Microgravity Science and Technology最新文献

{"title":"Prefrontal Oxygenation During Supine-to-Stand Transitions in Head-out Water Immersion as a Ground-based Microgravity Analog: An fNIRS Pilot Study","authors":"Denizhan TÜRKMEN,&nbsp;Erkan GÜNAY,&nbsp;Çağdaş GÜDÜCÜ","doi":"10.1007/s12217-026-10278-9","DOIUrl":"10.1007/s12217-026-10278-9","url":null,"abstract":"<p>Background: Thermoneutral head-out water immersion is used as a ground-based microgravity analog, but prefrontal hemodynamic responses to postural transitions in water are poorly characterized. This pilot study tested whether immersion attenuates the post-standing oxygenated hemoglobin (O₂Hb) reduction relative to land. Methods: Bilateral prefrontal O₂Hb and deoxygenated hemoglobin (HHb) were recorded with functional near-infrared spectroscopy (fNIRS) in eight healthy adults (22.8 ± 4.9 years; 4 males, 4 females) during counterbalanced, within-subject supine-to-stand transitions in water and on land. Responses were analysed in three 30-s epochs relative to condition-specific supine baselines. Conditions were compared using two-sided paired-samples t tests; exploratory one-sample t tests examined within-condition changes, with Cohen’s dz as the effect size. Results: No between-condition comparison was statistically significant. The largest mean difference occurred for O₂Hb at 60–90 s (land − water = − 1.87 µmol/L, 95% CI [− 4.19, 0.45]; p = 0.098; dᶻ = −0.68). Exploratory analyses showed O₂Hb significantly below baseline on land at all three epochs (p ≤ 0.010), whereas the reduction in water was not statistically significant (p = 0.086–0.139). HHb did not differ from baseline or between conditions (p ≥ 0.324). Conclusions: The primary analysis did not support the hypothesis that immersion attenuates the post-standing O₂Hb reduction. Although mean O₂Hb reductions were numerically greater on land than in water, no between-condition comparison reached statistical significance, and this within-condition pattern does not establish a difference between environments. Given the small pilot sample, these null findings do not establish equivalence, and they do not support a microgravity analog effect.</p>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Improved Air-Bearing Testbed Based on Pose Decoupling Strategy for Spacecraft Dynamics Simulation","authors":"Changwen Tian,&nbsp;Dan Wang,&nbsp;Jinguo Liu,&nbsp;Hao Zhou,&nbsp;Siyue Wang,&nbsp;Yan Yang,&nbsp;Shuangqing Yu,&nbsp;Kun Wu","doi":"10.1007/s12217-026-10275-y","DOIUrl":"10.1007/s12217-026-10275-y","url":null,"abstract":"<div><p>Air-bearing testbeds are widely adopted to verify spacecraft on-orbit maneuver technologies. As the core experimental facilities for simulating the space microgravity environment, their motion accuracy acts as a key indicator for evaluating the credibility of ground simulation experiments. Nevertheless, motion deviations can be induced by coupling effects between the translational and rotational control channels, which degrade control accuracy and thus impair the fidelity of on-orbit spacecraft motion simulation. To tackle this problem, this paper presents a three-degree-of-freedom (3-DOF) air-bearing testbed with pose decoupling. First, pose decoupling of the platform is realized by optimizing the hardware architecture to physically separate the translational and rotational control channels of the cold-gas propulsion system. Second, combined with the thruster layout, a sliding mode controller based on an improved exponential convergence law is designed to further enhance the motion precision and control stability of the system. Numerical simulations and experimental results verify that the proposed coordinated strategy of motion decoupling and control effectively suppresses pose coupling effects and improves the control performance of the air-bearing testbed, which validates the effectiveness and feasibility of the proposed method.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Evaluation of Critical Gas Breakthrough Pressure in Capillary Micro-Holes for Surface-Tension Propellant Management","authors":"Qi Yang,&nbsp;Deyou Li,&nbsp;Junjia Ran,&nbsp;Jintao Liu,&nbsp;Xiaolong Fu","doi":"10.1007/s12217-026-10276-x","DOIUrl":"10.1007/s12217-026-10276-x","url":null,"abstract":"<div><p>Capillary porous elements are critical for liquid retention and gas exclusion in surface-tension propellant management devices, particularly under reduced-gravity conditions where capillary forces dominate. Their anti-gas-ingestion capability is commonly characterized by the bubble point pressure, yet accurate evaluation remains challenging for complex micro-hole geometries such as laser-drilled conical holes. In this study, a numerical measurement framework based on computational fluid