Study of the radiation environment on MIR space station with SILEYE-2 experiment.

In this work we present preliminary results of nuclear composition measurements on board space station MIR obtained with SILEYE-2 particle telescope. SILEYE-2 was placed on MIR in 1997 and has been working since then. It consists of an array of 6 active silicon strip detectors which allow nuclear and energetic identification of cosmic rays in the energy range between approximately 30 and 200 MeV/n. The device is attached to an helmet and connected to an eye mask which shields the cosmonaut eyes from light and allow studies of the Light Flashes (LF) phenomenon. In addition to the study of the causes of LF, the device is used to perform real time long term radiation environment monitoring inside the MIR, performing measurements in solar quiet and active days.     

Biologically weighted measurement of UV radiation in space and on Earth with the biofilm technique.

Biological dosimetry has provided experimental proof of the high sensitivity of the biologically effective UVB doses to changes in atmospheric ozone and has thereby confirmed the predictions from model calculations. The biological UV dosimeter 'biofilm' whose sensitivity is based on dried spores of B. subtilis as UV target weights the incident UV radiation according to its DNA damaging potential. Biofilm dosimetry was applicated in space experiments as well as in use in remote areas on Earth. Examples are long-term UV measurements in Antarctica, measurements of diurnal UV profiles parallel in time at different locations in Europe, continuous UV measurements in the frame of the German UV measurement network and personal UV dosimetry. In space biofilms were used to determine the biological efficiency of the extraterrestrial solar UV, to simulate the effects of decreasing ozone concentrations and to determine the interaction of UVB and vitamin D production of cosmonauts in the MIR station.     

Main characteristics of biological components of developing life support system observed during the experiments aboard orbital complex MIR.

Since 1990, the orbital complex MIR has witnessed several incubator experiments for determination of spaceflight effects on embryogenesis of Japanese quail. First viable chicks who had completed the whole embryological cycle in MIR microgravity hatched out in 1990; it became clear that newborns would not be able to adapt to microgravity unaided. There were 8 successful incubations of chicks in the period from 1990 to 1999. In 1995-1997 the MIR-NASA space science program united Russian and US investigators. As a result, experiments Greenhouse-1 and 2 were performed with an effort to grow super dwarf wheat from seed to seed, and experiment Greenhouse-3 aimed at receiving two successive generations of Brassica rapa. But results of these experiments could not be used for definitive conclusions concerning effects of spaceflight on plant ontogenesis and, therefore, experiments Greenhouse-4 and 5 were staged within the framework of the Russian national space program. The experiments finally yielded wheat seeds. Some of the seeds was left on the space station and, being planted, gave viable seedlings which, in their turn, produced the second crop of space seeds.     

Pleurodeles waltl, amphibian, Urodele, is a suitable biological model for embryological and physiological space experiments on a vertebrate.

Pleurodeles waltl (amphibian, Urodele) is an appropriate biological model for space experiments on a vertebrate. One reason for interest in this animal concerns the study of the effects of absence of gravity on embryonic development. First, after mating (on Earth) the females retain live, functional sperm in their cloacum for up to 5 months, allowing normal in vivo fertilisation after hormonal stimulation. Second, their development is slow, which allows analyses of all the key stages of ontogenesis from the oocyte to swimming tailbud embryos or larvae. We have performed detailed studies and analyses of the effects of weightlessness on amphibian Pleurodeles embryos, fertilised and allowed to develop until the swimming larvae stage. These experiments were performed in space during three missions on the MIR-station: FERTILE I, FERTILE II and NEUROGENESIS respectively in 1996, 1998 and 1999. We show that in microgravity abnormalities appeared at specific stages of development compared to 1g-centrifuge control embryos and 1g-ground control embryos. In this report we describe abnormalities occurring in the central nervous system. These modifications occur during the neurulation process (delay in the closure of the neural tube and failure of closure of this tube in the cephalic area) and at the early tailbud stage (microcephaly observed in 40% of the microgravity-embryos). However, if acephalic and microcephalic embryos are not taken into account, these abnormalities did not disturb further morphological, biochemical and functional development and the embryos were able to regulate and a majority of normal hatching and swimming larvae were obtained in weightlessness with a developmental time-course equivalent to that of 1g-centrifuge control embryos (on the MIR station) and 1g-ground control embryos.     

