Soviet Space Clothing Requirements
SPACE SUITS AND CLOTHING
During the past 18 years, both Soviet cosmonauts and American astronauts have performed space walks [extravehicular activity (EVA)]. In order to survive the adverse environment of space, the space suits (EVA suit) must supply the life support found in the spaceship. The current EVA suits are designed so that they are capable of supporting EVA for up to 5 hours. (181)
The Soviet EVA suit has evolved over the years to its present configuration. It consists of a metal helmet and plastic visor with sleeves and trouser legs made of a flexible material, suitable for quick donning. The EVA suit contains all life support systems, in duplicated form for greater safety and dependability. These newer suits are twice as light as the earlier one worn by Leonov. The Soviets claim that the gloves permit sufficient finger dexterity for winding a watch or picking up a needle. (182) The space suit has a recycling system for absorbing carbon dioxide. The cosmonauts have a high degree of confidence in their EVA equipment, as exemplified in 1979, when a radio telescope antenna jammed during the jettison procedure and was corrected by employing EVA. (183) Current information suggests that one size EVA suit fits all sizes of cosmonauts.184 The arms and legs are made of flexible material, specifically designed to be adjusted to meet individual needs. The gloves are screwed into the space suit to meet individual fit and to permit the exacting use of the hands and fingers. As part of the space suit, the cosmonauts wear a harness which has incorporated medical monitoring equipment capable of telemetering back to Earth EKG data as well as pulse and respiratory rate. Under the EVA suit, the cosmonaut wears coveralls that carry water lines, permitting individual temperature regulation of the EVA suit. Power may be supplied to the EVA suit from the spaceship via an electrical line, however, it can also operate autonomously from the spaceship. The cosmonaut is connected to the surface of the spaceship by a safety line. (185, 186)
During routine space platform operations, the cosmonauts wear conventional flight garments. In earlier missions, the cosmonauts, for hygienic reasons, changed their undergarments at regular intervals and discarded the soiled clothing. Because of longer space missions, this practice is no longer practical, therefore, undergarments are cleaned and reused.
Still other garments are worn as countermeasures to weightlessness. These include the Penguin suit, a special garment which produces passive resistance to the musculature. To counteract the risk of muscle atrophy, the suit is worn during the entire working day in space. The Penguin suit partially compensates for the absence of gravity by offering a constant artificial gravitational load to the musculature of the legs and torso. (187)
During various phases of the Salyut mission, and as a prophylactic measure to the deconditioning of the cardiovascular system, the Soviets also utilize a lower body negative pressure suit (LBNP).
As experimental results dictate, a variety of other apparel, that may enhance man's survivability and comfort in space, will become integral components of the garments worn during space flights. (188)
RESPONSE TO EMERGENCY SITUATIONS
An emergency in space may be categorized as an equipment emergency or a medical emergency. Obviously an equipment emergency may rapidly evolve into a medical emergency.
The majority of systems found in the spaceship that permit man to survive in space have emergency backup systems (redundancy). Associated with and separate from these life support systems in the EVA suit, which contains its own oxygen, temperature, and pressure system. This permits, in an emergency, the EVA suit to "maintain a microspace cabin environment for up to 5 hours. In the event of equipment failure, this is sufficient time for the crew to return to Earth. In addition, the Soyuz descent module can separate from its work module. The descent module then serves as an emergency vehicle in the event of power failure occurring during the early launch phase. The module contains a variety of emergency equipment, including food, water, clothing and other survival gear for either land or water ditching. The Soviets have described an emergency reentry capsule for their Salyut space station (189) When constructed, it will have the capability of returning safely three people and maintaining a closed life support system for up to 24 hours. It will be capable of surviving either land or water touch-downs. Whether such an emergency vehicle has in fact been developed and deployed is not certain at this time.
In addition to the redundancy built into the spaceship system much of the equipment can be repaired by the cosmonauts. Some of the equipment is functional even at less than optimum capacity, so that if malfunctions occur in a support system, it can still provide the environmental controls to effectively sustain life. The spaceship or station is equipped with sensing devices that detect potential emergency situations in order to give the cosmonauts time tor remedial action. Such actions may include the repair of the malfunction, modification of the system, as well as the donning of garments and equipment to protect the cosmonaut from potential hazardous environments. Unfortunately these sensing devices did not prevent disaster in the Soyuz 11 return to Earth.
The personnel transport ships (Soyuz and Soyuz-T) which are utilized by the Soviets to at times resupply the Salyut stations as well as to change crews can act as an emergency vehicle in the event of space station emergencies. They contain food, water, and clothing supplies, as well as medical and electronic equipment to broadcast their location to rescue personnel. Survival equipment such as fishing gear, knives and other equipment necessary tor emergency survival is aboard. However, a critical point worth mentioning is the physical condition of the cosmonaut upon returning to Earth. The cosmonauts are required to readapt to terrestrial conditions after long space missions. Therefore, much of the emergency equipment found aboard the Soyuz may be of little use due to the inability of the cosmonauts to maintain orthostatic stability and the frequently observed muscle atrophy. Even during routine landings recovery teams are necessary to assist the crew out ot the space capsule. It is therefore imperative that emergency rescue vehicles and personnel be rapidly deployed to extricate returning cosmonauts from returning vehicles.
Medical emergencies in space can be of two types, those that are treatable aboard the spaceship and those that require expeditious return to Earth. Those that can be handled aboard the spaceship consist primarily of minor emergencies, as, for example, lacerations pain and minor infections. Cosmonauts are trained to handle these situations. Adequate medication is aboard the spaceship to handle such conditions.
Serious medical complications may require on-board action. A discussion of this can be found under "Medication and Emergency Drugs." In the event treatment aboard is not feasible, the individual would have to be brought back to Earth. Both Soviet and United States investigators are actively studying and developing equipment and protocols for the handling of complicated space medical emergencies.
