The journey back to an operating theatre may still be the greatest obstacle to an astronaut who is seriously injured, or falls badly ill during a mission.

BBC: 'Hidden health risks' of space travel

He has played the entire season with a three-inch pin in his ankle after he was seriously injured against Bath in May 2008 and has delayed having an operation to remove it in order to be available for England and the Lions, should he be required.

BBC: Jeremy Guscott column