Space food is a highly specialized component of human spaceflight, moving far beyond the simple squeeze tubes of the earliest missions. Every item must meet stringent criteria for nutrition, safety, and operational feasibility within a closed environment. The challenges of microgravity and long-duration missions require food scientists to create meals that are lightweight, shelf-stable for years, and designed to minimize the risk of contamination or loose particles. This process combines advanced preservation technology with a focus on crew health and psychological well-being.
Nutritional Requirements and Menu Planning
The dietary needs of astronauts are carefully calibrated to counteract the negative effects of microgravity on the human body. Caloric intake is tailored to the individual, with most astronauts requiring between 2,500 and 3,800 calories daily. This supports their metabolism and rigorous exercise routines, as astronauts spend two hours a day exercising to combat muscle and bone loss.
Menu planning focuses on specific micronutrients depleted during space travel. Astronauts require increased amounts of calcium (approximately 1,000 milligrams per day) and Vitamin D (about 800 to 1,000 international units daily) to mitigate the rapid loss of bone density, known as spaceflight osteopenia. The diet is also supplemented with antioxidants, such as Vitamin C and E, intended to protect cells against oxidative stress caused by exposure to cosmic radiation. The food system must maintain this nutritional value for up to a year on the International Space Station.
Categories of Space Food
Space food is categorized by its preservation method, which dictates how it is stored and prepared on orbit.
Rehydratable Foods
Rehydratable foods are freeze-dried, a process that removes nearly all moisture to drastically reduce weight and volume while providing an extended shelf life. These items, which include meals like scrambled eggs, chicken and rice, and beverages, require the astronaut to inject water back into the package before consumption.
Thermostabilized Foods
Thermostabilized foods are heat-processed in their packaging to destroy microorganisms, a method similar to commercial canning. These ready-to-eat meals, such as beef tips with mushrooms or chicken à la king, are sealed in flexible, multi-layered retort pouches. They only need to be warmed up before the astronaut eats them directly from the pouch.
Natural Form Foods
Natural Form foods are commercially available, shelf-stable items that require no preparation. This category includes items like nuts, granola bars, cookies, and dried fruit, packaged in clear, flexible pouches. Tortillas are a popular natural form food used in place of bread because they do not produce crumbs that could float away and interfere with sensitive equipment.
Packaging and Delivery Systems
The packaging is a sophisticated system designed to ensure food safety and efficiency in a zero-gravity environment. Flexible retort pouches, used for thermostabilized meals, are constructed from multiple layers of material to provide a strong barrier against moisture and oxygen. These pouches are lighter than traditional cans and can be compressed after use, aiding waste management.
Rehydratable and bite-sized foods are often vacuum-sealed in aluminum foil laminate overwraps to maximize shelf life and protect contents from microbial growth without refrigeration. The crew’s customized meals are tracked using a digital Inventory Management System (IMS). The system often uses color-coding on stowage containers to help crew members quickly identify and rotate stock, ensuring the first-in, first-out principle of food safety.
The Experience of Eating in Microgravity
Meal preparation takes place in the galley, a designated area equipped with a water dispenser that can inject precise amounts of hot or cold water into the rehydratable food packages. Thermostabilized pouches are warmed using a specialized food warmer, sometimes called a briefcase warmer, which heats the pre-packaged meals to a comfortable temperature.
The microgravity environment significantly alters the consumption experience and the sensory perception of food. Astronauts often experience a fluid shift, causing fluid to move to the upper extremities and leading to persistent sinus congestion similar to a head cold on Earth. This congestion dulls the sense of smell, a major component of taste, causing many foods to seem bland. As a result, astronauts frequently prefer stronger, spicier flavor profiles, making condiments like hot sauce and liquid pepper popular additions.
Since free-floating crumbs or liquid droplets could contaminate the air and damage equipment, food is engineered to be moist and cohesive. Liquids and semi-solids adhere to the packaging and utensils due to surface tension, a critical factor in microgravity dining. Astronauts primarily use spoons and scissors to cut open packages and scoop food. Many packages feature Velcro patches so the meal can be temporarily attached to a tray or wall while eating.