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~1 AN EDUCATI ON AL PUBLICAT ION OF THE NATIONAL AER ONAUT ICS AND SPACE ADMINI STRATI ON NF·41 /12·6 7
Food For Space Flight When man ventures into the hostile environment of space, he must take with him all the things he needs to keep him alive and comfortable: food, clothing, shelter, even the air he breathes and the water he dri nks. For protection during space fl ight , the ast ronaut must have a spacecraft specially designed to shelter him from the hazards of space . He also requires a spacesuit which can be pressur· ized to protect him during extravehicular activity or in case of spacecraft cabin pressure failure . For body energy, he must have food that is highly nutritious and specially prepared to be handled and
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cond~n~e~ountered
eaten during the in space flight . Explorers and travelers have always had to face the problem of how to carry enough food for their journey. They had to limit the size of their load and also find ways to keep the food from spoiling. This problem was especially important during the days of travel by sailing ships on long sea voyages . Not only was it necessary that the food remain edible throughout the voyage ; it also had to provid e the nutrients needed to avoid malnutrition and vitamin deficiency diseases.
Meal with Space Food Meal Equivalent
Very early in history, man discove red th at food would keep longer if it were dri ed an d kept in a cD'tl1 dry place until ready to be eate n. Grai ns of all kin ds could be stored for a ve ry long t ime if th ey were kept dry. Even meat and f ish and certa in frui ts could be kept for long periods of ti me if th ey were cut into thin strips and dri ed in the sun or over an open f ire . Man also found th at rubbi ng th e food wit h salt or soaking it in salt water helped t o preserve the food and improve its flavor . Thus, the first " dehydrated" and "cured" food s were prepa red . Later, man developed ways of cook ing and storing food in sealed conta iners, so that a wi der variety of foods cou ld be stored or carried on journeys. Eventual ly, he devel oped the processes fo r refrigerating and quick-freezing, whi ch hel ped to preserve t he f resh food fla vo r as well as prevent spoilage. Howeve r, t hese modern fo rms of preserved food products are not su it abl e for use on space fl ights. Because of weight an d spa ce limit ations in the spacecraft, the food wh ich t he astronauts ta ke with th em must be very li ght we ight and req uire very little storage space and no refri gerati on. Conven ience in handl ing is also im portant. Mea l components must be eaten directly from a sealed conta iner, because the condition of relative weightl essness during space flight makes it impossib le to keep
sol id foods on a plate or liquids in an open cup. To rr~et these requirements, special procedures for preparing, packaging, and storing food were developed for United States manned space flights .
Origin al Mercury Food Provisions
Eat ing in a Space Environment
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FOODS FOR PROJECT MERCURY Although most of the early manned flights in Project Mercury were of short duration and did not require storage of complete meals, the Mercury astronauts tested the physiology of swallowing so lids and liquids is a state of weightlessness. Tubed foods and compressed dry food mixes in cube form were used for these experiments. No problems were experienced in chewin g, drinking, and swallowing. The tubed foods were similar to those previously developed for Air Force pilots for use at high altitudes . These foods consisted of pureed meats , vegetables , and fruits, packaged in collapsible alum inum tubes. During space flights, when the space suit was not pressurized , the face plate was opened to allow the food to be squeezed directly from the container into the mouth. Cubed foods were also eaten with the face plate open . If the space suit was pressurized, a plastic tube was attached to the metal food t ube and then inserted through an opening in the face plate . The food was then squeezed from the container, thro ugh the tube, and into the mouth
of the astronaut without opening the face plate. Special coating materials were applied to the inner surface of the aluminum tubes to prevent formation of hydrogen gas, which would have resulted from reaction between the metal and the acids in certain foods , such as applesauce. Precision filling and sealing techniques were devised to eliminate any trapped gases which might expand and rupture the container when the pressure in the spacecraft cabin was reduced . A new gasketing material was developed to increase protection against leakage or spoilage during storage. Special in-the-tube sterilization techniques were also employed to preserve the contents. The average tube of food weighed 5% ounces, with the aluminum tube accounting for a large proportion of this weight. The weight of the tube in proportion to the weight of the food was considered to be too high, but subsequent development of a lightweight plastic container helped to overcome this problem. During the later Mercury flights, bite-size foods were tested. These were solid foods processed in the form of compressed and/or dehydrated 3;4-inch cubes which could be rehydrated by the saliva in the mouth as the food was chewed. Foods such as cinnamon toast, sandwich sections, compressed cakes of various kinds, and enriched cereals with
fruit were provided in this form . In most cases they were coated with an edible gelatin material , to control stickiness and greasiness and prevent crumbl ing. These food items were vacuum-packed in a container made of a four-ply laminated plastic film to protect them from moisture, loss of flavor, oxygen invasion, and microbial spoilage.
