On the evening of April 13, 1970, astronauts Jim Lovell, Fred Haise and Jack Swigert were on their way to the Moon aboard Apollo 13, the third lunar landing mission for NASA. They had launched from the Kennedy Space Center two days before and, despite an engine shut down during the climb to orbit, the flight was proceeding smoothly.

After the crew wrapped up a television show from space (which was not picked up by any of the networks), Mission Control ordered a couple of housekeeping chores. One assignment was to stir tanks inside the service module that held the liquid hydrogen and liquid oxygen that powered their electricity-generating fuel cells.

Swigert flipped a switch and almost immediately the crew heard a large bang and felt a shudder throughout the docked spacecraft. Telemetry to the ground indicated something had happened but flight controllers weren’t immediately sure what it meant. Swigert radioed the first words of trouble, and then Lovell repeated the warning, uttering one of the most famous lines in the history of the space program:

Several days later, when the crew could inspect its just-jettisoned service module -- seen in this picture -- everyone was shocked to witness the extent of the damage. But there was nothing anyone could do at that point. The crew still had to get home in the command module -- and failure was not an option.