Microgravity Science and Technology最新文献

This study focused on microhemodynamic and autonomic regulation changes during long-term isolation in a 366-day SIRIUS-23 experiment with 6 healthy volunteers (2 men and 4 women, aged 25–37 years). Heart rate variability analysis and laser Doppler flowmetry were used to assess cardiovascular system responses before, during, and after isolation. Volunteers demonstrated distinct autonomic regulation patterns, dividing into two groups based on vagal tone and vascular center activity. Group 2 showed consistently higher autonomic function throughout the experiment. Microcirculation parameters revealed decreased perfusion in the forehead area for Group 1 and fluctuating dynamics for Group 2. Both groups exhibited endothelial tone reduction and altered blood flow distribution in the toe area with increased shunt flow. Prolonged isolation significantly affects microhemodynamics and autonomic regulation. Individuals with higher vagal tone demonstrated better adaptation. These findings contribute to understanding physiological responses to long-term confinement and have implications for space mission medical support.

Fluid flow and phase-change processes under variable-gravity are of significant scientific interest in space science, thermal control engineering and planetary exploration. However, current variable and micro-gravity experiments mainly rely on space stations or parabolic flights, which are limited by short experimental durations, high costs, and restricted repeatability. To overcome these limitations, this study develops a ground-based experimental approach on diamagnetic levitation. Deionized water is adopted as the working fluid in a strong magnetic field to conduct representative variable-gravity experiments, including single-droplet levitation, liquid bridge formation, capillary flow, and boiling. The experimental results show that: in the single-droplet levitation experiment, stable levitation can be achieved when the central magnetic field reached 23.28 T. In the capillary rise experiment under typical gravity conditions, the maximum deviation between the measured liquid height and the theoretical prediction is 5.25%. In the liquid bridge experiment, the difference between the measured maximum diameter and the theoretical prediction is only 0.07 mm. In the boiling experiment, distinct boiling behaviors are successfully observed under different effective gravity levels. It can also be used to construct simulated gravity experimental conditions on the surfaces of planets such as the Moon and Mars. These results demonstrate that the proposed experimental approach enables stable, long-duration, high-precision, and cost-effective simulation of micro/reduced-gravity environments. This work establishes a ground-based diamagnetic gravity-compensation facility that enables controlled studies of fluid flow and phase-change heat transfer in diamagnetic fluids under magnetically compensated effective gravity conditions, offering valuable insights for space and planetary thermal-fluid applications.

Long-duration spaceflight has revealed a distinctive constellation of neuro-ocular abnormalities, collectively known as Spaceflight-Associated Neuro-Ocular Syndrome (SANS). These are hypothesized to result from cephalad fluid shifts in microgravity, leading to altered cerebrovascular dynamics and suspected mild elevations in intracranial pressure (ICP). Invasive ICP monitoring techniques are unsuitable for spaceflight, prompting the development and validation of non-invasive alternatives, including optic nerve sheath diameter (ONSD) ultrasound and transcranial Doppler (TCD), which offer practical and reliable surrogates for estimating ICP. When combined, these methods can improve diagnostic accuracy and enable multimodal neuromonitoring. Integration of rapidly advancing artificial intelligence (AI) models into ONSD and TCD systems can further enhance precision, reduce operator dependence, and enable automated trend analysis. This paper examines current advances in non-invasive ICP monitoring within space medicine, evaluates their readiness for operational deployment, and identifies key challenges related to standardization, calibration, and validation. These breakthroughs hold substantial promise for supporting astronaut health during spaceflight and planetary missions, while also advancing neurocritical care on Earth.

