NASA has confirmed that two astronauts spent nearly eight hours spacewalking in order to tackle an ammonia leak from a cooling system.
Station commander Scott Kelly and flight engineer Kjell Lindgren were about two hours into their planned 6½-hour spacewalk when the ammonia flakes spewed out - Lindgren reported intermittent flakes of toxic ammonia while making connections in a cooling line.
The primary cooling system was then recharged with ammonia and put back into service.
NASA had hoped to pack away the spare, but Kelly and Lindgren ran out of time to fold and cover its extended radiator panels.
NASA spokesman Dan Huot said that work likely would be rescheduled for a future spacewalk. No more space walks are scheduled for 2015.