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Above Image: Canadian astronaut Chris Hadfield juggles tomatoes in low gravity © Public Domain

Space Food: Feeding Astronauts on the ISS and Beyond

Eating is one of life’s great pleasures, even when orbiting 400 kilometres above the surface of the Earth. The quality of space food has improved since the early days of space travel. Learn how NASA is feeding today’s astronauts on the International Space Station (ISS) and see how they plan to feed tomorrow’s astronauts on a mission to Mars.

Early Beginnings

The first astronauts in the early 1960s had to eat small, dry food cubes or strange pastes of beef and vegetables that were squeezed out of tubes. Freeze-dried foods were a big change in the mid-1960s. Astronauts onboard the spacecraft would add water to rehydrate their meals. The next big advancement in the late 1960s was ready-to-eat food. This food was preserved using heat (thermostabilized).

During the first decade of space travel, food was not a high priority because missions were only a few days long. High quality, nutritious food is much more important now, because astronauts can spend months in space on the ISS.

Dining on the International Space Station

Astronauts choose their own food before their missions from 200 different items on NASA’s ISS menu. Nutritionists make sure that their food choices provide enough energy and nutrients. NASA is doing experiments to see if different space diets can help prevent some of the health problems like bone and muscle loss that humans experience in microgravity.

Today’s astronauts eat the same kinds of food in space as they do on Earth. The big difference is that most space food is pre-cooked and prepared to be shelf-stable. Shelf-stable foods can be stored at room temperature without going bad. This is important because there are no refrigerators on the ISS to keep food from spoiling. Space food must be tasty, nutritious, compact and not crumbly. Floating food crumbs can do damage if they get stuck in equipment…or someone’s eye!

Some foods, such as nuts, bite-sized cookies and tortillas can be packaged for space in their natural form, just like they are eaten on Earth. Other foods are cooked by NASA’s food scientists. These foods are treated to kill the microbes that cause spoiling, and packaged to keep them sterile and safe to eat (preserved). There are three main kinds of preserved space food.

  1. Rehydratable foods, including mashed potatoes and powdered beverages, are preserved by dehydration (removing the water from the prepared food). They are returned back to normal by adding water on the ISS (See Figure 1).
  2. Thermostablilized foods, including tuna and chocolate pudding cake, are preserved by heat treatment and are ready-to-eat.
  3. Irradiated foods, including chicken and turkey, are preserved by exposure to radiation and are also ready-to-eat. Irradiation kills microbes but does not make food radioactive.

Servings of food are packaged in plastic or foil pouches (See Figure 2). Rehydratable food pouches include an opening for adding water. For drink pouches, the same opening is used with a special straw that does not let liquids escape in microgravity.

Fresh fruits and vegetables are a rare treat on the ISS. They only arrive every 2-3 months on a resupply vehicle (See Figure 3). NASA’s Vegetable Production System, nicknamed ‘Veggie,’ is allowing astronauts to grow their own food on the ISS. In August 2015, astronauts onboard the ISS for the first time ate a space-grown vegetable, romaine lettuce. ‘Veggie’ will be used to grow Chinese cabbage in 2017 and cherry tomatoes in 2018. The biggest benefit of ‘Veggie’ is how it makes astronauts feel; caring for growing plants in space is an enjoyable and familiar activity. This will be very important in the future when astronauts are on a dangerous three-year mission to Mars.

Food for Mars

Feeding astronauts travelling to Mars will be much more challenging than feeding Earth-orbiting astronauts. The ISS is 400 kilometres from Earth, but Mars is 225 million kilometres from Earth (average distance). This does not make sending regular supply vehicles a realistic option for a Mars mission.

Leaving Earth, astronauts will take only enough food on their spacecraft for the six-month mission to Mars. A separate cargo spacecraft (with a longer travel time) will be sent earlier to drop off food for their time on the Martian surface and their trip home. This means that by the end of a Mars mission, astronauts will be eating food that is at least five years old! NASA can easily prepare food that will be safe to eat after five years, but the big challenge is making sure it will still be nutritious.

Many nutrients in food break down over time, even on Earth. Although space food is preserved and sealed, chemical reactions still occur that change the taste and texture of food. Very little is known about how space radiation affects food breakdown, beyond what would happen on Earth. NASA is researching different types of preservation and fortification options to figure out how to prepare nutritious food that people will still want to eat after five years. Nutrients in pill form are not a good option for space travel because they take away the fun and comfort of eating real food.

As you can see, space food is an important part of life on the ISS and will be an even bigger part of future missions to Mars and beyond.

Glossary

Fortification (of food)

Adding essential nutrients, usually vitamins and minerals, to food products. For example, Canadian milk is fortified with Vitamin D because Vitamin D levels are low in most commonly eaten foods.

Freeze-dried food

Food that has been preserved by removing almost all of the water. This limits the growth of microbes that cause spoiling. Freeze-dried foods are cooked, frozen very quickly, and slowly heated in a vacuum chamber to remove the ice crystals (water).

Irradiated food

Food that has been preserved by exposure to a controlled amount of radiation. Microbes that cause spoiling are killed by the kind of radiation used.

Microbes

Very small organisms (usually single-celled) that cannot be seen without a microscope. Bacteria and fungi (yeasts and some moulds) are examples of microbes. When microbes grow on foods, they can cause spoiling and make the food unsafe to eat.

Microgravity

Very weak gravity that exists in outer space.

Natural form

Food that is packaged for space travel in the same form that it is eaten on Earth.

Preserved food

Food that has been processed to prevent spoiling (e.g., microbe growth, nutrient breakdown, etc.). Preserved foods are often sterile and packaged to eliminate exposure to the air.

Radiation

The process of giving off energy in the form of waves or particles. There are many different kinds of radiation, with different levels of energy. Some examples of radiation are light, ultraviolet radiation, X-rays, nuclear radiation (atoms changing from one kind into another, often high energy) and cosmic radiation (particles travelling through space, very high energy).

Rehydratable food

Food that has been preserved by removing the water content. Adding water returns the food to its original, edible form. Freeze-drying is a common method to make rehydratable food.

Shelf-stable food

Food that can last for a long time at room temperature without spoiling.

Sterile

Free from microbes. This stops the spoiling of foods.

Thermostabilized food

Food that has been preserved by heat treatment, similar to canning.

References