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According to the results of the experiment performed on the ISS with participation of 15 Russian cosmonauts was fulfilled the comparative analysis of two models of preventive measures used by the Russian members of the long term space flight: the intense interval training in the aerobic-anaerobic zone power (recommended model) and the continuous low-intensity exercise in the aerobic zone energy power of the muscle activity. The interval trainings in the conditions of the space flight have provided the maintenance of the level of physical performance close to the preflight level; characterized by the maximum running speed, physiological value of work and lactate level after a standard load. The putative mechanisms of counteraction to adaptive remodeling of the propulsion system in zero gravity and enhanced understanding of the laws governing the interaction of the human body with the gravitational field of the Earth are described in the paper. The research results presented in the article show the high preventive efficacy of interval training compared with regular aerobic trainings, what is very important now in the time of searching of the means and methods of prevention of hypogravitation alterations during the interplanetary missions.

The paper reports the results of studying morphology and functioning of the visual analyzer of 8 male subjects following 11 days under dynamic light-emitting diode illumination. A comprehensive eye examination did not reveal any significant negative effect of the short-term exposure to the artificial light; however, physiological characteristics of the visual analyzer function were impaired. Loss of relative accommodation, narrowing of the peripheral vision fields for the green and blue. could be linked with asthenopia (visual fatigue) developing in closed space. Electrophysiological investigations discovered a P100 bifurcation which devidence that morphology of ocular evoked potentials changed for the reverse pattern. The phenomenon may be representative of a temporal discord of visual channels or a change in their temporal characteristics caused by the specific artificial illumination.

The paper reports changes in the main parameters of the lower limb veins in 36 cosmonauts in the course of 6-month space missions. Major reduction in the leg volume was shown in all cosmonauts, as well as a significant increase of venous capacity and compliance. Rate of vein filling exhibited different trends, i.e. decreased in the majority of cosmonauts (n = 26, 74%) and increased in the rest (n = 9, 26%). Increases in venous capacity, compliance and filling rate may impact orthostatic stability (OS). These changes are among the pathophysiological mechanisms of the OS loss in space flight.

Monitoring of the radiation loading on cosmonauts requires calculation of absorbed dose dynamics with regard to the stay of cosmonauts in specific compartments of the space vehicle that differ in shielding properties and lack means of radiation measurement. The paper discusses different aspects of calculation modeling of radiation effects on human body organs and tissues and reviews the effective dose estimates for cosmonauts working in one or another compartment over the previous period of the International space station operation. It was demonstrated that doses measured by a real or personal dosimeters can be used to calculate effective dose values. Correct estimation of accumulated effective dose can be ensured by consideration for time course of the space radiation quality factor.

The paper is devoted to the hemostasis studies in the course of long-term (520 d) isolation in an airtight chamber. Measured parameters included activated partial thromboplastin time (APTT), international normalized ratio (INR), thrombin time (TT); concentrations of fibrinogen (FBG), plasminogen (PG), Willebrand factor (WF), tissue factor pathway inhibitor (TFPI), and tissue plasminogen activator (TPA), thrombomodulin (TM); activities of the coagulation cascade factors (II, V, VII, X, VIII, IX, XI, XII), antithrombin III (ATIII), protein C (PC), C1-inhibitor (C1), α2-antiplasmin (AP), TPA and TFPI. The investigation revealed a diversity of changes in the plasma fibrinogen concentration, slower blood coagulation in the intrinsic pathway and the final stage, and a relative rise in the activities of ATIII and PC-inhibited factors. The rest parameters showed different trends.

The paper presents the results of measuring biologically significant characteristics of space radiation (spectra of linear energy transfer (LET), absorbed and equivalent doses and averaged quality factors) inside the descend capsule of biosatellite Bion-M1 in space experiment Bioradiation. Measurements combined the use of thermoluminescent detectors DTG-4 (TDL) and solid state nuclear track detectors CR-39 (Tastrak) (SSNTD). Differential and integral LET spectra of high-LET space radiation were determined in 4 points inside spacecraft using passive detectors assembles (PDA). Total absorbed dose rates for PDA boxes No 1-4 made up 2.4 ± 0.2; 1.1 ± 0.1; 1.6 ± 0.2; 2.0 ± 0.1 mGy/d respectively, whereas total equivalent dose rates estimated based on ICRP Publication 60 recommendations made up 3.4 ± 0.2; 2.0 ± 0.1; 2.6 ± 0.2; 3.1 ± 0.1 mSv/d respectively. Values of the averaged quality factor for different PDSs were in the range between 1.4 and 1.8.

