Space Microgravity Research Articles

Free Communication/Poster - Space Physiology and Microgravity

Free Communication/Poster - Space Physiology and Microgravity

Global Expression of Simulated Microgravity-Responsive Genes in Xenopus Liver Cells

The random positioning machine (RPM) is a method used to generate a simulated-microgravity environment at approximately 0 g. Using an RPM, we analyzed the global gene expression of A8 cells derived from the liver of adult Xenopus laevis. A range of genes on a Xenopus 44K-scale microarray were up- or downregulated two-fold or more: 43 genes (up, 36 genes; down, 7 genes) on culture day 5 in RPM, 74 genes (up, 48 genes; down, 26 genes) on day 8, 105 genes (up, 71 genes; down, 34 genes) on day 10, and 132 genes (up, 98 genes; down, 34 genes) on day 15. Five genes were upregulated two-fold or more throughout culturing in RPM, while only one gene was downregulated over the entire time. We then compared the expression patterns of the RPM-dependent genes in the A8 cells with those in A6 cells established from the kidney of adult Xenopus laevis. Six upregulated genes and three downregulated genes showed the same expression patterns throughout the culturing of A6 and A8 cells in RPM. Such globally responsive genes may play a common role in the cell response to simulated microgravity. We were particularly interested in the downregulation of SPARC in both cell types in RPM, which supported previous observations from simulated-microgravity experiments on earth or microgravity in space. We conclude that SPARC is plays a key role in the response of a cell to microgravity.

Free Communication/Poster - Space Physiology and Microgravity

Free Communication/Poster - Space Physiology and Microgravity

Development of an improved ground-based prototype of space plant-growing facility

Based on a formerly developed ground-based prototype of space plant-growing facility, the development of its improved prototype has been finished, so as to make its operating principle better adapt to the space microgravity environment. According to the developing experience of its first generation prototype and detailed demonstration and design of technique plan, its blueprint design and machining of related components, whole facility installment, debugging and trial operations were all done gradually. Its growing chamber contains a volume of about 0.5 m 3 and a growing area of approximate 0.5 m 2; the atmospheric environmental parameters in the growing chamber and water content in the growing media were controlled totally and effectively; lighting source is a combination of both red and blue light emitting diodes (LED). The following demonstrating results showed that the entire system design of the prototype is reasonable and its operating principle can nearly meet the requirements of space microgravity environment. Therefore, our plant-growing technique in space was advanced further, which laid an important foundation for next development of the space plant-growing facility and plant-cultivating experimental research in space microgravity condition.

Effects of lighting and air movement on temperatures in reproductive organs of plants in a closed plant growth facility

Temperature increases in plant reproductive organs such as anthers and stigmas could cause fertility impediments and thus produce sterile seeds under artificial lighting conditions without adequately controlled environments in closed plant growth facilities. There is a possibility such a situation could occur in Bioregenerative Life Support Systems under microgravity conditions in space because there will be little natural convective or thermal mixing. This study was conducted to determine the temperature of the plant reproductive organs as affected by illumination and air movement under normal gravitational forces on the earth and to make an estimation of the temperature increase in reproductive organs in closed plant growth facilities under microgravity in space. Thermal images of reproductive organs of rice and strawberry were captured using infrared thermography at air temperatures of 10–11 °C. Compared to the air temperature, temperatures of petals, stigmas and anthers of strawberry increased by 24, 22 and 14 °C, respectively, after 5 min of lighting at an irradiance of 160 W m −2 from incandescent lamps. Temperatures of reproductive organs and leaves of strawberry were significantly higher than those of rice. The temperatures of petals, stigmas, anthers and leaves of strawberry decreased by 13, 12, 13 and 14 °C, respectively, when the air velocity was increased from 0.1 to 1.0 ms −1. These results show that air movement is necessary to reduce the temperatures of plant reproductive organs in plant growth facilities.