FOODS FOR THE GEMINI PROGRAM To provide food for the Gemini Program that was more nearly like that eaten in an earth environment, the freeze-dehydration process was used. Freeze-dehydration or freeze-drying is a process in which moisture is removed from a quick-frozen food product without appreciably changing its shape, color, or taste. The process provides foods which can be rehydrated quickly within their own containers and which closely resemble the freshly prepared product in taste and texture. Foods prepared for freeze-drying are sliced, diced, granulated, powdered, or liquefied to facilitate processing. After the food has been cooked or otherwise processed, it is quick-frozen . The frozen food is then placed on drying trays which are inserted in a special vacuum chamber where the pressure is reduced to 1,500 microns (about .06 inch) of mercury or less. Heat is applied gradually through heating plates or coils, raising the temperature of the trays to 200-300° F.
Examples of Food and Hardware used on Gemini III and Gemini IV Missions
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Temperatures are then gradually reduced so that the temperature of the dried product does not exceed 140 0 F. Under these conditions the ice crystals in the frozen product change directly from a solid to a gaseous state-a process called sublimation "' -and the vapor is withdrawn from the vacuum chamber through a condenser tube. The freeze-dried food emerges with a porous texture and is extremely lightweight, retaining only two or three percent of its original water content. In practically all cases , only water is removed by the freeze -drying process , and the essential oils and ot her carriers of flavor remain . The freeze -dried food is vacuum-packed in a four-ply laminated plastic containe:r similar to that used for the bitesize food . However, in this case, the container is fitted with a one-way spring -activated water injection valve at one end and a folded eating tube at the other end. In this type of container, freeze-dried food can be kept at room temperature for long periods of time. To prepare the freeze -dried food for consump tion , the astronaut inserts a pistol -like water probe through the valve and injects a prescribed amount of water into the container for rehydrating the food . When the food is rehydrated , the astronaut cuts a plastic strip which holds down the folded eating tube and unfolds the tube. This tube serves as a passage through which the food is squeezed from the container directly into the mouth . After the food has been eaten, the astronaut removes a germicide tablet from a pouch attached to the outside of the food package, and places the germicide inside the package to inhibit spoilage of the residue . All space food is prepared and packaged to withstand the following conditions: 1. Temperatures ranging from about 20 0 F. to 135 0 F. 2. Pressures ranging from 19.7 psia (pounds per square inch absolute) at 70 0 F. (the pressure at which the spacecraft is purged prior to launch) to approximately 1 x 10- 12 psia , near vacuum condition, at 100 0 F. (the temperature expected in the spacecraft when the cabin is open during extravehicular activity and in the sunlight). 3 . Relative humidity which may vary from 30 percent to 90 percent ·Subl i mation means the change o f a solid directly to a vapor wi t hout becoming a liqu i d . A good ex ample of sublimation is " dry ice ·' (which is solidified carbon dioxide) changing d i rectly to carbon d io xi de gas without pass i ng through a liquid stage.
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4 . Cabin atmosphere of 100 % oxygen 5. Acceleration load force of 1 to 7.25 g's (7.25 ti mes the force of gravity) Production guides for NASA space foods establish strict requirements regarding size and weight, as well as the microbiological standards to be maintained to insure low bacterial count. The guides also require that specific weighed amounts of the rehydratable foods must reconstitute completely with a given amount of water, at a given temperature , within a specified time. The reconstituted product must possess a pleasing aroma and a flavor closely resembling that of the original fresh food item . Random samples are tested to assure that the finished product conforms to these requi rements.
