The results make for an interesting read. First, an analysis of nine astronauts, published in Scientific Reports in 2019. This study looked at crew members who stayed on the ISS between six and 12 months, and found that, surprisingly, their gut microbiomes actually grew more diverse in the relatively sterile and bacteria-free environment of space. This unexpected find might be a result of the carefully controlled diets on board the ISS: NASA works hard to make more than 200 food and drink options available on the space station, probably giving astronauts a more varied choice than they would get at...