Any emergency situation aboard a spacecraft has profound psychological effects on the crew. Consequently, scenarios have been developed and countermeasure practiced prior to going into space. It is important that cosmonauts can respond with rapidity and confidence to all emergencies. (190)
FUTURE SYSTEMS AND TRENDS
Space missions for up to 1 year in duration should contain a life support system that has the capacity to regenerate water from atmospheric moisture and human liquid waste. (191) Missions for up to 2 years also require that the life support system has the capacity to generate oxygen from carbon dioxide and waste water. (192) However, if flights are planned to last over 2 years, a closed controlled ecological life support system is a virtual requirement, particularly if the mission's task is to explore other planets. (193)
The goal of the Soviet Union is to develop a closed ecological system which could sustain life in space for an indefinite period. (194) This system would most likely utilize some form of plant life that could efficiently utilize human waste as nutrients to replicate itself and in the process produce a balanced diet for man. Oxygen would be the by-product of plant photosynthesis. In the process of photosynthesis, carbon dioxide would be utilized by the plant, thereby removing this product of human metabolism from the space capsule environment. Another by-product of such synthesis would be the production of potable water. A schematic of the Soviet concept of such a system. (195)
Ideally, a closed ecological system would be of minimal size and weight. Since the substrate utilized by planets would most likely be composed of human waste, great care will be necessary to control the various contaminants introduced in such a system. Previous studies on Earth both in the United States and the Soviet Union have employed algae as the organism to grow on the waste substrates. In this process the organism replicates and produces oxygen as well as consuming carbon dioxide. Unfortunately, numerous difficulties have been encountered. In order to produce food products more acceptable for human consumption, the Soviets have more recently attempted to select plants that could effectively grow on human waste and still be acceptable for subsequent human consumption. (196)
A multitude of problems can be envisioned in the development of a closed environmental system. First, one must consider the substrate used for propagation of the organism to be used for food, carbon dioxide conversion and oxygen synthesis. Since the substrate primarily will consist of human waste in the form of feces and urine, methods will have to be developed for the degradation of the substrate into a suitable composition. This will require that it be solubilized, decontaminated, and toxic substances removed. Techniques will be required that will prevent subsequent microbiological contamination. Conditions must be such that no mutations occur to the organism being grown for food. The substrate must be of a stable composition so that the organism can efficiently produce the by-products, i.e., oxygen and edible food substances. In addition, even when these conditions are met, it will be necessary that the products are acceptable, edible and nutritious. It is also critical that the ecological system functions optimally in removing toxic substances such as carbon dioxide and that sufficient oxygen is produced to sustain life aboard the spacecraft.
Even though the Soviets have been successful in sustaining human life in closed ecological systems operating on Earth, (197) the required volume and weight to accomplish this feat would most likely negate its use in space. In addition, with the more recent findings of psychological stress of long term space flights, the superimposition of food products that do not offer much variety and leave much to be desired as to taste, makes this a long term and difficult problem to resolve. However, with the development of genetic engineering technology, it is within scientific probability that biological systems can be constructed that have the desirable characteristics needed for functioning in a closed ecological system.
Space greenhouses have been developed and sent into space in order to develop a partial life-support system. The Soviets have devoted significant research efforts to accomplish this task. A more detailed discussion on this subject will follow in the section dealing with the Kosmos biosatellite program.
NEGATIVE AND POSITIVE GRAVITATIONAL FORCES
BASIC CONCEPTS
From a physiological point of view, it is now well recognized that weightlessness is not merely the reduction or removal of weight on the body. Rather, zero gravity brings about a number of physiological responses to which man must adapt. The various symptoms that become evident after initial exposure to weightlessness have been discussed in some detail previously. Briefly they consist of body fluid, particularly blood redistribution to the upper part of the body, i.e., head and chest, accompanied by nasal congestion, facial puffiness and headaches. At times it is also associated with disorientation, space motion sickness, and loss of appetite. On the opposite scale, the cosmonaut is also subjected to gravitational forces substantially higher than those normally experienced on Earth. These times of elevated G forces occur primarily during liftoff and reentry.
The superimposition and possible synergistic effects of gravitational stress during reentry on the consequences of deconditioning of the cardiovascular, skeletal, muscular, hematological and immunological systems require additional investigation. Unfortunately, the conditions responsible for these physiological phenomena occurring in space are difficult to reproduce and evaluate on Earth.
SIMULATION OF POSITIVE AND NEGATIVE GRAVITY
In order to study the influence of the various gravitional gradiations that a cosmonaut encounters from the time of lift-off to his return to Earth, a variety of experimental protocols and equipment have been developed. These permit the reproduction of some of the physiological responses observed during positive and negative gravitational stress experienced during spaceflights. Bed rest, among other means, has been used to simulate zero gravity and the associated hypokinetic effects. Since it became evident that zero gravity causes such physiological phenomena as cardiovascular deconditioning, bone demineralization, muscle atrophy and shifts in fluid and electrolyte balance, both the United States and the Soviet Union have devoted considerable monies and expertise in duplicating these effects on Earth. Simulation of zero gravity on Earth can, in part, be accomplished by inducing both hypokinesis and hypodynamic conditions. Therefore, researchers have devoted significant time on mammals in evaluating the effect of immobilizing, restraining, denervating as well as other means of decreasing mobility and motor functions. These studies all have been done in order to simulate certain conditions encountered in space, due to zero gravity. Even though it is well recognized that these simulations do not parallel zero gravity, hypokinetic studies do produce physiological conditions somewhat similar to those encountered under actual weightlessness. A recent compendium of over 700 pages developed by NASA covers the literature encompassing these studies through 1980. This reference is included both to demonstrate the extraordinary amount of effort that has been devoted to this problem and to provide the reader with the opportunity to review and evaluate this major research area. (198)
As has been mentioned in the section dealing with selection and training of cosmonauts, water immersion, utilizing a simulator Salyut space station submerged in a large pool of water, is a routine Soviet training procedure. This technique, as well as bed rest, particularly with a head down tilt at between 4 and 12 degrees, is used by the Soviets to simulate weightlessness. (199)
Significant differences between these experimental ground based simulations and true weightlessness do exist. In particular the distribution of pulmonary blood, body fluids, gas volume and flow are still subject to gravitational influences during both bed rest and water immersion. One must also take into consideration some of the organ systems that are influenced by zero gravity. For exampie, the lung has very little supportive structure and the pulmonary vascular bed is very responsive to pressure differences. Therefore, they react to both the experimental condition on Earth as well as the gravity encountered in ground based experiments. Additionally, the differences in density of respiratory gases and blood make these highly susceptible both to direction and magnitude of flow.
