Prolonged Weightlessness Research Articles

8 Locomotor problems of supersonic aviation and astronautics

Modern high-speed aviation and space flight are fraught with many problems and require a high standard of health and fitness. Those responsible for the health of pilots must appreciate the importance of early diagnosis even before symptoms appear. This is particularly true in terms of preventing spinal injuries where even a single Schmorl's node may make a pilot unfit for high-speed flying. Spinal fractures are frequent during emergency ejection and landing. Helicopter crews are particularly prone to spinal disc degeneration due to vibration. By effective lowering of vibration by changes in the seats, a reduction in such lesions is possible. The osteoporosis and muscle atrophy occurring among astronauts subjected to prolonged weightlessness can be prevented by regular physical exercises.

Man in space.

The Challenger disaster focused attention on the hazards as well as the possibilities of man in space. The physiological effects of prolonged weightlessness include important changes in vestibular, bone, muscle, cardiovascular, blood, renal, and pulmonary function. Much has been learned from US and Soviet experiments, but large areas of ignorance remain. Exceptional opportunities for physiological research are provided by Spacelab, a pressurized laboratory planned as a payload of the Space Shuttle.

M.I.T./Canadian vestibular experiments on the Spacelab-1 mission: 3. Effects of prolonged weightlessness on a human otolith-spinal reflex.

Reflex responses that depend on human otolith organ sensitivity were measured before, during and after a 10 day space flight. Otolith-spinal reflexes were elicited by means of sudden, unexpected falls. In weightlessness, "falls" were achieved using elastic cords running from a torso harness to the floor. Electromyographic (EMG) activity was recorded from gastrocnemius-soleus. The EMG response occurring in the first 100-120 ms of a fall, considered to be predominantly otolith-spinal in origin, decreased in amplitude immediately upon entering weightlessness, and continued to decline throughout the flight, especially during the first two mission days. The response returned to normal before the first post-flight testing session. The results suggest that information coming from the otolith organs is gradually ignored by the nervous system during prolonged space flight, although the possibility that otolith-spinal reflexes are decreased independent of other otolith output pathways cannot be ruled out.

Prolonged weightlessness and humoral immunity.

Preflight, inflight, and postflight serum samples obtained from crewmen aboard STS-9 were analyzed for immunoglobulin content. Control studies for circadian rhythm were conducted to further validate the analyses. Quantitation of immunoglobulins G, M, A, D, and E indicated relatively minor fluctuations in the concentration of each class of immunoglobulin during the experiment. Thus, microgravity effects on immunoglobulin levels during a 10-day flight were considered insignificant.

Mass discrimination during prolonged weightlessness.

Thresholds for mass discrimination under zero gravity in flight were found to be higher by a factor of about 1.8 than those for weight discrimination before flight. This suggests that humans are not as sensitive to inertial mass as they are to weight, and that adaptation can only partially compensate for loss of gravity. Weight discrimination thresholds were raised for 2 or 3 days after flight, suggesting an aftereffect of adaptation to weightlessness.

Earthbound female `astronauts' aid the men who go aloft

They weren't kidding when they called it<i>man</i>ned space flight. Only two women, both Russians, have flown in space in the nearly 22 years since the first human launching. Still, at the National Aeronautics and Space Administration's (NASA) Ames Research Center near San Francisco, women have been consistent volunteers for space-related medical studies that can be conducted without flight. These studies, particularly of the effects of prolonged weightlessness and how this may affect astronauts upon reentering earth's gravity, have been going on since the 1960s (<i>JAMA</i>[MEDICAL NEWS] 1981;245:1638; 1980;244:754). The last in the current series will be conducted in the fall of 1983 with eight women volunteers. The most recent study was completed last November. Eight women aged 30 to 45 years were tested in a simulated weightless environment that involved lying seven straight days in bed with their heads lowered 6° They below their feet. Such a position