dynamics (CFD) is developed to evaluate the critical breakthrough pressure of micro-holes under capillary-dominated conditions. The framework is verified for cylindrical holes against the Young–Laplace solution, with relative deviations below 2.5%, and is then extended to conical holes to examine apparent breakthrough behavior and interface evolution. The results show that the critical pressure of conical holes is bounded by the cylindrical-hole limits defined by the two end apertures. Under the present wetting and gas-loading configuration, the apparent critical pressure is mainly associated with the liquid-side aperture, while the gas-side aperture and hole depth exert secondary effects through interface confinement and meniscus stability. An engineering-equivalent aperture is further introduced for practical comparison and design evaluation. This work provides a numerical approach for evaluating gas breakthrough thresholds in complex micro-holes and supports the design of capillary porous structures in surface-tension tanks.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Two-dimensional Spatially Periodic Temperature Modulation on Floating Droplets Dynamics in the Presence of an Inclined Temperature Gradient","authors":"Ilya Simanovskii,&nbsp;Alexander Nepomnyashchy,&nbsp;Patrick Queeckers,&nbsp;Antonio Viviani","doi":"10.1007/s12217-026-10270-3","DOIUrl":"10.1007/s12217-026-10270-3","url":null,"abstract":"<div><p>Shapes and dynamics of floating droplets under the action of an inclined temperature gradient in the presence of two-dimensional spatial modulation of the vertical component of the temperature gradient are investigated. The case when the vertical component of the temperature gradient is directed downwards is considered. The problem has been studied numerically by the finite difference method. The precursor model has been considered. It is shown that the shape of the droplet is strongly influenced by the thermocapillary stresses caused by a non-uniform substrate heating and the gravity force.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical Training as a Component of Immune Status Maintenance during Long-Term Analog Mission","authors":"M. A. Kokueva,&nbsp;S. A. Ponomarev,&nbsp;M. P. Rykova,&nbsp;V. A. Shmarov,&nbsp;K. D. Orlova,&nbsp;V. D. Bakhtereva,&nbsp;O. V. Kutko,&nbsp;E. V. Fomina","doi":"10.1007/s12217-026-10274-z","DOIUrl":"10.1007/s12217-026-10274-z","url":null,"abstract":"<div><p>Countermeasures against the adverse effects of microgravity should be designed in such a way as to prevent the development of overexertion and pathological conditions. Changes in immune parameters serve as one of the sensitive indicators of the adequacy of physical activity and the state of the body’s adaptive capacity. The effectiveness and physiological adequacy of individualized training programs based on reaction of the cardiovascular and immune systems was assessed in a 366-day ground-based spaceflight analog study. Alternating 30- and 15-min aerobic exercise sessions individually tailored to each participant’s response to exercise was associated with maintenance of cardiorespiratory performance and, overall, was not accompanied by a statistically significant decrease in the studied cellular immunity parameters relative to baseline during the year-long isolation. A significant increase in the number of NK cells on days 67 and 160 of the experiment, compared to baseline values, was observed following training periods that involved 30‑minute protocols. Following the final training cycle, absolute peripheral blood levels of selected lymphocyte subpopulations were significantly increased, including CD3 + T cells, the CD3 + CD4+ T-cell subset, and CD3 − CD16+CD56 + NK cells.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148752335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation Analysis of Static Liquid Interface Evolution in Toroidal Tanks of On-Orbit Spacecraft","authors":"Nan Miao,&nbsp;Sen Wang,&nbsp;Yahang Du,&nbsp;Menghan Wang,&nbsp;Jing Wang,&nbsp;Zhanhe Liu","doi":"10.1007/s12217-026-10271-2","DOIUrl":"10.1007/s12217-026-10271-2","url":null,"abstract":"<div><p>Toroidal tanks offer geometric compatibility with launch vehicles and certain spacecraft configurations, making them suitable for liquid propellant storage in aerospace engineering. However, investigations into liquid behavior within such tanks under microgravity conditions remains relatively underexplored. This study addresses the static liquid interface generation in toroidal tanks under zero-gravity and microgravity environments, establishing a static equilibrium model based on surface free energy theory. Numerical simulations were conducted to investigate the static interface evolution under varying tank geometries, fill ratios, gravitational levels, and viscous models, thereby assessing the proposed liquid model. A comparative analysis was performed to evaluate the effects of these factors on the static interface morphology and the corresponding stabilization time. To improve propellant management, compartmentalization configurations with different numbers of compartments and perforations on baffle plates were implemented within the toroidal tank, and their effects on the static interface evolution process and final configuration were systematically analyzed. The findings of this research provide important insights for propellant management strategies in toroidal tanks.