Short intervals of a true weightless state can be achieved by flying an aircraft through a parabolic trajectory. Unfortunately, only certain sensory effects can be experienced during this maneuver, because the weightless state is obtained for rather short intervals (30 to 40 seconds). This therefore does not provide the time necessary to experience the myriad of physiological changes encountered during exposure to longer spans of zero gravity.
SIMULATION OF REENTRY GRAVITY
Even though both the Soviet Union and the United States have expended considerable research efforts in simulating zero gravity on Earth, none of these studies can replicate the conditions and body responses encountered at zero gravity. On the other hand, in the areas of positive gravitational forces, experimental conditions and protocols have significantly contributed to an understanding of the physiological responses obtained. By utilizing both high performance aircraft, human centrifuges and rapid deceleration equipment, massive amounts of data have accumulated on the response of man to gravitational forces greater than those normally experienced on Earth. (200) This information has led to the development of effective countermeasures. In addition, the development and application of such hardware as antigravity suits, harnesses and restraining devices all have been very helpful in preventing serious adverse physiological effects. This equipment has also considerably extended man's capacity to withstand high gravitational forces. Information gained from this research pointed toward means of positioning the body in reference to the gravitational force, so that it can tolerate even higher forces. It has been observed that the body can withstand transverse (front to back) gravitational forces much more readily than longitudinal forces (head to toe). (201)
Thus far, no adverse effects have been noted from the positive G forces encountered on reentry after long space missions.202 Nevertheless, there is the potential for adverse effects to the cardiovascular and the skeletal system. In the case of the skeletal system, this is because of the continued problems posed by bone demineralization. This process is not well understood, and up to this time no demineralization plateau has been reached. Demineralization seems to progress for the duration of the space flight. Potentially the skeletal system could become sufficiently weakened to suffer fractures when subjected to positive gravitational forces during reentry or when stressed immediately at touchdown. Similarly, the magnitude of deconditioning of the cardiovascular systems could sure system. This permits, in an emergency, the EVA suit to "maintain a microspace cabin environment for up to 5 hours. In the event of equipment failure, this is sufficient time for the crew to return to Earth. In addition, the Soyuz descent module can separate from its work module. The descent module then serves as an emergency vehicle in the event of power failure occurring during the early launch phase. The module contains a variety of emergency equipment, including food, water, clothing and other survival gear for either land or water ditching. The Soviets have described an emergency reentry capsule for their Salyut space station (189) When constructed, it will have the capability of returning safely three people and maintaining a closed life support system for up to 24 hours. It will be capable of surviving either land or water touch-downs. Whether such an emergency vehicle has in fact been developed and deployed is not certain at this time.
In addition to the redundancy built into the spaceship system much of the equipment can be repaired by the cosmonauts. Some of the equipment is functional even at less than optimum capacity, so that if malfunctions occur in a support system, it can still provide the environmental controls to effectively sustain life. The spaceship or station is equipped with sensing devices that detect potential emergency situations in order to give the cosmonauts time tor remedial action. Such actions may include the repair of the malfunction, modification of the system, as well as the donning of garments and equipment to protect the cosmonaut from potential hazardous environments. Unfortunately these sensing devices did not prevent disaster in the Soyuz 11 return to Earth.
The personnel transport ships (Soyuz and Soyuz-T) which are utilized by the Soviets to at times resupply the Salyut stations as well as to change crews can act as an emergency vehicle in the event of space station emergencies. They contain food, water, and clothing supplies, as well as medical and electronic equipment to broadcast their location to rescue personnel. Survival equipment such as fishing gear, knives and other equipment necessary tor emergency survival is aboard. However, a critical point worth mentioning is the physical condition of the cosmonaut upon returning to Earth. The cosmonauts are required to readapt to terrestrial conditions after long space missions. Therefore, much of the emergency equipment found aboard the Soyuz may be of little use due to the inability of the cosmonauts to maintain orthostatic stability and the frequently observed muscle atrophy. Even during routine landings recovery teams are necessary to assist the crew out ot the space capsule. It is therefore imperative that emergency rescue vehicles and personnel be rapidly deployed to extricate returning cosmonauts from returning vehicles.
Medical emergencies in space can be of two types, those that are treatable aboard the spaceship and those that require expeditious return to Earth. Those that can be handled aboard the spaceship consist primarily of minor emergencies, as, for example, lacerations pain and minor infections. Cosmonauts are trained to handle these situations. Adequate medication is aboard the spaceship to handle such conditions.
Serious medical complications may require on-board action. A discussion of this can be found under "Medication and Emergency Drugs." In the event treatment aboard is not feasible, the individual would have to be brought back to Earth. Both Soviet and United States investigators are actively studying and developing equipment and protocols for the handling of complicated space medical emergencies.
