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Introduction: The impact of spaceflight on the immune system and mitochondria has been investigated for decades. However, the molecular mechanisms underlying spaceflight-induced immune dysregulations are still unclear. Methods: In this study, blood from eleven crewmembers was collected before and during International Space Station (ISS) missions. Transcriptomic analysis was performed in isolated peripheral blood mononuclear cells (PBMCs) using RNA-sequencing. Differentially expresses genes (DEG) in space were determined by comparing of the inflight to the preflight samples. Pathways and statistical analyses of these DEG were performed using the Ingenuity Pathway Analysis (IPA) tool. Results: In comparison to pre-flight, a total of 2030 genes were differentially expressed in PBMC collected between 135 and 210 days in orbit, which included a significant number of surface receptors. The dysregulated genes and pathways were mostly involved in energy and oxygen metabolism, immune responses, cell adhesion/migration and cell death/survival. Discussion: Based on the DEG and the associated pathways and functions, we propose that mitochondria dysfunction was caused by constant modulation of mechano-sensing receptors in microgravity, which triggered a signaling cascade that led to calcium overloading in mitochondria. The response of PBMC in space shares T-cell exhaustion features, likely initiated by microgravity than by infection. Consequences of mitochondria dysfunction include immune dysregulation and prolonged cell survival which potentially explains the reported findings of inhibition of T cell activation and telomere lengthening in astronauts. Conclusion: Our study potentially identifies the upstream cause of mitochondria dysfunction and the downstream consequences in immune cells. [ABSTRACT FROM AUTHOR]

The Space Physics Laboratory (SPL) of Vikram Sarabhai Space Centre (VSSC) has launched a science program called the Indian network for Space Weather Impact Monitoring (InSWIM) to monitor the effects of Space Weather events on the Indian low-latitude ionosphere-thermosphere system. This program aims to study the impact of Space weather on the Indian ionospheric region and develop an Ionospheric Model. The InSWIM network stations will be equipped with instruments such as Global Navigation Satellite Systems (GNSS) receivers, Low Earth Orbit (LEO) receivers, ionosondes, magnetometers, and airglow photometers/imagers. Currently, multi-frequency, multi-constellation GNSS Receiver systems are operational at various stations in India. This network will enable us to understand (a) the quiet-time variability of the ionosphere over the Indian low-latitude region, (b) comprehensively study the response of the low-latitude ionosphere specific to the Indian longitudes under different space weather conditions, with the goal of understanding the various physical mechanisms causing variability in the ionospheric regions, and (c) develop an ionospheric model to reduce ionospheric errors in GNSS systems. Additionally, this network will provide complementary information for rocket and satellite-based experiments. This paper aims to provide details of the InSWIM network to the scientific community for its possible use in monitoring and studying the impact of space weather on the near-Earth space environment. [ABSTRACT FROM AUTHOR]

• Investigating the issue of computation of multi-revolution NRHO under the ephemeris model. • Analyzing the failure of computation by means of the condition number of STM (State Transition Matrices). • Proposing the strategy of segment selection to improve the convergence of computation. • Computing the lunar L1/L2 NRHOs up to 500 revolutions, the maximal number in the current publications. • No dedicated optimization algorithm or commercial software required for the proposed method. Near Rectilinear Halo Orbits (NRHOs) are vital to manned lunar and deep space exploration, which nowadays are of great interest for different space agencies and in particular with regard to the future space station. However, the required computation of multi-revolution NRHO under the ephemeris model is difficult, especially for the NRHOs with low periapsis relative to the secondary body. This paper explores this issue from the perspective of multiple shooting, first analyzing the influence of the state transition matrices by means of their condition number and then, focusing on a good selection of trajectory segments with suitable patch points. The methodology considerably improves the convergence and the computation under the ephemeris model. Numerical simulations show that at least 30 revolutions can be achieved for NRHOs with perilune radius of less than 12,000 km around L1 or period less than 8.8 days around L2; meanwhile, the number of segments used can be as low as 2 for each single revolution. As for the position of patch points, the first and last points of each revolution should be apart from the Moon, and the distance can be reduced only when the number of segments increases. The proposed method requires no dedicated optimization algorithm or commercial software to produce the multi-revolution NRHOs. [ABSTRACT FROM AUTHOR]

