Periods Of Microgravity Research Articles

The NATO project: nanoparticle-based countermeasures for microgravity-induced osteoporosis

Recent advances in nanotechnology applied to medicine and regenerative medicine have an enormous and unexploited potential for future space and terrestrial medical applications. The Nanoparticles and Osteoporosis (NATO) project aimed to develop innovative countermeasures for secondary osteoporosis affecting astronauts after prolonged periods in space microgravity. Calcium- and Strontium-containing hydroxyapatite nanoparticles (nCa-HAP and nSr-HAP, respectively) were previously developed and chemically characterized. This study constitutes the first investigation of the effect of the exogenous addition of nCa-HAP and nSr-HAP on bone remodeling in gravity (1 g), Random Positioning Machine (RPM) and onboard International Space Station (ISS) using human bone marrow mesenchymal stem cells (hBMMSCs). In 1 g conditions, nSr-HAP accelerated and improved the commitment of cells to differentiate towards osteoblasts, as shown by the augmented alkaline phosphatase (ALP) activity and the up-regulation of the expression of bone marker genes, supporting the increased extracellular bone matrix deposition and mineralization. The nSr-HAP treatment exerted a protective effect on the microgravity-induced reduction of ALP activity in RPM samples, and a promoting effect on the deposition of hydroxyapatite crystals in either ISS or 1 g samples. The results indicate the exogenous addition of nSr-HAP could be potentially used to deliver Sr to bone tissue and promote its regeneration, as component of bone substitute synthetic materials and additive for pharmaceutical preparation or food supplementary for systemic distribution.

Is oral health affected in long period space missions only by microgravity? A systematic review

BackgroundSince the starting of Space Age astronaut's health has been a subject of the utmost importance. To date, numerous studies describe the effect of microgravity on the body health of the astronauts. Some of these studies analyzed dental diseases and were conducted in conditions of microgravity and simulated microgravity, during short or long periods. Taking into account the increase of long space missions, it is necessary to systematically review the oral health events related with short and long periods spent in space missions with all the available evidence. MethodsTo identify all relevant oral diseases attributed to the effects of microgravity, we performed a rigorous systematic review regarding the published articles regarding microgravity and dental diseases from 1969 to 2018. Databases such as Pubmed, Cochrane, Scielo, Google Scholar and the NASA were consulted. Additional studies from the reference lists of the selected articles were included in order to get a greater complete overview. Ten scientific documents (containing 12 studies) with a direct relation with oral/dental health and microgravity were assessed. ResultsFive studies about short period missions (≤30 days) were included. The studies showed increases of cortisol as well as salivary immunoglobulin A (IgA) and salivary IgG. Seven studies about long period missions (>30–220 days) were included, and the more important fact retrieved was the increase of anaerobic bacteriae. ConclusionFuture long-term missions to Mars or to space stations will require 18–24 months of exposure to microgravity, that, added to other conditions, could have potentially deleterious effects on human physiology, including oral health. Preventive measures, adequate material and training of the crew have to be applied to avoid an oral health event to jeopardize the mission.

Skeletal adaptations in young male mice after 4 weeks aboard the International Space Station

Gravity has an important role in both the development and maintenance of bone mass. This is most evident in the rapid and intense bone loss observed in both humans and animals exposed to extended periods of microgravity in spaceflight. Here, cohabitating 9-week-old male C57BL/6 mice resided in spaceflight for ~4 weeks. A skeletal survey of these mice was compared to both habitat matched ground controls to determine the effects of microgravity and baseline samples in order to determine the effects of skeletal maturation on the resulting phenotype. We hypothesized that weight-bearing bones would experience an accelerated loss of bone mass compared to non-weight-bearing bones, and that spaceflight would also inhibit skeletal maturation in male mice. As expected, spaceflight had major negative effects on trabecular bone mass of the following weight-bearing bones: femur, tibia, and vertebrae. Interestingly, as opposed to the bone loss traditionally characterized for most weight-bearing skeletal compartments, the effects of spaceflight on the ribs and sternum resembled a failure to accumulate bone mass. Our study further adds to the insight that gravity has site-specific influences on the skeleton.

