Clock ticks on: 12 minutes of darkness to gopublished at 14:55
The astronauts are working hard to get the replacement Sequential Shunt Unit into place before sunlight returns to the solar panels...
Image source, NasaSummary
British astronaut Tim Peake completed his first spacewalk at 17:31 GMT on Friday 15 January after nearly five hours in space
Intended to be longer than six hours, the walk was cut short after his US colleague Tim Kopra reported water in his helmet
The duo successfully completed their main job, replacing a faulty unit that regulates power from the station's solar panels
Other scheduled work, including routing many metres of cables for new docking ports, was left for future spacewalks
Major Tim is currently on a six-month mission to the space station for the European Space Agency
Clock ticks on: 12 minutes of darkness to gopublished at 14:55
Image source, Nasaget involved Send us your commentspublished at 14:54
Mohammad Ahsan Jaffar, on our Facebook page, external:
Quote MessageUnbelievable. Space is beautiful isn't it?
Pamela Farries tweets:
Repairs going according to plan - so farpublished at 14:46
Working as the station races across the night-time face of the planet, Tim Peake and Tim Kopra have removed the faulty electrical unit.
It showed no external damage, Tim Peake told mission control.
Now they need to fit the replacement.
They have about 20 minutes more time...
Image source, NASA
Image source, NASAThis Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter postThe BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter postDarkness begins - time to go to workpublished at 14:38
This Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter postThe BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter postFollow the progress of the space stationpublished at 14:36
This graphic, which you can find in our main Tim Peake news story on the BBC News website, shows the location of the International Space Station.
The station is sweeping past the coast of western Australia as the team prepares for the most important part of their spacewalk.
Five minutes until darkness - and the hard work beginspublished at 14:32
As a reminder, the next night pass begins at 14:37 GMT.
This is when the two Tims will perform the main job they have gone into space to do: swapping a faulty electrical component that connects the power from the solar panels.
They need to make the switch when there is no power in the panels - a window of 31 minutes.
Not the same as training: Adjusting to the vacuumpublished at 14:30
Paul Rincon
Science editor, BBC News website
Image source, NASANasa astronaut Michael López-Alegría holds the US record for the most cumulative time outside in space.
Astronauts train for spacewalks in a water tank. But Mr López-Alegría told the BBC there were differences between being in a pool and being in space.
Quote MessageOne is that translation [moving from one point to another] in quite a bit different without the viscosity of the water... This fact will change his centre of gravity and will affect the results of the inputs he makes with his hands and arms during translation.
And for later in the spacewalk:
Quote Message[Mr Peake] has a fairly tight translation path while routing a cable for the International Docking Adapter. This translation is difficult to simulate... in the pool, because there he has always been connected to the surface by an umbilical.
But the Nasa astronaut said Tim Kopra, a veteran of two spacewalks, would be on hand to offer advice to Major Peake.
Ready to switch faulty component, the astronauts pose for photospublished at 14:22
The two Tims are both wearing helmet cameras which record their progress:
And they are now ready to make the switch of the Sequential Shunt Unit, as soon as they are in darkness again.
With about 20 minutes to go, they paused for some photography...
Image source, Nasa"That's perfect framing," said ground control.
"Poster quality."
Recap: 'Proud moment' as Tim Peake starts spacewalkpublished at 14:16
"Tim it's really cool seeing that Union Jack go outside," said Reid Wiseman earlier. He is the astronaut guiding Tim Peake and Tim Kopra from mission control today.
Quote MessageIt's great to be wearing it. It's a huge privilege - a proud moment.
Tim Peake, British astronaut
Monitoring health risks - and preparing for the repairspublished at 14:08
The astronauts will be monitored for radiation exposure throughout the spacewalk.
Meanwhile, Tim Kopra has been inspecting the faulty electrical box that he and Tim Peake will be replacing.
This needs to happen in the next night pass - beginning at 14:37 GMT - which offers a safe window of just half an hour.
This Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter postThe BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter postBoth astronauts reach the end of the stationpublished at 14:01
The two astronauts are now both at the "S6" truss segment, at the far end of the space station's starboard side.
