Formula DietsThe tacit assumption which now prevails, "Astronauts even on short-term missions require a diet of great variety," is apparently not well supported. In many parts of the world, people live on a monotonous diet consisting of only a few types of food with no apparent ill effects, provided their nutritional requirements are satisfied. Experimental evidence from many sources (e.g., the Army Medical Research and Nutrition Laboratory) shows that individuals can be kept on a single disagreeable formula diet for as long as 60 to 90 days without harm. Since highly motivated individuals are chosen for space flights, it is unlikely that they would object to the monotony of a formula diet and would probably prefer its simplicity. Also, there are definite possibilities of developing a much more acceptable formula than present types. There is no reason to anticipate adverse effects from the use of formula diets in short-term flights.Formula diets would be extremely desirable for short-term flights. A formula diet (a rehydrated liquid formula could be used) would considerably reduce the number of manipulations and the time required for in-flight preparation, compared to a varied diet. These two improvements could contribute materially to the safety of a flight, since the astronauts would not be preoccupied with food preparation for so long a period, and the food could be dispensed without removing suit components, such as gloves. Storage requirements could be simplified with this type of diet. Weight, however, would not be lowered without the development of more refined formulas than those now available. Formula diets could readily be adapted to the determined metabolic requirements of the individual astronaut. Packaging problems will be simplified by using formula diets, which can easily be given a variety of flavors and colors.WasteThe problem of waste production is intimately related to nutrition and can be solved or simplified by dietary changes. Any diet should be adjusted for the minimum production of feces, before and during even short flights. Water will be sequestered by accumulation in the feces, and the net loss, under normal conditions, would be approximately 40 to 60 grams per man per day. Flatus can be a serious problem, sinceconsiderable concentrations of toxic gases may accumulate. The purification system for the recirculated atmosphere must be able to remove these, although the diet should be planned to minimize the problem. The collection of urine and its storage is of importance, particularly on short-term flights, and individual packaging and labeling of urine specimens will be necessary for the analyses.MetabolismAn accurately measured intake of nutrients, calories, and water is necessary for determining metabolic demands imposed in any space flight. There is insufficient knowledge to predict total metabolic requirements under the numerous stresses which can be anticipated. Simulator studies are of great importance even for short-duration flights.The two most important variables to be considered in establishing the minimal diet are protein and energy requirements. NASA is supporting research at the University of California (Berkeley) to determine these requirements and to estimate individual variation in healthy young men. The possibility of minimizing need through biological adaptation is being explored.It is difficult to estimate the minimum protein requirement of an adult man. The generally accepted criterion of minimum adequate protein nutrition in the adult is the maintenance of nitrogen balance at minimum intake. The minimum protein requirements depend on endogenous nitrogen loss. Analysis of the little data available indicates a best estimate of 2 mg of nitrogen per kilocalorie of basal energy expenditure. However, this figure is higher than that noted in experiments in some human subjects.After minimum nitrogen requirements and minimum amino acid requirements have been established, studies will be directed toward investigating caloric restriction and adaptation to restriction of calories. It has been suggested that caloric restriction in animals and man results in apparent decreased energy need for the same activity. This apparent paradox has never been explained. It has been shown that there is adaptation to repeated episodes of caloric restriction both in animals and man, so that subsequent periods of caloric restriction result in decreased rate of weight loss, nitrogen loss, and longer survival.Additional experiments are urgently required to determine the metabolic demands for minerals—in particular, the metabolic balance of calcium, potassium, sodium, and phosphorus. Under conditions of high water consumption, large mineral losses are to be expected. Failure to replace these can cause an imbalance which could impair the efficiency of the individual to the extent of endangering the flight.Analysis of samples taken in flight, both of urine and feces, should be made. Respiratory quotients can be determined in flight, blood samples should be taken before and immediately after flight for analyzing selected components (in simulator studies these could be taken periodically), and nutritional intakes (which would be facilitated by formula diets) must be measured and analyzed.Short-Range TechnologyThere are many practical difficulties in providing for food storage and accessibility in spacecraft. The packaging of food materials, both dehydrated and liquid, has proceeded satisfactorily under the supervision of the Food and Container Institute. If packaging materials are to be made to withstand very high relative humidities and large variations in temperature, additional investigations are required, since such containers are not yet available. In packaging, serious consideration must be given to the ease with which the food may be reached and eaten.If dehydrated formula foods are to be fed on short-term missions, additional work is required on the rehydration of such formulas. Present methods of water measurement under weightless conditions are not satisfactory, and better methods will have to be contrived.Long-Term Nutritional ProblemsThere is a dearth of metabolic information, even for short-duration flights, without