Biological dosimetry to determine the UV radiation climate inside the MIR station and its role in vitamin D biosynthesis

The vitamin D synthesis in the human skin, is absolutely dependent on UVB radiation. Natural UVB from sunlight is normally absent in the closed environment of a space station like MIR. Therefore it was necessary to investigate the UV radiation climate inside the station resulting from different lamps as well as from occasional solar irradiation behind a UV-transparent quartz window. Biofilms, biologically weighting and integrating UV dosimeters successfully applied on Earth (e.g. in Antarctica) and in space (D-2, Biopan I) were used to determine the biological effectiveness of the UV radiation climate at different locations in the space station. Biofilms were also used to determine the personal UV dose of an individual cosmonaut. These UV data were correlated with the concentration of vitamin D in the cosmonaut's blood and the dietary vitamin D intake. The results showed that the UV radiation climate inside the Mir station is not sufficient for an adequate supply of vitamin D, which should therefore be secured either by vitamin D supplementat and/or by the regular exposure to special UV lamps like those in sun-beds. The use of natural solar UV radiation through the quartz window for ‘sunbathing’ is dangerous and should be avoided even for short exposure periods.     

The dose rate observed on 19-21 October 1989 and its modulation by geophysical effects.

The Liulin dosimeter-radiometer on the MIR space station detected the 19 October 1989 high energy solar proton event. These results show that the main particle increase contains protons with energies up to about 9 GeV. After the main particle onset the Liulin dosimeter observed a typical geomagnetic cutoff modulation of the dose rate from the solar particles as the MIR space station traversed magnetic latitudes. When the interplanetary shock and associated solar plasma enveloped the earth on 20 October between 14 and 17 UT the radiation exposure increased significantly due to the lowering of the geomagnetic cutoff. The analysis of this event shows how various geophysical phenomena can significantly modulate the dose rate encountered by earth-orbiting spacecraft.     

Behavior of Japanese tree frogs under microgravity on MIR and in parabolic flight.

Japanese tree frogs (Hyla japonica) were flown to the space station MIR and spent eight days in orbit during December, 1990. Under microgravity, their postures and behaviors were observed and recorded. On the MIR, floating frogs stretched four legs out, bent their bodies backward and expanded their abdomens. Frogs on a surface often bent their neck backward and walked backwards. This behavior was observed on parabolic flights and resembles the retching behavior of sick frogs on land--a possible indicator of motion sickness. Observations on MIR were carried out twice to investigate the frog's adaptation to space. The frequency of failure in landing after a jump decreased in the second observation period. After the frogs returned to earth, readaptation processes were observed. The frogs behaved normally as early as 2.5 hours after landing.     

Survival of microorganisms in space protected by meteorite material: results of the experiment 'EXOBIOLOGIE' of the PERSEUS mission.

During the early evolution of life on Earth, before the formation of a protective ozone layer in the atmosphere, high intensities of solar UV radiation of short wavelengths could reach the surface of the Earth. Today the full spectrum of solar UV radiation is only experienced in space, where other important space parameters influence survival and genetic stability additionally, like vacuum, cosmic radiation, temperature extremes, microgravity. To reach a better understanding of the processes leading to the origin, evolution and distribution of life we have performed space experiments with microorganisms. The ability of resistant life forms like bacterial spores to survive high doses of extraterrestrial solar UV alone or in combination with other space parameters, e.g. vacuum, was investigated. Extraterrestrial solar UV was found to have a thousand times higher biological effectiveness than UV radiation filtered by stratospheric ozone concentrations found today on Earth. The protective effects of anorganic substances like artificial or real meteorites were determined on the MIR station. In the experiment EXOBIOLOGIE of the French PERSEUS mission (1999) it was found that very thin layers of anorganic material did not protect spores against the deleterious effects of energy-rich UV radiation in space to the expected amount, but that layers of UV radiation inactivated spores serve as a UV-shield by themselves, so that a hypothetical interplanetary transfer of life by the transport of microorganisms inside rocks through the solar system cannot be excluded, but requires the shielding of a substantial mass of anorganic substances.     

