Hollywood often paints a romanticized vision of space travel, but living in a gravity-free environment has dirty downsides. It takes a lot of extra work for an astronaut to tend to their personal hygiene in space. Sometimes, they're even instructed to do some not-so-sanitary things, like wear the same pair of underwear for a week. When thinking about hygiene in space, the first thing to consider is that there are no showers or sinks. Gravity makes common earthly devices like sinks totally impractical. Think about it: water falls down a faucet and into a drain. In space, the water would float away - and ultimately endanger both an astronaut’s health and a spacecraft’s expensive equipment.