Virts reports a thin film of water inside his helmet, a similar occurrence to the water leak observed after Wednesday's spacewalk. He reports he is fine and the crew will proceed with their normal procedures to get Virts and Wilmore out of their spacesuits following today's spacewalk.

NASA says the issue is caused from condensation from the cooling system inside Virts' suit, a condition engineers say they fully understand.

Today's spacewalk is officially over with repressurization of the space station's Quest airlock underway. The official end time for the EVA was marked at 12:30 p.m. EST (1730 GMT), completing the fourth spacewalk in Wilmore's career and the third for Virts.

Virts and Wilmore have raced through their tasks in today's spacewalk, completing all the cable connections after running 400 feet of wiring on the port and starboard sides of the space station's main power truss.

The astronauts just made the final cable connection and installed retro-reflectors as docking aids for commercial crew spaceships as they approach the International Space Station.

The spacewalkers finished their work ahead of time, and mission control is directing Virts and Wilmore to begin cleaning up their work site and head back to the airlock to wrap up today's excursion.

The spacewalkers are continuing to route cables between the Destiny laboratory module and the antennas installed on the space station's port-side truss earlier in the EVA. They are working ahead of schedule in this task, which will be followed by a similar job to lay cables leading to the starboard-side antennas.

Virts has installed a boom and two antennas on the space station's port side truss, and Wilmore has finished up a similar procedure on the starboard side of the truss. The antennas will be used to communicate with approaching Boeing and SpaceX capsules carrying astronauts.

The astronauts will soon reunite to run four cables stretching 400 feet from the Destiny laboratory to the antenna sites out on the truss.

NASA astronauts Terry Virts and Barry Wilmore switched their spacesuits to battery power at 6:52 a.m. EST (1152 GMT), signifying the start of today's planned 6-hour, 45-minute spacewalk.

Virts is wearing a spacesuit with red stripes and is designated EV1. His helmet camera displays the number 20. Wilmore is wearing a spacesuit with no stripes and is designated EV2. His helmet camera displays the number 18. This is third spacewalk for Virts and the fourth for Wilmore.

Virts and Wilmore will install 400 feet of cable along the space station’s truss and other equipment associated with the Common Communications for Visiting Vehicles (C2V2). The system will be used by crewed commercial spacecraft to rendezvous with the space station in the coming years.

Virts has removed his helmet now after reporting water build-up following today's spacewalk. ESA astronaut Samantha Cristoforetti reported the water was cold to the touch, a clue that could help engineers troubleshoot nail down the source of the leak.

She also says there was not a significant amount of water, but an absorption pad inside the helmet was moist.

Safely back inside the space station, Virts has reported some water build-up in his helmet, a recurrence of a problem that occurred during a spacewalk with astronaut Luca Parmitano in July 2013.

The amount water in Virts's helmet is apparently not as severe as Parmitano's case, and the crew reports he is in no danger.

It's not yet clear how this problem could impact plans for another spacewalk scheduled for Sunday.

Today's spacewalk is complete with the start of repressurization of the Quest airlock at 1834 GMT (1:34 p.m. EST). The EVA lasted 6 hours and 43 minutes.

Wilmore has completed his third spacewalk, and Virts now has logged two EVAs in his career.

The astronauts are in the home stretch of today's spacewalk, now collecting their tools before heading back to the airlock.

Wilmore continues installing wire ties, while Virts is lubricating more components in the robot arm's Latching End Effector.

Now more than four hours into the spacewalk, Wilmore has finished up his work on the Tranquility module, verifying its forward and aft berthing mechanisms are functioning normally after removing launch locks left on the module after its launch on a space shuttle mission in February 2010.

While Virts continues lubricating parts of the space station's robotic arm, mission control is sending Wilmore to begin configuring wire ties for the installation of another 400 feet of cable planned for another spacewalk Sunday. The cabling will run to an antenna to communicate with approaching and departing commercial crew capsules when the vehicles begin flying in 2017.

The next task for Virts is to lubricate several parts inside the Latching End Effector on the space station's Canadian-built robotic arm. These components were never meant to be lubricated in space, but Virts has a specially-devised tool to apply grease to blind spots inside the arm's grapple system.

ESA astronaut Samantha Cristoforetti will operate the robot arm from inside the space station to assist Virts.

