VIRAL VIDEO OF THE DAY PART 2 - Astronauts take part in seven hour spacewalk off space station as urine recycler breaks

Astronauts on the international space station have begun the longest and hardest spacewalk of their maintenance mission as the system for converting urine into drinking water breaks down again.

NASA astronauts Heidemarie Stefanyshyn-Piper and Stephen Bowen were due to spend more than seven hours fixing a clogged solar wing-rotating joint. As they began their spacewalk, a new recycling system for converting urine into drinking water broke down again for the third day in a row. The problem could jeopardise NASA's plan to return recycled water to earth aboard space shuttle Endeavour next weekend. The £100 million water recycling system, delivered a week ago by space shuttle Endeavour, is essential for allowing more astronauts to live on the space station next year. The wing-rotating joint stopped working properly more than a year ago, after it became jammed with metal grit from grinding parts. It can no longer keep the solar wings on the right side of the space station pointed toward the sun. The astronauts first began their repair work – which involves cleaning, lubrication and the replacement of bearings – last week. Ms Stefanyshyn-Piper, who dropped a £67,000 tool kit during a previous spacewalk, was forced to share some of her equipment with Mr Bowen during the repair. As for the broken urine-recycling system, flight controllers and astronauts alike were disappointed when it stopped working again. Mission Control radioed up the bad news just before the spacewalk began. "I'm very sorry to hear that," astronaut Sandra Magnus replied. NASA wants samples of the recycled water returned aboard Endeavour in order to conduct tests and ensure that it is safe to drink. The equipment is supposed to run for at least 90 days before anyone takes a sip. The space agency cannot expand the size of the space station crew from three to six unless the water recycling system is working. NASA still hopes for that to happen by June. Endeavour is supposed to leave the space station at the end of this month but its departure could be put back a day in order to collect enough samples from the recycling equipment.