Biological dosimetry in Russian and Italian astronauts.

Large uncertainties are associated with estimates of equivalent dose and cancer risk for crews of long-term space missions. Biological dosimetry in astronauts is emerging as a useful technique to compare predictions based on quality factors and risk coefficients with actual measurements of biological damage in-flight. In the present study, chromosomal aberrations were analyzed in one Italian and eight Russian cosmonauts following missions of different duration on the MIR and the international space station (ISS). We used the technique of fluorescence in situ hybridization (FISH) to visualize translocations in chromosomes 1 and 2. In some cases, an increase in chromosome damage was observed after flight, but no correlation could be found between chromosome damage and flight history, in terms of number of flights at the time of sampling, duration in space and extra-vehicular activity. Blood samples from one of the cosmonauts were exposed in vitro to 6 MeV X-rays both before and after the flight. An enhancement in radiosensitivity induced by the spaceflight was observed.     

Experimental investigations of quasistable radiation belts formed after solar proton events in September–October 1989 and March 1991 based on measurements made by “Liulin” dosimeter-radiometer on board the “MIR” space station

Since 1988 high sensitivity dosimeter-radiometer “Liulin” has been installed on board the MIR space station. Device measured absorbed dose rate and flux of penetrating particles. Results of measurements showed that after powerful solar proton events (SPE) September–October, 1989 and March, 1991 additional quasistable radiation belts were formed in the near earth space within the interval L=1.8−3.0. These “new” belts were observed as an additional maximums in flux (and sometimes dose) channels when crossing the SAA region. “New” belts were quasi stable and existed at least several months, decaying slightly after SPE. Dose to flux ratio analysis showed that major components of these belts were energetic electrons and protons arising in connection with preceding SPEs.     

Creation of biological module for self-regulating ecological system by the way of polymerization of composite materials in free space.

The large-size frame of space ship and space station can be created with the use of the technology of the polymerization of fiber-filled composites and a liquid reactionable matrix applied in free space or on the other space body when the space ship or space station will be used during a long period of time. For the polymerization of the station frame the fabric impregnated with a long-life polymer matrix (prepreg) is prepared in terrestrial conditions and, after folding, can be shipped in a compact container to orbit and kept folded on board the station. In due time the prepreg is carried out into free space and unfolded. Then a reaction of matrix polymerization starts. After reaction of polymerization the durable frame is ready for exploitation. After that, the frame can be filled out with air, the apparatus and life support systems. The technology can be used for creation of biological frame as element of self regulating ecological system, and for creation of technological frame which can be used for a production of new materials on Earth orbit in microgravity conditions and on other space bodies (Mars, Moon, asteroids) for unique high price mineral extraction. Based on such technology a future space base on Earth orbit with volume of 10(6) m3 and a crew of 100 astronauts is considered.     

Space experiment on behaviors of treefrog.

Japanese treefrogs (Hyla japonica) are planned to be sent to the space station MIR. Experimental system was developed to observe their behaviors under microgravity.     

空间增材制造技术的应用

中国空间站旨在进行大量在轨科学实验和空间应用研究,在轨保障是支持空间站在全寿命周期内完成载人航天任务的重要途径.传统地面制造及上行补给方式难以满足较大规模应用的需求,亟需一种创新性的保障模式突破资源瓶颈,空间增材制造技术具有极大的潜力实现即造即用的资源保障模式.本文根据空间增材制造技术的最新研究进展,结合中国空间站和载人深空探测任务需求,对空间增材制造技术的在轨应用模式进行分析,提出了中国空间增材制造技术未来发展所面临的问题和解决途径.      

First flight of the ASTROCULTURE (TM) experiment as a part of the U.S. Shuttle/MIR program.