Comparisons of Resistance Training and "Cardio" Exercise Modalities as Countermeasures to Microgravity-Induced Physical Deconditioning: New Perspectives and Lessons Learned From Terrestrial Studies.

Prolonged periods in microgravity (μG) environments result in deconditioning of numerous physiological systems, particularly muscle at molecular, single fiber, and whole muscle levels. This deconditioning leads to loss of strength and cardiorespiratory fitness. Loading muscle produces mechanical tension with resultant mechanotransduction initiating molecular signaling that stimulates adaptations in muscle. Exercise can reverse deconditioning resultant from phases of detraining, de-loading, or immobilization. On Earth, applications of loading using exercise models are common, as well as in μG settings as countermeasures to deconditioning. The primary modalities include, but are not limited to, aerobic training (or “cardio”) and resistance training, and have historically been dichotomized; the former primarily thought to improve cardiorespiratory fitness, and the latter primarily improving strength and muscle size. However, recent work questions this dichotomy, suggesting adaptations to loading through exercise are affected by intensity of effort independent of modality. Furthermore, similar adaptations may occur where sufficient intensity of effort is used. Traditional countermeasures for μG-induced deconditioning have focused upon engineering-based solutions to enable application of traditional models of exercise. Yet, contemporary developments in understanding of the applications, and subsequent adaptations, to exercise induced muscular loading in terrestrial settings have advanced such in recent years that it may be appropriate to revisit the evidence to inform how exercise can used in μG. With the planned decommissioning of the International Space Station as early as 2024 and future goals of manned moon and Mars missions, efficiency of resources must be prioritized. Engineering-based solutions to apply exercise modalities inevitably present issues relating to devices mass, size, energy use, heat production, and ultimately cost. It is necessary to identify exercise countermeasures to combat deconditioning while limiting these issues. As such, this brief narrative review considers recent developments in our understanding of skeletal muscle adaptation to loading through exercise from studies conducted in terrestrial settings, and their applications in μG environments. We consider the role of intensity of effort, comparisons of exercise modalities, the need for concurrent exercise approaches, and other issues often not considered in terrestrial exercise studies but are of concern in μG environments (i.e., O2 consumption, CO2 production, and energy costs of exercise).

Thermo-Hydraulic Analysis of Semi-Transparent Flat Plate Pulsating Heat Pipes Tested in 1 g and Microgravity Conditions

Four Closed-Loop Flat Plate Pulsating Heat Pipes (FPPHP) with four different channel internal diameters have been tested under terrestrial (1 g), hyper (1.8-2 g) and micro-gravity conditions, during the ESA 64th Parabolic Flight campaign, at the same operating conditions (heat power range, cooling fluid temperature, vertical BHM orientation). During terrestrial gravity periods, the fluid stratifies with the liquid at the bottom of the system, and, in the lower part of the channels, where the heat is applied (Bottom Heated Mode), the thermo-hydraulic heat and mass transfer mode is purely linked to pool boiling, regardless the diameter. Instead, during microgravity periods, the fluid circulates naturally into a slug and plug flow pattern regime. Dry-out phenomena occur almost immediately after the change in gravity level followed by a fast motion of the liquid plugs, promoting a mass transfer through all PHP channels. A comparative analysis of the evaporator temperatures and the menisci velocities obtained through video post-processing, shows the influence of the channel diameter on the heat and mass transfers occurring inside the different PHPs. A quantitative comparison of the FPPHP thermal performance shows that, during microgravity transient phases, there is a limit of the channel diameter beyond which the thermal performances does not increase anymore, despite the decrease in viscous pressure losses.