Sleep under extreme environments: Effects of heat and cold exposure, altitude, hyperbaric pressure and microgravity in space

Human sleep is sensitive to the individual's environment. The present review examines current knowledge of human sleep patterns under different environments: heat exposure, cold exposure, altitude, high pressure and microgravity in space. Heat exposure has two effects. In people living in temperate conditions, moderate heat loads (hot bath, sauna) prior to sleep provoke a delayed reaction across time (diachronic reaction) whereby slow-wave sleep (SWS) augments in the following night (neurogenic adaptive pathway). Melanoids and Caucasians living in the Sahel dry tropical climate experience diachronic increases in SWS throughout seasonal acclimatization. Such increases are greater during the hot season, being further enhanced after daytime exercise. On the contrary, when subjects are acutely exposed to heat, diachronic decreases in total sleep time and SWS occur, being often accompanied by synchronic (concomitant) diminution in REM sleep. Stress hormones increase. Nocturnal cold exposure provokes a synchronic decrease in REM sleep along with an activation of stress hormones (synchronic somatic reaction). SWS remains undisturbed as it still occurs at the beginning of the night before nocturnal body cooling. Altitude and high pressure are deleterious to sleep, especially in non-acclimatized individuals. In their controlled environment, astronauts can sleep well in microgravity. Exercise-induced sleep changes help to understand environmental effects on sleep: well-tolerated environmental strains may improve sleep through a neurogenic adaptive pathway; when this "central" adaptive pathway is overloaded or bypassed, diachronic and synchronic sleep disruptions occur.

Free Communication/Poster - Space Physiology and Microgravity

Free Communication/Poster - Space Physiology and Microgravity

Experimental Examination of the Motion of a Tethered System with Large Deformation and Large Displacement

In this paper, experiments on the motion of a tethered system with large deformation and large displacement are discussed. A tethered subsatellite in space environment is a well-known example of this system. However, even fundamental experiments on the motion of the tethered system have not been conducted. Also, from the viewpoint of flexible multibody dynamics, it is expected that simple experiments for the motion of a very flexible body should be completed first in order to verify the validity of the proposed approach. In this study, the tethered system consists of a very flexible body and a rigid body. First, we conducted an experiment on the fundamental motion of a very flexible body with an attached mass in gravity space. We selected steel and rubber as tether materials. In the experimental results, the characteristics of the complex motion of a very flexible body were obtained. Second, an experiment in microgravity space was done. The coupled motion between the very flexible body and rigid body was investigated. It was verified that the motion of the system with large deformation is excited in microgravity space, and there is the coupling motion between the deflection of the very flexible body and the rotation of the rigid body.

The Outline and Significance of the Resist Wall Experiment: Role of Microtubule-Membrane-Cell Wall Continuum in Gravity Resistance in Plants

Resistance to the gravitational force is one of two major graviresponses in plants. However, only limited information has been obtained for its mechanism. The Resist Wall experiment aims to examine the role of the cortical microtubule-plasma membrane-cell wall continuum in gravity resistance, thereby clarifying its mechanism. For this purpose, we will cultivate Arabidopsis mutants defective in organization of cortical microtubules (tua6) or synthesis of membrane sterols (hmg1) as well as the wild type Columbia under microgravity and 1G conditions in the European Modular Cultivation System on the International Space Station up to reproductive stage, and compare phenotypes on growth and development using video images. These mutants are unable to form the normal cell wall and show disordered growth pattern on Earth. However, it is expected that the defects of such mutants are rescued and they can grow and develop more or less normally under microgravity in space, where formation of the tough cell wall is not required. We will also analyze changes in expression of genes involved in formation of the continuum and properties of related cellular components under microgravity conditions. The results of the Resist Wall experiment will clarify the molecular mechanism of gravity resistance and benefit efficient plant production not only in space but on Earth.

SELF-ORGANIZATION AND NONEQUILIBRIUM AGGREGATION PHENOMENA IN COLLOIDAL MATTER: WHY MICROGRAVITY MATTERS

The relevance of self-organization, nonlinear phenomena and nonequilibrium behavior in a wide range of problems in space science and microgravity research, calls for a concerted approach using the tools of statistical physics, thermodynamics, nonlinear dynamics, mathematical modeling and numerical simulation, in synergy with experimentally oriented work.The reason behind the ubiquity of such concepts is that in many instances of relevance in space science one witnesses an interplay between molecular and macroscopic-level entities and processes, such as nucleation in phase transitions or aggregation and self-assembly in materials science and biology. These phenomena are fundamentally dynamic in nature. We present two minimal models one dealing with issues of complex behavior at the microscopic level and the second referring to the strong nonlinear nature of macroscopic evolution, relevant to soft-condensed matter under observation both on the ground and in microgravity conditions.These investigations open the way to a whole class of unexpected situations whose proper characterization and control can only be expected in the framework of nonequilibrium physics and complexity theory.

