An anonymous reader writes "The official NASA home page has a writeup on one of the lesser-known dangers of living on a Space Station: space germs. 'Picture this: You're one of several astronauts homeward bound after a three-year mission to Mars. Halfway back from the Red Planet, your spacecraft starts suffering intermittent electrical outages. So you remove a little-used service panel to check some wiring. To your unbelieving eyes, floating in midair in the microgravity near the wiring is a shivering, shimmering globule of dirty water larger than a grapefruit. And on the wiring connectors are unmistakable flecks of mold.' The article goes on to describe the unlikely circumstances that form these micro-ecologies, and what astronauts do to deal with the situation."