which changes in metabolic patterns to longer flights cannot be extrapolated. However, using scattered information, certain changes which may be encountered can be hypothesized. Decalcification of bone and changes in water-holding capacity of the body may be anticipated. It is also possible that changes in proportion of fat to lean body mass could be experienced and should be considered in nutritional planning. Nutritional requirements depend on size, particularly lean body mass, sex, physiological state, and individual metabolic rates. Therefore, individuals for space flight should be screened with these factors in mind if it is desirable to minimize food intake in long flights. The factors which influence the total nutritional requirements of the individual also influence his mental and physical responses to stress.Synthetic FoodsThe development of food materials other than those derived directly from animal or vegetable origin is of interest. Advantages of such diets may be low residue, ease of storage, rehydration, and manipulation. Experiments with chemically defined synthetic diet for humans have been carried out by Medical Sciences Research Foundation, San Mateo,Calif. The complete liquid diet is composed of required amino acids, fat, carbohydrate, vitamins, and minerals. A cubic foot of the diet (50 percent solids in H2O) supplies 2500 calories per day for 1 month, and has been given a variety of artificial flavors.This synthetic diet has been fed to human volunteers for 6 months in a pilot study at the California Medical Facility, Vacaville, Calif., and the results are being reviewed. Schwarz Bioresearch, Inc., is studying the storage, stability, and packaging of chemically defined synthetic diets for human and animal flights.Food Production in SpaceLong-term feeding in space depends upon a payload of stored food unless food is produced during flight. If sufficient propulsive energy is available, the duration of missions using stored food may be quite long. However, in emergencies in which a mission lasts longer than planned, survival may depend on the ability to produce food extraterrestrially. Eventually it will be desirable or necessary to produce food beyond the confines of Earth.The nutritional requirements of the crew will be influenced by such factors as activity, physical and psychological stress, individual size of the members, and individual metabolic rates. The food intake will have to be adjusted to meet these requirements. It is necessary to know the nutritional requirements of each astronaut and the way in which these are altered by the conditions of space flight in order to estimate needs on long missions. Without this information, the food supplies for the longer flights may be too much, too little, or improperly balanced. Where dependence would not be on stored food alone, but on food produced en route, more exact information on requirements is needed to determine the capacity of food production units.In the discussion of bioregenerative systems, it was suggested that food materials could be produced by photosynthetic organisms (e.g., algae, duckweed, and other higher plants) or by nonphotosynthetic organisms (e.g.,Hydrogenomonas). In contrast to the use of living organisms, reprocessing waste materials by chemical treatment or the actual synthesis of high-energy compounds has been suggested. No chemical system has yet been demonstrated as workable for the economical production of food in space, and the systems considered produce materials which may be converted to food, but are not food as such.Algal cultures have had the most extensive investigation as food in space, but the technical problems of using this material as a food source have not yet been solved. It is apparent from the investigations to date that algae will require treatment before they can be used as food. Inlimited trials, difficulties have been experienced with amino acid deficiencies, digestibility, high residues, and gastric distress. Processing methods which would be applicable in space travel and the possibility of secondary conversion by other animals or plants should be systematically investigated.
Formula DietsThe tacit assumption which now prevails, "Astronauts even on short-term missions require a diet of great variety," is apparently not well supported. In many parts of the world, people live on a monotonous diet consisting of only a few types of food with no apparent ill effects, provided their nutritional requirements are satisfied. Experimental evidence from many sources (e.g., the Army Medical Research and Nutrition Laboratory) shows that individuals can be kept on a single disagreeable formula diet for as long as 60 to 90 days without harm. Since highly motivated individuals are chosen for space flights, it is unlikely that they would object to the monotony of a formula diet and would probably prefer its simplicity. Also, there are definite possibilities of developing a much more acceptable formula than present types. There is no reason to anticipate adverse effects from the use of formula diets in short-term flights.Formula diets would be extremely desirable for short-term flights. A formula diet (a rehydrated liquid formula could be used) would considerably reduce the number of manipulations and the time required for in-flight preparation, compared to a varied diet. These two improvements could contribute materially to the safety of a flight, since the astronauts would not be preoccupied with food preparation for so long a period, and the food could be dispensed without removing suit components, such as gloves. Storage requirements could be simplified with this type of diet. Weight, however, would not be lowered without the development of more refined formulas than those now available. Formula diets could readily be adapted to the determined metabolic requirements of the individual astronaut. Packaging problems will be simplified by using formula diets, which can easily be given a variety of flavors and colors.WasteThe problem of waste production is intimately related to nutrition and can be solved or simplified by dietary changes. Any diet should be adjusted for the minimum production of feces, before and during even short flights. Water