Freeze-dried ice cream
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Freeze-dried ice cream was developed by NASA for the Apollo missions and is still used today.
The phrase Astronaut Ice Cream is also sometimes used colloquially to refer to this product but is in-fact a trademark of American Outdoor Products, Inc. [1]
It is a dehydrated brick of ice cream that is always ready to eat, with no need to freeze. Freeze drying (or lyophilization), removes water from the ice cream by lowering the air pressure to a point where ice shifts from a solid to a gas. The ice cream is placed in a vacuum chamber and frozen until the water crystallizes. The air pressure is lowered, creating a partial vacuum, forcing air out of the chamber; next heat is applied, vaporizing the ice; finally a freezing coil traps the vaporized water. This process continues for hours, resulting in a perfect freeze-dried ice cream slice.
Astronaut ice cream is ubiquitous in science museum giftshops, sometimes accompanied by other freeze-dried foods such as ice-cream sandwiches, various sliced fruits, and even pizza. Much freeze-dried ice cream is sold, due to its unique texture and taste.