A number of space-based experiments have been conducted to assess the impact of microgravity on plant growth and development. In general, these experiments did not identify any profound impact of microgravity on plant growth and development, though investigations to study seed development have indicated difficulty in plants completing their reproductive cycle. However, it was not clear whether the lack of seed production was due to gravity effects or some other environmental condition prevailing in the unit used for conducting the experiment. The ASTROCULTURE (TM) flight unit contains a totally enclosed plant chamber in which all the critically important environmental conditions are controlled. Normal wheat (Triticum aestivum L.) growth and development in the ASTROCULTURE (TM) flight unit was observed during a ground experiment conducted prior to the space experiment. Subsequent to the ground experiment, the flight unit was transported to MIR by STS-89, as part of the U.S. Shuttle/MIR program, in an attempt to determine if super dwarf wheat plants that were germinated in microgravity would grow normally and produce seeds. The experiment was initiated on-orbit after the flight unit was transferred from the Space Shuttle to MIR. The ASTROCULTURE (TM) flight unit performed nominally for the first 24 hours after the flight unit was activated, and then the unit stopped functioning abruptly. Since it was not possible to return the unit to nominal operation it was decided to terminate the experiment. On return of the flight unit, it was confirmed that the control computer of the ASTROCULTURE (TM) flight unit sustained a radiation hit that affected the control software embedded in the computer. This experience points out that at high orbital inclinations, such as that of MIR and that projected for the International Space Station, the danger of encountering harmful radiation effects are likely unless the electronic components of the flight hardware are resistant to such impacts.     

Large-size space laboratory for biological orbit experiments.

The study of space factors on living systems has great interest and long-term experiments during orbital flight will be important tool for increasing our knowledge. Realization of such experiments is limited by constraints of modern space stations. A new technology of large-size space laboratory for biological experiments has been developed on the basis of polymerization techniques. Using this technique there are no limits of form and size of laboratory for a space station that will permit long term experiments on Earth orbit with plants and animals in sufficient volume for creation of closed self-regulating ecological systems. The technology is based on experiments of the behavior of polymer materials in simulated free space conditions during the reaction of polymerization. The influences of space vacuum, sharp temperature changes and space plasma generated by galactic rays and Sun irradiation on chemical reaction were evaluated in their impact on liquid organic materials in laboratory conditions. The results of our study shows, that the chemical reaction is sensitive to such space factors. But we believe that the technology of polymerization could be used for the creation of space biological laboratories in Earth orbit in the near future.     

Applied potential tomography shows differential changes in fluid content of leg tissue layers in microgravity.

Absence of hydrostatic forces in the human cardiocirculatory system normally leads to an overall body fluid deficit. It was hypothesized that this is mainly due to a loss of interstitial fluid. An experiment was performed on board the Russian MIR station. Cuffs were positioned around both thighs and inflated up to suprasystolic values. This maneuver took place just before and after immediately a lower body negative pressure session (LBNP). The redistribution of fluids underneath the cuffs was assessed by means of cross-sectional impedance tomography (Applied Potential Tomography, APT). A microgravity induced loss of interstitial fluid was measured in all layers of the observed cross-section. The APT-readings changed significantly (SD approximately +/- .9) from 3.0 at 1g to 1.7 at 0g for the outer layer and from 2.7 at 1g to 2.0 at 0g for the middle layer (expressed in arbitrary units). The LBNP maneuver was able to fill the interstitial space but only at levels higher than -15 mmHg LBNP. This suggests that the superficial tissues in the legs are as much affected as the deeper ones by changing g-conditions and LBNP can be used to counteract interstitial fluid loss in this area.     

