Microgravity Science and Technology最新文献

The enclosed space environment demands sustainable environmental control systems. Space stations and interstellar missions, both need reliable environmental control and life support systems for crewed flights and long-term habitation. These long-duration space missions require monitoring for potential pathogens and microbial contamination, which is crucial for astronaut health and the reliable operation of space equipment. To meet this critical need, the China Space Station (CSS) is equipped with the Microbial Online Monitoring Module (MOMM), which integrates two methods for microbial detection, the first method involves cultivating microorganisms in culture dishes for observation, while the second method uses isothermal nucleic acid amplification and detection technology based on Loop-mediated Isothermal Amplification(LAMP). This equipment is applied in the microgravity environment of the space station to achieve rapid detection of microbial species and abundance in orbit. Hardware function validation tests and validation experiments of the sensitivity and shelf life of the reagents were conducted on the ground, and several full-process microbial detection experiments were carried out to ensure the function and feasibility of the MOMM. Subsequently, an experimental process of microbial cultivation and observation was successfully carried out on the CSS using air samples from the space station. The MOMM allows for early detection of microbes in orbit, contributing to implementing targeted biosecurity and maintenance measures.

High Frequency Impulse for Microgravity (HIFIm) is an exercise countermeasure that is designed to minimize force and vibration transmission to the spacecraft during exercise without the need for an additional VIS. The purpose of this study was to evaluate the effectiveness of HIFIm in mitigating force transmission in microgravity during parabolic flight. Force between HIFIm and the aircraft was measured using a custom-made arrangement of load cells during repeated jumping by two participants. Mean peak force transmission to the aircraft was 4.79 ± 0.68 N.kg^− 1. In addition, the frequency spectra for the upper and lower fixations to the aircraft were within the envelope of what is permissible for an exercise countermeasure on Gateway. These data support the design concept of HIFIm and suggest that HIFIm could be installed in a space habitat with no, or minimal, additional VIS. Measuring the force and vibration transmission of exercise countermeasures in microgravity during parabolic flight is highly challenging due to the safety constraints of the experimental platform and the extreme changes in acceleration (from 0 to 1.8 g). The fact that this performance can be directly measured for HIFIm is a key advantage. The results presented here add to the mounting evidence that HIFIm is the future of exercise countermeasures.

Astronauts are exposed to microgravity-induced health problems in spaceflight missions. Countermeasures and physical exercises have received increasing attention and its current research trends and landscapes warranted investigation. We conducted a comprehensive bibliometric analysis on astronaut training/countermeasures using the available data from the Web of Science Core Collection database from 1992 to 2022 to summarize the research trends and identify future directions. A total of 1,520 relevant articles were identified. Annual publications of the field have been increased over the years with the emergence of new and effective countermeasures. ‘Microgravity’ was the centered hotspot surrounded by the topics included ‘spaceflight’, ‘hind leg hanging’, ‘simulated microgravity’, and ‘simulated weightlessness’. The top countries that produced the most publications included United States (726 articles), Germany (129 articles), and France (84 articles). The United States played a dominant role in the collaboration network with other countries. Meanwhile, NASA from the United States led the global collaborations and dominated the literature. Future research trend might lie on the design of physical training exercises to tackle the potential health problems on osteoporosis, muscle atrophy, and abnormality on the nervous and cardiovascular system; and artificial/simulated gravity with interdisciplinary sports countermeasure research on physiology, brain science, biomechanics, and aerospace medicine.

Propellant tanks provide non-entrained propellant for thrusters of satellites, which plays an important role in space mission. And the fluid transfer efficiency of tanks is the key to supply non-entrained propellant. An experiment cabin containing two different scaled tank models are designed and experiments of liquid reorientation under microgravity are carried out in the Chinese Space Station. Experiment results present the high liquid transportation efficiency of the two kinds of propellant management devices. Finite element models of the two tank models are established and verified by simulation matching with experiments. Furthermore, methylhydrazine is adopted to carry out more simulation analysis by considering different liquid contact angles and surface tension, and numerical results show smaller liquid contact angle and bigger surface tension can increase liquid flow speed. This research can provide theory and data support for the design of plate type tanks.

Gas-liquid and liquid-liquid two-phase flow are widely used in chemical engineering, biomedical engineering and other fields such as separation, reaction, and mass transfer in microfluidic systems. Studying the formation methods of droplets and bubbles in microfluidics is of great significance to the application of microchemical technology. In this review, according to the methods of droplets and bubbles formation, the research progress and development trend of droplets and bubbles formation in microfluidics in recent years are reviewed. Formation methods are divided into passive methods and active methods according to whether external energy is required. Passive methods include T-junction, flow-focusing, co-flowing and step emulsification. Active methods include surface acoustic waves, DC/AC electric fields, magnetic fields, and thermal fields. Finally, this review points out the future direction of research on liquid droplets and bubbles. This review sheds new light on monodisperses, highly controllable droplets and bubbles formation and its applications.

