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By Becky Wolfe, Manager of Science Education
Keeping astronauts healthy and fed is an important job for space agencies such as NASA. Without the ability to run to the grocery store or grow a large garden in space, all food has to be sent to the International Space Station. Through the years, NASA has sent a variety of food to space. Check out our infographic on the Evolution of Food in Space to learn more.
Preparing Space Food
There are several challenges to overcome when preparing food for space. One of the first challenges is making sure food is safe for astronauts to eat. Getting sick from spoiled food is never fun, and much more dangerous in space. This means food has to be preserved in a way that it can be kept safe, without refrigeration, for a long period of time. The lack of a refrigerator is also a challenge to solve. Astronauts need to have food in portion-sized containers, as there is no way to store leftovers, no matter how good the food might be!
Much of the food astronauts eat in space has been freeze dried. Food that you might eat at home such as spaghetti and meatballs, is prepared in a special kitchen at NASA Johnson Space Center. Food scientists use the same ingredients you might use when preparing family meals. The food is placed in single serving trays to be freeze dried in special equipment. During the freeze drying process, food is exposed to very cold temperatures and placed under a vacuum. This removes all of the water from the food, while keeping the structure or shape of the food intact. Each serving of food is vacuum-sealed to keep air away from the meal, and wrapped in a protective cover to keep out moisture. Once in space, astronauts add hot or cold water to the food packages to rehydrate the food, bringing it back to it’s original consistency.
The Role of Freeze-Dried Food
By removing the water from food, microbes that would spoil food at room temperate are not able to grow. This keeps it from spoiling on its way to space. Removing water from food, even fresh fruit, makes food lighter. As resupply missions are limited on the amount of weight that can be rocketed to the ISS, making food lighter means more snacks for the astronauts!
Not all food is freeze-dried. Some items such as certain crackers, granola bars or peanuts, don’t need to be freeze dried. When vacuum-sealed they will be fine when opened on the ISS. Other food goes through a process called thermostabilizaiton. Much like home canning, food is heated to very high temperatures under pressure to kill any food-spoiling microbes. The food doesn’t need to be refrigerated and can be eaten directly out of the package.
Astronauts aren’t the only people who use freeze-dried food. People who are hiking or camping may take freeze-dried food with them, as it doesn’t need to be kept cold. Freeze-dried fruits and vegetables can often be found with other dried fruits in the grocery store, at health food stores or even in your cereal. Several popular cereals contain freeze dried berries that rehydrate with milk.
Try It at Home!
Your family can try a fun, edible science experiment using freeze-dried fruit. Choose a fruit or vegetable that your family enjoys and purchase it freeze-dried from the store. Open up the package and observe a few pieces using a hand lens. How is it similar or different to what we normally eat? Taste the freeze-dried fruit or vegetables. Does it taste any different? What about texture? Remember, this food does not have any water.
Fill a small container with water. Using a kitchen scale, measure a piece of fruit directy from the package and jot in a piece of a paper. Place the fruit in the container of water and let is sit for approximately 2 hours. Measure the fruit again. Is there any difference it weight?
If you want, you can eat freeze-dried fruit that has been rehydrated. As you do, close your eyes and pretend you are floating in space, just like an astronaut.