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148750835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microgravity-Induced Gut Dysbiosis and its Consequences for Brain Health","authors":"Srija Sappa,&nbsp;Prakrathi Keremane,&nbsp;Kamalesh Dattaram Mumbrekar","doi":"10.1007/s12217-026-10269-w","DOIUrl":"10.1007/s12217-026-10269-w","url":null,"abstract":"<div><p>Astronauts face multiple physiological challenges during spaceflight, including exposure to microgravity, ionizing radiation, altered circadian rhythms, and psychological stress due to confinement. Among these hazards, microgravity is a significant disruptor of gastrointestinal homeostasis. This review synthesizes evidence from human spaceflight missions, ground-based analogue studies, and preclinical models to characterize microgravity-induced gut dysbiosis and its downstream effects on central nervous system function via the gut–brain axis. Consistent findings across studies include shifts in the Firmicutes-to-Bacteroidetes ratio, depletion of beneficial commensal bacteria (notably <i>Akkermansia muciniphila</i>, <i>Faecalibacterium prausnitzii</i>, and <i>Bifidobacterium</i> species), and enrichment of potentially pathogenic taxa. These compositional changes correlate with reduced production of short-chain fatty acids and other neuroprotective metabolites, compromised intestinal barrier integrity, and systemic low-grade inflammation. Through immune, neuroendocrine, and vagal pathways, these peripheral perturbations propagate to the central nervous system, contributing to neuroinflammation, blood–brain barrier dysfunction, and altered neurotransmitter metabolism. We critically evaluate the mechanistic pathways linking microbial changes to neurocognitive outcomes, address methodological limitations and confounding factors in current research, and propose candidate countermeasures and priorities for future evidence based. Understanding these gut–brain interactions are essential for developing interventions to protect astronaut cognitive performance and psychological well-being during long-duration space exploration.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12217-026-10269-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148628364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The engineering design of a 115 m microgravity drop tower facility within atmospheric condition","authors":"Isang Yu,&nbsp;Hyunjun Kim,&nbsp;Ji Hyuk Im,&nbsp;Sangbum Cho,&nbsp;Merle Cornelius,&nbsp;Thorben Könemann,&nbsp;Jaehyun Shin,&nbsp;Yungu Choi,&nbsp;Seungwhan Baek","doi":"10.1007/s12217-026-10268-x","DOIUrl":"10.1007/s12217-026-10268-x","url":null,"abstract":"<div><p>This study presents the engineering design, analysis, and experimental validation of a microgravity drop tower facility capable of providing approximately 3.26 s of microgravity under atmospheric conditions. Unlike conventional vacuum-based systems, the proposed approach employs a free-fall method within a 115 m vertical shaft, combined with a dual-capsule configuration to mitigate aerodynamic drag and enhance microgravity quality. A theoretical model describing the relative motion between the outer and inner capsules was developed based on drag-induced acceleration differences. The analysis demonstrated that minimizing the drag coefficient of the outer capsule is essential for maximizing the effective microgravity duration by delaying contact between the two capsules. Aerodynamic stability was achieved through appropriate center-of-gravity and center-of-pressure design, supported by a streamlined capsule geometry and rear-mounted fins. To enable safe and reusable operation, a multi-layered airbag recovery system was designed and validated through numerical simulations and repeated drop tests. Experimental results demonstrated a total drop time of 4.74 s and a microgravity duration of 3.26 s within the inner capsule. Acceleration measurements showed good agreement with simulation predictions, with peak residual accelerations below 10^− 3g and an effective microgravity quality approaching the 10^− 4g level during