Start-up in microgravity and local thermodynamic states of a hybrid loop thermosyphon/pulsating heat pipe

A wickless passive two phase closed loop heat transfer device especially designed for a future implementation on the heat transfer host module of the International Space Station is tested in relevant environment on board a parabolic flight. The tube internal diameter (3 mm) is larger than the static capillary threshold evaluated in normal gravity for this working fluid (FC-72), leading the device to work as a loop thermosyphon on ground and in hyper-gravity conditions, and as a Pulsating Heat Pipe when micro-gravity occurs. Novel start up tests, where the heat load has been provided after the occurrence of microgravity, show that the 20 s microgravity period is enough for the device activation and, most important, that the device activation is purely thermally induced and not affected by the previous acceleration field. Two miniaturized pressure transducers and direct fluid temperature measurement via two micro-thermocouples, allow to provide a detailed insight on the fluid local thermodynamics states both in the evaporator and in the condenser zone during microgravity. It is shown that the two-phase fluid close to the evaporator and the condenser is subjected to several degrees (up to 5 K) of superheating or subcooling. The level of subcooling seems to increase with the heat input level both in terms of temperature difference and in terms of percentage time with respect to the whole microgravity period.

Neurocognitive performance is enhanced during short periods of microgravity—Part 2

Previous studies showed a decrease in reaction time during the weightlessness phase of a parabolic flight. This effect was found to be stronger with increasing task complexity and was independent of previous experience of weightlessness as well as anti-nausea medication. Analysis of event related potentials showed a decreased amplitude of the N100-P200 complex in weightlessness but was not able to distinguish a possible effect of task complexity.The present study aimed to extend this previous work, by comparing behavioral (reaction time) and neurological (event related potentials analysis) performance to a simple (oddball) and a complex (mental arithmetic + oddball) task during weightlessness.28 participants participated in two experiments. 11 participants performed a simple oddball experiment in the 1G and 0G phases of a parabolic flight. 17 participants were presented a complex arithmetic task in combination with an oddball task during the 1G and 0G phases of a parabolic flight. Reaction time as well as event related potentials (ERP) were assessed.Results revealed a reduced reaction time (p < .05) for the complex task during 0G. No gravity effects on reaction time were found for the simple task. In both experiments a reduction of typical ERP amplitudes was noticeable in weightlessness.It is assumed that the weightlessness induced fluid shift to the brain is positively affecting neuro-behavioral performance.

Start-Up and Operation of a 3D Hybrid Pulsating Heat Pipe on Board a Sounding Rocket

A large tube may still behave, to a certain extent, as a capillary in a micro-gravity environment. This very basic concept is here applied to a two-phase passive heat transfer device to obtain a new family of hybrid wickless heat pipes. Indeed, a Loop Thermosyphon, which usually consists of a large tube, closed end to end in a loop, evacuated and partially filled with a working fluid and intrinsically gravity assisted, may become a capillary tube in space condition and turn its thermo-fluidic behavior into a Pulsating Heat Pipe. This work presents the results obtained on such a hybrid device heated at 200 W both on board a sounding rocket (ESA REXUS 22, microgravity period ~120 s), and on ground in vertical and anti-gravity orientation. Since no steady state occurred in microgravity conditions, the comparison between flight and ground data focuses on the startup phenomenon, whereas the thorough ground test campaign describes the limits and performances of the device working in thermosyphon mode. The expected thermal behavior in microgravity conditions is between that of a purely conductive tube in anti-gravity conditions on ground and that of a gravity assisted thermosyphon. Since a microgravity period of approximately 120 s is not enough to reach a pseudo steady state regime, further investigation on a longer-term weightless condition is mandatory.