Meanwhile, Wilmore is retrieving a socket from a toolbox, then he will go to the Tranquility module and remove a non-propulsive vent and hand rail to clear the way for the relocation of another module later this year.

He will also remove 16 launch locks from two of the Tranquility module's berthing ports, making the sites ready to receive the space station's relocated Pressurized Multipurpose Module and a new inflatable habitat built by Bigelow Aerospace.

Wilmore and Virts are finishing up installation of the last two cable sets to eventually be connected to the International Space Station's new docking adapters due for delivery later this year. In total, the astronauts will have laid 364 feet of cables in work completed on Saturday's spacewalk and today's excursion.

The astronauts have removed the cover from the front end of the PMA-2 docking port, clearing the way for the addition of a new docking mechanism there later this year. The next job for Wilmore and Virts will be to run the last couple of cables that will eventually lead to the new docking adapter.

Wilmore's helmet-mounted camera bears the No. 18. Virts has helmetcam No. 20.

Wilmore and Virts officially started their spacewalk at 1151 GMT (6:51 a.m. EST), when the astronauts switched their spacesuits to battery power. The spacewalkers are now outside the Quest airlock preparing for their first task.

Astronauts Butch Wilmore and Terry Virts are gearing up for the second in a series of three spacewalks to ready the International Space Station for dockings of new commercial spacecraft.

Wednesday's excursion is set to begin at 1210 GMT (7:10 a.m. EST) and will focus on routing cables and lubricating a component of the lab's robot arm.

Wilmore will be designated EV-1 for Wednesday's spacewalk, wearing the spacesuit with red stripes. Virts will wear the all-white suit.

The spacewalk will officially start when the astronauts switch their spacesuits to internal battery power inside the Quest airlock.

After exiting the airlock, the spacewalkers will move to the forward end of the space station, where Pressurized Mating Adapter No. 2 is attached to the Harmony module. PMA-2 was the docking port used by visiting space shuttles until the orbiters were retired in 2011.

Wilmore and Virts will remove a cover from the PMA-2 docking port and store it in a bag, clearing the adapter for the attachment of a new docking mechanism designed to be compatible with new commercial crew spaceships being built by Boeing and SpaceX.

The next job will be running another set of cables along PMA-2 to prepare for the arrival of the new docking adapters, completing the tasks Wilmore and Virts started on Saturday's spacewalk.

Once the astronauts clean up their work site at PMA-2, attention turns to maintenance of the space station's robotic arm.

European Space Agency astronaut Samantha Cristoforetti will be at the controls of the robot arm, and Virts will step into a foot restraint on a storage platform mounted next to the Quest airlock.

Virts will lubricate five different portions of the robot arm's latching end effector, the part that grabs on to modules, the space station's Dextre robotic handyman, and visiting Dragon, Cygnus and HTV supply ships.

Using a special tool resembling a "selfie stick" to reach blind spots -- plus a grease gun -- Virts will grease the end effector's latch ball screws, equalization brackets, deployment rollers, linear track bearings, and the rigidized central ball screw.

Wilmore will retrieve a socket from a toolbox and proceed to the space station's Tranquility module, where he will remove a valve and a hand rail to prepare for the planned relocation of the outpost's Permanent Multipurpose Module, or PMM, later this year.

He will also remove eight launch locks from the Tranquility module's unused forward and aft berthing ports, and open flaps to each port's window, to get the sites ready to receive the relocated PMM and an inflatable module built by Bigelow Aerospace due to launch to the station later this year.

Mission control will command petals to open on each berthing port, and Wilmore will visually verify the mechanisms work as designed.

If the spacewalkers run ahead of time, mission control could ask them to complete several "get-ahead" tasks, including the installation of wire ties on the space station's central truss segment, the removal of a faulty light fixture, reconfiguring a mobile tool cart, and adding a clamp on a hand rail on the Quest airlock to cover a sharp edge.

Astronauts Barry "Butch" Wilmore and Terry Virts floated outside the International Space Station Saturday and installed wiring needed for two new docking mechanisms that will be attached later this year for use by Boeing and SpaceX crew capsules.

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With repressurization of the Quest airlock underway, today's spacewalk is officially completed for a duration of 6 hours, 41 minutes.

