Thursday (11:14 p.m. EST). Docking with the space station is set for 1031 GMT (5:31 a.m. EST), just six hours after launch.

Tyurin, Mastracchio and Wakata will join an international crew of six astronauts already on the space station, temporarily boosting the crew size to nine people.

The international outpost has not hosted so many people at once since the final space shuttle mission in July 2011.

Check out photos of the Soyuz rollout.