"In the relative calm between these storms of all-out existential peril, Mir crews had to deal with a wide variety of smaller threats, like power outages, coolant leaks, computer failures, and orbital tumbling.
"But perhaps most infamously, they had to coexist with the microbial astronauts who hitched rides to the station in the crew’s bodies. Over the course of those 15 years in space, a steady war of attrition was waged between the crews and these mutating strains of mould and bacteria that also called Mir home.
"By the time the station was finally abandoned in 2000, its degeneration into a disgusting orbital stinkbomb had become an open secret. In one particularly egregious incident in 1998, American astronauts discovered that dirty water globules—some of which were roughly the size of basketballs—were casually free-floating behind some of the station’s service panels. These gross liquid orbs, which were alternately brownish or cloudy white in color, had become miniature planets of activity for the opportunistic microbes that were attempting to commandeer Mir.
"“Behind the panels the temperature was toasty warm - 82 degrees Fahrenheit (or 28 degrees Celsius) - just right for growing all kinds of microbeasties,” wrote science journalist Trudy E. Bell in a 2007 NASA article. “[S]amples extracted from the globules by syringes and returned to Earth for analysis contained several dozen species of bacteria and fungi, plus some protozoa, dust mites, and possibly spirochetes.”"