[5] The orbital Mercury Program flights of astronauts Glenn, Carpenter, Schirra, and Cooper demonstrated for food system planners that indeed man could consume and digest solid and liquid food in space. The experience gained in food packaging and in-flight handling led to the evolution of the Gemini and Apollo food systems and components. Prior to the Gemini program, engineers and biologists began in earnest to design and formulate foods and packages which were acceptable, nutritious, lightweight, low volume, low residue, high energy, and stable at spacecraft temperatures, which withstood launch vibration, could be consumed in zero gravity, contained no pathogens, withstood vacuum packaging and oxygen atmospheres, and would reconstitute with water or saliva. The Apollo and Gemini systems which evolved were the best possible under the circumstances. Any faults in the system then and now can be attributed to incomplete understanding of the definitions of food, acceptability, and nutrition as they apply to spaceflight .

The foods and packages often exceed physical requirements of the spacecraft, environment, and ground-based human test subjects. The nutrients provided exceed estimated metabolic requirements of the astronaut. Daily rations were balanced and calculated precisely. Food weights and dimensions were controlled and measured with microscopic accuracy. Volunteers ate the food for periods of up to 56 days without physiological or psychological aberrations. The astronauts were provided with a variety of these specially designed foods from which to select their in-flight menus. The flight foods were produced, packaged, and stowed on the spacecraft. Spacecraft were launched and missions completed successfully.

Despite all this, however, the astronauts did not eat, and invariably lost weight. What could have gone wrong? With 20-20 hindsight, it has become obvious that a part of the problem lies in our lack of complete understanding of the psychophysiology of eating. Man and his eating habits are not easily changed. Good nutrition begins with good food presented to the consumer in a familiar manner. A "good" spacecraft may be bigger, faster, more versatile and safer than the previous one. A "good" spacecraft food system is one which meets system requirements but is built around good foods that stimulate and satisfy hunger, that are readily prepared, that have a familiar flavor and texture, that provide diversion, relaxation, security, and adequate quantities of nutrients to maintain metabolic balance in the particular environment.

The initial Apollo food system was basically the same as that which was provided for the Gemini Program. The compressed and dehydrated ready-to-eat cube foods included meat, fruit, [6] dessert, and bread types. The uniform shape, high caloric density, and variety of flavors made the food ideally suited for the engineering requirements of spaceflight. Dehydrated fruits, beverages, salads, desserts, meats, and soups which required water for rehydration prior to consumption were available. These "rehydratables" were packaged in a specially designed laminated plastic bag which had a valve for water insertion at one end and a tube or zero-G feeder at the other end through which the foods could be consumed. The 3/4-in. diameter of this feeder tube restricted, the maximum food particle size to 1/8 by 1/4 in. A process to simulate a more natural meat texture, had resulted in a significant improvement in flavor compared with that of the early Gemini products Packages of these foods were arranged in meal units based upon nutrient balance and astronaut selection. Each meal was overwrapped in an aluminum-foil-plastic laminate which also served as a garbage bag for in-flight stowage of used food packages after each meal. The diet was designed to provide each astronaut in the command module with his estimated energy requirements of 2800 Kcal/day, 16 to 17 percent protein, 30 to 32 percent fat, and 50 to 54 percent carbohydrate. Certain foods were fortified with calcium lactate to provide a daily calcium intake of 1000 gm and a calcium-to-phosphorus ratio of approximately 2 to 1.

This approach to food management had been successful on the 14-day flight of Gemini 7 and had been verified by numerous ground-based altitude-chamber studies conducted by the USAF and NASA. A number of deficiencies were apparent in the baseline Apollo food system and development efforts to improve individual ration components for the Apollo Applications Program were being sponsored by NASA at the U. S. Army Natick Laboratories. The advances in foods and food systems which were being realized as a result of the USAF Manned Orbiting Laboratory (MOL) Program were available to NASA. These programs continue to be closely coordinated for the mutual benefit of both agencies.