Any emergency situation aboard a spacecraft has profound psychological effects on the crew. Consequently, scenarios have been developed and countermeasure practiced prior to going into space. It is important that cosmonauts can respond with rapidity and confidence to all emergencies. (190)
FUTURE SYSTEMS AND TRENDS
Space missions for up to 1 year in duration should contain a life support system that has the capacity to regenerate water from atmospheric moisture and human liquid waste. (191) Missions for up to 2 years also require that the life support system has the capacity to generate oxygen from carbon dioxide and waste water. (192) However, if flights are planned to last over 2 years, a closed controlled ecological life support system is a virtual requirement, particularly if the mission's task is to explore other planets. (193)
The goal of the Soviet Union is to develop a closed ecological system which could sustain life in space for an indefinite period. (194) This system would most likely utilize some form of plant life that could efficiently utilize human waste as nutrients to replicate itself and in the process produce a balanced diet for man. Oxygen would be the by-product of plant photosynthesis. In the process of photosynthesis, carbon dioxide would be utilized by the plant, thereby removing this product of human metabolism from the space capsule environment. Another by-product of such synthesis would be the production of potable water. A schematic of the Soviet concept of such a system is shown. (195)
Ideally, a closed ecological system would be of minimal size and weight. Since the substrate utilized by planets would most likely be composed of human waste, great care will be necessary to control the various contaminants introduced in such a system. Previous studies on Earth both in the United States and the Soviet Union have employed algae as the organism to grow on the waste substrates. In this process the organism replicates and produces oxygen as well as consuming carbon dioxide. Unfortunately, numerous difficulties have been encountered. In order to produce food products more acceptable for human consumption, the Soviets have more recently attempted to select plants that could effectively grow on human waste and still be acceptable for subsequent human consumption. (196)
A multitude of problems can be envisioned in the development of a closed environmental system. First, one must consider the substrate used for propagation of the organism to be used for food, carbon dioxide conversion and oxygen synthesis. Since the substrate primarily will consist of human waste in the form of feces and urine, methods will have to be developed for the degradation of the substrate into a suitable composition. This will require that it be solubilized, decontaminated, and toxic substances removed. Techniques will be required that will prevent subsequent microbiological contamination. Conditions must be such that no mutations occur to the organism being grown for food. The substrate must be of a stable composition so that the organism can efficiently produce the by-products, i.e., oxygen and edible food substances. In addition, even when these conditions are met, it will be necessary that the products are acceptable, edible and nutritious. It is also critical that the ecological system functions optimally in removing toxic substances such as carbon dioxide and that sufficient oxygen is produced to sustain life aboard the spacecraft.
Even though the Soviets have been successful in sustaining human life in closed ecological systems operating on Earth, (197) the required volume and weight to accomplish this feat would most likely negate its use in space. In addition, with the more recent findings of psychological stress of long term space flights, the superimposition of food products that do not offer much variety and leave much to be desired as to taste, makes this a long term and difficult problem to resolve. However, with the development of genetic engineering technology, it is within scientific probability that biological systems can be constructed that have the desirable characteristics needed for functioning in a closed ecological system.
Space greenhouses have been developed and sent into space in order to develop a partial life-support system. The Soviets have devoted significant research efforts to accomplish this task. A more detailed discussion on this subject will follow in the section dealing with the Kosmos biosatellite program.
NEGATIVE AND POSITIVE GRAVITATIONAL FORCES
BASIC CONCEPTS
From a physiological point of view, it is now well recognized that weightlessness is not merely the reduction or removal of weight on the body. Rather, zero gravity brings about a number of physiological responses to which man must adapt. The various symptoms that become evident after initial exposure to weightlessness have been discussed in some detail previously. Briefly they consist of body fluid, particularly blood redistribution to the upper part of the body, i.e., head and chest, accompanied by nasal congestion, facial puffiness and headaches. At times it is also associated with disorientation, space motion sickness, and loss of appetite. On the opposite scale, the cosmonaut is also subjected to gravitational forces substantially higher than those normally experienced on Earth. These times of elevated G forces occur primarily during liftoff and reentry.
The superimposition and possible synergistic effects of gravitational stress during reentry on the consequences of deconditioning of the cardiovascular, skeletal, muscular, hematological and immunological systems require additional investigation. Unfortunately, the conditions responsible for these physiological phenomena occurring in space are difficult to reproduce and evaluate on Earth.
SIMULATION OF POSITIVE AND NEGATIVE GRAVITY
In order to study the influence of the various gravitational gradiations that a cosmonaut encounters from the time of lift-off to his return to Earth, a variety of experimental protocols and equipment have been developed. These permit the reproduction of some of the physiological responses observed during positive and negative gravitational stress experienced during spaceflights. Bed rest, among other means, has been used to simulate zero gravity and the associated hypokinetic effects. Since it became evident that zero gravity causes such physiological phenomena as cardiovascular deconditioning, bone demineralization, muscle atrophy and shifts in fluid and electrolyte balance, both the United States and the Soviet Union have devoted considerable monies and expertise in duplicating these effects on Earth. Simulation of zero gravity on Earth can, in part, be accomplished by inducing both hypokinesis and hypodynamic conditions. Therefore, researchers have devoted significant time on mammals in evaluating the effect of immobilizing, restraining, denervating as well as other means of decreasing mobility and motor functions. These studies all have been done in order to simulate certain conditions encountered in space, due to zero gravity. Even though it is well recognized that these simulations do not parallel zero gravity, hypokinetic studies do produce physiological conditions somewhat similar to those encountered under actual weightlessness. A recent compendium of over 700 pages developed by NASA covers the literature encompassing these studies through 1980. This reference is included both to demonstrate the extraordinary amount of effort that has been devoted to this problem and to provide the reader with the opportunity to review and evaluate this major research area. (198)
As has been mentioned in the section dealing with selection and training of cosmonauts, water immersion, utilizing a simulator Salyut space station submerged in a large pool of water, is a routine Soviet training procedure. This technique, as well as bed rest, particularly with a head down tilt at between 4 and 12 degrees, is used by the Soviets to simulate weightlessness. (199)
Significant differences between these experimental ground based simulations and true weightlessness do exist. In particular the distribution of pulmonary blood, body fluids, gas volume and flow are still subject to gravitational influences during both bed rest and water immersion. One must also take into consideration some of the organ systems that are influenced by zero gravity. For example, the lung has very little supportive structure and the pulmonary vascular bed is very responsive to pressure differences. Therefore, they react to both the experimental condition on Earth as well as the gravity encountered in ground based experiments. Additionally, the differences in density of respiratory gases and blood make these highly susceptible both to direction and magnitude of flow.
