Space food is a type of food product created and processed for consumption by astronauts during missions to outer space. The food has specific requirements of providing balanced nutrition for individuals working in space, while being easy and safe to store, prepare and consume in the machinery-filled weightless environments of crewed spacecraft. Most space food is freeze-dried to ensure a long shelf life.
In recent years, space food has been used by various nations engaging on space programs as a way to share and show off their cultural identity and facilitate intercultural communication. Although astronauts consume a wide variety of foods and beverages in space, the initial idea from The Man in Space Committee of the Space Science Board in 1963 was to supply astronauts with a formula diet that would supply all the needed vitamins and nutrients.
There are several classifications of space food, as follows:
More common staples and condiments do not have a classification and are known simply by the item name.
Designing food for consumption in space is an often difficult process. Foods must meet a number of criteria to be considered fit for space. Firstly, the food must be physiologically appropriate. Specifically, it must be nutritious, easily digestible, and palatable. Secondly, the food must be engineered for consumption in a zero-gravity environment. As such, the food must be light, well packaged, fast to serve, and require minimal cleaning up. Finally, foods require a minimum of energy expenditure throughout their use; they must store well, open easily, and leave little waste behind (foods that tend to leave crumbs, for example, are ill-suited for space).
Carbonated drinks have been tried in space but are not favored due to changes in belching caused by microgravity. Without gravity to separate the liquid and gas in the stomach, burping results in a kind of vomiting called "wet burping". Coca-Cola and Pepsi were first carried on STS-51-F in 1985. Coca-Cola has flown on subsequent missions in a specially designed dispenser that utilizes BioServe Space Technologies hardware used for biochemical experiments. Space Station Mir carried cans of Pepsi in 1996.
Beer has also been developed that counteracts the reduction of taste and smell reception in space and reduces the possibility of wet burps in microgravity. Produced by Vostok 4-Pines Stout, a parabolic flight experiment validated that the reduced carbonation recipe met the criteria intended for space. Barley harvested from crops grown for several generations in space has also been brought back to Earth to produce beer. While not a space food (it used the same high carbonation 'Earth' recipe), the study did demonstrate that ingredients grown in space are safe for production.
Space bread has proved elusive because of a variety of challenges. By 2012 a method was suggested where the dough is leavened by dissolved CO2 (as opposed to yeast) and cooked by a low-temperature process, which could allow for fresh bread to be baked from bulk ingredients on future spaceflights.
The primary purpose of packaging space food is preserving and containing the food. However, the packaging must also be light-weight, easy to dispose of and useful in the preparation of the food for consumption. The packaging also includes a bar-coded label, which allows for the tracking of an astronaut's diet. The labels also specify the food's preparation instructions in both English and Russian.
Many foods from the Russian space program are packaged in cans and tins. These are heated through electro-resistive (ohmic) methods, opened with a can-opener, and the food inside consumed directly. Russian soups are hydrated and consumed directly from their packages.
NASA space foods are packaged in retort pouches or employ freeze drying. They are also packaged in sealed containers which fit into trays to keep them in place. The trays include straps on the underside, allowing astronauts to attach the tray to an anchor point such as their legs or a wall surface and include clips for retaining a beverage pouch or utensils in the microgravity environment.
Early space food was primarily composed of bite-sized cubes, freeze-dried powders, and thick liquids stuffed in aluminum tubes. Eventually, the tubes were discontinued, the powders made easier to re-freeze, and the cubes were coated in gelatin to prevent crumbling on the equipment. With the introduction of the "spoon bowl," astronauts were able to open the contents of the package and eat the simple meal with a spoon.
For lunch on Vostok 1 (1961), Yuri Gagarin ate from three 160 g (5.6 oz) toothpaste-type tubes, two of which contained servings of puréed meat and one which contained chocolate sauce.
In August 1961, Soviet Cosmonaut Gherman Titov became the first human to experience space sickness on Vostok 2; he holds the record for being the first person to vomit in space. This event "heralded the need for space flight nutrition."
