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PubMed1994

Needs of physiological and psychological research using artificial gravity.

In the next century, mankind will expand its activity to the moon and Mars. At that time, humans will be exposed to a low and micro-gravity environment in long term which causes physiological and psychological problems. The authors propose an artificial gravity space station for a research laboratory on human physiology and psychology at various gravity levels. The baseline specifications and the configuration of the space station are shown. Reviewing the history of manned space flight, the necessity of the research on an artificial gravity space station is discussed, including themes of research to be conducted on the station and the application of its results. Technical issues for realization of the space station such as environmental factors, system function and assembly scenario are also discussed.

Aerospace Medicine↗

PubMed1994

Human cardiovascular and vestibular responses in long minutes and low +Gz loading by short arm centrifuge.

1.4 G, 1.7 G, and 2.0 G of +Gz and 60 minutes centrifugation was adopted to 20 healthy male subjects using 1.8 m radius centrifuge equipped to Nihon University School of Medicine. G was applied from lower G, considering G training effect for the subjects. Effects on performance decline and side effects of such a short-arm centrifugation were especially observed in the experiments, because this size of centrifuge could be used in space station in future for a strong countermeasure of cardiovascular deconditioning, demineralization from bone, etc. G training effect was observed same as higher and rapid G acceleration in fighter pilot. Subjects suffered from many types of discomfort; such as sensation of heaviness of diaphragm, cold sweat, nausea, irritable feeling, arrhythmia, tachycardia, rapid decrease of blood pressure, which sometimes caused interruption of G load. As 2.0 G and 60 minutes centrifugation seemed very tough load to the subjects, there should be necessary some G suit or other countermeasure, if we apply a higher G and/or longer G duration. Performance decline due to the load commonly continued for 1 hour or so. Side effects were observed in relation to neuro-vestibular, cardio-vascular, and autonomic nervous system.

Adult↗

PubMed1994

Artificial G-load and chemical changes of saliva.

Effectiveness of artificial G load is expected when it is used as a countermeasure against various bio-medical mishaps which are taking place in the micro-gravity environment, and probably more importantly, to prepare re-entry to the earth 1-G environment. Regarding the salivary chemical analysis, it has been known that, in case of (experimental) motion sickness, symptomatic outputs are delivered through the autonomic nervous system, and changes in salivary chemical components occur. In this study, accordingly, quantitative analyses of salivary potassium, sodium, chloride and total protein were performed before and after various levels of G loads which were produced by our short-radius human centrifuge. When the results were compared, the subjects who failed 60 minutes ride exhibited significantly higher post-load levels of potassium and sodium than those of successful 60 minutes riders. However, the differences between two groups were less clear in chloride and total protein. The result of present study indicates that salivary potassium and sodium are good indicators to represent autonomic nervous system function under the stressful condition produced by an artificial G load.

Adult↗

PubMed1994

Systems integration in space flight environmental risk management.

This paper reviews the issues that must be addressed to define and integrate technologies, countermeasures, and medical care systems into space systems which will be developed for long duration space flight. This paper considers combined and cumulative effects, the broad range of space environmental health issues, including some examples, and a discussion of a management approach to these risks. While the primary emphasis is on space environmental health issues, other aspects of the space environment are also considered. Allocation of finite resources for optimal risk management is also considered.

Aerospace Medicine↗

PubMedDate not supplied

Comparison of gradual and rapid onset runs in a short-arm centrifugation.

A gradual onset run (GOR) in a short-arm centrifugation was performed on ten healthy students. The centrifuge had a 1.8 m radius, and the subjects sat on a chair in a cabin. The Gz force increased to 2.2 Gz at 0.1 degree/sec2 for 32 min. and the same Gz-level was maintained for 20 min. Three out of ten subjects completed the whole protocol; the load on the others was terminated because of symptoms or increased heart rate. There were few symptoms such as vertigo, that was a common problem with a rapid onset run (ROR) in former experiments, due to the short-arm centrifugation. The changes of the flicker test after the load were much less in the GOR protocol than in the ROR protocol, even in the terminated group. GOR seemed preferable to ROR in preventing vertigo even though it took longer to reach the necessary G load.

Acceleration↗

PubMedDate not supplied

Artificial gravity.

Explore the source record for details and available documents.

Animals↗

PubMed1981

The effect of artificial gravity on plasma and tissue lipids in rats: the Cosmos 936 experiment.

Plasma and tissue lipids in male SPF Wistar rats flown for 18.5 days aboard the Cosmos 936 biosatellite were analyzed. One group of rats was subjected to artificial gravity by use of a centrifuge during the flight. An experiment simulating known space flight factors other than weightlessness was done on Earth. An increase of total cholesterol in plasma, of nonesterified fatty acids in plasma and brown adipose tissue, of triacylglycerols in plasma, liver, thymus and bone marrow was noted several hours after biosatellite landing. Smaller changes were observed in the terrestrial control experiment. With the exception of triacylglycerol accumulation in bone marrow, these increases disappeared 25 days after biosatellite landing. Exposing the rats aboard the biosatellite to artificial gravity was beneficial in the sense that such exposure inhibited the phospholipid and triacylglycerol increase in plasma and inhibited the increase of triacylglycerol in liver and especially in bone marrow.