Short intervals of a true weightless state can be achieved by flying an aircraft through a parabolic trajectory. Unfortunately, only certain sensory effects can be experienced during this maneuver, because the weightless state is obtained for rather short intervals (30 to 40 seconds). This therefore does not provide the time necessary to experience the myriad of physiological changes encountered during exposure to longer spans of zero gravity.
SIMULATION OF REENTRY GRAVITY
Even though both the Soviet Union and the United States have expended considerable research efforts in simulating zero gravity on Earth, none of these studies can replicate the conditions and body responses encountered at zero gravity. On the other hand, in the areas of positive gravitational forces, experimental conditions and protocols have significantly contributed to an understanding of the physiological responses obtained. By utilizing both high performance aircraft, human centrifuges and rapid deceleration equipment, massive amounts of data have accumulated on the response of man to gravitational forces greater than those normally experienced on Earth. (200) This information has led to the development of effective countermeasures. In addition, the development and application of such hardware as antigravity suits, harnesses and restraining devices all have been very helpful in preventing serious adverse physiological effects. This equipment has also considerably extended man's capacity to withstand high gravitational forces. Information gained from this research pointed toward means of positioning the body in reference to the gravitational force, so that it can tolerate even higher forces. It has been observed that the body can withstand transverse (front to back) gravitational forces much more readily than longitudinal forces (head to toe). (201)
Thus far, no adverse effects have been noted from the positive G forces encountered on reentry after long space missions.202 Nevertheless, there is the potential for adverse effects to the cardiovascular and the skeletal system. In the case of the skeletal system, this is because of the continued problems posed by bone demineralization. This process is not well understood, and up to this time no demineralization plateau has been reached. Demineralization seems to progress for the duration of the space flight. Potentially the skeletal system could become sufficiently weakened to suffer fractures when subjected to positive gravitational forces during reentry or when stressed immediately at touchdown. Similarly, the magnitude of deconditioning of the cardiovascular systems could pose a problem when this system is subjected to the stresses of excessive gravitational forces on reentry. (203)
The problems encountered by the human body when placed under a weightless state has spurred the interest of scientists in both the Soviet Union and the United States. Significant information has accumulated with regard to the effects of zero gravity on the wellbeing of man in space. The Soviet Union has conducted extensive biological experimentation in its Kosmos series as well as its manned orbital studies on these problems and the countermeasures necessary during the various transitional and adaptive states of weightlessness.
BIOCHEMICAL AND IMMUNE RESPONSES
In addition to the physiological responses already discussed, there are other responses during space flights that warrant mentioning. Among these are the observed reduction in red blood cells numbers and mass as well as reduction in hemoglobin. (204, 205) Reductions of up to 21 percent in red blood cell (R.B.C.) mass, 26 to 50 percent in red blood cell number from 12 to 33 percent of hemoglobin and a 4 to 16 percent in plasma volume have been noted. R.B.C. and hemoglobin mass were restored to normal preflight levels within 45 to 67 days after return to Earth. Changes in these parameters were not significantly different after long or short duration space Hights. The changes in R.B.C. and hemoglobin are most likely due to the increased oxygen tension and/or the decrease in oxygen requirement due to decreased muscular activity brought on by zero gravity. On returning to Earth, there is a rapid return to normal and even above normal (40 to 50 percent) R.B.C. In spite of the dramatic fluctuations observed in R.B.C. number during the course of the Soviet 175 day mission, R.B.C.'s synthesized while the cosmonauts were in space (R.B.C. turnover is approximately 120 days) functioned normally. (206)
The Soviets have also reported on changes in the cosmonauts immune system brought about by zero gravity, including a reduced lysozyme level. (207) Lysozyme is found in saliva and plasma and is thought to have bacteriocidal properties. The Soviets have reported an appreciable increase in both complement and immunglobulins. This suggests that some immunological reactions are occurring in space. The increase in globulin levels has been attributed to an elevation in autoantibody production against degradation products of skeletal muscle, due to atrophy of the latter. These observations could lead to serious consequences at a later time. Once the body recognizes its own tissue and produces antibodies against it, there is the possibility of a reoccurrence. Antibodies being produced could react against normal body tissue and lead to pathological conditions. An example of this is found in Lupus erythematosis, a disease of unknown etiology, but due to autoantibody production (208, 209, 210)
The number of circulating leucocytes has been reported to be depressed during some missions and not changed during others. However, as previously mentioned under the section of biomedical findings, lymphocyte function has routinely been observed to be significantly depressed. (211) Even though the abnormalities observed all seem to return to normal preflight levels, the possible consequence to the cosmonauts and astronauts in later years are yet to be determined.
BASIC HUMAN'S ANIMAL PHYSIOLOGY
A summary of the various human and animal physiological responses experienced at zero gravity is presented in. (212)
Even though this table was compiled in 1975, the major difficulties detailed at that time still plague space crews today.
MOTION SICKNESS—THEORY AND RESEARCH
The environment of outer space and the absence of gravity have caused numerous adverse biomedical effects. It is important to point out, though, that none of the biological encountered abnormalities have required aborting any space mission.