Free Communication/Poster – Space Physiology and Microgravity

Free Communication/Poster – Space Physiology and Microgravity

Effects of microgravity on cell cytoskeleton and embryogenesis

The aim of this review is to compile, summarize and discuss the effects of microgravity on embryos, cell structure and function that have been demonstrated from data obtained during experiments performed in space or in altered gravity induced by clinostats. In cells and tissues cellular structure and genetic expression may be changed in microgravity and this has a variety of effects on embryogenesis which include death of the embryo, failure of neural tube closure, or final deformities to the overall morphology of the newborn or hatchling. Many species and protocols have been used for microgravity space experiments making it difficult to compare results. Experiments on the ways in which embryonic development and cell interactions occur in microgravity could also be performed. Experiments that have been done with cells in microgravity show changes in morphology, cytoskeleton and function. Changes in cytoskeleton have been noted and studies on microtubules in gravity have shown that they are gravity sensitive. Further study of basic chemical reactions that occur in cells should be done to shed some light on the underling processes leading to the changes that are observed in cells and embryos in microgravity.

The SOS-LUX-TOXICITY-Test on the International Space Station

For the safety of astronauts and to ensure the stability and integrity of the genome of microorganisms and plants used in bioregenerative life support systems, it is important to improve our knowledge of the combined action of (space) radiation and microgravity. The SOS-LUX-TOXICITY test, as part of the TRIPLE-LUX project (accepted for flight at Biolab in Columbus on the International Space Station, (ISS)), will provide an estimation of the health risk resulting from exposure of astronauts to the radiation environment of space in microgravity. The project will: (i) increase our knowledge of biological/health threatening action of space radiation and enzymatic DNA repair; (ii) uncover cellular mechanisms of synergistic interaction of microgravity and space radiation; (iii) provide specified biosensors for spacecraft milieu examination; and (iv) provide experimental data on stability and integrity of bacterial DNA in spacecrafts. In the bacterial biosensor “SOS-LUX-Test” developed at DLR (patent), bacteria are transformed with the pBR322-derived plasmid pPLS-1 or the similar, advanced plasmid SWITCH, both carrying the promoterless lux operon of Photobacterium leiognathi as the reporter element controlled by a DNA damage-dependent SOS promoter as sensor element. A short description of the space experiment is given, and the current status of adaptation of the SOS-LUX-Test to the ISS, i.e. first results of sterilization, biocompatibility and functional tests performed with the already available hardware and bread board model of the automated space hardware under development, is described here.

Experimental Examination of the Motion of a Tethered System with Large Deformation and Large Displacement

In this paper, experiments on the motion of a tethered system with large deformation and large displacement are discussed. A tethered subsatellite in space environment is a well-known example of this system. However, even fundamental experiments on the motion of the tethered system have not been conducted. Also, from the viewpoint of flexible multibody dynamics, it is expected that simple experiments for the motion of a very flexible body should be completed first in order to verify the validity of the proposed approach. In this study, the tethered system consists of a very flexible body and a rigid body. First, we conducted an experiment on the fundamental motion of a very flexible body with an attached mass in gravity space. We selected steel and rubber as tether materials. In the experimental results, the characteristics of the complex motion of a very flexible body were obtained. Second, an experiment in microgravity space was done. The coupled motion between the very flexible body and rigid body was investigated. It was verified that the motion of the system with large deformation is excited in microgravity space, and there is the coupling motion between the deflection of the very flexible body and the rotation of the rigid body.

