Drying is a method of food preservation that works by removing water from the food, which prevents the growth of microorganisms and decay. Drying food using the sun and wind to prevent spoilage has been known since ancient times. Water is usually removed by evaporation (air drying, sun drying, smoking or wind drying) but, in the case of freeze-drying, food is first frozen and then water is removed by sublimation.Bacteria and micro-organisms within the food and from the air need the water in the food to grow. Drying effectively prevents them from surviving in the food. It also creates a hard outer-layer, helping to stop micro-organisms from entering the food.

I (not so) fondly recall Chicken-a-la-Death and the Tuna Casserole, my leaast favorite were the dehydrated beef/pork patties (supposedly reconstituable with water... not). The "gorilla cookie", likened by some as hard-packed sawdust covered in chocolate, was the favorite desert. But what they're doing now is a little different.

Think paella. Beef brisket. And in the space shuttle this week, lots of stuff you can eat with your fingers. Space dining has changed drastically since the days of the Mercury and Gemini missions of the early 1960s. Tasteless victuals then came in toothpaste-like tubes, or dehydrated chunks, but not anymore.