will be sequestered by accumulation in the feces, and the net loss, under normal conditions, would be approximately 40 to 60 grams per man per day. Flatus can be a serious problem, sinceconsiderable concentrations of toxic gases may accumulate. The purification system for the recirculated atmosphere must be able to remove these, although the diet should be planned to minimize the problem. The collection of urine and its storage is of importance, particularly on short-term flights, and individual packaging and labeling of urine specimens will be necessary for the analyses.MetabolismAn accurately measured intake of nutrients, calories, and water is necessary for determining metabolic demands imposed in any space flight. There is insufficient knowledge to predict total metabolic requirements under the numerous stresses which can be anticipated. Simulator studies are of great importance even for short-duration flights.The two most important variables to be considered in establishing the minimal diet are protein and energy requirements. NASA is supporting research at the University of California (Berkeley) to determine these requirements and to estimate individual variation in healthy young men. The possibility of minimizing need through biological adaptation is being explored.It is difficult to estimate the minimum protein requirement of an adult man. The generally accepted criterion of minimum adequate protein nutrition in the adult is the maintenance of nitrogen balance at minimum intake. The minimum protein requirements depend on endogenous nitrogen loss. Analysis of the little data available indicates a best estimate of 2 mg of nitrogen per kilocalorie of basal energy expenditure. However, this figure is higher than that noted in experiments in some human subjects.After minimum nitrogen requirements and minimum amino acid requirements have been established, studies will be directed toward investigating caloric restriction and adaptation to restriction of calories. It has been suggested that caloric restriction in animals and man results in apparent decreased energy need for the same activity. This apparent paradox has never been explained. It has been shown that there is adaptation to repeated episodes of caloric restriction both in animals and man, so that subsequent periods of caloric restriction result in decreased rate of weight loss, nitrogen loss, and longer survival.Additional experiments are urgently required to determine the metabolic demands for minerals—in particular, the metabolic balance of calcium, potassium, sodium, and phosphorus. Under conditions of high water consumption, large mineral losses are to be expected. Failure to replace these can cause an imbalance which could impair the efficiency of the individual to the extent of endangering the flight.Analysis of samples taken in flight, both of urine and feces, should be made. Respiratory quotients can be determined in flight, blood samples should be taken before and immediately after flight for analyzing selected components (in simulator studies these could be taken periodically), and nutritional intakes (which would be facilitated by formula diets) must be measured and analyzed.Short-Range TechnologyThere are many practical difficulties in providing for food storage and accessibility in spacecraft. The packaging of food materials, both dehydrated and liquid, has proceeded satisfactorily under the supervision of the Food and Container Institute. If packaging materials are to be made to withstand very high relative humidities and large variations in temperature, additional investigations are required, since such containers are not yet available. In packaging, serious consideration must be given to the ease with which the food may be reached and eaten.If dehydrated formula foods are to be fed on short-term missions, additional work is required on the rehydration of such formulas. Present methods of water measurement under weightless conditions are not satisfactory, and better methods will have to be contrived.Long-Term Nutritional ProblemsThere is a dearth of metabolic information, even for short-duration flights, without which changes in metabolic patterns to longer flights cannot be extrapolated. However, using scattered information, certain changes which may be encountered can be hypothesized. Decalcification of bone and changes in water-holding capacity of the body may be anticipated. It is also possible that changes in proportion of fat to lean body mass could be experienced and should be considered in nutritional planning. Nutritional requirements depend on size, particularly lean body mass, sex, physiological state, and individual metabolic rates. Therefore, individuals for space flight should be screened with these factors in mind if it is desirable to minimize food intake in long flights. The factors which influence the total nutritional requirements of the individual also influence his mental and physical responses to stress.Synthetic FoodsThe development of food materials other than those derived directly from animal or vegetable origin is of interest. Advantages of such diets may be low residue, ease of storage, rehydration, and manipulation. Experiments with chemically defined synthetic diet for humans have been carried out by Medical Sciences Research Foundation, San Mateo,Calif. The complete liquid diet is composed of required amino acids, fat, carbohydrate, vitamins, and minerals. A cubic foot of the diet (50 percent solids in H2O) supplies 2500 calories per day for 1 month, and has been given a variety of artificial flavors.This synthetic diet has been fed to human volunteers for 6 months in a pilot study at the California Medical Facility, Vacaville, Calif., and the results are being reviewed. Schwarz Bioresearch, Inc., is studying the storage, stability, and packaging of chemically defined synthetic diets for human and animal flights.Food Production in SpaceLong-term feeding in space depends upon a payload of stored food unless food is produced during flight. If sufficient propulsive energy is available, the duration of missions using stored food may be quite long. However, in emergencies in which a mission lasts longer than planned, survival may depend