APOLLO PROGRAM FOODS Experience gained during the Mercury and Gemini missions in the preparation, handling, and consumption of space foods provided a valuable background for the development of foods for the Apollo Program. Apollo foods are similar to the bite-size and rehydratable products used in the Gemini missions , with add itional food items pro vided to give the astronauts a wider variety of preference in the selection of flight menus . To increase food palatability, the Apollo spacecraft is equipped to provide either hot or cold water for reconstituting foods and beverages. Water from the potable water supply can be heated to about 150 0 F. in a ten fluid ounce capacity reserExamples of Freeze-dehydrated Foods for Apollo
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PEACHes ALMON
A~AO
P AS
COCOA
ORANGE DRINK 1 Examples of Freeze -dehydrated Foods for Apollo Examples of Cubed Foods for Apollo
DATE FRUIT CAKE
A
WIeHE
BEEF SA
OWICHES
STRA W BE RY CU ES 5
DAY 1
DAY 2
Meal 1 Type Peaches R* Sausage Patties . _ . .... . _ . _ R Toasted Bread Cubes ... . . _ . B* Orange Drink (21 gms) .... _ . R
Meal 2 Corn Chowder (56 gms) Cheese Sandwiches .... _ . .. Chocolate Cubes .. . . .... _ _ .... _ . _ . . _ . . . . Brownies Cocoa (42 gms) . _ . . . . . . . . .
Meal 3 Tuna Salad ... . ... . . _ . . . .. Pea Soup (49 gms) . _ . . . . .. Chocolate Pudding (70 gms) . . Graham Cracker Cubes . _ . . .. Pineapple-Grapefruit Drink (21 gms) .. __ _...... _ . _ Total
.. _ . . . ... .. __..... .
R B B B R
Calories
98 223 215 83 619
252 158 180 321 190 1101
R R R B
214 220 307 239
R
83 1063 2783
Meal 1 Type Bacon Squares .. . __ . . . . . .. B Textured Ham and App lesauce R B Apricot Cereal Cubes .. __ . .. Chocolate Cubes . _... _ ... _ B Cocoa (42 gms) ... _ . . . . _. . R
Meal 2 Chicken Salad . . .. __ _ ... _. Beef Sandwiches .... _ . ' .' _. Date Fruitcake . __ ... _ .... _ Pineapple·Grapefru it Drink (21 gms) .... . .... _ . _ ..
Meal 3 Beef Pot Roast Potato Soup . . ... _ ... __ . . . Brownies ............ . . . . Chocolate Pudd ing (70 gms) .. Grapefruit Drink (21 gms) Total
.... ____ .... ... . __ _
Calories
180 127 171 180 190 848
R B B
237 138 393
R
83 851
R R B R R
119 220 321 307 83 1050 2749
* R-RehYdratable * B-Bite-size (6-8 cubes)
voi r, every thirty minutes , for use in preparing hot food. One ounce of hot water is released from the rese rvoir through a fixed water dispenser each time the release button is pressed. Cold water is f urnis hed from a water chiller which coo ls six ounces of water to 50° F. eve ry 24 minutes. The water is drawn through the fi xed water dispenser or a po rtable hand-held water probe which meters 1/ 2 ou nce increments of cold water for d ri n ki ng or for preparation of cold foods and beverages. The menu listed be low is an example of a twoda y food selection by an astronaut for an Apollo mission . A random sample of each space food item is an alyzed to dete rmine its exact caloric and nutrient value , and this information is used in the prepara· t ion of a balanced menu . This information also provides a bas is fo r calcul ating the nutrient intake
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for each man for each day and for the total mission . Each astronaut is furnished 1.4 pounds of food per day, which provides a total intake of approxi · mately 2800 calo ries. The nutrit ional content is balanced to provide 20% protein , 62% ca rbohy· drates, and 18% fats . The caloric distri but ion is 17 % f rom protein, 51 % f rom carbohydrates , and 32 % from fats. All food and beverage pac kets fo r one meal for one man are placed in alumi num overwrap pack· ages . Each ove rwrap has a color·coded tab to des ignate the mea ls selected by each ast ronaut. Crew members are also furnished items fo r persona l hygiene , includ ing chew ing gum (for after mea ls) , tooth brush , wet cleansi ng cloth , dry cleans ing cloth and towels . Both the food and the hyg iene com · ponents are stored aboard the Apollo spacec raft in firep roof co nta ine rs.