The brief analytic review of exceedingly important, tough, but the insufficient investigated problem of experimental investigation of spaceflight factors (SF) combined influence on animal organism functions is the content of this paper. The basic limited factor for interplanetary spaceflights is ionizing radiation. Therefore, in the paper studies the matters of the effects of combined influence and the different nonradiation SF. In this case the possible disturbances of central nervous system functions are the most important, because they present the basic danger for space mission performance and the cosmonauts life directly in spaceflight. Besides of that, in the paper studies the matters of character of interaction and mutual modifications of the combined effects of different SF: hypodynamia, G force, vibration, hypoxia, hyperthermia. The effects of this factor may have additive, potentiative, synergic or antagonistic character. In studies of SF combined influence effects the accentuation of the key factor and organism system that is targeted for this factor influence is necessary.

The paper considers key methodical, logistics and tactical aspects of enhancing cosmonaut's medical monitoring to ensure crew safety in long-duration space mission. Activities toward extension of the diagnostic capabilities included hardware development, choice of examination procedures and defining the content of physiological information that would be necessary and sufficient for evaluation, including in real-time, of the cardiovascular system function and capacity, planning functional tests procedures as close as possible to the generally accepted clinical protocols used in selection of candidates for cosmonauts, and pre- and post-flight examination; refining the objective criteria of test tolerance and termination, and end-of-mission LBNP training tolerance and effectiveness; constructing a fundamentally new structure for medical telemetry data acquisition and processing at the Moscow Mission Control Center (MCC-M).

The paper presents ideas of optimizing the mineral nutrition system for salad crops in a space greenhouse. Experiments showed that to use mineral-saturated fiber ionite BIONA-V3 as an artificial soil will require to upmass a lot of expandable materials because of low specific content of nutrients. An additionally mineralized fiber soil makes possible to reduce mass of ionite in 5.6 times and volume in 28 times. The proposed mineral supply system is composed of two enrichment catridges with granulated ionite BIONA-V3 and slow-releasing fertilizer Osmocote 114-14-4, and a controller of irrigation water electric conduction stabilizer. Tests showed that this system provides sufficient mineral nutrition to plants and can be recommended for in-flight testing.

The paper deals with the results of the effects of 520-day isolation and confinement modeling some elements of a mission to Mars on the immune system. Longitudinal analyses revealed that the mechanisms of adaptive response of the human immune system to the conditions of extremely long isolation led to a change of the parameters, characterizing innate and adaptive immunity. Among them the most important are: changes in the signaling PRRs--TLR, manifested in the reduction of the percentage of circulating monocytes and granulocytes expressed on its own surfaces TLR2, TLR4 and TLR6, decreases early NK cell activation potential, increases in the percentage T- and B-lymphocytes, that expressed early activation marker CD69 after adequate stimulation, and in production of cytokines in response to PHA stimulation. The active mobilization of the mechanisms of adaptive immunity, the implementation of the function of the level of immunity to a qualitatively different level, apparently, should be taken as a sign of adaptive adjustment of an organism in response to the complex influence of unfavorable factors, aimed at the preservation of immune homeostasis.

Missions of unmanned spacecraft Foton-M2 (2005) and Foton-M3 (2007) of 16 and 12 days in duration, respectively, provided an opportunity to conduct the Russian/US experiments with snails (Helix lucorum and Helix aspera), newts (Pleurodeles waltli), geckos (Pachydactilus turneri) and microorganisms (Streptomyces lividans 66, E. coli and others). Besides, Foton-M3 carried a Russian experiment with Mongolian gerbils (Meriones unguiculatus). Objectives of the space experiments were to study the micro-g effects on the living systems' behavior, structure and functioning, post-traumatic regeneration of bone and organs, stable inheritance of plasmid pIJ 702, and melanin pigment synthesis by streptomycets. The survey paper presents the major findings of a large team of investigators.

Sine qua non for piloted exploration missions is a system of biomedical support. The future system will be considerably different from the analogous systems applied in current orbital missions. The reason is the challenging conditions in expeditions to remote space. In a mission to Mars, specifically, these are high levels of radiation, hypomagnetic environment, alternation of micro- and hypogravity, very long mission duration and autonomy. The paper scrutinizes the major issues of medical support to future explorers of space.

