On April 17, 1970, Apollo 13 returned to Earth after narrowly avoiding a deadly disaster in space. [‘On This Day in Space’ Video Series on Space.com]

This was supposed to be the third mission to land on the moon. Astronauts Jim Lovell, Jack Swigert and Fred Haise launched on April 11 and were two days into their trip to the moon when an oxygen tank exploded, and NASA had to abort the mission. When the astronauts called mission control to report the incident, Swigert uttered the famous quote, "Houston, we've had a problem." With the service module running out of oxygen, they opted to use the lunar lander as a lifeboat. Because the oxygen was also used to power the spacecraft's fuel cells, they were also running out of power. They shut down all nonessential systems and turned down the heat, and spent four cold, miserable days heading back to Earth. They had to go back into the service module for reentry, and they didn't know if their heat shield had been damaged by the explosion. Luckily they survived reentry and safely splashed down in the Pacific Ocean.