On May 23, 2017, NASA astronauts Peggy Whitson and Jack Fischer took an urgent and unplanned spacewalk to replace a broken data relay box outside of the International Space Station. [‘On This Day in Space’ Video Series on Space.com]

The problematic device, known as a multiplexer/demultiplexer, had been installed less than two months earlier during another spacewalk by Peggy Whitson and Shane Kimbrough. Two multiplexer/demultiplexers are fixed to the outside of the space station’s truss segment, and they’re responsible controlling vital systems like the solar arrays, radiators, cooling loops and other robotic equipment. That second unit kicked in as a backup when the newer one failed, so the station itself wasn’t affected. However, NASA had to scramble to install another spare to make sure the space station would be prepared in case the second computer failed as well. So, Whitson built a new multiplexer/demultiplexer using spare parts. It took the spacewalkers 2 hours and 46 minutes to swap out the boxes, and they had some time left to enjoy the view of Earth from space, which Fischer said was “epically amazeballs."