The paper considers the fundamental principles of the Russian countermeasures system validated successfully in multiple long-term missions to the Russian space stations. The system adopted on the ISS Russian segment is detailed. In particular, it is pinpointed that physical training of cosmonauts was adjusted to the demands of the stages of ISS assembly and utilization. The locomotion training performed with departures from the flight documentation (ODFs) is described. The concluding section of the paper lays out the picture of vistas for the system of countermeasures in future exploration missions.

The paper presents the results of investigating the lower limbs venous status in cosmonauts (n = 13) with the use of occlusion plethysmography in 6-month missions to the Russian segment of the International space station (ISS). An interrelation of shifts in venous capacitance, compliance and filling with orthostatic tolerance (OT) in the lower body negative pressure test (LBNP) was stated. OT predictability by the leg vein status in the course of space flight was demonstrated. The objective changes of veins predictive of OT reduction were identified. There are 3 levels of changes in venous capacitance, compliance and filling that prognosticate respective reductions in LBNP tolerance and were attested in 91% of the in-flight LBNP testing.

The paper presents the view of space medicine and human factor experts on the problems of cosmonaut's research activities. Readiness of ISS crewmembers for conducting experiments and research equipment handling depends on the pre-flight training quality and course of adaptation to the flight conditions, the latter of particular criticality for participation in human use tests as an object.

This paper considers to physiological effects of microgravity affecting different organs systems such as cardiovascular, neurohumoral, immune, and musculoskeletal systems. These physiologic changes suggest adverse influence with pathological processes during space flight and associated with high risk of morbidity of cosmonauts.

The paper report the results of studying mitotic activity and cytogenetic disorders in marrow and retinal epithelium cells of Mongolian gerbils in 21 - 23 hrs. of landing space apparatus Foton-M3, and the animals of synchronous and vivarium controls. Cells of the space flown gerbils displayed a statistically significant (p < 0.05) gain in the ratio of mitosis prophases and metaphases to the sum of ana- and telophases (1.7 +/- 0.3 and 2 +/- 0.1, respectively) as compared to these parameters in the synchronous and vivarium controls, where the ratio made up 0.6 +/- 0.1 and 0.7 +/- 0.1, respectively. Frequency of aberrant mytoses in the form of bridges was increased equally in both types of cells. Patterns of chromosome damages occurred in flight infer that the major portion of changes was not due to chromosome breakage but adhesion and ensuing wrong disjunction. These results seem to have been caused by acute g-stress to organism during re-entry and return from micro-g to the normal gravity.

The present paper deals with studying ofhemostasis system indices after short-term (10-11 days) space flights as well as in the course of the experiment with a 7-day "dry" immersion. The following values were determined: activated partial thromboplastin time, prothrombin time, prothrombin index, international normalized ratio (INR), thrombin time (TT); fibrinogen, soluble fibrin-monomer complexes, D-dimer, plasminogen (PG) concentration; activity of antithrombin III (ATIII), protein C (PC), alpha2-antiplasmin (AP). In the 1st day after space flights a fibrinogen concentration was increased significantly as well as TT shortening tendency and fibrinolysis activation tendency were observed. There were no significant changes in ATI I11 and PC activities. During the immersion period there were no significant changes in investigated indices, with the exception of AP activity increase in 3rd day of experiment. In readaptation period, however, a decrease in ATIII and PC activities as well as PG concentration was observed. Hemostasis system response features after space flights and during immersion are probably due to different intensity and duration of external factors effects.

The work was aimed at analysis and generalization of the hemodynamic data collected over 20 years from 26 cosmonauts flown 8 to 438 days aboard orbital stations Salyut 7 and Mir. The paper presents the results of ultrasonic investigations of the heart, arterial and venous peripheral vessels in different parts of human body, and measurements of leg veins capacity with the use of occlusive plethysmograpy. It was shown that in the resting condition such prime hemodynamic parameters as the pumping function of the heart and blood supply of the brain, and integral parameters, i.e. arterial pressure and heat rate, were best "protected" as they demonstrated stability throughout long exposure in microgravity. In the absence of gravitational stimulation, arterial resistance went down in essentially all vascular regions below the heart level; to put it differently, the anti-gravity distribution of the vascular tone was annulled gradually as unneeded in microgravity. Compared with the data about arteries, venous hemodynamics was found to be particularly sensitive considering the early advent and significance of changes. Venous return slowed down, resistance of the lower body vessels declined and capacity of the leg venous net increased. Functional testing with the lower body negative pressure revealed degradation of the gravity-dependent reactions that became more conspicuous as flight duration extended further. Cardiovascular deconditioning showed itself clearly on return to Earth's gravity by decreased g-tolerance during re-entry and orthostatic instability post flight. These investigations provided objective evidence for multifactorial genesis of orthostatic instability during space flight including blood redistribution, altered tone regulation of leg's venous and arterial vessels and hypovolemia.