NASA research fosters rehabilitative device

More than two years ago, a National Aeronautics and Space Administration (NASA) physician arranged for some Philadelphia researchers visiting NASA's Ames Research Center, Moffett Field, Calif, to see some of the minimum-friction devices used to simulate satellite motion, spacecraft acceleration, and prolonged weightlessness. Out of that visit has come a device that may help some brain-injured children and adults learn or relearn how to crawl. The visitors, from the independent, private Institutes for the Achievement of Human Potential, talked that day with Hubert C. (Vic) Vykukal, BSME, a NASA research scientist. From this and subsequent conversations evolved the vehicle for initial crawling, so named because its acronym is the same as its developer's nickname—VIC. The crawling-assistance device is being evaluated for possible roles in rehabilitation efforts. Fifty such devices have been built for the Philadelphia facility by a contractor at a cost of $110 apiece. Essentially, the device consists of

Biomedical aspects of artificial gravity

Artificial gravity generated by spacecraft rotation may prove a universal countermeasure against adverse effects of weightlessness in the future. The paper summarizes the results of ground-based biomedical, investigations of artificial gravity and flight experiments aboard Soviet biosatellites Cosmos-782 and Cosmos-936. It is believed that at the present stage the major goal of such investigations is to determine the minimum efficient value of artificial gravity in long-term flights which may eliminate adverse effects of prolonged weightlessness. In ground-bound studies the highest priority should be given to the development of methods on increasing human tolerance to the rotating environment.

Effect of weightlessness on sympathetic-adrenomedullary activity of rats

Three cosmic experiments were performed in which rats spent 18–20 days in space on board the biosatellites “COSMOS 782”, “COSMOS 936” and “COSMOS 1129”. The following indicators of the sympathetic-adrenomedullary system (SAS) activity were measured: tissue and plasma catecholamines (CA), CA-synthesizing enzymes—tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH), phenylethanolamine-N-methyltransferase (PNMT)—as well as CA-degrading enzymes—monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). Adrenal epinephrine (EPI) and norepinephrine (NE) as well as CA-synthesizing and degrading enzymes were not significantly changed in the animals after flight on COSMOS 782. On the other hand, a significant increase was found in heart CA, the indicator which is usually decreased after stress. 26 days after landing all values were at control levels. The results obtained, compared to our previous stress experiments on Earth, suggest that prolonged weightlessness does not appear to be a pronounced stressful stimulus for the SAS. Heart and plasma CA, mainly NE, were increased both in the group living in the state of weightlessness and the group living in a centrifuge and exposed to artificial gravitation 1 g (COSMOS 936), suggesting again that prolonged weightlessness is not an intensive stressful stimulus for the SAS. The animals exposed after space flight on COSMOS 1129 to repeated immobilization stress on Earth showed a significant decrease of adrenal EPI and an expressive increase of adrenal TH activity compared to stressed animals which were not in space. Thus, the results corroborate that prolonged state of weightlessness during space flight though not representing by itself an intensive stressful stimulus for the sympathetic-adrenomedullary system, was found to potentiate the response of “cosmic rats” to stress exposure after return to Earth.

Study of physiological effects of weightlessness and artificial gravity in the flight of the biosatellite Cosmos-936

In the 18.5-day flight of the Soviet biosatellite Cosmos-936 (3–22, August 1977) comparative investigations of the physiological effects of prolonged weightlessness (20 rats) and artificial gravity of 1 g (10 rats) were carried out. Throughout the flight artificial gravity was generated by means of animal rotation in two centrifuges with a radius of 320 mm. Postflight examination of animals and treatment of the flight data were performed by Soviet scientists in collaboration with the specialists from Bulgaria, Czechoslovakia, the German Democratic Republic, Hungary, Poland, Rumania, France and the U.S.A. During the flight the total motor activity of the weightless rats was higher and their body temperature was lower than those of the centrifuged animals. Postflight examination of the weightless rats showed a greater percentage of errors during maze tests; an increase in water intake and a decrease in diuresis; a fall of the resistance of peripheral red blood cells; an increase in the conditionally pathogenic microflora in the mouth; a decrease of oxygen consumption, carbon dioxide production and energy expenditures; a drop in the static physical endurance; a decline in the capacity to keep balance on the rail; an increase in the latent period of the lifting reflex, etc. The centrifugal animals displayed lesser or no change of the above type. These findings together with the biochemical and morphological data give evidence that during and after flight adaptive processes in the centrifuged rats developed better.