Visualization of Flow Patterns in Closed Loop Flat Plate Pulsating Heat Pipe Acting as Hybrid Thermosyphons under Various Gravity Levels

ABSTRACTA particular flat plate pulsating heat pipe (FPPHP), filled with FC72, is tested during the 62th and 64th ESA parabolic flight campaigns under vertical orientation. The FPPHP is made of a thin copper plate, in which a curved channel disposed with 11 U-turns is milled and closed on the top face by a transparent borosilicate plate. The particular characteristics is that the equivalent hydraulic diameter of the square channel (2.5 × 2.5 mm²) is above the working fluid capillary diameter on ground, inducing a stratification of the liquid/vapor phases under ground and hyper-gravity conditions, whatever the orientation. The energy transfer mode in such conditions is represented either by pure pool boiling inside the channels almost completely filled by the liquid phase or by an annular flow pattern inside the channels mostly filled by the refrigerant vapor. Instead, during the microgravity phases, the fluid regime naturally turns into a slug-plug flow pattern. During the transition from 1.8 g to 0 g a rapid dry-out may occur in some of the channels, followed by a similarly fast reaction of liquid plugs moving towards the evaporator from the condenser zone. Such stop-and-start motion events continue during the whole microgravity period, leading to strong temperature oscillations, but also to a still acceptable thermal performance of the device.

ISOLATION, SLEEP, COGNITION AND NEUROPHYSIOLOGICAL RESPONSES – AN INVESTIOGATION IN THE HUMAN EXPLORATION RESEARCH ANALOG (HERA)

ISOLATION, SLEEP, COGNITION AND NEUROPHYSIOLOGICAL RESPONSES – AN INVESTIOGATION IN THE HUMAN EXPLORATION RESEARCH ANALOG (HERA)

Analysis of Vibratory Data Collected by the Space Acceleration Measurement System (SAMS) on Blue Origin, June 19, 2016

Abstract On Sunday, June 19, 2016, a Space Acceleration Measurement System triaxial sensor head flew on a suborbital flight aboard Blue Origin's New Shepard vehicle to collect precision vibratory accelerometry data. The Space Acceleration Measurement System (SAMS) sensor head was mounted inside of a Blue Origin single payload locker inside of the crew capsule. This paper describes the configuration, capture, and analysis of the SAMS data from this flight along with other, related flight log information provided by Blue Origin. Three overlapping periods during the flight were identified and characterized to provide future users of the platform with insight into options that may prove suitable for their research needs. Average accelerations in the Post-Separation Period were consistent with other low-g research platforms, while the shorter Microgravity Period in the middle of the flight showed ultra-quiet vibratory acceleration environments. Researchers can consider this microgravity quality versus time a tradeoff in their experimental designs.

Intracranial pressure-induced optic nerve sheath response as a predictive biomarker for optic disc edema in astronauts.

A significant proportion of the astronauts who spend extended periods in microgravity develop ophthalmic abnormalities. Understanding this syndrome, called visual impairment and intracranial pressure (VIIP), has become a high priority for National Aeronautics and Space Administration, especially in view of future long-duration missions (e.g., Mars missions). Moreover, to ensure selection of astronaut candidates who will be able to complete long-duration missions with low risk of the VIIP syndrome, it is imperative to identify biomarkers for VIIP risk prediction. Here, we hypothesize that the optic nerve sheath response to alterations in intracranial pressure may be a potential predictive biomarker for optic disc edema in astronauts. If confirmed, this biomarker could be used for preflight identification of astronauts at risk for developing VIIP-associated optic disc edema.

Effect of gravity and microgravity on intracranial pressure.