The unique conditions of space experiments place austere requirements to bio-objects and biological methods of radiation effects evaluation. The paper discusses suitability of a number of bio-objects varying in stage of evolution and metabolism for space researches aimed to state common patterns of the radiation damage caused by heavy ions (HI), and character of HI-cell interaction. Physical detectors in space experiments of the BIOBLOCK series make it possible to identify bio-objects hit by space HI and to set correlation between HI track topography and biological effect. The paper provides an all-round description of the bio-objects chosen for two BIOBLOCK experiments (population of hydrophyte Wolffia arrhiza (fam. duckweed) and Lactuca sativa seeds) and the method of evaluating effects from single space radiation HI. Direct effects of heavy ions on cells can be determined by the criteria of chromosomal aberrations and delayed morphologic abnormalities. The evaluation results are compared with the data about human blood lymphocytes. Consideration is being given to the procedures of test-objects' treatment and investigation.

In the period when Russia had embarked on construction of long-duration orbital stations, few data was collected about potential damaging effects of space flight (SF) factors, first of all microgravity, on structure and functions of various tissues, organs and physiological systems. At the same time designers of space vehicles requested from doctors and biologists the scientific substantiation of the feasibility of long-term SF by humans. Recognizing the necessity of a comprehensive approach to the issue, it was decided to fulfill fundamental and applied biological investigations aboard dedicated satellites of the BION series. Implementation of Programme BION and development of associated equipment required cooperation of dozens of organizations. Later on, investigations from Bulgaria, Hungary, Germany, the Netherlands, Canada, China, Poland, Romania, USA, France and Czechoslovakia joined in the programme. Eleven biosats were launched successfully in the period between 1973 and 1986. Cell and tissues cultures, single-celled organisms, insects, fishes, amphibians, reptiles, bird eggs and mammals, such as Wistar rats and primates Macaca Rhesus, were flown in space 5 to 22.5 days. Data from these investigations helped, on the one hand, obtain further insight into the patterns of structural and functional reactions of living systems to the SF conditions and, on the other, contribute to finding practical solutions for the system of crew medical support. The Federal space research programme of Russia for 2006-2015 provides development and launch of 3 biosats BION-M. The paper presents conceivable scenarios of researches in these flights.

One of the challenges for space biology and medicine is resolution of lots of problems of biomedical support of humans in the extreme environment of space flight. These problems include also designing of robust and efficiently functioning life support systems (LSS). The paper gives an overview of the investigations of ground-based BLSS with human subjects conducted in Russia and other countries. Also, it contains the basic data of studying the BLSS photoautotrophic components (higher plants) in the series of experiments with the total duration of 630 days fulfilled on orbital complex Mir and the series of experiments with the total duration of 820 days in the ISS Russian segment. Analysis of the results from the BLSS investigations on Earth and in space flights drives to the conclusion that some of the BLSS components, greenhouses specifically, can be integrated even now into the currently used systems of space crew life support.

The paper illuminates some issues of the psychophysiological support (PPS) of piloted flights to space discussed with academician O.G. Gazenko. Already in initial space flights monitoring and assessment of the psychic state and mental performance of crew members were the key PPS component that needed all-round investigations and development of associated methods. The poly-effect method of registering the physiological functions (ECG, EEG, GSR) was recognized as a potent tool for gathering information to be used in actual state assessment. Starting from the 96-d flight of Yu. Romanenko and G. Grechko, the enhanced PPS system has been an indispensable component of long-term missions to orbital complexes Salyut, Mir, and the International space station. The practical experience with the PPS system showed its major contribution to maintenance of space crew mental health and performance.

Established with the personal participation of O.G. Gazenko, the Russian system of medical care for cosmonauts' health has been largely preserved till this day. The system was fully functional on board the orbital complex MIR and, with appropriate modifications, has been adopted as a core of the medical care for Russian members of the ISS crews. In the period of 2000-2008, 22 cosmonauts were members of 17 ISS increments from 140 to 216 days in duration. The main functions of the medical care system were to control health, physical and mental performance, and to support implementation of space researches. The flow of readaptation to the normal gravity was, in most cases similar to what has been typical on return from the Russian orbital stations; some deviations are accounted for by application of the in-flight countermeasures. The paper familiarizes reader with some aspects of the theoretical work of academician O.G. Gazenko in the field of medical care in space flight. It outlines the principles of ISS medical management. The integrated medical support system combines medical equipment and items available on the Russian and US segments; the integrated medical group consists of flight surgeons, medical experts and biomedical engineers of the international partners and coordinates planning and implementation of medical operations. Also, challenges of health care on the phase of ISS utilization are defined.

