The engineers who developed the Apollo program spacecraft really liked to try and think of everything, and that included emergency procedures for almost every contingency. In one scenario an astronaut would leave the Lunar Module with a set of cables designed to transfer power to a stranded lunar module. Lunar Module Handbooks for most of the procedures https://www.hq.nasa.gov/alsj/LM10HandbookVol1.pdf https://www.hq.nasa.gov/alsj/LM11HandbookVol2.pdf I originally found this story here, so full credit goes to the author. http://finleyquality.net/dont-get-me-started/