An unplanned spacewalk

2016-11-25 - During Chris Hadfield's expedition to the International Space Station, two of his crewmates conducted an unplanned spacewalk to perform urgent repairs on the cooling system. Expedition 35 flight engineers Tom Marshburn (left) and Chris Cassidy (right) completed a 5.5-hour spacewalk to replace a pump controller box that was leaking ammonia coolant. (Credit: NASA)