on the ability to produce food extraterrestrially. Eventually it will be desirable or necessary to produce food beyond the confines of Earth.The nutritional requirements of the crew will be influenced by such factors as activity, physical and psychological stress, individual size of the members, and individual metabolic rates. The food intake will have to be adjusted to meet these requirements. It is necessary to know the nutritional requirements of each astronaut and the way in which these are altered by the conditions of space flight in order to estimate needs on long missions. Without this information, the food supplies for the longer flights may be too much, too little, or improperly balanced. Where dependence would not be on stored food alone, but on food produced en route, more exact information on requirements is needed to determine the capacity of food production units.In the discussion of bioregenerative systems, it was suggested that food materials could be produced by photosynthetic organisms (e.g., algae, duckweed, and other higher plants) or by nonphotosynthetic organisms (e.g.,Hydrogenomonas). In contrast to the use of living organisms, reprocessing waste materials by chemical treatment or the actual synthesis of high-energy compounds has been suggested. No chemical system has yet been demonstrated as workable for the economical production of food in space, and the systems considered produce materials which may be converted to food, but are not food as such.Algal cultures have had the most extensive investigation as food in space, but the technical problems of using this material as a food source have not yet been solved. It is apparent from the investigations to date that algae will require treatment before they can be used as food. Inlimited trials, difficulties have been experienced with amino acid deficiencies, digestibility, high residues, and gastric distress. Processing methods which would be applicable in space travel and the possibility of secondary conversion by other animals or plants should be systematically investigated.
Formula DietsThe tacit assumption which now prevails, "Astronauts even on short-term missions require a diet of great variety," is apparently not well supported. In many parts of the world, people live on a monotonous diet consisting of only a few types of food with no apparent ill effects, provided their nutritional requirements are satisfied. Experimental evidence from many sources (e.g., the Army Medical Research and Nutrition Laboratory) shows that individuals can be kept on a single disagreeable formula diet for as long as 60 to 90 days without harm. Since highly motivated individuals are chosen for space flights, it is unlikely that they would object to the monotony of a formula diet and would probably prefer its simplicity. Also, there are definite possibilities of developing a much more acceptable formula than present types. There is no reason to anticipate adverse effects from the use of formula diets in short-term flights.Formula diets would be extremely desirable for short-term flights. A formula diet (a rehydrated liquid formula could be used) would considerably reduce the number of manipulations and the time required for in-flight preparation, compared to a varied diet. These two improvements could contribute materially to the safety of a flight, since the astronauts would not be preoccupied with food preparation for so long a period, and the food could be dispensed without removing suit components, such as gloves. Storage requirements could be simplified with this type of diet. Weight, however, would not be lowered without the development of more refined formulas than those now available. Formula diets could readily be adapted to the determined metabolic requirements of the individual astronaut. Packaging problems will be simplified by using formula diets, which can easily be given a variety of flavors and colors.WasteThe problem of waste production is intimately related to nutrition and can be solved or simplified by dietary changes. Any diet should be adjusted for the minimum production of feces, before and during even short flights. Water will be sequestered by accumulation in the feces, and the net loss, under normal conditions, would be approximately 40 to 60 grams per man per day. Flatus can be a serious problem, sinceconsiderable concentrations of toxic gases may accumulate. The purification system for the recirculated atmosphere must be able to remove these, although the diet should be planned to minimize the problem. The collection of urine and its storage is of importance, particularly on short-term flights, and individual packaging and labeling of urine specimens will be necessary for the analyses.MetabolismAn accurately measured intake of nutrients, calories, and water is necessary for determining metabolic demands imposed in any space flight. There is insufficient knowledge to predict total metabolic requirements under the numerous stresses which can be anticipated. Simulator studies are of great importance even for short-duration flights.The two most important variables to be considered in establishing the minimal diet are protein and energy requirements. NASA is supporting research at the University of California (Berkeley) to determine these requirements and to estimate individual variation in healthy young men. The possibility of minimizing need through biological adaptation is being explored.It is difficult to estimate the minimum protein requirement of an adult man. The generally accepted criterion of minimum adequate protein nutrition in the adult is the maintenance of nitrogen balance at minimum intake. The minimum protein requirements depend on endogenous nitrogen loss. Analysis of the little data available indicates a best estimate of 2 mg of nitrogen per kilocalorie of basal energy expenditure. However, this figure is higher than that noted in experiments in some human subjects.After minimum nitrogen requirements and minimum amino acid requirements have been established, studies will be directed toward investigating caloric restriction and adaptation to restriction of calories. It has been suggested that caloric restriction in animals and man results in apparent