Houston, We Have A Problem: The True Story Of Apollo 13

The Apollo 13 mission was supposed to be NASA's third lunar landing, but it was plagued with misfortune from the very beginning. In fact, the crew that wound up going, consisting of James Lovell, Jack Swigert, and Fred Haise, wasn't even the original crew. Only days before takeoff, it was discovered that several of the training Apollo astronauts had been exposed to the measles thanks to an outbreak at one of their kids' schools, so Jack Swigert had to replace Ken Mattingly as the command module pilot only two days before liftoff.
Still, everything seemed fine at liftoff, usually the most dangerous time for such missions. Things were smooth sailing until hour 56, when the electricity suddenly went haywire and the astronauts were startled by a loud bang. They quickly learned, to their horror, that an oxygen tank on board had exploded. It turned out that during construction of the spaceship, the liquid oxygen tank had been dropped on the factory floor, damaging the delicate interior plumbing. Though it worked once in the equipment test days prior to launch, by refilling the damaged tank with liquid oxygen, they had inadvertently turned it "into a bomb waiting to go off."

Even worse, the explosion caused the nearby gas oxygen tank to rupture, creating a large gash in the side of the spaceship and leaving the astronauts in a very precarious position. NASA's Space Center in Houston, Texas initially thought it was an instrument error until they received the now famous radio call from Swigert, "Houston, we've had a problem." Screenwriter William Broyles, Jr. later changed the line for the iconic Tom Hanks film Apollo 13 to "Houston, we have a problem" because he thought it sounded more urgent.
But things were urgent enough on the flight. Clearly, they weren't going to the moon in a shredded shuttle, and their only hope was to slingshot more than 1,000 miles around it back to Earth. With their electricity failing and their oxygen running out, they had to use the lunar module as a lifeboat and transfer their entire guidance system alongside new angle numbers from the command module in fewer than 15 minutes. Otherwise, they'd be stranded in the cold abyss of space with no way back.
Houston flew into action, with every department simultaneously coming up with possible solutions for the endangered astronauts. Within minutes, mathematicians had formulated five possible new trajectory options for slingshotting the damaged modules, and mission control ran through every possible outcome on their simulators (even Ken Mattingly helped out, probably happy that he wasn't on the actual mission after all). However, as the very small lunar module was only designed to house two astronauts for a short period of time, the buildup of carbon dioxide was a serious threat to their survival, and the lithium hydroxide canisters aboard the lunar module (which cleaned the air) just weren't cutting it.

The good news was that there were still canisters available on the command module, but for some reason, they were designed as squares, unlike the circular canisters provided for the lunar. If the astronauts were going to survive, they'd have to figure out how to stick a square peg in a round hole. Using only what the crew had aboard, mission control devised a solution involving the plastic manual covers, duct tape, cardboard, and parts of the space suits themselves and guided the stranded men through the improvised construction, which allowed them to breathe clean air.
However, because the electricity was shut off to conserve power for reentry, the module had no temperature regulation, leaving it near freezing and forcing the astronauts to constantly wipe down the condensation collecting inside, lest their equipment be ruined. Their water had to be rationed, and they became so dehydrated on the trip back that Haise developed a painful kidney infection. Thankfully, the crew did make it back to Earth relatively unharmed on April 17, 1970, when they splashed into the South Pacific Ocean near American Samoa. Though not the sort of discovery they were looking for, NASA learned many lessons, made many design changes to the shuttle for subsequent missions, and instituted better inspection procedures. None of the three astronauts aboard Apollo 13 ever went to space again, and the Apollo missions closed for good in 1972 after the public lost interest.