Spaceflight missions have advanced techniques over the last decades, with astronauts spending their time for more than 6 months aboard the International Space Station. Nevertheless, the living and working conditions in outer space remain highly challenging and demanding for astronauts. Space science has also been a frontier area in life science research, which targets studying the human physiology of living beings and their physiological changes under microgravity. This review highlights the impact of microgravity on the alteration of human, plant, microbial, and rodent physiology, emphasising the effects of microgravity on the physiology of these organisms in a space environment. Different countries have their own space agencies, and they have increased their space research over the past few decades in preparation for future space missions. The spaceflight radiation-induced carcinogenic effects have emerged as a health risk during deep spaceflight missions. In the recent era, a huge number of cell-line and animal model experimental studies have been conducted to explore the microgravity radiation, lower and higher doses of radiation, heavy ions, and low Earth orbital environments have identified evident carcinogenicity. Deep space flight mission leads to Spaceflight Associated Neuro-ocular Syndrome and associated other diseases such as glaucoma, alzheimer’s disease, cerebral edema, and cancer. In this review, we have summarized the objectives of space biology, the historical background of different space agencies, different types of space radiation associated with several diseases, multiscale biological experiments under microgravity, and biological specimen experiments under different space agencies.

The paper is devoted to the study of the process of cleaning a microchannel contaminated by impurity particles settling on its walls. The most common reason of microchannel clogging is the sorption of impurity particles by pore walls or “physical sorption”. This paper describes the problem of drift of solid non-interacting particles in a microchannel, which can stick to its walls under the action of the van der Waals forces and break away from the wall due to thermal noise and viscous stresses arising from the flow. The pressure drop is given between the channel inlet and outlet. At the initial moment of time, the channel walls are contaminated with adhered particles, i.e. the walls are uneven, which affects the formation of the flow structure through the channel. Over time, under the action of viscous stresses and thermal noise, the particles break away from the channel walls, causing its cleaning. The interaction of the detached particles with the flow is taken into account in the approximation of the laminar flow regime. In addition, the model takes into account random particle motion caused by diffusion. The problem is solved numerically within the framework of the random walk model. The evolution of the liquid flow in the channel during its cleaning is obtained: stream function, pressure, and vorticity fields. It is demonstrated that three cleaning scenarios can be observed: no cleaning, slow cleaning, and fast cleaning. To control the cleaning scenario the modulation of the pressure drop at the channel borders is investigated. It is shown that resonance phenomena can be observed. The dependencies of cleaning time on the modulation amplitude and frequency is obtained and studied. It is shown that changing the modulation parameters leads to a significant change in the cleaning time and helps control the cleaning process.

The study investigates the combined influence of uniform volumetric heating and an alternating current (AC) electric field on the onset of convection in an anisotropic, dielectric fluid-saturated Brinkman porous layer heated from below. The porous medium is anisotropic in both permeability and thermal diffusivity, with the vertical permeability fixed at twice the horizontal value, while the thermal anisotropy parameter is allowed to vary freely. The layer is bounded by isothermal surfaces subject to rigid-rigid, free-free, or rigid-free velocity conditions, with appropriate electric potentials applied. The generalized eigenvalue problem is solved numerically using Galerkin’s method, establishing the validity of the exchange of stabilities. The results show that increasing the AC electric Rayleigh number, Darcy number, and internal heat generation parameter hastens the onset of convection, whereas greater thermal anisotropy delays it. These trends persist across all boundary conditions, with rigid-rigid boundaries being the most stabilizing and free-free the least. However, at higher heat source strengths, the threshold values exhibit a reversal in trend between the rigid-free and free-free boundaries. The electric field alone can trigger instability at sufficiently high AC electric Rayleigh numbers, accompanied by a higher critical wavenumber. The findings elucidate the interplay among anisotropy, volumetric heating, and electric forcing, offering insights relevant to electrohydrodynamic cooling, microscale thermal management, porous insulation design, and energy conversion systems where coupled electric–thermal effects govern heat transport.

