This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.bbc.co.uk/news/science-environment-35273912

The article has changed 14 times. There is an RSS feed of changes available.

Version 1 Version 2
Tim Peake set for historic spacewalk Tim Peake set for historic spacewalk
(35 minutes later)
Tim Peake is set to carry out the first ever spacewalk by an "official" British astronaut.Tim Peake is set to carry out the first ever spacewalk by an "official" British astronaut.
Major Peake and Nasa astronaut Tim Kopra are scheduled to step outside the International Space Station at 12:55 GMT.Major Peake and Nasa astronaut Tim Kopra are scheduled to step outside the International Space Station at 12:55 GMT.
They will replace a faulty component on the station's exterior, which has compromised a power channel on the outpost.They will replace a faulty component on the station's exterior, which has compromised a power channel on the outpost.
Michael Foale became the first Briton to carry out a spacewalk in 1995.Michael Foale became the first Briton to carry out a spacewalk in 1995.
He flew under a US banner with Nasa.He flew under a US banner with Nasa.
"I think a spacewalk is absolutely the pinnacle of an astronaut's career," Major Peake told BBC Stargazing Live this week."I think a spacewalk is absolutely the pinnacle of an astronaut's career," Major Peake told BBC Stargazing Live this week.
"We've put a huge amount of effort into this spacewalk. It's hugely exciting and we're ready to go." The European Space Agency (Esa) astronaut added: "We've put a huge amount of effort into this spacewalk. It's hugely exciting and we're ready to go."
The six-and-a-half hour extra-vehicular activity (EVA) - the technical term for a spacewalk - will see the two Tims replace a failed electrical box which regulates power from the solar panels.The six-and-a-half hour extra-vehicular activity (EVA) - the technical term for a spacewalk - will see the two Tims replace a failed electrical box which regulates power from the solar panels.
They will have to make their way across half the length of the space station, travelling roughly 50m - equivalent to an Olympic-sized swimming pool - while holding on to the exterior with their arms.They will have to make their way across half the length of the space station, travelling roughly 50m - equivalent to an Olympic-sized swimming pool - while holding on to the exterior with their arms.
Colonel Kopra will head out first; laying down anchor points on the outside of the ISS. The US astronaut will then give a "Go" signal and Major Peake will follow his colleague, carrying the replacement box.
Note: This tracker uses the time set on the device you are using to predict where the space station is. If your pc, tablet or mobile has the wrong time set then the graphic will not show the correct position.Note: This tracker uses the time set on the device you are using to predict where the space station is. If your pc, tablet or mobile has the wrong time set then the graphic will not show the correct position.
Colonel Kopra will head out first; laying down anchor points along the exterior. The US astronaut will give a "Go" signal. Major Peake will then follow his colleague, carrying the replacement box. "I'll have a few moments where I'll just be hanging beneath the airlock and I can have a look around... look down on planet Earth and see what that feels like," said Major Peake.
Luca Parmitano, an Italian Esa astronaut who conducted two spacewalks in 2013, told BBC Five: "It is unimaginable... there are no words to describe the feeling of seeing our planet from above through a visor - that's all that separates us from the view, a thin visor of plexiglass."
"When language evolved, it described what we saw around us. Being on the space station, doing an EVA, walking outside is not something we have experienced [as a species]."
The failed electrical component - known as a Sequential Shunt Unit (SSU) - is relatively straightforward to swap out: it involves undoing just one bolt.The failed electrical component - known as a Sequential Shunt Unit (SSU) - is relatively straightforward to swap out: it involves undoing just one bolt.
But the ISS takes 90 minutes to orbit the Earth, so the astronauts experience 45 minutes of daylight followed by 45 minutes of total darkness.But the ISS takes 90 minutes to orbit the Earth, so the astronauts experience 45 minutes of daylight followed by 45 minutes of total darkness.
Peake and Kopra can only work on the SSU in darkness, because in daylight, there could be a current running through the box.Peake and Kopra can only work on the SSU in darkness, because in daylight, there could be a current running through the box.
Tim Peake in space: Want to know more?Tim Peake in space: Want to know more?
Special report page: For the latest news, analysis and videoSpecial report page: For the latest news, analysis and video
Guide: A day in the life of an astronautGuide: A day in the life of an astronaut
Explainer: The journey into space and backExplainer: The journey into space and back
Social media: Twitter looks ahead to lift-offSocial media: Twitter looks ahead to lift-off
They have been given a safe window of 31 minutes to work on changing the SSU.They have been given a safe window of 31 minutes to work on changing the SSU.
"We have to be very careful when we go out to the worksite, because there's nothing protecting us from the high voltages generated by the solar panel," said Mr Peake. "We have to be very careful when we go out to the worksite, because there's nothing protecting us from the high voltages generated by the solar panel," said Major Peake.
"We need to change that box out and then hopefully the fresh one will work correctly and we can continue with some more tasks.""We need to change that box out and then hopefully the fresh one will work correctly and we can continue with some more tasks."
After changing the SSU, Major Peake and Col Kopra will deploy some cables for new docking ports and reinstall a valve that was removed for relocation of the station's Leonardo module last year.After changing the SSU, Major Peake and Col Kopra will deploy some cables for new docking ports and reinstall a valve that was removed for relocation of the station's Leonardo module last year.
Michael Foale, who was born in Louth, Lincolnshire, became the first Briton to make a spacewalk on 9 February 1995, during a US space shuttle mission.Michael Foale, who was born in Louth, Lincolnshire, became the first Briton to make a spacewalk on 9 February 1995, during a US space shuttle mission.
Born to a British father and American mother, Mr Foale has dual British and US citizenship. He was selected under Nasa's astronaut programme and therefore "flew" as an American.Born to a British father and American mother, Mr Foale has dual British and US citizenship. He was selected under Nasa's astronaut programme and therefore "flew" as an American.
Traditionally, the British government has not funded human spaceflight, leading a generation of budding astronauts to look to the US space agency as their only route to orbit.Traditionally, the British government has not funded human spaceflight, leading a generation of budding astronauts to look to the US space agency as their only route to orbit.
But the UK changed its policy after Mr Peake was selected in 2009 as a European Space Agency astronaut. Thus, Mr Peake is the first person since Helen Sharman in 1991 to wear the British flag in space.But the UK changed its policy after Mr Peake was selected in 2009 as a European Space Agency astronaut. Thus, Mr Peake is the first person since Helen Sharman in 1991 to wear the British flag in space.
Ms Sharman flew to the Soviet Mir space station for a week-long mission under a privately funded programme called Project Juno.Ms Sharman flew to the Soviet Mir space station for a week-long mission under a privately funded programme called Project Juno.
Follow Paul on Twitter.Follow Paul on Twitter.