Interaction of growth-determining systems with gravity

The experiments have been carried out with lettuce shoots on board the Salyut-7 orbital station, the Kosmos-1667 biological satellite and under ground conditions at 180° plant inversion. By means of the centrifuge Biogravistat-1M the threshold value of gravitational sensitivity of lettuce shoots has been determined on board the Salyut-7 station. It was found to be equal to 2.9 × 10⁻³g for hypocotyls and 1.5 × 10⁻⁴g for roots. The following results have been received in the experiment performed on board the Kosmos-1667 satellite: a) under microgravity the proliferation of the meristem cells and the growth of roots did not differ from the control; b) the growth of hypocotyls in length was significantly enhanced in microgravity; c) under microgravity transverse growth of hypocotyls (increase in cross sectional area) was significantly increased due to enhancement of cortical parenchyma cell growth. At 180° inversion in Earth's gravity root extension growth and rate of cell division in the root apical meristem were decreased. The determination of DNA-fuchsin value in the nuclei of the cell root apexes showed that inversion affected processess of the cell cycle preceeding cytokinesis.     

The response of endocrine system to stress loads during space flight in human subject.

The responses of endocrine system to the exposure to stress-work load and hormonal changes during oral glucose tolerance tests were studied in the Slovak astronaut before (three weeks before flight), during (on the 4th and the 6th days of space flight), and after space flight (1-3 days and 15-17 days after space flight) on board of space station MIR. Blood samples during the tests were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Preflight workload produced an increase of plasma norepinephrine and a moderate elevation of epinephrine levels. Plasma levels of insulin, growth hormone, prolactin and cortisol were not markedly changed immediately or 10 min after the end of work load. The higher increases of plasma growth hormone, prolactin and catecholamine levels were noted after workload during space flight as compared to preflight response. The higher plasma glucose and insulin levels were noted during the oral glucose tolerance test in space flight and also in the post flight period. Plasma epinephrine levels were slightly decreasing during glucose tolerance test; however, plasma norepinephrine levels were not changed. The similar patterns of catecholamine levels during glucose tolerance test were found when compared the preflight, in-flight and post flight values. These data demonstrate the changes of the dynamic responses of endocrine system to stress-work and metabolic loads during space flight in human subject.     

The closed equilibrated biological aquatic system: a 12 months test of an artificial aquatic ecosystem.

The Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) is finally disposed for long-term multi-generation experiments with aquatic organisms in a space station. Therefore a minimum operation time of three months is required. It is verified in three versions of laboratory prototypes. The third one passed successfully a 12 months mid-term test in 1995/96 thus demonstrating its high biological stability. The third version of the C.E.B.A.S. consists of a 100 l animal tank, two plant cultivators with a volume of 15 l each with independent illuminations, a 3.0 l semibiological "mechanical" filter, a 3.0 l bacteria filter, a heating/cooling device and a dummy filter unit. The live-bearing teleost Xiphophorus helleri is the vertebrate and the pulmonate water snail Biomphalana glabrata the invertebrate experimental animal in the system. The rootless higher water plant Ceratophyllum demersum is the producer organism. Ammonia oxidizing bacteria and other microorganisms settle in the filters. A sample data acquisition is combined with temperature and plant illumination control. Besides of the space aspects the C.E.B.A.S. proved to be an extremely suitable tool to investigate the organism and subcomponent interactions in a well defined terrestrial aquatic closed ecosystem by providing physical, chemical and biological data which allow an approach to a comprehensive system analysis. Moreover the C.E.B.A.S. is the base for the development of innovative combined animal-plant aquaculture systems for human nutrition on earth which could be implemented into bioregenerative life support systems with a higher degree of complexity suitable for lunar or planetary bases.     

How human sleep in space--investigations during space flights.

Sleep problems have been observed during many of the space flights. The existence of poor quality of sleep, fatigue, insomnia or different alterations in sleep structure, organization and sleep cyclicity have been established. Nevertheless results obtained from investigations of human sleep on board manned space vehicles show that it is possible to keep sleep patterns related to the restorative and adaptive processes. For the first time in the frame of the "Intercosmos" program a multi-channel system for recording and analysis of sleep in space was constructed by scientists of the Bulgarian Academy of Sciences and was installed on board the manned Mir orbiting station. In 1988 during the joint Bulgarian-Russian space flight continues recording of electro-physiological parameters necessary to estimate the sleep stages and sleep organization was made. These investigations were continued in next space flights of different prolongation. The results were compared with the findings obtained under the conditions during the pre- and post-flight periods.