the stable free-fall period. High-speed video analysis was further performed to quantify the relative motion between the inner and outer capsules, revealing that the inner capsule advanced relative to the outer capsule more rapidly than predicted by the simplified analytical model. This observation provides a plausible explanation for the reduction in the experimentally obtained microgravity duration and identifies the release mechanism and capsule interaction as important subjects for future investigation. Additional qualitative experiments, including flame shape observation and object behavior tests, further confirmed the successful realization of microgravity conditions. The proposed facility provides a practical, low-cost platform capable of performing approximately six to seven experiments per working day, offering a viable alternative to conventional vacuum-based drop towers for repeated microgravity research.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mission Scheduling Optimization for Extravehicular Material Exposure Experiments","authors":"Ronghan Qin,&nbsp;Man Fang,&nbsp;Hongen Zhong,&nbsp;Ping Ma,&nbsp;Yuxue Guo,&nbsp;Fangshu Xiong","doi":"10.1007/s12217-026-10267-y","DOIUrl":"10.1007/s12217-026-10267-y","url":null,"abstract":"<div><p>The extravehicular material exposure experiments on the China Space Station (CSS) face a significant challenge: a mismatch between limited experimental resources and extensive scientific demands. This paper addresses the task planning problem of extravehicular material exposure experiments by constructing a unified modeling framework that covers experimental period, layout of exposure slots, and experiment scheduling. On this basis, a Mixed-Integer Linear Programming (MILP) model is formulated with the objective of maximizing the number of experimental projects, subject to primary constraints such as experimental period and the facility capacity. Furthermore, focusing on different engineering scheduling strategies, we develop and comparatively analyze two scheduling models: a fixed-frequency model and an optimizable-node model for payload installation and retrieval (PIR), examining their impact on experimental tasks. Numerical experiments demonstrate that the fixed-frequency PIR model, based on the current engineering practice, can provide decision-makers with selection recommendations among various options according to different planning priorities; however, it still faces a trade-off between the quantity and quality of experiments. Because fixed PIR nodes force actual exposure durations to passively adapt to engineering windows rather than strictly match scientifically required exposure periods, they may lead to an engineering-to-science constraint inversion in scheduling. To address this issue, the optimizable PIR-node model incorporates exposure-duration requirements as key constraints and optimizes PIR nodes while also considering the objective of maximizing the number of completed experiments. As a result, it can improve exposure-duration satisfaction while maintaining high experimental efficiency, thereby providing an effective decision-support method for task planning of extravehicular material exposure experiments on the space station.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correlation between Undercooling and Atomic Structure in a Ni-Nb Melt Under Electrostatic Levitation and Microgravity","authors":"Sheng-Hao Liu,&nbsp;Xiao-Dong Wang,&nbsp;Qing-Ping Cao,&nbsp;Dong-Xian Zhang,&nbsp;Qiong-Jie Wang,&nbsp;Jian-Zhong Jiang","doi":"10.1007/s12217-026-10261-4","DOIUrl":"10.1007/s12217-026-10261-4","url":null,"abstract":"<div><p>Using containerless electrostatic levitation (ESL) facility aboard China Space Station (CSS), we fulfil on-orbit undercooling and density measurements for a binary Ni₆₀Nb₄₀ eutectic melt in a microgravity environment. It is found that at a short isothermal time of overheating, the undercooling gradually increases with overheating but saturates after passing a threshold when combined with ground-based ESL experiments and molecular dynamics (MD) simulations. In contrast, at a long isothermal time, the undercooling remains almost constant within the studied overheating range. It demonstrates that the microstructure of the melt does not reach equilibrium instantaneously after melting. Instead, a certain time duration is required to complete the melting process. Our results propose that the residual medium range ordered structures (MROs) significantly influence the deep undercooling behavior of the melt during the solidification process, which might be applicable across different alloy systems as well.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148465570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}