The paper presents the factual data about 6 participants in short-duration space flights of three age groups (according to the WHO classification). The scope of medical care for three young SFPs whose health status was qualified as good replicated the program adopted in Russia for crewmembers trained for short-duration orbital flights. To safeguard three SFPs of middle and elderly age among whom two had deviations in body functions, the standard medical care program was reinforced by prescription of corrective pharmaceuticals to be taken during space flight, supply of personal kits with preventive medicine, inclusion of additional examinations into the standard medical monitoring and modification of the in-flight countermeasure program, if necessary. As a result, all the SFPs missions were accomplished safely and successfully.

Regression analysis has been applied to determine the dependence of the motor system status (MSS) in long-duration space flight on the physical training programme (PTP), and flight duration (FD). Analyzed were graphical data presented in previous papers. Statistical analysis brought to light a high level of MSS-PTP relationship described as a 5-degree polynomial and a less explicit, yet statistically reliable MSS-FD relationship which is most adequately approximated by a 6-degree polynomial.

When in flight, cosmonauts are to resolve problems in the conditions of deterministic and stochastic disturbances. To a considerable degree successful problem resolution is dependent on interactions of the parietofrontal and parietooccipital areas of the right and left cortexes. The paper illustrates the relationship between the baseline state according to the Luscher test, productivity indices of activities involving two areas of the cortex, and spatial synchronization of their bio-potentials.

Some magnetobiological problems of orbital (in the geomagnetic field--GMF) and interplanetary (in hypomagnetic conditions) flights are considered. The influence of electromagnetic fields (EMF) created by systems and equipment of the space vehicle (SV) are touched also. A level of the geomagnetic field (GMF) onboard during the orbital flights is discussed. Its periodic variations onboard owing to movement of SV on an orbit are analyzed. The reader's attention in attracted to the papers by R.M. Baevsky et al. in which the influence of magnetic storms and periodic variations of GMS on the cardiovascular system of astronauts onboard are shown. Possible ways and mechanisms of the influence are discussed. The wrong assertions in a number of works namely that at orbital flights an appreciable electrical field is induced in an organism of an astronaut in a space-craft and the electrical field may by responsible for some biological impacts are analyzed. The situation at the future in the terplanetary flights (for example Martian missions) when a crew and biological objects for a long time will be in the interplanetary magnetic field (by several orders less then GMF) is considered. As applied to the flights the opportunities of generation onboard the "artificial" GMF are outlined. The ensuing biological and technical questions are discussed.

The paper presents results of investigations into the effects of space flight and simulation experiments of various length on the hormonal regulation of metabolism in the human body. Microgravity was shown to instigate shifts on different levels of the hormonal regulation and consequent adjustment of metabolism to this new environment. For instance, adaptation occurs on the level of basal secretory activity resulting in altered metabolism and formation of a pool of hormones. Metabolism readaptation to the Earth's gravity is dependent on polymorphic processes in the system of hormonal regulation developing in the course of time. Trends in the hormonal regulation of water-electrolyte metabolism during early adaptation point to inequality of contributions of the antidiuretic hormone, natriuretic peptide, and the renin-angiotensin-aldosterone system. In the ground-based simulations responses of the hormonal regulation of water-electrolyte metabolism differ in intensity and types of hormones involved. Temperature variation can modify reactions of the comosis and volume regulating hormones at the beginning of adaptation. Physical-chemical regulation of calcium homeostasis in microgravity reveals itself by a rapid decline of the calcium-binding ability of blood buffers and, later on, degradation of the relative ability of extraplasmic structures to bind calcium. Qualitative and quantitative changes in the diurnal rhythm of the suprarenal steroidogenesis are indicative of modification of intensity of reactions of the main biosynthetic sequences. Countermeasures used by test-subjects in these investigations loosened significantly the aldosterone-secreting biosynthetic sequences but were favorable to the synthesis of testosterone and hydrocortisone. Some of the highly variable processes of hormonal regulation were mute to the diurnal rhythms in the pre-flight and preexperimental periods.