Life support systems in space have been developed to recover a certain amount of oxygen and water. However, we still rely on resupplies for gas tanks, water bags, and food. To achieve sustainable human space exploration, we must also consider the astronauts' wellbeing. This research analyzes and assesses the status of essential life support elements, which are air, water, and food, as well as wellbeing elements, including clothing, hygiene, and healthcare, on the International Space Station. The types and quantities of resupplies for each element were estimated by synthesizing data from multiple sources and compared against baseline values established by the National Aeronautics and Space Administration (NASA) for one crew member per day. To evaluate the qualitative and psychological dimensions of dependence on resupply missions, astronaut feedback and comments documented in reports and articles from space agencies were also analyzed as important references. The results show that resupplies involve not only gas tanks and water bags but also a significant number of spare items to maintain recovery systems. Food completely relies on resupplies, and regarding wellbeing elements, although the mass supplied from Earth seems to meet the space agency's requirements, astronauts feel uncomfortable wearing the same clothes and using the same towels for days, especially exercise clothes, which can develop odors. It was also discovered that each resupply mission is inefficient as resupplies account for only 0.21% of the total launch mass. Relying on resupply missions has been associated with negative effects on both physical and psychological aspects, such as anxiety about the risk of running out of life support consumables, issues with stowage and odors caused by waste, and stress due to complicated cargo unloading and loading transfer operations. As humans explore the Moon and beyond, frequent resupplies will become impractical due to higher launch costs and longer delivery times, and suggestions for developing technologies to realize a sustainable human presence in space are being proposed. [ABSTRACT FROM AUTHOR]

The development of precise time synchronization technology is key to the effective application of time–frequency standards. It will significantly promote the application of precise time–frequency standards in the areas such as Positioning, Navigation, and Timing, lunar navigation, and cutting-edge fundamental physics research. This study presents an improved carrier-phase-based method for time synchronization, which was demonstrated through both laboratory and satellite-ground experiments via the China Space Station (CSS)-ground synchronization system. Initial laboratory experiments confirmed the system's stability, achieving picosecond-level accuracy, highlighting the robustness of the method in controlled environments. Then, preliminary satellite-to-ground synchronization experiments were conducted using the CSS and ground stations, validating the effectiveness of the carrier-phase-based method. The time synchronization accuracy reached the picosecond-level, significantly surpassing traditional pseudocode techniques, which typically achieve sub-nanosecond level accuracy. Additionally, the Allan Deviation results indicated an improvement in stability by about an order of magnitude compared to traditional pseudocode-based methods. This demonstrates that the carrier-phase-based method can effectively mitigate common sources of system errors and enhance time synchronization capabilities. Therefore, this method can provide an effective technical reference for future applications requiring higher precision in time synchronization. [ABSTRACT FROM AUTHOR]

The MISSE-Seed project was designed to investigate the effects of space exposure on seed quality and storage. The project tested the Multipurpose Materials International Space Station Experiment—Flight Facility (MISSE-FF) hardware as a platform for exposing biological samples to the space environment outside the International Space Station (ISS). Furthermore, it evaluated the capability of a newly designed passive sample containment canister as a suitable exposure unit for biological samples for preserving their vigor while exposing to the space environment to study multi-stressor effects. The experiment was launched to the ISS on Northrup Grumman (NG)-15. The exposure lasted eight months outside the ISS in the MISSE-FF at the Zenith position. The specimens consisted of eleven seed varieties. Temperature dataloggers and thermoluminescent dosimeters were included in each container to record environmental data. We presented here the hardware and experimental design, environmental profiles, and seed survival from post-flight germination tests. [ABSTRACT FROM AUTHOR]

Magnetic flux ropes are a fundamental component in both space and laboratory plasmas. We present a Hall-MHD simulation exploring the interaction between two isolated magnetic flux ropes under mesoscale solar wind conditions. The interaction interface is resolved with a resolution approaching the kinetic scale, to reveal unprecedented details of this process. As we replicate previous findings that such interactions can lead to the formation of two new ropes, we also find that magnetic reconnection occurs in multiple locations inside the central current sheet, leading to transient small flux ropes, which is qualitatively consistent with previous magnetospheric multiscale observations. Consequently, each field line undergoes multiple reconnections that alter its connectivity before it exits the current sheet. Later, each flux rope divides into two branches: the reconnected flux moving away from the current sheet to form the transition regions of the new ropes and the remnant flux sustaining the current sheet. For each magnetic flux rope (MFR), the core field reconnects after most surface fields are reconnected so that the reconnecting MFRs maintain a relatively symmetric shape. These results in unprecedented detail highlight the complex internal dynamics and call for further observational and theoretical studies. [ABSTRACT FROM AUTHOR]