Adipose Tissue, Brown↗

PubMed1981

Changes of deoxyribonucleoprotein in the spleen, thymus and liver of rats exposed to weightlessness and artificial gravity aboard the Cosmos biosatellites.

Changes of deoxyribonucleoprotein in the spleen, thymus and liver of rats exposed to weightlessness or artificial gravity on board biosatellites Cosmos 782 and Cosmos 936 after 20 days of flight were investigated. The level of polydeoxyribonucleotides in the spleen and thymus of rats exposed during the flight to weightlessness increased 4-11 hours after landing, suggesting breakdown of a part of the deoxyribonucleoprotein present. The use of artificial gravity prevented this breakdown in the thymus but not in the spleen. The breakdown was accompanied in the majority of cases by a decrease in the deoxyribonucleoprotein content. We believe the breakdown of deoxyribonucleoprotein is due to a nonspecific stress reaction to the change from the weightless state to that of terrestrial gravity during landing. The polydeoxyribonucleotide level and amount of deoxyribonucleoprotein in the majority of cases returned to normal values during the 25 days of readaptation. No substantial change of deoxyribonucleoprotein was found in the liver. The different findings in the three organs are due to the fact that breakdown of deoxyribonucleoprotein takes place in sensitive cells underlying pycnosis. These cells are found in the spleen and thymus, but not in the liver.

Animals↗

PubMed1986

Effects of gravity perturbation on developing animal systems.

Developing systems provide unique opportunities for analyzing the effects of microgravity on animals. Several unusual types of cells as well as various extraordinary cellular behavior patterns characterize the embryos of most animals. Those features have been exploited as test systems for space flight. The data from previous experiments are reviewed, and considerations for the design of future experiments are presented.

Animals↗

PubMed1989

Gas bubble coalescence in reduced gravity conditions.

The effects of low gravity, as produced by a reduced gravity aircraft, the KC135, on the formation and coalescence of gas bubbles were examined over a range of gas-liquid ratios and with various medium constituents. These effects will influence design considerations of fermentors operating in reduced gravity conditions.

Acceleration↗

PubMed1992

Possible mechanism of microgravity impact on Carausius morosus ontogenesis.

Experiments aboard "Spacelab-D1" and "Cosmos-1887" revealed an adverse effect of space flight on Carausius morosus embryos. The main influencing factor for stick insect eggs turned out to be microgravity, while the contribution of HZE particles of cosmic radiation was relatively low. Flight experiments indicated an increased vulnerability of stick insect eggs to microgravity at intermediate stages of development, that could support the "convection" hypothesis.

Animals↗

PubMed1992

Long-term effects of microgravity and possible countermeasures.

It is well known that long-term exposure to microgravity causes a number of physiological and biochemical changes in humans; among the most significant are: 1) negative calcium balance resulting in the loss of bone; 2) atrophy of antigravity muscles; 3) fluid shifts and decreased plasma volume; and 4) cardiovascular deconditioning that leads to orthostatic intolerance. It is estimated that a mission to Mars may require up to 300 days in a microgravity environment; in the case of an aborted mission, the astronauts may have to remain in reduced gravity for up to three years. Although the Soviet Union has shown that exercise countermeasures appear to be adequate for exposures of up to one year in space, it is questionable whether astronauts could or should have to maintain such regimes for extremely prolonged missions. Therefore, the NASA Life Sciences Division has initiated a program designed to evaluate a number of methods for providing an artificial gravity environment.

Adaptation, Physiological↗

PubMed1994

Artificial gravity as a countermeasure of physiological deconditioning in space.

The displacement of humans from our planet to space and back to our planet or to another planet necessarily causes the exposure to transitional gravitational forces which create a need for countermeasures of physiological deconditioning. One of the alternative approaches to counteracting physiological deconditioning is the simulation of a gravitational field. An apparatus named the artificial gravity simulator (AGS) has been designed and constructed. The AGS is a short radius rotating platform capable of producing a +Gz 100% gradient of a variable magnitude up to 3-g. It supports four beds for testing four subjects at a time. The AGS is suitable for short and long duration experiments on various physiological systems. At present it is being used to study the cardiovascular response to various g-levels and exposure times.

Cardiovascular Deconditioning↗

PubMed1996

Performance of a centrifugal phytotron.

It is possible to cultivate plants under an artificial gravity field generated by a centrifugal device in space. In order to determine an optimal magnitude of gravity, there is a need to investigate the relationship between plant and growth and gravity, including not only reduced gravity but also gravity greater than 1G. A prototype centrifugal phytotron was designed and fabricated in order to investigate the relationship between plant growth and increased gravity. This device enables us to cultivate plants over the long term by controlling environmental conditions in the phytotron such as temperature, relative humidity, CO2 concentration and light intensity. The results of our experiment indicate that plant seeds can germinate and grow even under an artificial gravity which changes sinusoidally from 2G to 4G.

