Long-term biological investigations in space

Missions in space within the next two decades will be of longer duration than those carried out up to the present time, and the effects of such long-term flights on biological organisms are unknown. Results of biological experiments that have been performed to date cannot be extrapolated to results in future flights because of the unknown influence of adaptation over a long period of time. Prior experiments with Axolotl, fishes, and vertebrates by our research team (in part with sounding rockets) showed that these specimens did not appear to be suitable for long-term missions on which minimization of expense, technique, and energy is required. Subsequent investigations have shown the suitability of the leech (Hirudo medicinalis), which consumes blood of mammals up to ten times its own weight (1 g) and can live more than 2 years without further food supply. Emphasis in the experiments with Hirudo medicinalis is placed on metabolic rhythm and motility. Resorption and diffusion in tissue, development, and growth under long-term effects of cosmic proton radiation and zero-gravity are other focal points. The constancy of cellular life in the mature animals is a point in favor of these specimens. We have also taken into account the synergistic effects of the space environment on the problems just mentioned. The life-support system constructed for the leech has been tested successfully in four sounding rocket flights and, on that basis, has been prepared for a long-term mission. Long-term investigations out of the terrestrial biosphere will provide us with information concerning the degree of adaptation of certain physiological and biochemical functions and as to what extent biological readjustment or repair processes can occur under the specific stress conditions of space flight.     

Accomplishments in bioastronautics research aboard International Space Station

The tenth long-duration expedition crew is currently in residence aboard International Space Station (ISS), continuing a permanent human presence in space that began in October 2000. During that time, expedition crews have been operators and subjects for 18 Human Life Sciences investigations, to gain a better understanding of the effects of long-duration space flight on the crewmembers and of the environment in which they live. Investigations have been conducted to study: the radiation environment in the station as well as during extravehicular activity (EVA); bone demineralization and muscle deconditioning; changes in neuromuscular reflexes; muscle forces and postflight mobility; causes and possible treatment of postflight orthostatic intolerance; risk of developing kidney stones; changes in pulmonary function caused by long-duration flight as well as EVA; crew and crew–ground interactions; changes in immune function, and evaluation of imaging techniques. The experiment mix has included some conducted in flight aboard ISS as well as several which collected data only pre- and postflight. The conduct of these investigations has been facilitated by the Human Research Facility (HRF). HRF Rack 1 became the first research rack on ISS when it was installed in the US laboratory module Destiny in March 2001. The rack provides a core set of experiment hardware to support investigations, as well as power, data and commanding capability, and stowage. The second HRF rack, to complement the first with additional hardware and stowage capability, will be launched once Shuttle flights resume. Future years will see additional capability to conduct human research on ISS as International Partner modules and facility racks are added to ISS. Crew availability, both as a subject count and time, will remain a major challenge to maximizing the science return from the bioastronautics research program.     

The space life sciences strategy for the 21st century

In the past, space life sciences has focused on gaining an understanding of physiological tolerance to spaceflight, but, for the last 10 years, the focus has evolved to include issues relevant to extended duration missions. In the 21st century, NASA's long-term strategy for the exploration of the solar system will combine the assurance of human health and performance for long periods in space with investigations aimed at searching for traces of life on other planets and acquiring fundamental scientific knowledge of life processes. Implementation of this strategy will involve a variety of disciplines including radiation health, life support, human factors, space physiology and countermeasures, medical care, environmental health, and exobiology. It will use both ground-based and flight research opportunities such as those found in current on-going programs, on Spacelab and unmanned biosatellite flights, and during Space Station Freedom missions.     

A 6 D.O.F. opto-inertial tracker for virtual reality experiments in microgravity.

Gravity plays a role in many different levels of human motor behavior. It dictates the laws of motion of our body and limbs, as well as of the objects in the external world with which we wish to interact. The dynamic interaction of our body with the world is molded within gravity's constraints. The role played by gravity in the perception of visual stimuli and the elaboration of human movement is an active research theme in the field of Neurophysiology. Conditions of microgravity, coupled with techniques from the world of virtual reality, provide a unique opportunity to address these questions concerning the function of the human sensorimotor system. The ability to measure movements of the head and to update in real time the visual scene presented to the subject based on these measurements is a key element in producing a realistic virtual environment. A variety of head-tracking hardware exists on the market today, but none seem particularly well suited to the constraints of working with a space station environment. Nor can any of the existing commercial systems meet the more stringent requirements for physiological experimentation (high accuracy, high resolution, low jitter, low lag) in a wireless configuration. To this end, we have developed and tested a hybrid opto-inertial 6 degree-of-freedom tracker based on existing inertial technology. To confirm that the inertial components and algorithms will function properly, this system was tested in the microgravity conditions of parabolic flight. Here we present the design goals of this tracker, the system configuration and the results of 0g and 1g testing.     

