UK & World News
Nasa Orders Three Urgent ISS Spacewalks
Nasa has ordered a series of spacewalks to fix a broken cooling line at the International Space Station - including one on Christmas Day.
Station managers will send two American astronauts out on Saturday, Monday and Wednesday.
Nasa astronaut Rick Mastracchio tweeted from space: "The next week will be busy with space walks - so not much tweeting from here."
The spacewalks are taking priority over the launch of a supply ship from Virginia, which has now been delayed until at least mid-January.
Half of the station's cooling system shut down last Wednesday, forcing the six-man crew to turn off all non-essential equipment, including some scientific experiments.
The space station's cooling system, which runs ammonia through the lines, is critical for dispelling heat generated by on-board equipment.
Flight controllers tried in vain to fix a valve problem remotely, then came up with a plan to use another valve to regulate the temperature.
Some success was reported, and for a while, engineers thought the space station could limp along with the short-term solution. However the decision has now been taken to make a more permanent fix.
While the astronauts are safe and comfortable, Nasa wants the system back up to full strength in case of another failure that could leave the orbiting outpost even more vulnerable than it is right now.
This is the same pump that was replaced by a pair of spacewalking astronauts in 2010. Three spacewalks were needed then.
The station crew includes three Russians and one Japanese, as well as the two Americans.
:: Watch Sky News live on television, on Sky channel 501, Virgin Media channel 602 and Freeview channel 82.