Prolonged weightlessness and calcium loss in man

Data have been accumulated from a series of studies in which men have been subjected to weightlessness in orbital space flight for periods of up to 12 weeks. These data are used to predict the long term consequences of weightlessness upon the skeletal system. Space flight induced a loss of calcium which accelerated exponentially from about 50 mg/d at the end of 1 week to approx. 300 mg/d at the end of 12 weeks. The hypercalciuria reached a constant level within 4 weeks while fecal calcium losses continued to increase throughout the period of exposure. This apparent diminution of gastrointestinal absorptive efficiency was accompanied by a slight decline in the plasma level of parathyroid hormone and a slight elevation in the plasma level of calcium and phosphorus. Although losses in mineral from the calcaneus were closely correlated with the calcium imbalance, no changes were detected in the mineral mass of the ulna and radius. From the data presented it is concluded that the process of demineralization observed in space flight is more severe than would be predicted on the basis of observations in immobilized, bed rested, or paralyzed subjects. It is, moreover, suggested that the process may not be totally reversible.

Prolonged weightlessness.

Prolonged weightlessness.

Prolonged weightlessness.

Prolonged weightlessness.

Prolonged weightlessness.

Prolonged weightlessness.

UNDERWATER PRESSURE-COMPENSATED BREATHING CONTROL VALVES FOR PROLONGED WATER IMMERSION. AMRL-TR-64-130.

Abstract : Two water-pressure-compensated breathing devices for prolonged immersion have been designed, fabricated, and tested underwater. One valve is a continuous-flow regulator and the other is a demand regulator. Both valves allow exhalation through a hose directly into the surface atmosphere for air analysis. One of the two valves has been used extensively during prolonged weightlessness simulation tests by immersion.

Biologistics for a manned space station based on the metabolic approach

Specification of biologistics for future space stations will require accurate and standardized sets of environmental specifications, nutritional data, and metabolic calculations, which must take into account the effects of prolonged weightlessness (or hypogravity in the case of a rotating space station). It is proposed that the catabolic effects of weightlessness on the musculoskeletal system, and indirectly on the cardiovascular system, should be related to the daily work output of the body. By controlled diets and exercises, astronauts could be titrated to their normal earth (or other prescribed) metabolic rates. (This hypothesis is, of course, subject to verification in space.) A coincident, desirable result of this metabolic approach is that biologistics for all types of spacecraft and space stations can be calculated (or, better, experimentally determined) in standard units per man-day without regard to the metabolic effects of variable gravity. A table of biological specifications is developed and then applied, with associated engineering constraints and tradeoffs on requirements for power supply, heat rejection, and integration of the power system with the life-support system, to describe optimum life-support requirements for 30to 100-day missions.

Prolonged Weightlessness

Prolonged Weightlessness

Prolonged Weightlessness

Prolonged Weightlessness

Medical and Biological Problems of Space Flight: Proceedings of a Conference Held in Nassau, the Bahamas, November, 1961.

ABSTRACT To workers in the field this book will probably tell little that is new, but for the casual reader it is a fascinating collection. Although occasionally quite technical, it vividly conveys the complexity of space flights with their medical relationships, allowing the reader to share in the excitement of the venture.At first this book appears to be a collection of random papers given at a somewhat disorganized symposium. It contains serious scientific work ranging from a device for simulating weightlessness, through maintenance of cardiovascular adaptability during prolonged weightlessness, cosmic ray effects, water recovery systems, to the food use of the alga Chlorella. Also included are interesting articles on the history and development of space vehicles, remote monitoring of medical data, and the possible problems of manned space flight. Apparent throughout is the authors' commitment to this great adventure of our times, and the historical awareness of its import.Creating

PHYSIOLOGIC ASPECTS OF PROLONGED WEIGHTLESSNESS. BODY-FLUID DISTRIBUTION AND THE CARDIOVASCULAR SYSTEM.

JUST as we are accustomed to think of the physiology of exercise, we should be thinking too about the pathology of inactivity and disuse.1 For as long as man has contemplated space flight his imag...