In future interplanetary missions that will take up to two years the role of monitoring of the main human body systems and prevention of the effects of microgravity for the benefit of crew health and performance will rise eminently. In contrast to the orbital flights, diagnostics and prophylaxis will be a responsibility of the doctor within the crew who will consult solely own expertise and judgment. Hence, criteria and requirements to health monitoring and medicare systems and items are to be defined. The paper substantiates a concept and principles of diagnostics and prophylaxis, ideas concerning the scope of associated measures on the way to Mars, during the visit to the planet and on return to Earth; potentiality of a short-arch centrifuge as a means of prophylaxis is also discussed.

The paper deals with the results of electrocardiographic investigations of relatively resting 59 cosmonauts at the age of 30 to 52 during long-term space missions. Heart rate (HR), T-wave amplitude and an electric systole interval were analyzed. During their missions, the cosmonauts consistently combined HR rises with aggravated repolarization manifested by a relative elongation of the phase and T-depression. All alterations were statistically significant (p < 0.05); however, no pathology was detected in the myocardial bioelectrical activity. With this dynamics, values of the parameters under study did not, as a rule, leave the boundaries of the physiological norm.

Purpose of the investigation was to develop a technique of irradiation sterilization of batch syringes with concentrated salt solutions (CaCl2 solution and a mixed solution of MgSO4, NaHCO3 and K2SO4). The syringes are used for mineralization of water produced by orbital systems of electrochemical regeneration of air humidity condensate, and deionized or distilled water from other sources. The paper describes composition of resultant potable water and analyzes quality of irradiation sterilization and stability of concentrated salts inside the syringes irradiated on gamma-source RTs-100M.

This paper presents a method of assessment of radiation hazard for cosmonauts. The method is based on a new dosimetric function, which enables a complicated nature of space radiation exposure to be reduced to the condition of a standard irradiation on Earth. It can be obtained on the basis of mean-tissue absorbed dose values calculated for each space radiation source, and transmission coefficients. The transmission coefficients define relative biological effectiveness of radiation and assess the influence on the radiobiological effects of the complex spatial and temporal distribution of the absorbed dose in the cosmonaut's body. The combination of cosmic ionizing radiation with other non-radiation nature factors in flight can be accounted.

Slovak experiment Quail SK-6 aboard orbital station Mir in the period of February 20-27, 1999 resulted in hatching out of viable chicks of the Japanese quail. The paper presents morphologic results of investigation of m. gastrocnemius of the chicks after 4-5-d life in space microgravity. On the whole, histologically the gastrocnemius of the space chicks was very much similar to that of the control group. Muscular fibers were, which is typical, striated; bundles of myofibrills and numerous nuclei were on the periphery of the fiber under the sarcolemma. However, despite the similarity of the muscular histology, the chicks borne and exposed in microgravity displayed some deviations in the gastrocnemius as compared to their controls. Thus, Z-lines in some of the muscular fibers had a zigzag form or were doubled. In places, mitochondria were increased in size and lined up in chains longer than a sarcomere; internal membranes of the mitochondria were thickened and vacuolized, there were expanded tubules in the sarcotubular apparatus, and muscular fibers with multiple fatty vacuoles.

The paper describes the procedure of estimating total radiation risk to crewmembers during lifetime and possible lifetime reduction in consequence of participation in the Mir and ISS missions in different periods of the solar activity. The procedure includes analysis of data of vehicle and personal dosimetry, and calculations of radiation doses in various Mir compartments and accumulated by body tissues of cosmonauts. Calculated doses showed good consistency with the doses measured with R-16 on board Mir and personal dosimeters. To a first approximation, estimation of doses to cosmonauts and radiation risk as a result of participation in ISS missions took into account similarity of the Mir and ISS basal modules (geometry, dimensions and mass values) and was performed with the use of the space station shielding model that had been described elsewhere. The model of ISS radiation shielding will be updated as data of dosimetry of ISS compartments and phantom studies are available.