At the time of the fire which resulted in the loss of the Apollo 1 crew and spacecraft, the food system met all of the engineering constraints of the mission while providing adequate nutrients. Most "creature comforts" such as improved foods and packaging, however, were relegated to the longer duration flights (28 and 56 days) of the Apollo Applications Program. As a result of the spacecraft fire in January 1967, each spacecraft system, subsystem, and component received thorough reevaluation and analysis to identify and reduce the hazards of flammable materials. Since nonflammable foods are an impossibility, our attention was directed toward finding a packaging material which would not support combustion in a pure oxygen environment. At this point in time, responsibility for design, procurement, and spacecraft integration of flight foods was transferred to the Medical Directorate at the Manned Spacecraft Center. Prior to this, our only responsibility in aerospace food systems had been in food and nutrition research with rather tenuous control of the actual flight item.

Extensive changes in the types of food and packaging will be implemented in an orderly manner for the forthcoming Apollo flights. These changes are necessary because (1) In-flight food consumption is inadequate to maintain metabolic balance (negative energy, loss of tissue fluid and electrolytes); (2) meal preparation and consumption requires too much time and effort; (3) water for reconstitution of dehydrated foods is off flavor and contains large quantities of [7] undissolved hydrogen and oxygen gas; (4) functional failures occur in rehydratable food packages; (5) a system of foods and packaging which is more familiar in appearance, flavor, and method of consumption is needed, and (6) in-flight illness and anorexia must be reduced.

The demands for improvement have not emanated from the astronauts with quite the strength that the news media would lead one to believe. In fact, the demands have come from ourselves and the program managers once we realized that an improvement was possible that would result in a crew that would eat more during the mission and maintain a higher level of morale. The improved foods and packaging which have been integrated into the Apollo food system are not new to us or the rest of the consumer and scientific community. For instance, the first real breakthrough occurred with the most mundane and seemingly simple procedure that the Apollo 8 crew performed on Christmas Day during man's first successful lunar orbital mission. Borman, Lovell, and Anders opened a thermostabilized flexible can of turkey chunks and gravy and ate with a spoon! The dish required no water for rehydration since the normal water content (67-percent by weight) had been retained. This crew had experienced considerable problems with nausea and vomiting, a water supply with excessive gas and objectionable flavor, and an exciting mission of critical spacecraft maneuvers to escape the pull of Earth gravity and achieve lunar orbit. They were about 250 000 miles from home on Christmas Day and faced the possibility of being unable to escape the pull of the lunar gravity and the possibility of reentering the Earth's atmosphere at an angle that would deflect them back into Earth orbit with no chance of reentry before fuel or oxygen supplies were exhausted.

The meal was quite a morale booster. During the preflight menu selection period, the crew had specifically stated they did not want to have the wetpack on their mission. This was probably a result of their desire to prevent unrealistic demands on the system and personnel supporting their mission.

The Christmas dinner of the Apollo 8 mission was in one sense a last-minute affair; i. e., actual planning of the components did not start until 3 months prior to flight, but, in truth, development had started several years before for NASA and military ration use. The wetpack turkey and gravy was a heat-sterilized product in a flexible package. Similar products had been under development and field-tested by the U. S. Army Natick Laboratories as possible replacements for the canned combat rations, with the idea of reducing package weight and allowing the field soldier greater mobility while carrying the flexible containers in his pocket. The term wetpack came into use to describe and differentiate it from the nominal dehydrated Apollo foods which require the addition of water for rehydration prior to consumption. This type of food had not been used because of a number of disadvantages of food with normal moisture content. Since moisture is available for bacterial growth, heat sterilization and a failsafe hermetic seal is required. The weight of a wetpack with its 60 to 70 percent moisture content is approximately four times greater than that of the comparable dehydrated product. Vacuum packaging is virtually impossible in a high-moisture food and the absolute vacuum of outer space could cause rupture of the package from internal gas expansion during spacecraft decompression. The possibility of Cl.botulinum [8] toxin also causes justifiable concern over the use of these products. Each of these potential problem areas was carefully evaluated and solved prior to the flight.

The success of the wetpacks in the Apollo 8 and 9 missions can be attributed to a combination of several factors: The men could see and smell what they were eating with relative ease compared with the complete containment afforded by the zero-G food package; the texture and flavor of the food was not affected by the characteristics of spacecraft water and frequent incomplete rehydration of the freeze-dehydrated item; and the wetpack does not require tedious installation of water, kneading, waiting, and manipulation prior to consumption. Overcoming these "little" irritants is an important part of a successful food system in any situation. Unfortunately, there has been a tendency to require that all food be of the wetpack type and this extreme swing of the pendulum was not easy to bring back into line.