John Glenn, as the first American to orbit Earth in 1962, was to experiment with eating in weightless conditions. Some experts had been concerned that weightlessness would impair swallowing. Glenn experienced no such difficulties, and it was determined that microgravity did not affect the natural swallowing process, which is enabled by the peristalsis of the esophagus.
Astronauts in later Mercury missions (1959–1963) disliked the food that was provided. They ate bite-sized cubes, freeze-dried powders, and tubes of semiliquids. The astronauts found it unappetizing, experienced difficulties in rehydrating the freeze-dried foods, and did not like having to squeeze tubes or collect crumbs. Prior to the mission, the astronauts were also fed low residual launch-day breakfasts to reduce the chances that they would defecate in flight.
Several of the food issues from the Mercury missions were addressed for the later Gemini missions (1965–1966). Tubes (often heavier than the foods they contained) were abandoned, gelatin coatings helped to prevent bite-sized cubes from crumbling, and simpler rehydration methods were developed. The menus were also expanded to include items such as shrimp cocktail, chicken and vegetables, toast squares, butterscotch pudding, and apple juice.
The crew of Gemini 3 sneaked a corned beef sandwich on their spaceflight. Mission Commander Gus Grissom loved corned beef sandwiches, so Pilot John Young brought one along, having been encouraged by fellow astronaut Walter Schirra. However, Young was supposed to eat only approved food, and Grissom was not supposed to eat anything. Floating pieces of bread posed a potential problem, causing Grissom to put the sandwich away (although he did enjoy it) and the astronauts were mildly rebuked by NASA for the act. A congressional hearing was called, forcing NASA deputy administrator George Mueller to promise no repeats. NASA employed renewed vigilance regarding what astronauts brought along on future missions.
Prior to the Apollo program (1968–1975), early space food development was conducted at the US Air Force School of Aerospace Medicine and the Natick Army Labs. The variety of food options continued to expand for the Apollo missions. The new availability of hot water made rehydrating freeze-dried foods simpler and produced a more appetizing result. The "spoon-bowl" allowed more normal eating practices. Food could be kept in special plastic zip-closure containers, and moisture allowed the food to stick to a spoon. However the lack of taste was an issue at that time. In order not to over-stimulate the intestinal system, the food was prepared using few spices. Thus astronauts were always looking for something that had a little more taste. Apollo 17 moonwalker Harrison Schmitt's favorites were the bacon squares. Buzz Aldrin enjoyed the shrimps. Paul Weitz went for the ice cream. 
Buzz Aldrin partook of the Presbyterian Christian sacrament of Holy Communion on the Moon. It had been consecrated by his pastor, the Rev. Dean Woodruff, two weeks prior to the space mission.
"I poured the wine into the chalice our church had given me. In the one-sixth gravity of the moon, the wine curled slowly and gracefully up the side of the cup. It was interesting to think that the very first liquid ever poured on the moon, and the first food eaten there, were communion elements." —Buzz Aldrin
Aldrin received the Eucharist in the same hour that his local church did on that Sunday Sabbath and he later stated that "I sensed especially strongly my unity with our church back home, and with the Church everywhere".
Larger living areas on the Skylab space station (1973–1974) allowed for an on-board refrigerator and freezer. This allowed perishable and frozen items to be stored, making microgravity the primary obstacle of future missions.: 142–144 When Skylab's solar panels were damaged during its launch and the station had to rely on minimal power from the Apollo Telescope Mount until Skylab 2 crewmembers performed repairs, the refrigerator and freezer were among the systems that Mission Control kept operational. The OWS module had a specially designed wardroom dedicated for food preparation and dining (see image on the right). The table was designed to avoid hierarchical positions through its triangular layout and to support social cohesion. It could accommodate all three crew members at the same time using a variety of microgravity restraints.