[Display omitted] In order to understand the basic mechanisms affecting emulsion stability, the intrinsic dynamics of the drop population must be investigated. We hypothesize that transient ballistic motion can serve as a marker of interactions between drops. In 1G conditions, buoyancy-induced drop motion obscures these interactions. The microgravity condition onboard the International Space Station enable this investigation. We performed Diffusing Wave Spectroscopy (DWS) experiments in the ESA Soft Matter Dynamics (SMD) facility. We used Monte Carlo simulations of photon trajectory to support data analysis. The analysis framework was validated by ground-based characterizations of the initial drop size distribution (DSD) and the properties of the oil/water interface in the presence of surfactant. We characterized the drop size distribution and found to be bi-disperse. Drop dynamics shows transient ballistic features at early times, reaching a stationary regime of primarily diffusion-dominated motion. This suggests different ageing mechanisms: immediately after emulsification, the main mechanism is coalescence or aggregation between small drops. However at later times, ageing proceeds via coalescence or aggregation of small with large drops in some emulsions. Our results elucidate new processes relevant to emulsion stability with potential impact on industrial processes on Earth, as well as enabling technologies for space exploration. [ABSTRACT FROM AUTHOR]

As space science advances, the significance of space robotics research escalates, particularly in control methodologies. Addressing the work efficiency requirements during the mission of the in-cabin robot, it is necessary to develop a fast and robust position and attitude coupling controller for in-cabin robots. This paper presents a predefined-time sliding mode position and attitude coupling control method, employing the SE(3) frame description. The first, the dynamic model of the in-cabin robot is developed within the SE(3) framework. Then, the predefined-time position and attitude coupling sliding mode controller is designed with a sliding surface based on the dynamic error model, and a hyperbolic tangent function is used to suppress system chattering. In addition, the stability of the proposed control method is rigorously confirmed using the Lyapunov theorem, ensuring that the convergence time is accurately predefined. Finally, simulation results are provided to demonstrate the effectiveness of this novel control strategy. A comparative analysis with fixed-time sliding mode control highlights its superior performance. [ABSTRACT FROM AUTHOR]

The Three Gorges (TG) in central China is an earthquake prone region that lacks active-source seismic surveys, hence requiring high-resolution passive seismic imaging to reveal crustal structures in detail. While teleseismic virtual-source reflection (TVR) profiling is effective for imaging gently dipping upper crustal structures, it is unsuitable for mapping steep structures beneath rugged topography in the TG region. Here we develop a teleseismic virtual-source reverse time migration (TV-RTM) to improve the imaging of steep structures. Synthetic tests are conducted to demonstrate the validity and resolution of the TV-RTM method. To mitigate the imaging inaccuracy due to sparse station spacing, we interpolate direct-arrival waveforms to achieve a doubling of the minimally required station spacing from 2 to 4 km. The TV-RTM images of the upper crustal structure beneath a 2-D array in the TG region reveal significant fold and thrust structures that correlate well with the surface geology and tectonic framework. The resolution of the images is assessed using 2-D and 3-D synthetic models with the station and source geometry of field data. The TV-RTM method provides a new passive seismic solution for studying upper crustal structures in regions that lack active-source seismic data. [ABSTRACT FROM AUTHOR]

Future human expeditions into deep space will encounter unique design challenges posed by the increasing distance from Earth, one of which is the inability to maintain near-continuous communication with ground support teams. As a result, the habitat and crew will require a higher level of operational self-sufficiency informed by onboard self-awareness and decision-making capabilities to accomplish functions that have historically involved extensive support from mission control personnel. These include, for example, task planning and anomaly detection, diagnosis and correction, as well as monitoring of consumable usage rates and system performance. Novel emergent technologies in the domain of 'smart' systems and digital twins can be employed to enable the onboard capabilities needed to function with minimal Earth communication. However, these technologies are generally low-TRL and difficult to incorporate through traditional systems engineering methods. This work proposes an extension of utility theory to assess the potential reduction in Earth communication reliance between baseline and emergent technologies, scored through a summation of weighted attributes and evaluated against future deep space mission needs and constraints. Case studies are defined from technology under development in the NASA Habitats Optimized for Missions of Exploration (HOME) Space Technology Research Institute (STRI), a project charged with developing and evaluating technologies to enable highly autonomous deep space habitats, and compared to the current baseline technologies used onboard the International Space Station. Notional deep space mission needs and constraints are informed from current NASA plans for the Moon and Mars. These in turn are broken out into higher resolution attributes that are used to assess the operational capabilities of each emergent technology and whether it offers a potentially viable solution for deep space. These technology attributes are scored through a series of semi-structured subject-matter interviews and compared to notional deep space mission constraints. Additional considerations for technology maturation and integration are also discussed. The design analysis paradigm described and demonstrated here can be adapted to assess the degree to which other emergent technologies rely on Earth-based communication, and is intended to provide trade space considerations for future research and development towards deep space habitat self-sufficiency. • Presents a case study of a previously proposed framework for assessing the contributions of emergent technology towards mission self-reliance. • Proposes a scoring framework based on utility theory to assess contributions of emergent technology under constraints. • Technologies from the NASA HOME STRI are assessed via conversations with subject-matter experts. [ABSTRACT FROM AUTHOR]