Future investigations onboard Soviet biosatellites of the Cosmos series.

Many rat experiments onboard Cosmos biosatellites have furnished information concerning the effects of weightlessness, artificial gravity, and ionizing radiation combined with weightlessness on structural and biochemical parameters of the animal body. The necessity to expand the scope of physiological investigations has led to the project of flight primate studies. It is planned to carry out the first primate experiments onboard the Cosmos biosatellite in 1982. At present investigations of weightlessness effects on the cardiovascular and vestibular systems, higher nervous activity, skeletal muscles and biorhythms of two rhesus monkeys are being developed and tested. It is also planned to conduct a study of weightlessness effects on embryogenesis of rats and bioenergetics of living systems onboard the same biosatellite. Further experiments onboard Cosmos biosatellites are planned.     

Physiology, medicine, long-duration space flight and the NSBRI

The hazards of long-duration space flight are real and unacceptable. In order for humans to participate effectively in long-duration orbital missions or continue the exploration of space, we must first secure the health of the astronaut and the success of such missions by assessing in detail the biomedical risks of space flight and developing countermeasures to these hazards. Acquiring the understanding necessary for building a sound foundation for countermeasure development requires an integrated approach to research in physiology and medicine and a level of cooperative action uncommon in the biomedical sciences. The research program of the National Space Biomedical Research Institute (NSBRI) was designed to accomplish just such an integrated research goal, ameliorating or eliminating the biomedical risks of long-duration space flight and enabling safe and productive exploration of space. The fruits of these labors are not limited to the space program. We can also use the gained understanding of the effects and mechanisms of the physiological changes engendered in space and the applied preventive and rehabilitative methods developed to combat these changes to the benefit of those on Earth who are facing similar physiological and psychological difficulties. This paper will discuss the innovative approach the NSBRI has taken to integrated research management and will present some of the successes of this approach.     

Summary of medical investigations in the U.S.S.R. manned space missions.

The results of biomedical investigations carried out in the U.S.S.R. manned space missions are discussed. Their basic result is well-documented evidence that man can perform space flights of long duration. The investigations have demonstrated no direct correlation between inflight or postflight physiological reactions of crewmembers and flight duration. In all likelihood, this can be attributed to the fact that special exercises done inflight efficiently prevented adverse effects of weightlessness. However, human reactions to weightlessness need further study. They include negative calcium balance and anemia as well as vestibulo-autonomic disorders shown by crewmembers at early stages of weightlessness. Attention should be given to psychological, social-psychological and ethical problems that may also limit further increase in flight duration.     

The future of space medicine.

In November 2000, the National Aeronautics and Space Administration (NASA) and its partners in the International Space Station (ISS) ushered in a new era of space flight: permanent human presence in low-Earth orbit. As the culmination of the last four decades of human space flight activities. the ISS focuses our attention on what we have learned to date. and what still must be learned before we can embark on future exploration endeavors. Space medicine has been a primary part of our past success in human space flight, and will continue to play a critical role in future ventures. To prepare for the day when crews may leave low-Earth orbit for long-duration exploratory missions, space medicine practitioners must develop a thorough understanding of the effects of microgravity on the human body, as well as ways to limit or prevent them. In order to gain a complete understanding and create the tools and technologies needed to enable successful exploration. space medicine will become even more of a highly collaborative discipline. Future missions will require the partnership of physicians, biomedical scientists, engineers, and mission planners. This paper will examine the future of space medicine as it relates to human space exploration: what is necessary to keep a crew alive in space, how we do it today, how we will accomplish this in the future, and how the National Aeronautics and Space Administration (NASA) plans to achieve future goals.     