Acceleration↗

PubMed1996

The effect of gravity on plant germination.

An axis clinostat was constructed to create micro and negative gravity also a rotated flat disk was constructed with different rotation rates to give increased gravity, by centrifugal force up to 48 g. Rice seeds were grown on agar in tubes at the constant air temperature of 20 degrees C under an average light condition of 110 micromol/m2/sec(PPF). Humidity was not controlled but was maintained above 90%. Since the tube containers were not large enough for long cultivation, shoot and root growth were observed every 12 hours until the sixth day from seeding. The lengths of shoots and roots for each individual plant were measured on the last day. The stem lengths were increased by microgravity but the root lengths were not. Under the negative gravity, negative orthogeotropism and under microgravity, diageotropism was observed. No significant effect of increased gravity was observed on shoot and root growth.

Centrifugation↗

PubMed1994

Locomotion in a rotating space station: a synthesis of new data with established concepts.

Despite technical problems associated with designing a rotating space station it is still thought that such a device may provide a more tolerable work environment and prevent some of the physiological changes that currently pose a threat to long-duration space missions. In the present analysis four case studies are presented and the results show that centrifugal and Coriolis effects could hinder one's ability to walk or run in a natural way in such an environment. In a rotating station that has a nominal 'G-level' equal to that on earth it can be shown that a person running at 3.8 m s -1 could experience foot 'heaviness' effects that range from 1 to 3 g and fore-aft foot 'forces' that range fom -0.5 to +0.5 g. In contrast the hip region could sense a relatively constant 'force' equal to 2 g. With regard to the body as a whole there would be 'weight changes' that depended on the direction of gait. While these conditions imply that locomotion in a rotating space station would be different from normal gait, it is likely that given sufficient training, astronauts could learn optimal strategies to account for centrifugal and Coriolis effects on individual body segments. The learning process would also entail developing strategies on which route to take when moving from one location to another, since in many cases the shortest route would not be the least energy consuming. Such training would be justified if it were shown that artificial gravity was an effective countermeasure to the problems of muscle atrophy and bone loss.

Coriolis Force↗

PubMed1974

Interaction between radiation effects, gravity and other environmental factors in Tribolium confusum.

Multicellular organisms possess homeostatic control systems, which, in responding to changes of the external environment, modify the internal milieu of the organism accordingly, in order to make survival and normal physiological processes possible. This group has studied effects on physiological processes of single and combined environmental factors in the flour beetle, Tribolium confusum. Studies included low- and high-LET radiation, gravity compensation, near-weightlessness in space flight, ambient temperature, atmospheric composition, and magnetic field effects on the growth and development of Tribolium. For somatic effects, there appears to be a "normal physiological range" for each of these environmental variables; moreover, their effects seem independent of each other. When one of the listed environmental factors is near the limits of normal physiological tolerance, however, marked synergism has been observed between the effects of this factor and other environmental stresses. Fertilized Tribolium eggs showed a differential radiosensitivity to external irradiation, and a linear, dose-effect relationship was obtained, as accelerated heavy nitrogen and oxygen ions were used. Synergism was found when Tribolium were irradiated with ionizing radiation and subsequently exposed to temperature either below or above their normal physiological range. Gravity compensation or near-weightlessness in space flight have adverse effects on the development of Tribolium when an ambient temperature is near the higher or lower limit of tolerance. Similar results were observed when pupae were exposed to a combination of oxygen, temperature and magnetic field stresses.

Animals↗

PubMed1979

Hornet building orientation in a vertically rotating centrifuge.

Hornets build combs that are clearly oriented toward the center of gravity and they compensate for any change made in the direction of their cells, provided the gravitational vector remains unchanged. Under natural conditions the first few cells are built by the queen in the spring, following the hibernation period, and building is then continued by the workers. Recently several reports have been published concerning the fact that groups of hornets (V. orientalis workers) may build in the absence of the queen and that such combs resemble those built by the queen. In previous investigations on building orientation, hornets placed in artificial breeding boxes (ABBs) on a horizontal centrifuge were subjected to constant centrifugal and gravitational forces, the resultant of which ranged between 1-1.5 g. Under these conditions young hornets (1-2 days of age) built combs in the direction of the resultant force, while the direction of building by adult hornets (3-7 days of age) was dependent on the presence or absence of a straight roof. Adults placed in the ABBs of rectangular shape built combs the orientation of which was determined by the Earth's gravity alone (perpendicular to the roof) whereas those in spherical ABBs with a convex roof built combs in the direction of the resultant gravitational and centrifugal forces, much the same as combs built by the young hornets. We were, however, also interested in studying the building orientation of hornets placed under conditions of changing resultant forces. The present paper describes comb building by hornets under the alternating gravitational forces of a vertical centrifuge.

Age Factors↗