The present paper investigated the dynamics of coating flow on array of cylindrical fibres. In the experiments, it is observed that there exist three distinct flow regimes when the fiber array is fully coated by liquid film, namely, regime ‘a’, ‘b’ and ‘c’. The flow regime ‘a’ is characterized by the formation of a streamwise uniform film; The flow regime ‘b’ and ‘c’ are in the form of traveling waves consisting of asymmetrical wavy structures and symmetrical beads, respectively. We conducted a comprehensive parametric study on the dynamics of the coating flow on fiber array, including the flow rate, fiber spacing and droplet amplitude, all of which serve as reliable indicators of different flow regimes.

The authors present an analytical solution of equations describing the diffusion transfer and recombination of positive lithium ions and negative benzoate ions in benzoic acid after their injection from the surface of a protonated lithium niobate substrate. In the course of the solving one-dimensional stationary problem, the profiles of ions concentrations and electric potential distribution have obtained, corresponding to different values of governing parameters. The benzoate ions form thin boundary layer, while the ions of lithium completely fill considered region and have relatively uniform distribution. The comparison of analytical solution with numerical results permits to estimate the degree of the influence of electric field on the final distributions, which is formed due to the difference of ions concentrations. The expression, which determines the thickness of boundary layer, is obtained by the multiple scales method.

The effects of a ground-based model of microgravity on executive functions (namely, inhibition) were investigated in this study. Volunteers participated in so-called dry immersion (DI), during which they spent 21 days in a water-filled tub in the supine position. During this period, they performed an auditory Go/NoGo task while multichannel EEG activity was recorded. The Go/NoGo task was performed one time outside of the DI and two times during the stay in the DI. ERPs were computed on correct NoGo and Go trials. While no behavioral deterioration of the Go/NoGo task was found during their stay in the DI, a significant difference was found in amplitudes between NoGo N2 ERP peaks before DI and during DI. The N2 peak was smaller on the 17th day of DI, indicating a potentially lower level of inhibitory control during simulated microgravity conditions. The amplitudes of the N1 and P3 peaks did not change significantly. The dry immersion procedure reproduces some of the important physiological factors of real space flights (support withdrawal, bodily liquid redistribution), thus our results hint at possible brain and behavioral alterations in real space flight that have so far been unnoticed.

This paper presents data from large, isolated n-dodecane droplets burning in microgravity on the International Space Station, along with preliminary comparisons with numerical and analytic predictions indicating general agreement in trends. The tests involved were primarily in air (a few in reduced oxygen) at ambient pressures ranging from 0.50 to 5.0 atm. After ignition, the droplets burn with a hot flame that extinguishes when the radiant energy loss causes the flame temperature to drop below the hot-flame-required value. The total flame radiative loss at extinction is nearly independent of pressure, while the peak flame diameter prior to hot-flame extinction decreases with increasing pressure. The maximum hot-flame temperature, inferred from fiber-support radiative emisssions, decreases with increasing pressure, and the hot flames become dimmer with increasing pressure. At 1.0 atm and below there is a prolonged period of coolflame burning that ends with cool-flame extinction at a finite droplet size; the cool-flame-extinction droplet diameter increases and the cool-flame burning rate decreases with decreasing ambient pressure. Above 1.25 atm warm-flame burning and hot-flame re-ignitions become prevalent. At 5.0 atm, there is no abrupt hot-flame extinction with transition to a cool flame; the flame gradually gets dimmer, and the flame temperature decreases over a much longer time, the transition between hot-flame and warm-flame burning becoming almost undiscernible.

The pool boiling heat transfer (phase-change immersion cooling) phenomenon holds significant importance in the energy consumption management of large-power electronics. However, the optimization of surface structure for achieving stable and efficient heat transfer during boiling process remains a significant challenge. Herein, we propose a simplified and direct hybrid surface strategy that combines crossed mini channels and a capillary wick to address the cooling issues faced by high-performance power devices. The copper capillary wick is combined with the crossed mini channel to form a hybrid surface by a simple integrated sintering method. This study investigates the combined effects of different parameters of the capillary wick (average diameter size and powder addition) and minichannels (depth and width) on enhancing the nucleate boiling performance on these hybrid surfaces. The working fluid used in this investigation is HFE-7100. At ΔT_sub = 30 K, the CHF achieved by the hybrid surfaces combining capillary wicks and minichannels can reach 131 W/cm², while the highest HTC is measured at 2.32 W/(cm²·K), both CHF and HTC achieve multiplicative enhancement compared to smooth surfaces. Furthermore, we have developed a CHF prediction model for the hybrid surfaces, which exhibits a prediction error of less than 15%.