decreased energy need for the same activity. This apparent paradox has never been explained. It has been shown that there is adaptation to repeated episodes of caloric restriction both in animals and man, so that subsequent periods of caloric restriction result in decreased rate of weight loss, nitrogen loss, and longer survival.Additional experiments are urgently required to determine the metabolic demands for minerals—in particular, the metabolic balance of calcium, potassium, sodium, and phosphorus. Under conditions of high water consumption, large mineral losses are to be expected. Failure to replace these can cause an imbalance which could impair the efficiency of the individual to the extent of endangering the flight.Analysis of samples taken in flight, both of urine and feces, should be made. Respiratory quotients can be determined in flight, blood samples should be taken before and immediately after flight for analyzing selected components (in simulator studies these could be taken periodically), and nutritional intakes (which would be facilitated by formula diets) must be measured and analyzed.Short-Range TechnologyThere are many practical difficulties in providing for food storage and accessibility in spacecraft. The packaging of food materials, both dehydrated and liquid, has proceeded satisfactorily under the supervision of the Food and Container Institute. If packaging materials are to be made to withstand very high relative humidities and large variations in temperature, additional investigations are required, since such containers are not yet available. In packaging, serious consideration must be given to the ease with which the food may be reached and eaten.If dehydrated formula foods are to be fed on short-term missions, additional work is required on the rehydration of such formulas. Present methods of water measurement under weightless conditions are not satisfactory, and better methods will have to be contrived.Long-Term Nutritional ProblemsThere is a dearth of metabolic information, even for short-duration flights, without which changes in metabolic patterns to longer flights cannot be extrapolated. However, using scattered information, certain changes which may be encountered can be hypothesized. Decalcification of bone and changes in water-holding capacity of the body may be anticipated. It is also possible that changes in proportion of fat to lean body mass could be experienced and should be considered in nutritional planning. Nutritional requirements depend on size, particularly lean body mass, sex, physiological state, and individual metabolic rates. Therefore, individuals for space flight should be screened with these factors in mind if it is desirable to minimize food intake in long flights. The factors which influence the total nutritional requirements of the individual also influence his mental and physical responses to stress.Synthetic FoodsThe development of food materials other than those derived directly from animal or vegetable origin is of interest. Advantages of such diets may be low residue, ease of storage, rehydration, and manipulation. Experiments with chemically defined synthetic diet for humans have been carried out by Medical Sciences Research Foundation, San Mateo,Calif. The complete liquid diet is composed of required amino acids, fat, carbohydrate, vitamins, and minerals. A cubic foot of the diet (50 percent solids in H2O) supplies 2500 calories per day for 1 month, and has been given a variety of artificial flavors.This synthetic diet has been fed to human volunteers for 6 months in a pilot study at the California Medical Facility, Vacaville, Calif., and the results are being reviewed. Schwarz Bioresearch, Inc., is studying the storage, stability, and packaging of chemically defined synthetic diets for human and animal flights.Food Production in SpaceLong-term feeding in space depends upon a payload of stored food unless food is produced during flight. If sufficient propulsive energy is available, the duration of missions using stored food may be quite long. However, in emergencies in which a mission lasts longer than planned, survival may depend on the ability to produce food extraterrestrially. Eventually it will be desirable or necessary to produce food beyond the confines of Earth.The nutritional requirements of the crew will be influenced by such factors as activity, physical and psychological stress, individual size of the members, and individual metabolic rates. The food intake will have to be adjusted to meet these requirements. It is necessary to know the nutritional requirements of each astronaut and the way in which these are altered by the conditions of space flight in order to estimate needs on long missions. Without this information, the food supplies for the longer flights may be too much, too little, or improperly balanced. Where dependence would not be on stored food alone, but on food produced en route, more exact information on requirements is needed to determine the capacity of food production units.In the discussion of bioregenerative systems, it was suggested that food materials could be produced by photosynthetic organisms (e.g., algae, duckweed, and other higher plants) or by nonphotosynthetic organisms (e.g.,Hydrogenomonas). In contrast to the use of living organisms, reprocessing waste materials by chemical treatment or the actual synthesis of high-energy compounds has been suggested. No chemical system has yet been demonstrated as workable for the economical production of food in space, and the systems considered produce materials which may be converted to food, but are not food as such.Algal cultures have had the most extensive investigation as food in space, but the technical problems of using this material as a food source have not yet been solved. It is apparent from the investigations to date that algae will require treatment before they can be used as food. Inlimited trials, difficulties have been experienced with amino acid deficiencies, digestibility, high residues, and gastric distress. Processing methods which would be applicable in space travel and the possibility of secondary conversion by other animals or plants should be systematically investigated.