We realize that a system based on all wetpack food would become just as monotonous and objectionable as that with the all-dehydrated approach. For Apollo 10 we shall include five new freeze-dehydrated foods which will be packaged in a "spoon-bowl" package. This package has a water inlet valve at one end similar to that of the nominal rehydratable food package. The main difference will be in the large zippered opening on the other end which will allow access to the rehydrated food with a spoon. With this large opening, the pieces of dehydrated meat and vegetables can be larger and thereby have a more familiar and acceptable mouth feel and flavor. Many of these foods are preferred over some of the wetpack items.

The use of a spoon while in weightlessness was no simple impulse. Simulations of weightlessness and eating from an open package with a spoon had been conducted by the U. S. Air Force in high-performance aircraft in parabolic flight patterns. Numerous foods, packages, and utensils have been tested in that program and in our own tests. While these aircraft tests are not a completely accurate simulation because of the short duration of the weightless condition, the results indicated that our spacecraft test would be successful without undue concern for dispersal of liquid food throughout the cabin. Subsequent use of open packages and utensils on the Apollo 9 flight was accomplished without difficulty. That crew even experimented with using the spoon to eat from the nominal rehydratable food package. In retrospect it is easy to see that spoon and bowl eating would be successful since in the absence of gravity liquid motion is controlled by forces that are negligible on Earth, e. g., surface tension, capillary action, cohesion, and adhesion.

Food system design for the Gemini and Apollo programs was constrained by requirements to prepare for worst case situations. The most significant progress in space food systems was realized on the Apollo 8 mission when the crew calmly went about their business of opening a package of thermostabilized turkey and gravy that had no zero-G feeder tube or valve for rehydration. The only support equipment provided was a pair of scissors to open the package and a 10-cent stainless-steel spoon. The crew ate their wetpack with ease and were highly pleased with the whole affair. The significance of this feat is not apparent to those who have not been intimately involved with the program of space food development and integration of life support equipment in manned spacecraft. The spoon and the "canned" turkey and gravy (heat processed and packaged in a flexible pouch) were significant in that some of the most difficult constraints to space food development [9] were lifted in a matter of minutes while man first circled the Moon. The following items are a few of those constraints

(1) Vacuum packaging of all food items

(2) Positive containment of liquid food during consumption

(3) Caloric density of food

(4) Tedious procedures for food preparation by rehydration

Design requirements for the Apollo food system were actually more stringent than those in the Gemini Program. This resulted in foods and packaging for Apollo that were quite simile those used on Gemini. It was a generally accepted fact that the Apollo foods would be highly acceptable and would present no problems of any consequence. We had begun to believe that assumption ourselves, for, after all, the hot and cold water systems to be available in Apollo would permit the astronaut to prepare a really hot meal with a chilled beverage. We placed a great deal of reliance upon the characteristics and quality of the water system. We had good reason for this since ground-based simulators had proven the reliability of the fuel-cell-generated water system.

All spacecraft life support systems were exhaustively tested during an 8-day manned test of the command module (designated Spacecraft 2TV-1 /101) which was exposed to the thermal and vacuum conditions of space. The test could not, however, simulate weightlessness. The astronauts in this test were quite well pleased with the food system and consumed virtually every morsel of food provided. The crew experienced some difficulty in rehydration of foods because of gas in the water supply. The quantity of undissolved gas was not consistent but averaged approximately 30 percent by volume. The crew solved this problem by venting the gas periodically from the food package during rehydration. Venting was accomplished by depressing the food-package water inlet valve. This worked satisfactorily because the gas and liquid food were readily separated in the package by gravity prior to venting. This technique would not work in orbit since, in the absence of gravity, liquids are no longer heavier than vapors and attempts to vent off gas trapped in the food package to allow insertion of adequate water for food rehydration result in venting liquid food as well as gas.