Analyzed were quantitative and qualitative characteristics, and processes of formation and transformation of microflora in the atmospheric humidity condensate (AHC) and potable water (PW) regenerated from the condensate by the long-operating system (SRV-K) aboard space station Mir. The paper presents data on species composition of microflora of AHC, and PW regenerated by SRV-K in the period from 1989 through to 1999. The following microbial species were identified in AHC: Alcaligenes (14.8%), Bacillus (3.7%), Citrobacter (7.4%), Clostridium (11.1%), Enterobacter (7.4%), Proteus (7.4%), Pseudomonas (18.5%), and Staphylococcus (100%). There were two PW cocks in SRV-K--"hot" and "cold". "Hot" PW microflora included Alcaligenes (15%), Bacillus (5%), Citrobacter (20%), Clostridium (5%), Enterobacter (15%), Proteus (10%), Pseudomonas (15%), and Staphylococcus (75%). "Cold" PW microflora included Aeromonas (14.3%), Alcaligenes (21.4%), Bacillus (7.1%), Citrobacter (7.1%), Clostridium (7.1%), Enterobacter (7.1%), Moraxella (7.1%), Pseudomonas (7.1%), and Staphylococcus (78.5%). Microbial content averaged 8.9 x 10(2) +/- 1.3 (0.01-4) x 10(3) CFU/ml in condensate and 1.5 +/- 0.1 (0-3.0) CFU/ml in regenerated potable water.

The paper describes the specific clinical/physiological symptoms of hypokinesia developing in bedrested female and male subjects. It was shown that hypokinesia calls forth a peculiar syndrome that substantially impairs human performance. Experimental and clinical data indicate that hypokinesia should be regarded as a serious risk factor stimulating pathological alterations in the visceral organs. Proceeding from this assumption, investigations along the line should be persevered in order to contribute to the general theory of key reactions of organism to hypokinesia, and search for preventive means and methods to be applied both to space medicine and public health.

The paper summarizes results of electro-oculography of all ways of visual tracking: fixative eye movements (saccades), smooth pursuit of linearly, pendulum-like and circularly moving point stimuli, pursuit of vertically moving foveoretinal optokinetic stimuli, and presents values of thresholds and amplification coefficients of the optokinetic nystagmus during tracking of linear movement of foveoretinal optokinetic stimuli. Investigations were performed aboard the Salyut and Mir space stations with participation of 31 cosmonauts of whom 27 made long-term (76 up to 438 day) and 4 made short-term (7 to 9 day) missions. It was shown that in space flight the saccadic structure within the tracking reaction does not change; yet, corrective movements (additional microsaccades to achieve tracking) appeared in 47% of observations at the onset and in 76% of observations on months 3 to 6 of space flight. After landing, the structure of vertical saccades was found altered in half the cosmonauts. No matter in or after flight, reverse nystagmus was present along with the gaze nystagmus during static saccades in 22% (7 cosmonauts) of the observations. Amplitude of tracking vertically, diagonally or circularly moving stimuli was significantly reduced as period on mission increased. Early in flight (40% of the cosmonauts) and shortly afterwards (21% of the cosmonauts) the structure of smooth tracking reaction was totally broken up, that is eye followed stimulus with micro- or macrosaccades. The structure of smooth eye tracking recovered on flight days 6-8 and on postflight days 3-4. However, in 46% of the cosmonauts on long-term missions the structure of smooth eye tracking was noted to be disturbed periodically, i.e. smooth tracking was replaced by saccadic.

The paper presents results of calculating mean daily values of absorbed and equivalent doses from galactic cosmic rays (GCR) and Earth's radiation belts (ERB) to crew members on orbital missions aboard Mir and the International space station during solar minimum and maximum. Calculated doses were corrected in accordance with the dosimetric and spectrometric data from Mir missions 18 through to 23 that took place in the period of solar minimum. Contribution of local and albedo neutrons to equivalent dose was also taken into account. Presented are calculated total radiation risk and tumor risk over life time for Mir and ISS crews following missions of varying duration, and predictions for reduction in life span in view of recent dosimetric data.

Subject of the paper is possibility to estimate radiation risk of determined consequences of exposure to solar space rays as a probability of violation of established dose limits. Analysis of specifies of spacecrew exposure to solar space rays in a long-term, particularly interplanetary mission suggests that immediate introduction of the principle in the radiation health policy can result in serious errors, mainly exaggeration, in determination of radiation risk. Proposed are approaches to radiation risk estimation with consideration of the specific of human exposure in space.

The progress of science and technology at the end of the XIXth and first half of the XXth century paved the way to start space exploration by humanity. The flight of Yu. A. Gagarin on April 12, 1961 was one of the history watersheds that had a great many of social implications. Piloted missions to space demonstrated the possibility for humans to adapt to the spaceflight factors which, nonetheless, can provoke various unfavorable reactions, particularly on return to Earth. Step-by-step extension of mission length paralleled enhancement of the methods of monitoring of crew health, life support systems, and development of modalities to maintain crew health and performance. The paper contains brief discussion of data acquired in short- and long-term missions including the 438-d mission of cosmonaut-physician V.V. Polyakov. The final section is devoted to the mainstream problems of future piloted space programs.