The tacit assumption which now prevails, "Astronauts even on short-term missions require a diet of great variety," is apparently not well supported. In many parts of the world, people live on a monotonous diet consisting of only a few types of food with no apparent ill effects, provided their nutritional requirements are satisfied. Experimental evidence from many sources (e.g., the Army Medical Research and Nutrition Laboratory) shows that individuals can be kept on a single disagreeable formula diet for as long as 60 to 90 days without harm. Since highly motivated individuals are chosen for space flights, it is unlikely that they would object to the monotony of a formula diet and would probably prefer its simplicity. Also, there are definite possibilities of developing a much more acceptable formula than present types. There is no reason to anticipate adverse effects from the use of formula diets in short-term flights.
Formula diets would be extremely desirable for short-term flights. A formula diet (a rehydrated liquid formula could be used) would considerably reduce the number of manipulations and the time required for in-flight preparation, compared to a varied diet. These two improvements could contribute materially to the safety of a flight, since the astronauts would not be preoccupied with food preparation for so long a period, and the food could be dispensed without removing suit components, such as gloves. Storage requirements could be simplified with this type of diet. Weight, however, would not be lowered without the development of more refined formulas than those now available. Formula diets could readily be adapted to the determined metabolic requirements of the individual astronaut. Packaging problems will be simplified by using formula diets, which can easily be given a variety of flavors and colors.
WasteThe problem of waste production is intimately related to nutrition and can be solved or simplified by dietary changes. Any diet should be adjusted for the minimum production of feces, before and during even short flights. Water will be sequestered by accumulation in the feces, and the net loss, under normal conditions, would be approximately 40 to 60 grams per man per day. Flatus can be a serious problem, sinceconsiderable concentrations of toxic gases may accumulate. The purification system for the recirculated atmosphere must be able to remove these, although the diet should be planned to minimize the problem. The collection of urine and its storage is of importance, particularly on short-term flights, and individual packaging and labeling of urine specimens will be necessary for the analyses.
The problem of waste production is intimately related to nutrition and can be solved or simplified by dietary changes. Any diet should be adjusted for the minimum production of feces, before and during even short flights. Water will be sequestered by accumulation in the feces, and the net loss, under normal conditions, would be approximately 40 to 60 grams per man per day. Flatus can be a serious problem, sinceconsiderable concentrations of toxic gases may accumulate. The purification system for the recirculated atmosphere must be able to remove these, although the diet should be planned to minimize the problem. The collection of urine and its storage is of importance, particularly on short-term flights, and individual packaging and labeling of urine specimens will be necessary for the analyses.
MetabolismAn accurately measured intake of nutrients, calories, and water is necessary for determining metabolic demands imposed in any space flight. There is insufficient knowledge to predict total metabolic requirements under the numerous stresses which can be anticipated. Simulator studies are of great importance even for short-duration flights.The two most important variables to be considered in establishing the minimal diet are protein and energy requirements. NASA is supporting research at the University of California (Berkeley) to determine these requirements and to estimate individual variation in healthy young men. The possibility of minimizing need through biological adaptation is being explored.It is difficult to estimate the minimum protein requirement of an adult man. The generally accepted criterion of minimum adequate protein nutrition in the adult is the maintenance of nitrogen balance at minimum intake. The minimum protein requirements depend on endogenous nitrogen loss. Analysis of the little data available indicates a best estimate of 2 mg of nitrogen per kilocalorie of basal energy expenditure. However, this figure is higher than that noted in experiments in some human subjects.After minimum nitrogen requirements and minimum amino acid requirements have been established, studies will be directed toward investigating caloric restriction and adaptation to restriction of calories. It has been suggested that caloric restriction in animals and man results in apparent decreased energy need for the same activity. This apparent paradox has never been explained. It has been shown that there is adaptation to repeated episodes of caloric restriction both in animals and man, so that subsequent periods of caloric restriction result in decreased rate of weight loss, nitrogen loss, and longer survival.Additional experiments are urgently required to determine the metabolic demands for minerals—in particular, the metabolic balance of calcium, potassium, sodium, and phosphorus. Under conditions of high water consumption, large mineral losses are to be expected. Failure to replace these can cause an imbalance which could impair the efficiency of the individual to the extent of endangering the flight.Analysis of samples taken in flight, both of urine and feces, should be made. Respiratory quotients can be determined in flight, blood samples should be taken before and immediately after flight for analyzing selected components (in simulator studies these could be taken periodically), and nutritional intakes (which would be facilitated by formula diets) must be measured and analyzed.
An accurately measured intake of nutrients, calories, and water is necessary for determining metabolic demands imposed in any space flight. There is insufficient knowledge to predict total metabolic requirements under the numerous stresses which can be anticipated. Simulator studies are of great importance even for short-duration flights.