Nevertheless, space motion sickness (SMS) has been and still is one of the adverse effects that seems to be both transitory and highly arbitrary in whom it affects. It has significantly impaired the effectiveness of some cosmonauts, principally during the early portion of a space flight. Approximately 50 percent of the cosmonauts and astronauts succumb to SMS to one degree or another. These manifestations have ranged from mild nausea to severe nausea and vomiting. (213) The Soviets were the first to report vestibular disturbances in the flight of Vostok 2. Subsequent to this, both American astronauts and Soviet cosmonauts have reported various degrees of SMS, accompanied by gastric discomfort, spatial illusions, yawning, drowsiness and a general indifference toward accomplishing physical or mental tasks.
The genesis of terrestrial motion sickness and its space counterpart are not well understood. The sequence of events leading to the severe symptoms of motion sickness are most likely initiated by a series of physiological and perhaps psychological signals. (214, 2l5) The lack of a precise understanding of motion sickness precludes a means of preselecting more tolerant individuals. (216) For the same reason, the use of antimotion sickness drugs has not been totally satisfactory both due to erratic results obtained and also because of the side effects that are at times produced by these drugs.
After 2 to 5 days in space, most individuals become resistant to further episodes of SMS. However, during some Salyut 6 missions the Soviets have reported that some members of the crew experienced symptoms of SMS during head and torso movements, for up to 130 days.217 In fact upon return to Earth, some cosmonauts experience recurrent symptoms during head and body movements as well as when going from a horizontal to a vertical position. (218) The fact that SMS seems to be manifested during the first few days of a mission could be a particular problem during early stages of brief space missions.
As has been mentioned previously, the cause of SMS is not well understood; however, it is recognized that certain types of motion can precipitate it. At times it can even be brought about by eye perception of a particular motion. In space, though, sickness is brought about by rather gentle movements of the head and body, those that would not initiate the symptoms on Earth.
Based on these observations, one can deduce that SMS may be partially associated with zero gravity. However, studies conducted both by Soviet and American scientists suggest that head and/or body movement is a required associated factor. (219, 220)
Several theories exist as to causative and associated SMS factors. Individuals that are deaf do not get motion sickness on Earth. This suggests that the existence of a functional vestibular apparatus is necessary. This functional organ may then also be stimulated by other sensory inputs, including changes in partial pressures and effects of zero gravity. Some experts have concluded that there may be confusion in sensory signal inputs or overstimulation, resulting in multiple messages from the center of equilibrium to centers that generate feelings of motion sickness. (221) However, other theories still persist including the idea that there is a mismatch between information being received and that which is stored from prior experience. (222) It has also been suggested that there may be an overstimulation of the vestibular organ due to exposure to vigorous motion. (223) Another hypothesis suggests that labryinthine fluid imbalance could be due to fluid shift toward the head as a consequence of zero gravity. (224) Other experts believe that SMS results from an amnestic response to previous life-threatening situations which effect the vestibular organ. (225) The Soviets, a number of years ago, developed the Voyachek-Khilov Tossing Theory. (226) This theory encompasses eight basic principles.
The first principle states that motion sickness can develop in any person under numerous situations. Second, motion sickness is a reflex of numerous body sensors, including the vestibular, visual and tissue sensors, all playing their part. The third principle states that the essential role in motion sickness is played by conditional reactions. The fourth states that the tossing sensation develops as a result of the summation of normal adjustment reactions coming from sensors that are analyzing the situation. The fifth principle is related to the fact that the feeling of tossing about arises when the body changes vertical location in space. The sixth principle suggests that one must be aware of the status of the nervous system. The seventh principle delineates those conditions in the environment that favor the development of motion sickness, as for example high temperatures and certain odors. The eighth principle states that man can adapt to mechanical as well as other factors that lead to motion sickness. This theory has led the Soviets to firmly believe that effective training of the individual cosmonaut can reduce or prevent SMS. (227) They believe that the basic reasons for SMS are due to the action of mechanical forces acting upon the body and repeatedly communicating small but multidirectional accelerating forces. This results in the body simultaneously moving through space in multiple directions. (228)
Associated with the primary causes are situations that aggravate the condition such as optokinetic stimuli on visual analyzers, and multiple barometric pressure changes similar to those experienced in transition to zero gravity. (229) Contributing to this are such factors as high temperatures, lower partial oxyen pressure, gas fumes, and noxious chemical fumes. Psychological factors stemming from overwork, chronic fatigue, emotional stress and boredom all contribute to the development of SMS. (230)
A factor that may eventually increase the SMS problems is the reported desire by the Soviets to produce artificial gravity in their space station. (231) In order to accomplish this, particularly for long term space platform operations, the Soviets are considering the application of centrifugal forces (rotation). Not only would gravitational forces differ at different radiae from the center of the platform, thereby requiring continual physiological adaption, but continued rotation may exacerbate SMS.