The physical price of a ticket into space

As a direct consequence of exposure to microgravity astronauts experience a number of physiological changes, which can have serious medical implications when they return to Earth. Most immediate and significant are the head-ward shift of body fluids and the removal of gravitational loading from bone and muscles, which lead to progressive changes in the cardiovascular and musculoskeletal systems. Cardiovascular adaptations result in an increased incidence of orthostatic intolerance (fainting) post-flight, decreased cardiac output and reduced exercise capacity. Changes in the musculoskeletal system contribute significantly to the impaired functions experienced in the post-flight period. The underlying factor producing these changes is the absence of gravity. Countermeasures, therefore, are designed primarily to simulate Earth-like movements, stresses and system interactions. Exercise is one approach that has received wide operational use and acceptance in both the US and Russian space programmes, and has enabled humans to stay relatively healthy in space for well over a year. Although it remains the most effective countermeasure currently available, significant physiological degradation still occurs. The development of other countermeasures will therefore be necessary for longer duration missions, such as the human exploration of Mars.     

New challenges for life sciences flight project management

Scientists have conducted studies involving human spaceflight crews for over three decades. These studies have progressed from simple observations before and after each flight to sophisticated experiments during flights of several weeks up to several months. The findings from these experiments are available in the scientific literature. Management of these flight experiments has grown into a system fashioned from the Apollo Program style, focusing on budgeting, scheduling and allocation of human and material resources. While these areas remain important to the future, the International Space Station (ISS) requires that the Life Sciences spaceflight experiments expand the existing project management methodology. The use of telescience with state-of-the-art information technology and the multi-national crews and investigators challenges the former management processes. Actually conducting experiments on board the ISS will be an enormous undertaking and International Agreements and Working Groups will be essential in giving guidance to the flight project management Teams forged in this matrix environment must be competent to make decisions and qualified to work with the array of engineers, scientists, and the spaceflight crews. In order to undertake this complex task, data systems not previously used for these purposes must be adapted so that the investigators and the project management personnel can all share in important information as soon as it is available. The utilization of telescience and distributed experiment operations will allow the investigator to remain involved in their experiment as well as to understand the numerous issues faced by other elements of the program. The complexity in formation and management of project teams will be a new kind of challenge for international science programs. Meeting that challenge is essential to assure success of the International Space Station as a laboratory in space.     

A review of muscle atrophy in microgravity and during prolonged bed rest

With the prospect of long duration space missions in Earth orbit or to Mars, there is a need for adequate information on the physiological adaptations that will occur. One consequence of prolonged exposure to microgravity is muscle atrophy (loss of muscle mass). After a long duration space flight, muscle atrophy along with skeletal calcium loss would affect the capacity of astronauts to re-adapt to gravity on return to Earth. Of importance are any countermeasures which can attenuate the adaptive responses to microgravity. Experimentation is difficult in space with small subject numbers and mission constraints. Prolonged bed rest using healthy volunteers is used as an Earth-based model to simulate the muscle atrophy which occurs in the microgravity environment.     

The properties of alamethicin incorporated into planar lipid bilayers under the influence of microgravity.

During evolution, life on earth had adapted to the gravity of 1g. Due to space flight, in the last decades the question arose what happens to the brain under microgravity on the molecular level. Ion channels among others are the molecular basis of brain function. Therefore, the investigation of ion channel function under microgravity seems to be a promising approach to gather knowledge on brain function during space flight. In a first step, the ion channel forming peptide Alamethicin was used as a model channel in an artificial membrane. It is well suitable for this kind of investigation, since its properties are well described under standard gravity. For that reason, changes due to microgravity can be detected easily. All experiments were performed in the German drop tower at ZARM-FAB, Bremen. A special set-up was constructed based on the bilayer technique introduced by Mueller and Rudin. All functions of this set-up can be observed and controlled remotely. In the first set of experiments, a dramatic change of electrical properties of Alamethicin under microgravity could be observed. Mainly, the pore frequency is significantly reduced.     

Isolation,confinement, and sensory deprivation

Long-duration space flight involves sensory monotony, isolation, and confinement. Obviously, data from other such environments are relevant to our concerns; and the application of the concept of arousal both to interpersonal relations and to task performance in space can point to appropriate selection, training, and spacecraft design features. In the context of space flight, all of these leads remain conjectural--simulation as well as laboratory research and initiation of long-duration flights will be the crucial test of the hypotheses.     

