Fermented foods are enjoyed around the world for their potent, often salty, spicy and umami flavours. This makes them particularly attractive to astronauts, who report that their palates can get dulled in space. Although many dishes have been eaten and prepared on the International Space Station (ISS), nothing has ever been fermented there. Indeed, given that microgravity and the high levels of radiation in space might disrupt the microbial interactions needed to make this process happen, it has always been unclear if fermentation was even possible in space.