Results of the investigation of the interrelation between cosmonauts' erroneous actions and work and rest schedule intensity in fourteen long-duration Mir missions are presented in the paper. The statistical significance of this dependence has been established, and its nonlinear character has been revealed. An algorithm of short-range planning of crew operations has been developed based on determination of critical crew work loads deduced from increases in erroneous actions. Together with other methods the suggested approach may be used to raise cosmonauts' performance reliability.

The paper summarizes the main trends and milestones of space immunology starting with initial ground-based investigations with animals to recent experiments in piloted and automatic space vehicles data of which have been highlighted in numerous publications. There is a brief description of lines and results of investigations with participation of cosmonauts, and using laboratory animals and cell cultures. The author dwells upon the present-day notion of immune responses to extreme conditions and future topics of investigations.

Investigations conducted in and following space flights showed consistent decreases in cosmonauts' orthostatic stability due to the effects of long-term microgravity. Degree of this orthostatic disturbance depends on many factors prime of which is adequacy of countermeasures and least consequential is length of space flight, personal features, and others. Shifts in initial circulatory status and establishment of a new level of circulation and functioning of the other body systems in microgravity appear to play the central role in loss of orthostatic stability. The paper contains an in-depth analysis of processes occurring in human body during long-term stay in microgravity impacting orthostatic stability post flight.

The paper considers model concepts of cell blast-transformation and oncogenesis in humans consequent to ionizing irradiation with varying dose rates and lengths of exposure. Presented are data of epidemiologic studies of oncologic risks for different organs and body tissues at different ages in a year since exposure calculated per a unit of absorbed dose (1 cGy). Probability of tumor development in males of different age due to chronic irradiation of various lengths was determined per a dose unit. Based on these data and with regard for possible dose loads on interplanetary and orbital crews, oncologic risk for cosmonauts was calculated in terms of life time. The dependence of radiation-induced oncologic risks on type and duration of space mission, shielding thickness, and solar cycle was analyzed. The authors compare values of the total radiation risk and oncologic risk for cosmonauts launched at various ages.

The paper reports experimental data about the effects of operative memory restrictions on the indices of reliability of the visual identification of changes in external objects represented on the onboard visual indicator display. It was demonstrated that parallel piloting and visual tracking reduced the probability of identification of changes in two external objects up to 0.89 and deteriorated the ability to sustain the designated mode of piloting in six and more times. Two types of erroneous responses were delineated: overlooking changes in symbol-targets and false anxieties. Changes in the background symbols appeared to provoke false anxieties. The highest levels of reliability of eye tracking could be reached by changing color and/or contours of symbols-targets on the display.

The paper considers in retrospective the criteria of radiation hazard during space flight, and approaches to safeguarding the radiation safety to crew members adopted in a sequence of Russian and US standards defining the space radiation limits. Based on comparison of the magnitudes of radiation risk in space flight, total radiation risk over lifetime, the risk of fatal cancer, and risk relation to age, the most meaningful and age-independent criterion has been chosen to set limits and admissible total doses over cosmonaut's career. Justification is given to the range of these doses that still ensures socially acceptable levels of health and performance by the end of space career. Impliable dose limits for critical tissues (blood-forming organs, skin, lenticular epithelium) in consequence of a single acute or continuous exposure for a month, a year or career are discussed.

The paper describes an original methodology for evaluation of the radiation hazard to cosmonauts on mission based on generalized dose from ionizing radiations. This is a new dosimetric functional that allows convert the complex radiation of space to standard radiation. The conversion is achieved by calculation of mean tissue equivalent doses from each source of radiation hazard in space flight and scaling factors which take into account the radiobiological effect of intricate macrospatial and temporal dose distributions along the human body. Besides, consideration is given for the impact of non-radiation factors inherent to space flight. The generalized dose which is the dose from standard radiation inducing radiation damage similar to the multicomponent space radiation can be used to ascertain the character and degree of performance degradation, and radiation risk for cosmonauts both in and long after mission.

The paper presents results of project HUBES with 135-day simulation of the MIR mission by the European cosmonaut. The project was sponsored by the Long-Range Program Department/ESA Directorate of the Space Stations and Microgravity. Besides, ECOPSY-95 (90-day isolation and confinement) concerned with the human-environment interaction is featured.