Short duration microgravity experiments in physical and life sciences during parabolic flights: the first 30 ESA campaigns

Aircraft parabolic flights provide repetitively up to 20 s of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences, to test instrumentation and to train astronauts before a space flight. The European Space Agency (ESA) has organized since 1984 thirty parabolic flight campaigns for microgravity research experiments utilizing six different airplanes. More than 360 experiments were successfully conducted during more than 2800 parabolas, representing a cumulated weightlessness time of 15 h 30 m. This paper presents the short duration microgravity research programme of ESA. The experiments conducted during these campaigns are summarized, and the different airplanes used by ESA are shortly presented. The technical capabilities of the Airbus A300 'Zero-G' are addressed. Some Physical Science, Technology and Life Science experiments performed during the last ESA campaigns with the Airbus A300 are presented to show the interest of this unique microgravity research tool to complement, support and prepare orbital microgravity investigations.     

深空探测重力模拟飞行器方案设想

为解决失重环境对航天员生理健康的影响,在调研国内外重力飞行器研究现状的基础上,结合重力模拟飞行器的原理及人造重力舒适度影响因素,提出了一种通过自旋产生人造重力的深空探测飞行器方案设想。最后给出了重力模拟飞行器建设的实施规划、总体方案、在轨组装流程及技术难点。深空探测重力模拟飞行器稳定运转可为空间工作生活的航天员提供与地面无异的重力环境,将为执行深空探测任务提供必要的环境保障。     

Effects of Microgravity on Human Physiology and Ground-Based Models for Space Physiological Studies

With the development of manned spaceflight, more and more researches are involved in the area of gravitation physiology. When astronauts are exposed to microgravity, a series of special physiological or pathological changes will occur, which will start self-regulation mechanisms to reduce abnormalities and help the organism to better adapt to microgravity. However, these adaptive changes may also induce degradation or damage to physiological functions. This paper summarizes the physiological effects of microgravity on the human body from the aspects of skeletal and mineral metabolism, muscle structure and function, vestibular functions, cardiovascular function and pulmonary function, as well as expounds some commonly used ground-based space analogies. The paper will provide a reference for further study on the physiological effects of microgravity.     

载人深空探测任务航天医学工程问题研究

航天医学工程问题关系到载人深空探测任务中的人员生存及健康。文章从人员长期生存的生命保障、变重力生理效应及防护、地外环境效应与防护、人员生理健康监测与维护、人员心理健康等方面的问题入手,分析了问题产生的原因及解决的必要性,并提出了解决思路,为后续深入开展相关关键技术的攻关提供参考。最后,以载人月球基地任务为案例,提出了生命保障、变重力防护、辐射及月尘防护、生理及心理健康监测及维护等问题的解决方案。     

Effects of space flights on human allergic status (IgE-mediated sensitivity)

Suppression of the immune system after space flights of different duration has been reported earlier by Konstantinova [Immune system in extreme conditions, Space immunology. B. 59. M. Science 1988. 289p. (in Russian) [4]; Immunoresistance of man in space flight, Acta Astronautica 23 (1991) 123–127 [5]]. Changes in T- and B-mediated activities of the immune system were demonstrated during and after space flight. However, the influence of the space flight conditions on the allergic status of cosmonauts and astronauts is still unclear. The goal of this investigation was to analyze total blood IgE levels, specific IgE-antibodies and interleukin-4 in blood of Russian crew members before and after space flights to the International Space Station (ISS) and during a long-term isolation study. For this purpose, we used the ELISA assays as well as other special kits. It was noticed that four out of nine cosmonauts had high total serum IgE (more than normal clinical values of 120 IU/ml). At the same time, there were no statistically significant changes in serum IgE levels before and after long-term space flights (128–195 days). A similar situation was observed regarding preflight IgE levels of cosmonauts who performed short-term flights (7–11 days). However, seven out of 11 cosmonauts had increased IgE level in blood post short flights as compared with pre-flight values. We also measured specific IgE-antibodies, because their high concentration may cause the increased production of total IgE indicating sensitization of cosmonauts. This becomes more important when humans spend a longer time in the closed environment of a space vehicle. Also our ground-based investigations showed that a stay in such conditions does not enhance sensitization to allergens (total number of tested allergens 27) including food, inhalants and cross-reactive proteins. Serum interleukin-4 level measured after short- and long-term space flights was identical. A linear correlation between levels of immunoglobulin E and interleukin-4 also was not significant. Despite the fact that our investigations did not establish any influence of space flight on sensitization and development of immediate-type allergic reactions, they demonstrated the necessity to control the allergic status of cosmonauts very carefully both before and after space flights. At the same time, it is necessary to pay special attention to outcomes of atopic individuals with high pre-flight level of total blood IgE.