The Slingshot, and A Square Peg in a Round Hole
With an unknown amount of damage done to the Service Module, which held their air and fuel, turning around wasn’t a viable option. Instead, the brilliant minds at NASA devised a new solution: pass by the Moon close enough that its gravitational pull would slingshot them back towards the Earth.
They now had a plan, but one big problem still loomed: how would the astronauts stay alive long enough for the plan to succeed? To conserve power, all possible systems within the Service and Command Modules, jointly named Odyssey, were shut off, and the crew crawled into the Lunar Landing Module Aquarius.
Even with the heat turned off, leaving the astronauts in near-freezing temperatures, Aquarius was only built to sustain two men for a small period of time, not three men for days. Eventually, the lander’s small air filter had to be replaced—but the Landing Module used a round filter, and the only replacements left were for the Command Module, which were square. Enter again the geniuses at NASA, who devised a way to fit the square filter into the round hole using the few items the astronauts could spare.