This paper presents the mission scenarios of using spinning tether system to conduct space stations fly-around mission and validates its feasibility. The main challenge of fly-around mission lies in the difficulty of balancing low fuel consumption and long-term fly-around observation. To deal with this problem, a novel spinning tether system is proposed. Firstly, the fly-around process with spinning tether system is introduced, and the tether system is modeled based on Newton-Euler method with a novel description of spinning motion. Secondly, Given the unique structural limitations of space stations, two fly-around schemes and referenced fly-around trajectories are detailed. Thirdly, a backstepping controller is proposed for tracking the reference motion of fly-around satellites, and the fuel consumption among different fly-around schemes is compared and analyzed. In the end, numerical results validate that under the proposed control strategy, the spinning tether system can maintain a stable fly-around configuration in both the planar and vertical plane, the symmetrical formation configuration prevents the central space station from being affected by the motion of fly-around satellites. Moreover, energy consumption analysis indicates that tethered system can save 62.8 % of impulse compared to traditional schemes when flying in the planar plane, making it the most energy-efficient option. • A novel tethered fly around scheme was proposed for space station observation. • A modified model was introduced to address the singularity and coupling issues. • An impulse analysis was conducted to assess the mission feasibility. [ABSTRACT FROM AUTHOR]

The Global Space-based Stratospheric Aerosol Climatology (GloSSAC) is essential for understanding and modeling the climatic impacts of stratospheric aerosols. It relies primarily on data from the Stratospheric Aerosol Gas Experiment (SAGE) satellite series, supplemented by the Optical Spectrograph and Infrared Imaging System (OSIRIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). GloSSAC currently provides stratospheric aerosol extinction coefficients and aerosol optical depths at 525 and 1020 nm. With CALIPSO decommissioned and OSIRIS nearing the end of its operational life, SAGE III/ISS (International Space Station) will soon become the sole data source for GloSSAC, but it will only be available as long as the ISS is operational, until around 2030. Therefore, incorporating other measurements, such as those from the Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP), is critical. OMPS-LP has provided continuous aerosol extinction coefficient measurements since 2012 with a retrieval algorithm developed by NASA, i.e., OMPS(NASA). However, OMPS(NASA) has been shown to overestimate aerosol extinction coefficients, particularly after the 2022 Hunga Tonga eruption, compared to the tomographic retrieval of OMPS developed by the University of Saskatchewan (OMPS(SASK)) and SAGE III/ISS. Our analysis shows that OMPS(NASA) indeed exhibits a consistently high bias (>50 %) following large volcanic eruptions and pyrocumulonimbus plumes from intense wildfires, while OMPS(SASK) shows reasonable agreement with SAGE III/ISS between 40° S and 40° N. This overestimation by OMPS(NASA) leads to an overestimation of the aerosol effective radiative forcing (ERF) and the associated model-simulated global surface temperature response by a factor of about 2. [ABSTRACT FROM AUTHOR]