PREVENTIVE APPROACHES
Both the Soviet Union and the United States have conducted Earthbound and in orbit studies to determine the efficacy of both pharmacological as well as body conditioning protocols to control SMS. Even though ground-based studies have suggested that individuals can develop a tolerance to conditions that lead to motion sickness, adaptive training, according to U.S. specialists thus far has not worked well in actual space flight. (232)
Among the approaches that have been considered to prevent or reduce SMS are the use of prophylactic and/or therapeutic medication. This medication consists primarily of central anticholinergic acting drugs that augment central sympathetic activity. (233) In addition to training and medication, consideration has also been given for the preselection of resistant individuals as well as providing biofeedback training and physically restricting head and body movement. (234, 235)
The application of physical devices such as pneumatic thigh cuffs, lower body negative pressure as well as special headgear to restrict head movement have all been reported by the Soviets to be beneficial. The headgear, in particular, reportedly reduced space motion sickness. (236)
NOISE AND VIBRATION
Physical as well as biological consequences have been reported from exposure of man as well as animals to noise and vibration. In the presence of high-frequency noise levels (74 to 76 dB), for extended time periods, man feels poorly. However, the absence of any noise is just as psychologically and physiologically detrimental. (237)
Aboard a spacecraft the primary sources of noise are the electrical motors and equipment, ventilators and equipment that provide orientation. During liftoff, the space traveller is subjected to intensive, painful exposures of noise levels up to 145 dB. (238)
It has been suggested that noise levels need to be modulated by using low-noise motors, electrical commutators and sound absorbency material. Soviet scientists have concluded that work and rest areas should have noise levels that are not the same and that the rest area must have a noise level not to exceed 40 dB. Moreover, it has been determined that a background noise level in general of from 60 to 65 dB is not detrimental to the cosmonaut. (239)
Technical data suggests that high intensity noise can not only cause an alteration in nerve cells that perceive sound, but also can influence the functional and psychological state of the central nervous system. This can lead to a reduction to the capacity to perceive constantly changing conditions of the external environment and bring about such manifestations as irritability and fatigue. This may, in extreme conditions, lead to death. (240) In the opinion of some researchers, noise may bring about premature aging. (241) Infrasound (sound not captured by the human ear), such as certain frequencies caused by ventilators, compressors, and diesel and jet engines, nevertheless can be very stressful causing depression, decreased reaction capacity, and nausea. (242)
SYNERGISTIC EFFECTS
The synergistic imposition of noise, isolation, hypodynamia, biorhythm changes and the general consequences of weightlessness, all impinge on sensory mechanisms. In order to modify such adverse environmental factors encountered during space flight, the Soviets have been experimenting with the concept of noise modification using selected music, particularly during rest periods. They have also adapted the music to the taste and habits of the individual crew. The use of music not only modulates noise levels aboard the spacecraft but it also has been recognized that music may have exceptionally strong influence on man's emotional state. By using music abroad the spaceship they are attempting to enhance the cosmonauts capacity of work. (243) To stimulate the capability to work effectively, music is selected to bring about the appropriate mood. Certain music may stimulate certain activities while other renditions may distract attention from performing certain tasks. (244)
As certain activities increase in complexity, music may in fact become bothersome. During the performance of certain very complex tasks, the operator may be so absorbed in his work, he may stop paying attention both to the music and to the background noise. Therefore, the selection of music during the cosmonaut's work period requires consideration of the type of work being performed, the psychlogical state of the cosmonaut, and the individual responsiveness and perception of the music in question. The Soviets are also experimenting with music and color changes to regulate mood. (245)
As the duration of space missions increase, noise modification and mood enhancement may become even more significant factors in the development of a compatible space cabin environment.
Although vibration particularly during liftoff and reentry are of some concern, it does not seem to be a significant problem.
PROBLEMS OF RADIATION IN SPACE
IONIZING SPACE RADIATION
The amount of radiation encountered while on a space mission is dependent on numerous factors, including the length of the mission and the trajectory of the flight. When evaluating radiation hazards to the crew, consideration also needs to be given to the composition of its members, including their age and sex. Protection needs to be provided against both permanent and nonpermanent sources of radiation. The former consists of galactic cosmic radiation and the Van Alien radiation belts surrounding the Earth. The Van Alien belts consist of geomagnetically trapped radiation, while galactic cosmic radiation is composed of extremely high energy and variable charged composition particles. (246) The nonpermanent sources of radiation eminate primarily from solar radiation. Solar radiation comes from eruptions occuring on the surface of the Sun. The intensity of these episodes go through 11-year cycles and can pose serious radiation hazards to man if he is beyond the altitude of 200 to 800 km. (247)
To date, the radiation exposure of both the Soviet cosmonauts and U.S. astronauts have been very low because the flights have been of relatively short duration, the trajectories have been carefully planned and the missions have not encountered serious unscheduled solar activity. As the space flights increase in duration and in distance from Earth, the risk of higher exposure levels is appreciably enhanced. Therefore, it becomes important to develop means of protecting the crew against hazardous radiation exposure.
PREVENTION OF RADIATION SICKNESS
Various methods of providing such protection have been suggested and explored. These include:
1. The use of physical barriers, by either increasing the thickness of spacecraft covering or by crew compartment shielding;
2. Physical protection of the most radiation sensitive body organs;
3. Pharmocological protection; and
4. Active protection by means of magnetic or electrical deflection or capture. (248)
Most of these methods of protection are fraught with difficulties. The use of additional shielding has two major shortcomings. As the thickness of the shield is increased to specific limits, space radiation itself causes secondary radiation emission from the shield. In addition, the added weight reduces the effective payload capacity of the spacecraft. Protection of the most radiation sensitive organs such as the hematopoietic system, gastrointestinal tract, gonads and the eye lenses have some merit. However, it is technically difficult to protect all these organs in the absence of developing a protective suit, but anything less would not deal with low-level exposure and the unknown consequences of long-term delayed radiation effects.
Pharmacologic protection has been under extensive investigation for many years. Even though radiation protective compounds have been developed and tested on experimental animals and man, none are without side effects, including potential additive adverse effects due to the space environment and possible long-term adverse harm posed by such drugs. The most promising protection may be that provided by active protection with an electrical field surrounding the spaceship. Active protections consist of creating and maintaining a strong electrical field around the spacecraft resulting in a deflection of radiation particles away from the space cabin. (249) These techniques are in their infancy.