Only minor modifications in the fuel-cell water supply system were possible if launch schedules were to be maintained. One of the modifications implemented was to reduce the temperature of the hot water from 155° to 135° F. The higher temperature is very close to the boiling point of water at the nominal cabin pressure of 5 psia. The net result of this quantity of gas in the water supply is that the water is not hot enough to improve the rate of food rehydration, and by the time all of the required water is added and as much gas is expelled as possible the food is not hot and usually is incompletely rehydrated because of the small bubbles of gas dispersed throughout the package which prevent intimate contact of water with food. Also, after several cycles from the water dispenser, the food package could be distended to the point of bursting and still not have adequate water to rehydrate the food. (The Apollo 9 crew reported that the water supply was approximately 30 percent water and 70 percent undissolved gas. ) All three flight crews have reported an off-flavor in the water that was not entirely due to the water chlorination procedures. This off-flavor is probably due to some of the materials used in the flexible tubing. The Apollo 9 crew [10] found the water so distasteful that they consistently drank water that had been first mixed with one of the beverage powders.

The list of accomplishments that we can point to after only three Apollo flights is more extensive than the introduction of more familiar foods and methods of eating. Not quite so dramatic but equally as difficult and significant was the design of a nonflammable meal overwrap which also serves as a barrier to moisture and oxygen, a method of meal orientation, and a garbage bag. The quantity and variety of rehydratable beverages has been increased and modifications mad to improve the reliability, use, and size of the rehydratable food package. Food and packaging processing, testing, and inspection procedures have been extensively revised in conjunction with the USAF MOL development program.

A new approach to supplying food to an astronaut in a full-pressure suit in a possible loss of cabin pressure has been developed and flight qualified. This contingency feeding system employs a pontube with a valve to control liquid food flow. It is inserted into the water inlet valve of a nominal rehydratable food package on one end, and at the other end is put through a port in the pressure suit helmet. The crewmember squeezes and sucks liquid from the food package through the pontube and into his mouth. A valve in the pontube allows gradual equalization of the suit pressure (3. 5 psia) with the vacuum of the food package which helps to prevent rupture of the food package due to sudden pressure change. The food package is further restrained by a zippered nylon bag to prevent inadvertent rupture. The Apollo food sets also provide an oral hygiene kit which contains a tube of edible toothpaste, toothbrushes, and a spool of dental floss. In listing these accomplishments, we do not imply that they constitute the final answer to a requirement. Each can and will be optimized for future flights in spite of the heavy activity required to support missions that are launched on 2-month cycles and the austere staff of personnel available to work with the systems and problems.

In addition, for the future Apollo program food developments will center around more thermostabilized wetpacks, a larger variety of intermediate-moisture foods, a spoon-bowl package that will allow larger pieces of dehydrated foods, and a liquid nutrient dispenser for extravehicular use on the lunar surface that will supplement the nominal lunar module food supply.

The acceptance and effectiveness of the food system for a particular flight can be evaluated by the quantity of food consumed, the functioning of food preparation and dispensing equipment, postflight debriefing comments by the crews, changes in body weight, and biochemical and psychological measurements. These measurements leave a lot to be desired in both objectivity and accuracy. We have observed that the nature of preflight briefing on the food system has a direct effect on the overall acceptance of the foods. The more thoroughly the crews understand the purpose and design of foods, packaging, and menus, the more likely their reaction in flight will be favorable.

We must rely heavily upon the evaluation given by the consumer but a favorable postflight comment cannot be construed to mean success. Postflight inventory of returned foods and package and examination of the pilot's log are not without inherent errors. Frequently, critical mission tasks must be performed and a crewmember will find it necessary to eat foods programmed [11] (and color coded) for one of the other men. The inevitable swapping of foods occurs and these changes are not always recorded. At one point in the Apollo 7 mission a package of freeze-dehydrated tuna salad could have been traded for an entire meal.

The preference for the salad was greater than the need for extra foods and the offer to trade was denied. One objective measurement of the effectiveness of the food is body weight changes. These measurements can be misleading and require careful examination of normal metabolic rates and weight fluctuations which are not always available.