Our experiments aboard the Chinese Space Station reveal a gravity-driven transition in intruder dynamics within vibrated granular media. While vibrations typically enable an intruder to ascend in a granular bed, low-gravity conditions induce it to descend under similar vibrations. Using a Hall-sensor array tracking method, we monitor the intruder's movement throughout each vibration cycle and identified two competing mechanisms: inertia and gravity-dependent penetration. As gravity decreases, we observe a significant reduction in the scaled damping coefficient and hydrostatic pressure coefficient indicating that bed particles disperse more readily upon intruder impact, facilitating deeper penetration. Our findings highlight a critical transition from downward to upward motion of the intruder as vibration acceleration exceeds a threshold, which increases as gravity decreases. These insights into intruder dynamics in low-gravity environments have significant implications for asteroid exploration and lunar base construction, enhancing our understanding of the Brazil nut effect and the formation of planetesimal. Granular segregation may play a role in shaping the surface features of small celestial bodies such as asteroids that can be explained with the Brazil-nut effect. The authors study intruder dynamics in granular media on board the Chinese Space Station, finding that contrary to what occurs on Earth intruders tend to descend in microgravity conditions under specific vibration parameters [ABSTRACT FROM AUTHOR]

Colloidal solids (COLIS) is a state-of-the-art light scattering setup developed for experiments onboard the International Space Station (ISS). COLIS allows for probing the structure and dynamics of soft matter systems on a wide range of length scales, from a few nm to tens of microns, and on time scales from 100 ns to tens of hours. In addition to conventional static and dynamic light scattering, COLIS includes depolarized dynamic light scattering, a small-angle camera, photon correlation imaging, and optical manipulation of thermosensitive samples through an auxiliary near-infrared laser beam, thereby providing a unique platform for probing soft matter systems. We demonstrate COLIS through ground tests on standard Brownian suspensions, and on protein, colloidal glasses, and gel systems similar to those to be used in future ISS experiments. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2 ${\mathrm{C}\mathrm{O}}_{2}$) emissions from combustion sources are uncertain in many places across the globe. Here, we estimate CO2 ${\mathrm{C}\mathrm{O}}_{2}$ emission rates from a small number of collocated observations from the Orbiting Carbon Observatory‐3 (OCO‐3) and the Earth Surface Mineral Dust Source Investigation (EMIT), both onboard the International Space Station (ISS). These near‐simultaneous measurements allow for an unprecedented comparison of two unique space‐based CO2 ${\mathrm{C}\mathrm{O}}_{2}$ sensors over both isolated coal‐fired power plants and multi‐source scenes in China. We estimate CO2 ${\mathrm{C}\mathrm{O}}_{2}$ emission rates using integrated mass enhancement and a Gaussian plume model. Where validation data is available, 15 of the 19 estimated emission rates have errors less than 37%. For the multi‐source scenes, EMIT can estimate emissions from individual facilities but its aggregate emissions are 42% lower than OCO‐3, likely because it cannot detect small sources or diffuse emissions. OCO‐3, with its excellent precision, may better constrain CO2 ${\mathrm{C}\mathrm{O}}_{2}$ emissions over the entire scene. Plain Language Summary: We do not know exactly how much carbon dioxide is emitted from combustion point sources, like power plants that burn coal, in many places across the globe. Satellites orbiting Earth can detect these carbon dioxide emissions, but research is needed to better understand and improve this capability. In this work, we use measurements taken at about the same time from the Orbiting Carbon Observatory‐3 (OCO‐3) instrument and the Earth Surface Mineral Dust Source Investigation (EMIT) instrument, both onboard the International Space Station (ISS), to estimate how much carbon dioxide is emitted from a small number of power plants. For power plants where we know how much carbon dioxide they emit, both OCO‐3 and EMIT can accurately measure the rate of carbon dioxide emission, if we average enough data together. For a small region in northwest China that has 11 power plants, EMIT can estimate emission rates from individual power plants but OCO‐3 may be better able to estimate the total amount of carbon dioxide emitted over the entire scene. Key Points: Near‐simultaneous observations of CO2 point sources from OCO‐3 and EMIT allow for a comparison of emission rate estimates from both sensorsEMIT's high spatial resolution allows it to estimate CO2 emission rates from individual facilities within a multi‐source sceneOCO‐3's excellent precision allows it to constrain total CO2 emissions from multi‐source scenes [ABSTRACT FROM AUTHOR]