Astronauts have recently been discovered to have impaired vision, with a presentation that resembles syndromes of elevated intracranial pressure on Earth. Gravity has a profound effect on fluid distribution and pressure within the human circulation. In contrast to prevailing theory, we observed that microgravity reduces central venous and intracranial pressure. This being said, intracranial pressure is not reduced to the levels observed in the 90deg seated upright posture on Earth. Thus, over 24h in zero gravity, pressure in the brain is slightly above that observed on Earth, which may explain remodelling of the eye in astronauts. Astronauts have recently been discovered to have impaired vision, with a presentation that resembles syndromes of elevated intracranial pressure (ICP). This syndrome is considered the most mission-critical medical problem identified in the past decade of manned spaceflight. We recruited five men and three women who had an Ommaya reservoir inserted for the delivery of prophylactic CNS chemotherapy, but were free of their malignant disease for at least 1year. ICP was assessed by placing a fluid-filled 25 gauge butterfly needle into the Ommaya reservoir. Subjects were studied in the upright and supine position, during acute zero gravity (parabolic flight) and prolonged simulated microgravity (6deg head-down tilt bedrest). ICP was lower when seated in the 90deg upright posture compared to lying supine (seated, 4±1 vs. supine, 15±2mmHg). Whilst lying in the supine posture, central venous pressure (supine, 7±3 vs. microgravity, 4±2mmHg) and ICP (supine, 17±2 vs. microgravity, 13±2mmHg) were reduced in acute zero gravity, although not to the levels observed in the 90deg seated upright posture on Earth. Prolonged periods of simulated microgravity did not cause progressive elevations in ICP (supine, 15±2vs. 24h head-down tilt, 15±4mmHg). Complete removal of gravity does not pathologically elevate ICP but does prevent the normal lowering of ICP when upright. These findings suggest the human brain is protected by the daily circadian cycles in regional ICPs, without which pathology may occur.

Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5–6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g), hypergravity (1.8 g), and normal gravity (1 g). Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

Neuro-Cognitive Performance Is Enhanced During Short Periods Of Microgravity

Neuro-Cognitive Performance Is Enhanced During Short Periods Of Microgravity

Experimental investigation of liquid retention in a cyclone evaporator under variable gravity conditions

For the first time a cyclone evaporator has been designed and tested with perfectly wetting liquids in two separate experiments on condensation, at variable gravity conditions during parabolic flights. Two liquids (FC-72 and HFE-7100), with surface tension coefficient of 12–15 mN/m, were used in the experiments. The concept of the liquid retention by the centrifugal force and the specific design of the walls were validated in the first series of experiments in isothermal conditions. The liquid behaviour inside the experimental cell in weightlessness is reported and discussed for the variable liquid volume (100–200 ml) inside the cell and the rotating velocity of the magnetic stirrer inside the evaporator (0–900 rpm). The data obtained during the isothermal case were used to improve the design of the evaporation cell for the non-isothermal case, tested during a second parabolic flight campaign. In this second experiment, both the power (1.8–16 W) and rotational velocity of the magnetic stirrer (0–250 rpm) were varied. For a fluid charge of 100 ml the same fluid never left the evaporator in all tests performed with rotation of the magnetic stirrer. The vapour pressure in the cell increased during microgravity period. It was found that the stabilization of vapour pressure after transition to microgravity decreases with an increase in the rotational speed of the magnetic stirrer. We conclude that the cyclone evaporator is also an ideal candidate for those systems that have to work in microgravity and rely on pool boiling, because the cyclone chops large bubbles that would otherwise occupy the whole evaporator space and reduce the heat-transfer rate.

微小重力場における被覆導線の過電流連続通電時の着火限界に関する数値的検討

Ignition limits (limiting current value) of insulated electric wire with continuous current supply under microgravity was studied with numerical method. From previous study, we mentioned that results of ignition limits obtained by microgravity experiments are limited by microgravity period (20 s). Then in present work, we conducted numerical analysis to find limiting current values without the effect of microgravity period. As a result, a limiting current value by numerical calculation are lower than that by microgravity experiments. In addition to that, we discussed a mechanism to decide limiting current values with numerical analysis. Results of numerical analysis indicated that limiting current values could be determined by exhaustion of insulation. After all of the insulation was thermally decomposed and gasified, air which was removed near the wire surface by fuel gas diffused back towards wire surface. This leaded to increase in heat release rate near the wire surface. On the other hand, such inflow of air removes fuel gas from near the surface. When current value was higher than a limiting current value, heat release rate can increase enough to cause ignition even though fuel concentration near the wire surface decreased. Thus it was mentioned a possibility that amount of insulation, which controlled air diffusing, could decide limiting current values. Therefore, numerical calculation for thicker insulation cases were also conducted. The numerical results showed thicker insulation caused ignition with lower current values. This indicated that ignition limits could be dominated by thickness of insulation.