Though experts have developed recommended maximum permissible exposure levels for different lengths of space flights, there is no unanimity in the scientific community either as to the maximum nor minimum levels of radiation exposure that are safe. When considering long-term, low-level adverse effects, such data have been difficult to develop. Current U.S. career exposure limits for astronauts are set at 400 rems. This level is calculated to increase the cancer risk by 2.3 percent. This is equivalent to doubling the cancer mortality rate of the 35 to 55 year age group. (250) However, in experimental animals there does not seem to be a level below which some form of damage, primarily genetic, is not observed. (251)
BlO-MEDICAL EFFECTS OF IONIZING SPACE RADIATION
The primary objective of radiobiological research in space is the development of data which will permit an accurate definition of safety. It is doubtful, however, that research conducted and data obtained in space will significantly differ from data that can be generated on Earth. The biological effects of space radiation with the possible exception of heavy particles such as argon and iron and some other cosmic particles does not differ from the effects that are observed on Earth. Nevertheless, the Soviet Union supports a significant amount of space radiation research. An obvious concern is the possible interaction, either additive or synergistic, of the various interacting factors encountered in the space environment. Recent synergistic effects of ionizing radiation and heat have been reported, as have antagonistic effects of hypoxia and radiation. The former observation in particular is receiving close scrutiny as a possible regime for cancer treatment. (252)
Appreciable information has accumulated over the years on the clinical consequences of whole-body, acute radiation effects. This data is summarized in table 22. (253)
TABLE 22.—Expected short-term effects from acute, whole-body radiation
Dose in Rads Probable effect
10 to 50................... No obvious effect, except, probably, minor blood changes.
50 to 100................. Vomiting and nausea for about 1 day in 5%-10% of exposed
personnel. Fatigue, but no serious disability. Transient reduction in lymphocytes and neutrophils.
100 to 200............... Vomiting and nausea for about 1 day, followed by other symptoms of radiation sickness in about 25%-50% of personnel. No deaths anticipated. A reduction of approximately 50% in lymphocytes and neutrophils will occur.
200 to 350............... Vomiting and nausea in nearly all personnel on first day, followed by other symptoms of radiation sickness, e.g., loss of petite, diarrhea, minor hemorrhage. About 20% deaths within 2-6 weeks after exposure; survivors convalescent for about 8 months, although many have second wave of symptoms at about 8 weeks. Up to 75% reduction in all circulating blood elements.
350 to 550............... Vomiting and nausea in most personnel on first day, followed by other symptoms of radiation sickness, e.g., fever, hemorrhage, diarrhea, emaciation. About 50% deaths within 1 month;
survivors convalescent for about 6 months.
550 to 750............... Vomiting and nausea, or at least nausea, in all personnel within 4 hours from exposure, followed by severe symptoms of radiation sickness, as above. Up to 100% deaths; few survivors convalescent for about 6 months.
1000......................... Vomiting and nausea in all personnel within 1-2 hours. All dead within days.
5000......................... Incapacitation almost immediately (minutes to hours). All personnel will be fatalities within 1 week.
Source: (Langham, 1967) as cited in The Bioastronautics Data Book, 1974.
Unfortunately, low-level radiation effects below 10 rads, as well as delayed effects of low-level radiation, are still not well understood, but are under active study. Data thus far obtained, using the mouse as a model, and compared with data derived from human studies, has demonstrated a close correlation in biological response between man and mouse. (254)
Observations by the U.S. Apollo 11 astronauts of flashes of light in their darkened cabin, accelerated studies by both the United States and the Soviets, on this form of radiation. The initial observations by the Apollo crew were apparently due to the penetration of the space cabin and the eyes of the crew of high energy and heavy cosmic rays. These rays impart their energy on the retina of the eye, accounting for the observed illumination.
The galactic cosmic radiation HZE particles [HZE—(H= high-; Z= atomic number greater than 2; E= energetic)] have energies sufficiently high to be able to penetrate at least 1mm of spacecraft or spacesuit shielding. (255) Earlier studies had suggested possible biological damage due to HZE, when black mice that were exposed to space radiation showed localized graying of their fur. (256)
Subsequent dosimetry studies performed during the Apollo-Soyuz Test Project (257) as well as on Apollo 16 and 17, demonstrated that serious biological damage can be caused by the interaction of the HZE particles with biological matter. These studies demonstrated neurological damage to the brain of pocket mice (258) and tissue damage to several biological specimens (shrimp, maize, B. subtilis spores). (259) Analysis of these results indicated that the damage directly correlated with the area on the tissue through which the HZE particles passed. Similar results have been obtained by the application of heavy ions generated from accelerator experiments on Earth (260. 261)
The potential hazard posed by the HZE to humans in space is still an open question. However, it is known that man is much more sensitive to radiation damage than the biological materials that have been studied thus far. (262) Of major concern is the damage that may be caused to nonregenerating tissue, such as the central nervous system and the eye lens. Additionally, sublethal damage to cells could manifest itself in several delayed, pathological events, such as leukemia, solid tumors, cataracts and decreased fertility Once more, the possible synergistic interaction of radiological processes with other space flight factors needs to be more fully explored.
NONIONIZING RADIATION
The Soviet Union and several Eastern European countries have devoted extensive research efforts toward the demonstration of biological effects produced by nonionizing radiation. In particular electromagnetic radiation at energy levels encountered in house current are being studied. Both epidemiological and experimental data generated by the Soviet Union and the United States, as well as other countries, point to possible adverse biological effects due to these types of radiation.
In addition to the previously mentioned Soviet Union's interest in developing fields (electrostatic and magnetic) to protect space crews from solar radiation, they are also very interested in studying the effects of electromagnetic radiation on a variety of biological systems. (263, 264)
It should be pointed out that space travel by its very pioneering nature entails some degree of risk. Apparently, this risk is willingly accepted by those individuals who volunteer for space missions. In light of this acceptance, the minimal additional acute risks posed by radiation, particularly nonionizing radiation, may not be a significant deterent factor, particularly when considering the more apparent physiological risks undertaken by space travelers.
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