Nutritional studies conducted for NASA * showed that the nutrient value of space flight food was as good as the equivalent fresh food, and that under simulated space flight conditions, nutrient requirements were not significantly different than expected. In these studies, a group of test subjects performed a prescribed schedule of work, exercise, relaxation, and sleep, wearing a venti lated pressure suit continuously during fourteen -day and twenty-eight-day test periods. The studies indicated that approximately 2680 calories per day were required for subjects weighing about 68 kilograms (150 pounds) and a proportionately greater number of
calories for heavier subjects. Nutritional studies will be conducted by the Apollo astronauts to obtain new data for determining the caloric energy requirements needed during periods of activity in weightlessness. These data will provide new guidelines for the preparation of in-flight menus to meet the nutritional needs of each individual. The food products prepared for Mercury, Gemini , and Apollo missions illustrate the evolution of food for use in space. Improved and more elaborate food systems are yet to be developed for space flights which may be extended for long periods of t ime.
WAHl. DISPENSER . METERING
APOllO MAN M EAlS ,C OlOR CO O
One-meal Overwraps with Components
Apollo Meal Overwrap with Equipment
Color code designates type of meal
Personal Hygiene Material
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APOllO MAN - MEAlS , COlOR CODED
· Conducted by the Aerospace Medical Research Wright· Patterson Air Force Base.
Laboratories at
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TEACHING SUGGESTIONS AND ACTIVITIES
Suggested Vocabulary List
l. subl i mation 2. kilogram 3 . dehydration 4 . germicide
5. 6. 7. 8.
cube laminated micron probe
9 . reservoi r 10. potable 1l. freeze -dehyd rated or freeze-d ri ed
Suggested Activities
l. Discuss the reasons for establ is hing strict weight, volume, packaging , and nutritional requirements for space food . 2. As a class preject, have the pupils make a t ime line showihg the development of food process ing from l the prehistoric caveman era to the present space age . 3. To provide fo a simulation of the eating of space foods, purr e some food in a blender and sea l the pureed rood in small plastic bags. Let t he pupils imagi ~ e that they are taking a space t rip and must eat the food as astronauts would. Show them how to clip a small hole in one corne r of the bag and squeeze the food into t he mouth. 4. Let the children check the menus on page six t o see whether the astronaut meals include t he basi c fou r food requ ire ments and the proper am ounts of each . 5. Usi ng the information on page six, write t he number of calories for each mea l for each day on the blackboard . Let the children add the caloric values to see whether the foods provide
the approxi mate 2800 calories needed by the astronauts per day. Encourage the ch ildren to prepare other arithmetic problems from the information given on page six . 6. One kilogram weighs 2 ~ (2.2) pounds . Let the students determine the weight of 15 kilograms in pounds. 7. Ask the pupils to bring to class some of the fruit from commercial cereals containing freezedried fru it. Place the fruit in a small bowl with a small amount of water for a few minutes. Let the pupils observe what happens to the fruit and to the wate r. Ask them : Is the fruit still as hard as when it was first placed into the bowl of water? Let them measure the water before and after the fruit is placed in the bowl. Weigh the fruit before and after rehydration. 8 . Assign pupils to make a report to the class on Franc is Appert and on how and why he deve loped the process of canning. 9 . Assign pupils to read about Louis Pasteu r and report to the class on what contributions he made to the food processing industry.
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