The Nutrient-upgraded Rodent Food Bar (NuRFB) is the standard diet for mice in NASA's Rodent Research Project aboard the International Space Station (ISS). Given the nature of spaceflight and the lengthy production process of the food bars, a shelf-life assessment was conducted to evaluate nutritional stability over time (ranging from 0 to 27 months) and under different storage conditions (refrigerated, ambient, and refrigerated + ambient), where ambient is 22–23 °C. Lipid oxidation markers and fat- and water-soluble vitamins were assessed under various time and temperature conditions using AOAC International methods. Vitamin D levels showed a minor decrease, and riboflavin fluctuated slightly over time, but all vitamin levels remained above National Research Council (NRC) minimum requirements. Food bars stored at 4 °C showed significantly higher thiamine levels than the bars that underwent some degree of ambient temperature storage, but all met the NRC guidelines. Minimal lipid oxidation was observed for up to 18 months, and no mold or yeast growth occurred despite the high moisture content of the bars. This study confirms that NuRFBs maintain stable vitamin and lipid oxidation indices, ensuring adequate nutrition for rodents during spaceflight. [ABSTRACT FROM AUTHOR]

The International Space Station currently requires four annual replenishments for food supply, a practice that won't be feasible for deep space missions due to the greater distances. Based on the design of closed ecological life support systems, two waste streams were identified: urea from the crew urine, volatile fatty acids (VFAs) from a first stage of anaerobic digestion of waste. The objective of this study was to assess the ability of bacterium Cupriavidus necator to produce single cell protein on urea and VFAs. Thus, the effect of carbon sources (glucose vs VFAs) and the dilution rate on the biomass composition was determined in continuous cultures. Complete transformation of the carbon source into protein-rich biomass was achieved up to 78 % cell dry weight (CDW). For both carbon sources, the protein content increased from 55.0 %CDW to 78 %CDW with a decrease in the dilution rate. Conversely, the nucleic acid and polyhydroxyalkanoate contents decreased with the dilution rate from 8.8 %CDW to 4.8 %CDW and 9.8 %CDW to 0.6 %CDW respectively. Working at a low dilution rate seems to be a good way to maximize protein content while minimizing unwanted nucleic acids and polyhydroxyalkanoates. [Display omitted] • C. necator continuous cultivations led to total consumption of the carbon sources. • Biomass composition changes with dilution rate regardless carbon source. • Bioplastics were produced even under carbon limitation. [ABSTRACT FROM AUTHOR]

Introduction: Current and future astronauts will endure prolonged exposure to spaceflight hazards and environmental stressors that could compromise cognitive functioning, yet cognitive performance in current missions to the International Space Station remains critically under-characterized. We systematically assessed cognitive performance across 10 cognitive domains in astronauts on 6-month missions to the ISS. Methods: Twenty-five professional astronauts were administered the Cognition Battery as part of National Aeronautics and Space Administration (NASA) Human Research Program Standard Measures Cross-Cutting Project. Cognitive performance data were collected at five mission phases: pre-flight, early flight, late flight, early post-flight, and late post-flight. We calculated speed and accuracy scores, corrected for practice effects, and derived z-scores to represent deviations in cognitive performance across mission phases from the sample's mean baseline (i.e., pre-flight) performance. Linear mixed models with random subject intercepts and pairwise comparisons examined the relationships between mission phase and cognitive performance. Results: Cognitive performance was generally stable over time with some differences observed across mission phases for specific subtests. There was slowed performance observed in early flight on tasks of processing speed, visual working memory, and sustained attention. We observed a decrease in risk-taking propensity during late flight and post-flight mission phases. Beyond examining group differences, we inspected scores that represented a significant shift from the sample's mean baseline score, revealing that 11.8% of all flight and post-flight scores were at or below 1.5 standard deviations below the sample's baseline mean. Finally, exploratory analyses yielded no clear pattern of associations between cognitive performance and either sleep or ratings of alertness. Conclusion: There was no evidence for a systematic decline in cognitive performance for astronauts on a 6-month missions to the ISS. Some differences were observed for specific subtests at specific mission phases, suggesting that processing speed, visual working memory, sustained attention, and risk-taking propensity may be the cognitive domains most susceptible to change in Low Earth Orbit for high performing, professional astronauts. We provide descriptive statistics of pre-flight cognitive performance from 25 astronauts, the largest published preliminary normative database of its kind to date, to help identify significant performance decrements in future samples. [ABSTRACT FROM AUTHOR]