The two most important variables to be considered in establishing the minimal diet are protein and energy requirements. NASA is supporting research at the University of California (Berkeley) to determine these requirements and to estimate individual variation in healthy young men. The possibility of minimizing need through biological adaptation is being explored.
It is difficult to estimate the minimum protein requirement of an adult man. The generally accepted criterion of minimum adequate protein nutrition in the adult is the maintenance of nitrogen balance at minimum intake. The minimum protein requirements depend on endogenous nitrogen loss. Analysis of the little data available indicates a best estimate of 2 mg of nitrogen per kilocalorie of basal energy expenditure. However, this figure is higher than that noted in experiments in some human subjects.
After minimum nitrogen requirements and minimum amino acid requirements have been established, studies will be directed toward investigating caloric restriction and adaptation to restriction of calories. It has been suggested that caloric restriction in animals and man results in apparent decreased energy need for the same activity. This apparent paradox has never been explained. It has been shown that there is adaptation to repeated episodes of caloric restriction both in animals and man, so that subsequent periods of caloric restriction result in decreased rate of weight loss, nitrogen loss, and longer survival.
Additional experiments are urgently required to determine the metabolic demands for minerals—in particular, the metabolic balance of calcium, potassium, sodium, and phosphorus. Under conditions of high water consumption, large mineral losses are to be expected. Failure to replace these can cause an imbalance which could impair the efficiency of the individual to the extent of endangering the flight.
Analysis of samples taken in flight, both of urine and feces, should be made. Respiratory quotients can be determined in flight, blood samples should be taken before and immediately after flight for analyzing selected components (in simulator studies these could be taken periodically), and nutritional intakes (which would be facilitated by formula diets) must be measured and analyzed.
Short-Range TechnologyThere are many practical difficulties in providing for food storage and accessibility in spacecraft. The packaging of food materials, both dehydrated and liquid, has proceeded satisfactorily under the supervision of the Food and Container Institute. If packaging materials are to be made to withstand very high relative humidities and large variations in temperature, additional investigations are required, since such containers are not yet available. In packaging, serious consideration must be given to the ease with which the food may be reached and eaten.If dehydrated formula foods are to be fed on short-term missions, additional work is required on the rehydration of such formulas. Present methods of water measurement under weightless conditions are not satisfactory, and better methods will have to be contrived.
There are many practical difficulties in providing for food storage and accessibility in spacecraft. The packaging of food materials, both dehydrated and liquid, has proceeded satisfactorily under the supervision of the Food and Container Institute. If packaging materials are to be made to withstand very high relative humidities and large variations in temperature, additional investigations are required, since such containers are not yet available. In packaging, serious consideration must be given to the ease with which the food may be reached and eaten.
If dehydrated formula foods are to be fed on short-term missions, additional work is required on the rehydration of such formulas. Present methods of water measurement under weightless conditions are not satisfactory, and better methods will have to be contrived.
Long-Term Nutritional ProblemsThere is a dearth of metabolic information, even for short-duration flights, without which changes in metabolic patterns to longer flights cannot be extrapolated. However, using scattered information, certain changes which may be encountered can be hypothesized. Decalcification of bone and changes in water-holding capacity of the body may be anticipated. It is also possible that changes in proportion of fat to lean body mass could be experienced and should be considered in nutritional planning. Nutritional requirements depend on size, particularly lean body mass, sex, physiological state, and individual metabolic rates. Therefore, individuals for space flight should be screened with these factors in mind if it is desirable to minimize food intake in long flights. The factors which influence the total nutritional requirements of the individual also influence his mental and physical responses to stress.
There is a dearth of metabolic information, even for short-duration flights, without which changes in metabolic patterns to longer flights cannot be extrapolated. However, using scattered information, certain changes which may be encountered can be hypothesized. Decalcification of bone and changes in water-holding capacity of the body may be anticipated. It is also possible that changes in proportion of fat to lean body mass could be experienced and should be considered in nutritional planning. Nutritional requirements depend on size, particularly lean body mass, sex, physiological state, and individual metabolic rates. Therefore, individuals for space flight should be screened with these factors in mind if it is desirable to minimize food intake in long flights. The factors which influence the total nutritional requirements of the individual also influence his mental and physical responses to stress.
