Space-walk astronauts 'not in danger'

Astronauts from the International Space Station will be making an emergency space walk today to fix a leak from the station's power system.

Commander Chris Hadfield, on board the station, told Nasa how he had seen a "very steady stream" of flakes of ammonia coolant leaking from the system.

Dr Geraint Jones, who used to work for Nasa and is now at the Space Science Lab at University College London, told the Today programme that "they may have to lose some power" but the astronauts "aren't in any direct danger", adding that the emergency space walk is "exactly what they've been trained for".

First broadcast on BBC Radio 4's Today programme on Saturday 11 May 2013.