Background: Electroencephalogram (EEG) biomarkers with adequate sensitivity and specificity to reflect the brain's health status can become indispensable for health monitoring during prolonged missions in space. The objective of our study was to assess whether the basic features of the posterior dominant rhythm (PDR) change under microgravity conditions compared to earth-based scalp EEG recordings. Methods: Three crew members during the 16-day AXIOM-1 mission to the International Space Station (ISS), underwent scalp EEG recordings before, during, and after the mission by means of a dry-electrode self-donning headgear designed to support long-term EEG recordings in space. Resting-state recordings were performed with eyes open and closed during relaxed wakefulness. The electrodes representative of EEG activity in each occipital lobe were used, and consecutive PDR oscillations were identified during periods of eye closure. In turn, cursor-based markers were placed at the negative peak of each sinusoidal wave of the PDR. Waveform averaging and time-frequency analysis were performed for all PDR samples for the respective pre-mission, mission, and post-mission EEGs. Results: No significant differences were found in the mean frequency of the PDR in any of the crew subjects between their EEG on the ISS and their pre- or post-mission EEG on ground level. The PDR oscillations varied over a ±1Hz standard deviation range. Similarly, no significant differences were found in PDR's power spectral density. Conclusions: Our study shows that the spectral features of the PDR remain within normal limits in a short exposure to the microgravity environment, with its frequency manifesting within an acceptable ±1 Hz variation from the pre-mission mean. Further investigations for EEG features and markers reflecting the human brain neurophysiology during space missions are required. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the adverse relationships (flows) related to health, education, and consumption among small cities in the Immediate Geographic Region of Araxá, Minas Gerais, Brazil, to verify the existing relationships of dependence and complementarity, as well as the thresholds with aspects of quality of life. To this end, we analyzed the established flows, through the results of the study of Region of Influence of Cities, with 2018 as the reference year, carried out by the Brazilian Institute of Geography and Statistics. The Region of Influence of Cities microdata was extracted from the Brazilian Institute of Geography and Statistics website, tabulated, and subsequently spatialized using ArcGis 10.2 software. The results showed strong dependence of small cities in the Immediate Geographic Region in relation to medium and high complexity health, on the existing equipment in Araxá and Uberaba, respectively. In relation to education, the Immediate Geographic Region flows occur both to Araxá (the only city offering in-person higher education courses within the space laboratory analyzed), but also to Uberaba, Uberlândia, Rio Paranaíba and other cities with campuses of public and private institutions. The relationships presented by consumption demonstrated the tendency of flows to the largest cities, with a greater variety of businesses and services, but also between the small cities, especially for consumption related to agricultural products and services. [ABSTRACT FROM AUTHOR]

Many biological markers of normal and disease states can be detected in saliva. The benefits of saliva collection for research include being non-invasive, ease of frequent sample collection, saving time, and being cost-effective. A small volume (≈1 mL) of saliva is enough for these analyses that can be collected in just a few minutes. For "dry" saliva paper matrices, additional drying times (about 30 min) may be needed, but this can be performed at room temperature without the need for freezers and specialized equipment. Together, these make saliva an ideal choice of body fluid for many clinical studies from diagnosis to monitoring measurable biological substances in hospital settings, remote, and other general locations including disaster areas. For these reasons, we have been using saliva (dry as well as wet) from astronauts participating in short- and long-duration space missions for over two decades to conduct viral, stress, and immunological studies. We have also extended the use of saliva to space analogs including bed rest, Antarctica, and closed-chamber studies. Saliva is a biomarker-rich and easily accessible body fluid that could enable larger and faster public health screenings, earlier disease detection, and improved patient outcomes. This review summarizes our lessons learned from utilizing saliva in spaceflight research and highlights the advantages and disadvantages of saliva in clinical diagnostics. [ABSTRACT FROM AUTHOR]

Robotics, Automation, and Autonomous Systems form the cornerstone for ambitious large-scale in-orbit missions. However, the harsh space environment presents unique challenges that demand careful consideration. Key requirements for next-generation space manipulators include dexterity, modularity, redundancy, workspace enhancement, and autonomous mobility. To address the limitations of conventional walking manipulators, this paper presents a novel seven-degrees-of-freedom dexterous End-Over-End Walking Robot (E-Walker) for future In-Space Assembly and Manufacturing missions. The use-case considers the in-situ robotic assembly of the primary mirror of a 25 m Large Aperture Space Telescope (LAST). This research is timely given the constant clamour for high-resolution astronomy and earth observation within the space community and serves as a baseline for future missions with telescopes of much larger aperture, missions requiring assembly of space stations, and solar-power generation satellites to list a few. The paper starts by eliciting the mission Concept of Operations (ConOps) for the in-situ assembly of a 25 m LAST utilising the next-generation E-Walker space manipulator, which serves as a narrative backdrop to present the feasibility analysis. Comparing the power, time, control and motion planning complexities of eleven mission ConOps, the trade-off analysis shortlists a potential mission scenario. Furthermore, operational assessments of two potential mission ConOps are compared to estimate the time required for assembly. The study offers new insights into mission time requirements for these scenarios, shedding light on multi-robot collaborative task-sharing and practical applicability of the E-Walker in executing complex and high-value in-orbit assembly missions. • The paper presents the novel E-Walker robot for In-Space Assembly and Manufacturing. • In-orbit robotic assembly of modular 25 m primary mirror of a large space telescope. • The mission architecture and top-level design of the 25 m LAST are outlined. • Collaborative task-sharing capabilities of multiple E-Walkers presented. • Estimation of mission trade-off parameters: Time, Power, Control, and Lifting-mass. [ABSTRACT FROM AUTHOR]

