Astronaut Brian Duffy samples a beverage during a food evaluation session.

Proper nutrition is central to the maintenance of good health. The primary purpose of a diet, whether on Earth or in orbit, is to provide adequate levels of essential nutrients and energy. However, nutritional requirements change under microgravity conditions and diets need to reflect these changes. There are a number of physical constraints on the presentation and preparation of foods during piloted space missions. These include issues of weight, volume, preparation time, and waste generation. The psychosocial benefits of mealtime on motivation and morale also must be considered.

Food products for spaceflight need to be safe, easy to prepare and consume, compact, and produce little waste. For short-term missions of two weeks or less, such as those of Apollo and the space shuttle, foods are stored at room temperature. Food products are thermostabilized, freeze-dried, or specially packaged...