Image source, NasaQuote MessageIt's really nice to see you both there together, at the tip of the world.
Reid Wiseman, Nasa astronaut at mission control
Image source, NasaImage caption, A view from Tim Peake's helmet camera
What makes a spacewalk so challenging?published at 14:00
Helen Briggs
BBC NewsBoth astronauts have prepared for spacewalks in training, but things can go wrong.
Space suits provide protection for the astronauts but their bulk can make it hard to carry out delicate tasks.
As Paul Dum, Nasa's lead spacewalk officer, puts it: "Spacewalking is challenging - you have to wear a spacesuit which is sort of your own independent space ship to protect you from the harshness of the environment.
"So there's a trade-off between having as much protection as possible but still maintaining mobility.
"So imagine going out with thick winter gloves on and trying to do anything that takes fine dexterity. That's going to be challenging."
Like climbers, the astronauts must always be tethered to space station supports, to prevent them floating away.
Image source, EsaImage caption, Tim Peake adjusts to his own personal space ship
Back in daylight, the work beginspublished at 13:52
Image source, NasaImage caption, Sunlight bathes the ISS once again
Image source, NasaImage caption, Tim Kopra reaches the far end of the station
What the astronauts are going out to fixpublished at 13:49
The main reason for the spacewalk is to fix an electrical box that transfers power from one of the solar panels to the space station.
The station has been running at reduced power since it failed in November 2015.
Image source, NasaImage caption, The box is known as the sequential shunt unit (SSU)
The astronauts will use any remaining time for other tasks, including laying cables for new docking ports and reinstalling a valve that was removed last year.
Navigating 50m in space - and a lot of acronymspublished at 13:44 Greenwich Mean Time 15 January 2016
This from the European Space Agency:
This Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter postThe BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter postMeanwhile, BBC science correspondent Rebecca Morelle tweets:
This Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter post 2The BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter post 2This Twitter post cannot be displayed in your browser. Please enable Javascript or try a different browser.View original content on TwitterThe BBC is not responsible for the content of external sites.Skip twitter post 3The BBC is not responsible for the content of external sites.Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
End of twitter post 3Recap: The two Tims prepare for today's spacewalkpublished at 13:41 Greenwich Mean Time 15 January 2016
Watch Nasa footage from earlier today, of Tim Peake and Tim Kopra 'suiting up' for their spacewalk:
Astronauts move out across the space stationpublished at 13:32
Tim Kopra and Tim Peake have started to head away from the airlock, using trusses on the starboard side of the space station.
Image source, NasaImage caption, Tim Kopra (left) moving away from the airlock
The replacement of the Sequential Shunt Unit, one of their main jobs today, needs to be done during one of the periods when the station is in darkness.
The next of these night passes begins at 14:37 GMT.
Then there will be a safe period of 31 minutes, when the solar panels are devoid of charge, for the pair to swap out the component.
Everything going according to plan - and ahead of schedulepublished at 13:14
Speaking to the two spacewalking Tims from mission control in Houston, Nasa astronaut Reid Wiseman said everything was looking good.
Quote MessageJust passed over northern Australia and you're running about 10-15 minutes ahead on the timeline.
Reid Wiseman
Wiseman has previously completed a similar repair effort outside the space station, and will be guiding Tim Kopra and Tim Peake throughout their efforts today.
Tim Peake is officially on a spacewalk!published at 13:10
BreakingBritish astronaut Tim Peake is now outside the International Space Station, on his first spacewalk.
"It's a privilege," he said in response to station commander Scott Kelly saying he was pleased to see the Union Jack on the sleeve of a spacewalking astronaut.
Unfortunately it is difficult to see him at the moment because the station has moved round to the night-time side of the planet.
Image source, Nasa
Image source, NasaOne of two astronauts is now outside the stationpublished at 13:02
Tim Kopra of Nasa is already out in space.
You can see him near the centre right of this photo...
Image source, NasaThis shot, meanwhile, filmed by one of the crew still on board, shows Tim Peake - and the flag on his suit - from inside the hatch.
Image source, Nasa