Synthetic FoodsThe development of food materials other than those derived directly from animal or vegetable origin is of interest. Advantages of such diets may be low residue, ease of storage, rehydration, and manipulation. Experiments with chemically defined synthetic diet for humans have been carried out by Medical Sciences Research Foundation, San Mateo,Calif. The complete liquid diet is composed of required amino acids, fat, carbohydrate, vitamins, and minerals. A cubic foot of the diet (50 percent solids in H2O) supplies 2500 calories per day for 1 month, and has been given a variety of artificial flavors.This synthetic diet has been fed to human volunteers for 6 months in a pilot study at the California Medical Facility, Vacaville, Calif., and the results are being reviewed. Schwarz Bioresearch, Inc., is studying the storage, stability, and packaging of chemically defined synthetic diets for human and animal flights.
The development of food materials other than those derived directly from animal or vegetable origin is of interest. Advantages of such diets may be low residue, ease of storage, rehydration, and manipulation. Experiments with chemically defined synthetic diet for humans have been carried out by Medical Sciences Research Foundation, San Mateo,Calif. The complete liquid diet is composed of required amino acids, fat, carbohydrate, vitamins, and minerals. A cubic foot of the diet (50 percent solids in H2O) supplies 2500 calories per day for 1 month, and has been given a variety of artificial flavors.
This synthetic diet has been fed to human volunteers for 6 months in a pilot study at the California Medical Facility, Vacaville, Calif., and the results are being reviewed. Schwarz Bioresearch, Inc., is studying the storage, stability, and packaging of chemically defined synthetic diets for human and animal flights.
Food Production in SpaceLong-term feeding in space depends upon a payload of stored food unless food is produced during flight. If sufficient propulsive energy is available, the duration of missions using stored food may be quite long. However, in emergencies in which a mission lasts longer than planned, survival may depend on the ability to produce food extraterrestrially. Eventually it will be desirable or necessary to produce food beyond the confines of Earth.The nutritional requirements of the crew will be influenced by such factors as activity, physical and psychological stress, individual size of the members, and individual metabolic rates. The food intake will have to be adjusted to meet these requirements. It is necessary to know the nutritional requirements of each astronaut and the way in which these are altered by the conditions of space flight in order to estimate needs on long missions. Without this information, the food supplies for the longer flights may be too much, too little, or improperly balanced. Where dependence would not be on stored food alone, but on food produced en route, more exact information on requirements is needed to determine the capacity of food production units.In the discussion of bioregenerative systems, it was suggested that food materials could be produced by photosynthetic organisms (e.g., algae, duckweed, and other higher plants) or by nonphotosynthetic organisms (e.g.,Hydrogenomonas). In contrast to the use of living organisms, reprocessing waste materials by chemical treatment or the actual synthesis of high-energy compounds has been suggested. No chemical system has yet been demonstrated as workable for the economical production of food in space, and the systems considered produce materials which may be converted to food, but are not food as such.Algal cultures have had the most extensive investigation as food in space, but the technical problems of using this material as a food source have not yet been solved. It is apparent from the investigations to date that algae will require treatment before they can be used as food. Inlimited trials, difficulties have been experienced with amino acid deficiencies, digestibility, high residues, and gastric distress. Processing methods which would be applicable in space travel and the possibility of secondary conversion by other animals or plants should be systematically investigated.
Long-term feeding in space depends upon a payload of stored food unless food is produced during flight. If sufficient propulsive energy is available, the duration of missions using stored food may be quite long. However, in emergencies in which a mission lasts longer than planned, survival may depend on the ability to produce food extraterrestrially. Eventually it will be desirable or necessary to produce food beyond the confines of Earth.
The nutritional requirements of the crew will be influenced by such factors as activity, physical and psychological stress, individual size of the members, and individual metabolic rates. The food intake will have to be adjusted to meet these requirements. It is necessary to know the nutritional requirements of each astronaut and the way in which these are altered by the conditions of space flight in order to estimate needs on long missions. Without this information, the food supplies for the longer flights may be too much, too little, or improperly balanced. Where dependence would not be on stored food alone, but on food produced en route, more exact information on requirements is needed to determine the capacity of food production units.
In the discussion of bioregenerative systems, it was suggested that food materials could be produced by photosynthetic organisms (e.g., algae, duckweed, and other higher plants) or by nonphotosynthetic organisms (e.g.,Hydrogenomonas). In contrast to the use of living organisms, reprocessing waste materials by chemical treatment or the actual synthesis of high-energy compounds has been suggested. No chemical system has yet been demonstrated as workable for the economical production of food in space, and the systems considered produce materials which may be converted to food, but are not food as such.
Algal cultures have had the most extensive investigation as food in space, but the technical problems of using this material as a food source have not yet been solved. It is apparent from the investigations to date that algae will require treatment before they can be used as food. Inlimited trials, difficulties have been experienced with amino acid deficiencies, digestibility, high residues, and gastric distress. Processing methods which would be applicable in space travel and the possibility of secondary conversion by other animals or plants should be systematically investigated.