Motion sickness is linked to nystagmus-related trigeminal brain stem input: a new hypothesis

Motion sickness is a common and distressing but poorly understood syndrome associated with nausea/vomiting and autonomic nervous system accompaniments that develops in the air or space as well as on sea or land. A bidirectional aetiologic link prevails between migraine and motion-sickness. Motion sickness provokes jerk nystagmus induced by both optokinetic and vestibular stimulation. Fixation of gaze or closure of eyes generally prevents motion sickness while vestibular otolithic function is eliminated in microgravity of space, indicating a predominant pathogenetic role for visuo-sensory input. Scopolamine, dimenhydrinate, and promethazine reduce motion-related nystagmus. Contraction of extraocular muscles generates proprioceptive neural traffic and can provoke an ocular hypertensive response. It is proposed that repetitive contractions of the extraocular muscles during motion-related jerk nystagmus rapidly augment brain stem afferent input by increasing proprioceptive neural traffic through connections of the oculomotor nerves with the ophthalmic nerve in the lateral wall of the cavernous sinus as well as by raising the intraocular pressure thereby stimulating anterior segment ocular trigeminal nerve fibers. This verifiable hypothesis defines the pathophysiological basis of individual susceptibility to motion sickness, elucidates the preventive mechanism of gaze fixation or ocular closure, advances the aetiologic link between MS and migraine, rationalizes the mechanism of known preventive drugs, and explores new therapeutic possibilities.

426 微小重力下における,大変形,大変位を伴うテザードシステムの運動に関する研究

In this paper we discuss the motion of a tethered system. We considered the tethered system consisting of a very flexible body (the tether) and rigid bodies at one end as our analytical model. A flexible body in planer motion is described using the Absolute Nodal Coordinate Formulation. The combination of flexible body motion and rigid body motion is performed and interaction between them is discussed. We performed experiments to investigate the fundamental motion of the tethered system and to evaluate the validity of the numerical formulation. We conducted experiment of the motion of the tethered system with a rigid body in microgravity space. The numerical solutions using the proposed methods for modeling and formulation for the tethered system are in good agreement with the experimental results.

宇宙環境利用と微小重力実験における可視化の歩み

宇宙環境利用と微小重力実験における可視化の歩み

Role and Regulation of σ s in General Resistance Conferred by Low-Shear Simulated Microgravity in Escherichia coli

Life on Earth evolved in the presence of gravity, and thus it is of interest from the perspective of space exploration to determine if diminished gravity affects biological processes. Cultivation of Escherichia coli under low-shear simulated microgravity (SMG) conditions resulted in enhanced stress resistance in both exponential- and stationary-phase cells, making the latter superresistant. Given that microgravity of space and SMG also compromise human immune response, this phenomenon constitutes a potential threat to astronauts. As low-shear environments are encountered by pathogens on Earth as well, SMG-conferred resistance is also relevant to controlling infectious disease on this planet. The SMG effect resembles the general stress response on Earth, which makes bacteria resistant to multiple stresses; this response is sigma s dependent, irrespective of the growth phase. However, SMG-induced increased resistance was dependent on sigma s only in stationary phase, being independent of this sigma factor in exponential phase. sigma s concentration was some 30% lower in exponential-phase SMG cells than in normal gravity cells but was twofold higher in stationary-phase SMG cells. While SMG affected sigma s synthesis at all levels of control, the main reasons for the differential effect of this gravity condition on sigma s levels were that it rendered the sigma protein less stable in exponential phase and increased rpoS mRNA translational efficiency. Since sigma s regulatory processes are influenced by mRNA and protein-folding patterns, the data suggest that SMG may affect these configurations.

Space Robotics

In this second of three short papers, I introduce some of the basic concepts of space robotics with an emphasis on some specific challenging areas of research that are peculiar to the application of robotics to space infrastructure development. The style of these short papers is pedagogical and the concepts in this paper are developed from fundamental manipulator robotics. This second paper considers the application of space manipulators to on-orbit servicing (OOS), an application which has considerable commercial application. I provide some background to the notion of robotic on-orbit servicing and explore how manipulator control algorithms may be modified to accommodate space manipulators which operate in the micro-gravity of space.

Human Visual Perception under Altered Gravity Environment

Eye movements have been studied in a Japanese Spacelab payload specialist carrying out a visual task on earth (1g gravity) before and after a space flight. The experiment was repeated in space (microgravity) using the same subject. In addition to eye movements, EMG activity of the trapezius muscle was recorded while performing the visual task in space. Results show that eye movements are not affected by variations in gravity. The EMG activity of the trapezius muscle recorded during the visual task in space was found to depart from the EMG activity such as present under everyday conditions on earth.