Menus included 72 items; for the first time about 15% was frozen. Shrimp cocktail and butter cookies were consistent favorites; Lobster Newberg, fresh bread, processed meat products, and ice cream were among other choices. A dining room table and chairs, fastened to the floor and fitted with foot and thigh restraints, allowed for a more normal eating experience. The trays used could warm the food, and had magnets to hold eating utensils and scissors used for opening food containers.: 142–144 : 29 The food was similar to that used for Apollo, but canned for preservation. The crew found it to be better than that of Apollo but still unsatisfying, partially due to food tasting different in space than on Earth.: 292–293, 308 The frozen foods were the most popular, and they enjoyed spicy foods: 130 due to sinus congestion from weightlessness dulling their senses of taste and smell.: 292–293, 308 Weightlessness also complicated both eating and cleaning up; crews spent up to 90 minutes a day on housekeeping.
After astronaut requests, NASA bought cream sherry for one Skylab mission and packaged some for testing on a reduced-gravity aircraft. In microgravity smells quickly permeate the environment and the agency found that the sherry triggered the gag reflex. Concern over public reaction to taking alcohol into space led NASA to abandon its plans. The astronauts instead drank the purchased supply while consuming their pre-mission special diet.
The astronauts of the Apollo–Soyuz Test Project (1975) received samples of Soviet space food when the combined crew dined together. Among the foods provided by Soyuz 19 were canned beef tongue, packaged Riga bread, tubes of borscht (beet soup), and caviar. The borscht was labeled "vodka".
The Soviet Union's Salyut stations were the first to be structured in zones for different activities, including a table for work and having dinner together. By the mid-1970s, cosmonauts and astronauts on the Russian Salyut space research stations were able to eat fresh food such as tomatoes, coriander and cucumbers from their orbital space gardens, and some even had the possibility of a sip of wine or vodka with their food. The pioneering Oasis greenhouse on Salyut 1 (launched in April 1971) led to the implementation of plant-growing facilities on the later Salyut stations, on Mir and on the International Space Station, and the first space-grown vegetables were reportedly eaten in 1975 onboard Salyut 4. 
As part of the Interkosmos space program, allies of the Soviet Union, including the People's Republic of Bulgaria, actively participated in the research and deployment of space technologies from the 1960s until the end of communism in 1989-1990 in the Eastern Bloc. The Institute of Cryobiology and Lyophilization (now the Institute of Cryobiology and Food Technology), founded in 1973 as a part of the Bulgarian Academy of Sciences, produced space food for the purposes of the program. The menu includes traditional Bulgarian dishes such as tarator, sarma, musaka, lyutenitza, kiselo mlyako, dried vegetables and fruits, etc.
Modern astronauts have a greater variety of main courses to choose from and many astronauts request personalized menus from lists of available foods including items like fruit salad and spaghetti. Fresh fruits and vegetables that can be safely stored at room temperature are eaten on space flights. Astronauts sometimes request beef jerky for flights, as it has an extended shelf life and a strong flavor.
Since 2002, the small LADA Greenhouse system (the leaf chamber is just 16 x 20 x 26 cm/6 x 8 x 10 inches) has been used onboard the International Space Station to study how plants grow in microgravity and to grow edible vegetables for the astronauts. LADA includes a control module and was sent to the station already equipped with the root media for the plants to be grown and eaten in space.
NASA's Advanced Food Technology Project (AFT) is researching ways to ensure an adequate food supply for long-duration space exploration missions.
Capitalizing on the popularity of the Apollo space missions in the early 1970s, Pillsbury marketed "Food Sticks" (also known as "Space Food Sticks") for the consumer market. Fourteen individually packaged sticks were included in a box, and came in six flavors such as peanut butter, caramel, and chocolate. Food Sticks were marketed as a "nutritionally balanced between meal snack".
Examples of derivative products can be found in NASA Space Center gift shops, general sweets and novelty shops, online retailers, or at Army Surplus stores. A popular example is freeze-dried ice cream. Tang, originally marketed in 1959, saw an increase in popularity in the 1960s due to its inclusion on American human space flights.
Because there is no gravity, the contents of your stomach float and tend to stay at the top of your stomach, under the rib cage and close to the valve at the top of your stomach. Because this valve isn't a complete closure (just a muscle that works with gravity), if you burp, it becomes a wet burp from the contents in your stomach.