Cosmonauts’ tolerance of the chest-back G-loads during ballistic and automatically controlled descents of space vehicles

Analysis of cosmonauts' +Gx tolerance on the stage of ballistic or automatically controlled Soyuz descent after missions to the International space station of varying duration was performed. As compared with automatically controlled descents, tolerance of descent re-entry +G(x) following short (8-14 d) missions was marked by reliably more frequent instances of visual disorders, difficult breathing, sensation of a lump in the throat and vestibulovegetative disorders (p < 0.05). The ballistic but not controlled re-entry after long-term mission provoked visual disorders, difficulties with breathing and speech, and vestibulovegetative disorders more often (p < 0.05). A considerable HR rise due to the ballistic rather than control descent was associated with re-entry and the main parachute re-hooking for symmetrical suspension; respiration rate was the highest during parachuting. By and large, these factual data infer that the ballistic descent after various periods in spaceflight microgravity, especially after extended space missions (164-169 d), led to a dramatic loss in the body functional reserves.

Neuro-cognitive performance is enhanced during short periods of microgravity

There is increasing interest in the effects of microgravity on cognitive processing, particularly as it relates to the potential for human space travel. While findings to date are quite inconsistent, studies reporting a decrement in cognitive performance have generally not been able to distinguish between the direct influence of microgravity, and any associated influence of stress. Furthermore, the currently available findings are primarily based on behavioral observations, and there is a need to better understand the underlying neurophysiological responses.The current study aimed to determine the effects of microgravity on neurophysiological processing during a mental arithmetic task (executive function). During the normal- and microgravity phases of a parabolic flight, four levels of a mental arithmetic task were presented on a touchscreen tablet. The latency between the appearance of the problem and the participants' response was identified as reaction time. In addition visual evoked potentials N1 and P2 were determined using an active EEG system and analyzed using source localization algorithms.Results showed an increase in reaction time with increasing levels of task difficulty. During the most complex levels, reaction time was significantly reduced during microgravity. This observation was independent of previous parabolic flight experience as well as the use of anti-motion-sickness medication. P2 amplitude decrease during microgravity was concomitant to a related involvement of the superior frontal and medial frontal gyrus.It is concluded that cortical processes are enhanced during microgravity, and that previously reported impairments in cognitive performance are likely attributable to increased stress rather than weightlessness itself.

Responses of Microcrustaceans to Simulated Microgravity (2D-Clinorotation) - Preliminary Assessments for the Development of Bioregenerative Life Support Systems (BLSS)

Bioregenerative Life Support Systems (BLSS) are an endeavor to create environments able to maintain human life e.g. on future long-duration space missions like flights to Mars. Based on cyclic biological processes, these systems will be independent from material resupply (such as food, water and oxygen). Due to their central role in limnic ecosystems, herbivorous microcrustaceans could act as key player in aquatic BLSS as they link oxygen liberating, autotrophic producers like algae to higher trophic levels, such as fish. However, before such BLSS can be utilized in space, organisms inhabiting these systems have to be studied thoroughly to disclose the gravitational impact on the biological processes. This is possible in real microgravity, but requires high financial resources, is opportunity-limited or periods of microgravity are very short. Yet, cost-effective and almost permanently accessible tools for gravitational research are ground-based facilities (GBFs), providing simulated microgravity. Among those GBFs is the so called 2D-clinostat. In the present study we demonstrate, that rotation of clinostat tubes does not generate acceleration in form of (predator resembling) small scale turbulence, which can be perceived by Daphnia cucullata. Additionally, embryonal development is not disturbed in subitaneous eggs of Daphnia magna and resting eggs of the ostracod Heterocypris incongruens (besides through restrictions in space within the narrow clinostat tubes), just as subsequent hatching from the respective eggs. Hence, our results indicate that clinorotation is a suitable method to simulate microgravity for microcrustaceans.