As was observed during the Gemini program, changes in body weight show little or no correlation to mission activity, mission duration, food intake, and occurrence of in-flight illness Preflight and postflight body weights along with estimated caloric intakes of the crew of the first three Apollo missions are shown in table I. The values of caloric intake attributed to each man are arbitrary because we could not determine the amount of food trading that occurred. It will be noted that if our only criteria for successful mission food supply depended upon prevention of body weight loss we have failed miserably. Weight losses have been recorded on every American and Russian spaceflight to date. Weight losses will not be corrected only by providing better food and more of it. First, we must discover methods for insuring that food will be consumed. It is of little use to expend much effort to minimize the weight and volume of a flight food item if that item is to be carried into space and returned unconsumed. It is of prime importance to maximize consumption after which the food must be designed to provide the quantity of critical nutrients based on rhythmic demands of metabolism, and not on hunger stimuli.

[12] It has not been possible to measure the precise food intake for each astronaut. We know the quantity of food stowed preflight and the quantity returned. Meals and individual food packages are color coded (red, white, or blue) for each astronaut and it should be a simple matter to calculate the precise quantity of food consumed. lt is inevitable that the crewmember will exchange foods or will eat an item from another man's meal if he does not have time to stop required mission tasks and prepare his meal. When this happens, the astronaut usually records the deviation in his log book. This system is not completely reliable, and understandably so when one considers the types of missions these men are on. What we obtain is a good estimate of each crewmember's food consumption and an accurate knowledge of the total food consumption by all three astronauts over the course of the mission.

Apollo astronauts have experienced varying degrees of in-flight illness. Symptoms of upper respiratory and gastrointestinal viral disease occurred in several of the Apollo 7 and 8 crewmembers. Nausea and vomiting experienced by one of the crew of Apollo 9 presented a real problem in the early stages of the flight, but the symptoms gradually disappeared and performance of mission tasks was highly satisfactory. Of course, the thought of food during this period aggravated the situation. During this flight, the problems with gas in the water supply and a very disagreeable flavor were most intense. During some periods, the crew was not able to drink the water at all and resorted to using rehydratable foods to mask the flavor of the water. The only foods that were satisfactory for this purpose were the beverage powders, fruit cocktail, and peaches. The limited supply of these items precluded their use as a sole source of energy, water, and electrolytes for all three astronauts. To help one of the crew maintain an acceptable metabolic balance, the other crewmen gave him their rehydratable beverages and fruits.

Also, it appears that our preflight diet and procedures require reevaluation, since most crewmembers have lost weight during the last few days prior to launch. Efforts to calculate precise preflight requirements and to provide well-balanced meals alone are not adequate to correct this situation. It is no secret that our intensive efforts to portion and balance inflight nutrients are of little value if the food is not eaten.

If the space food program has taken on a significant new face, it is in our efforts to improve the foods available, simplify food preparation procedures, improve the crew's understanding of our approach to nutrition, and emphasize the requirements to define in-flight food problems accurately now, before critical long-duration flights are undertaken. Concurrently with this approach, we have an active research program to define the nutrient content of actual and prototype flight foods and to define overall and critical nutrient requirements of the man. Even if it were possible to define nutrient requirements and provide the foods which made these nutrients available, all would be to no avail if we did not have an equally definitive program to determine the physical requirements to make food and food systems in the flight environment functional and psychologically acceptable. Therefore, in the Apollo Program we are placing less emphasis upon dietary manipulation and increased emphasis on systematic improvement of foods, packaging, and crew training to determine, or be able to predict, those foods which have the best chance of being consumed in the flight environment. As we gather this information on food acceptance, [13] nutrient definition and modifications to maintain metabolic balance is accomplished. Of course, the conventional familiar foods are the most likely candidates, but we have no parochial interest in natural foods to the complete exclusion of synthetics. Indeed, for missions in the not-too-far-distant future spacecraft food supplies may be partially derived from chemical regeneration of metabolic waste. The best available food that will most efficiently meet the requirements of man and machine will always be used. To be acceptable a food must be processed, prepared, and served in the precise manner that makes it familiar and desirable in the first place.

One of the most frequent mistakes made by food system planners, especially for unique habitats, is that they neglect to recognize the subtle differences that will have significant impact on food acceptance. Food prepared in the finest restaurant in town will not necessarily be acceptable in a spacecraft, a submarine, or even in the home if the overall characteristics of the consumer and his particular environment are not considered.

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