Freeze-dried ice cream

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Freeze-dried Neapolitan ice cream, shown with air-tight foil partially unwrapped

Freeze-dried ice cream, also known as astronaut ice cream^[1] or space ice cream is a brick of dehydrated ice cream that is always ready to eat, with no need for refrigeration. It was developed by Whirlpool Corporation under contract to NASA for the Apollo missions.^[2]

Apollo 7 in 1968 was the only NASA mission on which space ice cream flew in outer space.^[3] According to a NASA food scientist, although it was developed on request, "It wasn't that popular."^[4] Skylab had a refrigerator that was used for real ice cream.^[5], and occasionally shuttle and International Space Station astronauts have enjoyed real ice cream.^[6]

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 freeze-dried ice cream slice.

Freeze-dried foods were developed so that foods could be sent on long-duration spaceflights, as to the Moon, and to reduce the weight of the water and oxygen normally found in food.^[2]

Freeze-dried 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. It is even sold by mail-order, and is a "top five seller" at the Kennedy Space Center gift shop.^[7]