Astronauts Chris Cassidy and Tom Marshburn completed the most impromptu spacewalk in NASA history ahead of schedule. The two men spent roughly five hours outside of the International Space Station repairing an ammonia pump used to cool the laboratory's engine system.
NASA scientists on the ground walked the two men through the pain-staking process of replacing the pump Saturday morning. They stayed outside while the pump was activated to make sure no flecks were seen forming around the newly installed pump. "No evidence of any ammonia leakage whatsoever. We have an airtight system — at the moment," Mission Control reported. After about an hour of observation the two were brought back inside. It was a job well done. "No leaks! We're bringing Tom & Chris back inside," Hadfield tweeted.
The emergency situation thankfully never put the astronauts life in danger, but it was a stressful way for Hadfield and Marshburn to spend their last few days on the ISS. The two return to earth in a Russian Soyuz spaceship on Monday.