What do astronauts eat?

The idea of food pills never got past science fiction. On board, astronauts eat recognizable food, prepared on Earth and packaged to last without refrigeration and to avoid causing problems in the absence of weight. There are three main families: dehydrated dishes, rehydrated by injecting hot water into the pouch; thermostabilized foods, heat-sterilized like canned goods and ready to warm up; and natural foods, from nuts to snack bars.

Bread was ruled out early on because crumbs float and can end up in eyes or air filters, so wheat tortillas replace it as the base for almost any bite. Salt and pepper travel dissolved in liquid for the same reason. Drinks arrive as powder, in pouches with a nozzle to which water from the recycling system is added.

The ration is calculated at around 2,500 kilocalories a day, adjusted to each person's size and activity level, and calcium and vitamin D intake are monitored because bone loses density without weight. Sodium is limited for the same reason. Standard menus rotate to avoid sensory fatigue, and each crew member also has a quota of personal food items chosen before the flight.

Fluid shifting toward the head dulls the sense of smell during the first few days, so flavors are perceived as muted. Hence the popularity of hot sauces and strong condiments, among the most requested items in every resupply.

Every cargo ship carries fresh fruit and vegetables, consumed in the first few days because there's no refrigeration for food. For years the station has also grown small crops of its own in experimental greenhouses: lettuce, Chinese cabbage, radishes, and even peppers, which serve both as an agronomic trial for long missions and as a welcome addition to the table.