In this study, a review of the state of knowledge of the propagation of evaporation waves in the superheated liquid is presented, along with the motivation for continuing research. To understand the physics of rapid evaporation, numerous experiments have been conducted. Research findings from the past six decades have been summarized to provide an overview of the current state of knowledge regarding rapid evaporation and wave propagation. General experimental methods have been reported and compared. This review also includes the different mechanisms involved in the wave propagation of flash evaporation. The existing instrumentation of experiments for identifying the physics of rapid evaporation is still limited. Some related topics, like atomization and evaporation under microgravity, are also discussed. In this review, motivation is provided for the development of careful experiments that can be used to test the theories and reveal new phenomena.

To investigate the effects of different gravity conditions on the solution flow fields and crystal growth rates during the dissolution and growth processes of InGaSb crystals utilizing the vertical gradient freezing (VGF) methods, two-dimensional numerical simulations were conducted. Nine numerical simulations were performed under a range of gravity conditions, including microgravity: 1 × 10^− 4 G, 0.01 G; small gravity: 0.1 G, 0.17 G (lunar gravity), 0.38 G (Mars); normal gravity: 1.0 G, and high gravity: 2.0 G, 5.0 G, and 10.0 G. The results demonstrated that the natural convection induced by gravity significantly affects the growth rates of InGaSb crystals. The growth rates were highly sensitive to variations in gravity, decreasing as gravity increased within the range of 0.01 to 2.0 G. Under microgravity conditions (no larger than 0.01 G), growth rates values were very similar, indicating that under microgravity the InGaSb growth process is diffusion-dominant. When gravity exceeds 2.0 G, the growth rates of InGaSb stabilize, but larger non-uniform areas develop as gravity increases, compromising the quality of the grown crystals.

This study employs two-dimensional numerical simulation to characterize droplet migration and collision dynamics on unidirectional and symmetrical multi-level wettability gradient (WG) surfaces under Earth (g₀), Martian (0.38 g₀), and microgravity (10⁻⁶g₀). Parametric analysis reveals WG = -15/2°/mm optimizes single-droplet migration time in microgravity, exhibiting minimal sensitivity to gravity reduction, while WG = -20/2°/mm maximizes efficiency under g₀. Larger droplets (D = 3 mm) accelerate terrestrial transport but severely impede microgravity migration, where smaller droplets (D = 2 mm) excel. Peak velocity (> 0.3 m/s), governed by WG and D independent of gravity, dictates acceleration capability. Final equilibrium morphology mainly depends on WG. For dual droplets, microgravity collision requires WG = ∓ 15/2& ∓ 20/2°/mm and D = 2 mm; lower gradients or larger diameters prevent collision. The results demonstrate that reduced gravity disrupts mirror-synchronized droplet motion observed under g₀, delaying collision initiation. These findings provide critical guidelines for designing passive capillary fluidic systems in variable-gravity environments, particularly space applications.

Microgravity environments significantly impact soot formation and flame stability in laminar diffusion flames, yet the underlying mechanisms remain poorly understood, especially in high-pressure combustion systems. This study utilizes a hybrid moment method (HMOM) coupled with P1 radiation modeling to investigate the radiation-induced modifications to temperature fields, flow structures, and soot evolution in ethylene-air co-flow flames under elevated pressures (1–8 bar), comparing normal gravity and microgravity conditions. Results show that microgravity environments amplify soot volume fractions by 200–300% compared to normal gravity, due to extended reactant residence times. Radiative heat losses lower peak flame temperatures by 20–150 K, with this reduction becoming more pronounced at higher pressures due to increased radiation from both gases and soot. At critical pressure thresholds in microgravity, a transition from closed-tip to open-tip flame structures occurs in co-flow laminar diffusion flames, driven by radiative heat losses approaching 45%–60% of total chemical energy. Unlike spherical flame extinction, laminar diffusion flames experience local extinction triggered by heat release rate (HRR) decay at the flame tip, followed by the opening of the hydroxyl radical (OH) zone. This structural modification creates an oxidative boundary discontinuity, preventing the OH zone from fully encapsulating soot particles, thus allowing soot to escape oxidation pathways.