Butch Wilmore and Terry Virts installed and routed eight cables for the International Space Station's new docking adapters due to arrive on SpaceX Dragon cargo ships later this year. The adapters will be used for dockings of astronauts aboard future Boeing and SpaceX crew vehicles.

The astronauts laid 340 feet of cable today, leaving two more cables to be installed on a spacewalk planned for Wednesday, before the spacewalkers move on to lubricating components on the space station's robotic arm.

Today's EVA was the first spacewalk for Virts, and the second for Wilmore, who now has 13 hours, 15 minutes of spacewalking time.

The spacewalk was the 185th EVA in support of space station assembly and maintenance, representing 1,159 hours and 8 minutes of time working outside the complex since December 1998.

The astronauts have returned to the Quest airlock and closed the hatch. The official end of the spacewalk will be marked when repressurization of the airlock begins.

Mission control has directed Wilmore and Virts to begin cleaning up their work site and head back to the airlock after completing all the primary tasks in today's spacewalk.

As the EVA passes five hours in duration, mission control is looking at extending today's spacewalk up to seven hours in duration to capture a couple of "get-ahead" tasks. The extra work involves laying two more cables that were originally set to be installed on the next spacewalk Wednesday.

The astronauts have finished up connections on the starboard side of the Harmony module, replacing the debris shield there once the work was complete.

Next up is the running of 364 feet of cables on the Destiny laboratory module, the Harmony module and the PMA-2 docking adapter.

Wilmore will initially focus on a cable running from Destiny across Harmony to PMA-2, while Virts will uncoil the cables just plugged in on the port side of Harmony.

Wilmore and Virts are passing the three-hour point in today's spacewalk. After securing disconnected shuttle-era wiring leading to the PMA-2 docking adapter, they have re-installed a debris shield over the work site on the port side of the Harmony module.

Next up, they will remove a debris panel from the starboard side of Harmony to complete a similar series of tasks to the work just finished.

The spacewalkers have connected the first set of four power and data cables that will lead to new docking adapters due to arrive at the space station later this year. They will soon put the debris shield removed earlier in the spacewalk back over the work site on the port side of Harmony, then move to the starboard side of the module to do a similar task as the one just completed.

The astronauts have removed a debris shield from the port side of the Harmony module to begin disconnecting four cables leading to the PMA-2 docking adapter. Wilmore will replace the cables with four new ones for the new docking adapter.

After leaving the space station's Quest airlock carrying bags containing bundles of cables to be installed during today's spacewalk, Wilmore and Virts moved to the forward end of the Harmony module, their prime work site for the next six-and-a-half hours.

A docking port named Pressurized Mating Adapter No. 2, or PMA-2, is attached to the forward side of Harmony. Visiting space shuttles docked there when they delivered crews, supplies and modules to the complex.

One of two new Boeing-built docking adapters will be added to PMA-2 on another spacewalk this summer to prepare for the arrival of CST-100 and Dragon commercial crew ferry craft.

The astronauts are installing wire ties on handrails to prepare for routing the cables later in today's spacewalk, then they will remove a shield from the port side of Harmony to begin connecting the new wiring.

Today's spacewalk officially began at 1245 GMT (7:45 a.m. EST) as Butch Wilmore and Terry Virts switched their spacesuits to internal battery power.

Wilmore is designed EV-1 for today's excursion, and he wears a spacesuit with red stripes. His helmet-mounted camera bears the No. 18. Virts is EV-2, wearing an all-white spacesuit with helmetcam No. 20.

The spacewalk marks the second EVA in Wilmore's career going outside the space station in October. It is Virts's first spacewalk.

NASA space station managers decided Thursday to delay the first two of three planned spacewalks by one day to give flight controllers and engineers a chance to catch their collective breath after exhaustive troubleshooting to verify the health of critical internal spacesuit components.

Expedition 42 commander Barry “Butch” Wilmore and Terry Virts plan to install more than 760 feet of power and data cables needed for new docking mechanisms that will be used by commercial crew ferry ships being built by Boeing and SpaceX. They also plan to install and hook up two sets of antennas, part of a new communications system that will be used by crews approaching and departing the lab complex.

The first spacewalk, originally planned for Friday, will slip to Saturday, starting around 7:10 a.m. EST (GMT-5) and the second outing will move one day to Wednesday. The third EVA remains on track for March 1 as originally planned pending additional review.

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