Accurate estimation of photometric redshifts (photo- z s) is crucial for cosmological surveys. Various methods have been developed for this purpose, such as template fitting methods and machine learning techniques, each with its own applications, advantages, and limitations. In this study, we propose a new approach that utilizes a deep learning model based on recurrent neural networks with long short-term memory (LSTM) to predict photo- z. Unlike many existing machine learning models, our method requires only flux measurements from different observed filters as input. The model can automatically learn the complex relationships between the flux data across different wavelengths, eliminating the need for manually extracted or derived input features, thereby providing precise photo- z estimates. The effectiveness of our proposed model is evaluated using simulated data from the Chinese Space Station Telescope (CSST) sourced from the Hubble Space Telescope Advanced Camera for Surveys (HST-ACS) and the COSMOS catalogue, considering anticipated instrument effects of the future CSST. Results from experiments demonstrate that our LSTM model, compared to commonly used template fitting and machine learning approaches, requires minimal input parameters and achieves high precision in photo- z estimation. For instance, when trained on the same data set and provided only with photometric fluxes as input features, the proposed LSTM model yields one-third of the outliers |$f_{\mathrm{out}}$| observed with a multi-layer perceptron neural network (MLP) model, while the normalized median absolute deviation |$\rm \sigma _{NMAD}$| is only two-thirds that of the MLP model. This study presents a novel approach to accurately estimate photo- z s of galaxies using photometric data from large-scale survey projects. [ABSTRACT FROM AUTHOR]

Metal additive manufacturing in space is a cutting-edge technology that is designed to meet the needs of space exploration and space station construction. This technology is capable of customizing and repairing key metallic parts in a space microgravity environment, providing the feasibility for long-term space tasks. It enables astronauts to perform on-site repairs and replace broken parts, significantly reducing the risk of mission failure on the International Space Station or during future deep space missions. Further, this technique opens new possibilities for constructing space bases by directly utilizing the materials from space, thereby reducing reliance on Earth's resources. However, metal additive manufacturing in space faces challenges due to the unclear underlying mechanisms that lie in (I) the significant differences in the melting behaviors of materials in a space microgravity environment compared to those on Earth; and (II) extreme environmental factors, i.e., radiation and temperature fluctuations, that influence the metal additive manufacturing process and, consequently, the properties of the manufactured materials. This review provides a comprehensive analysis of those mechanisms underlying metal additive manufacturing in space, based on published works. Emphasis is placed on aluminum, titanium, iron, and copper-based metals. Our work may offer valuable guidance for reducing mission costs, improving safety, and enabling the on-demand production of complex components in the harsh environment of space by using metal additive manufacturing. [ABSTRACT FROM AUTHOR]

The supply and exhaust system of the experimental rack on the Chinese space station is a complex integrated system. In this paper, a multi-stage simulation, testing, and verification method is designed for a multi-team, multi-location, and multi-stage integrated gas system. This method is designed to solve the problem of missing input parameters between the gas supply system and the exhaust system. Preliminary tests and strategy verifications were carried out through theoretical simulation and semi-physical simulation, and good calculation results were obtained for the single-rack product. The external systems were tested using a simulation system, and a calculation method was designed to obtain relatively accurate parameters. In the early stage, the performance of the product was predicted using the parameter library of Flomaster and semi-physical simulation methods, but the error was large. In the middle and late stages of development, as some products became realistic, multi-stage testing was carried out using a vacuum simulator, simulated flow resistance, and other methods, achieving a performance prediction with an error of 12% before ground testing. The final ground test and on-orbit test showed that the design and calculation method of this paper is effective. The multi-stage design method proposed in this paper was successfully applied to the integrated gas system of the Chinese space station, which can provide a reference for the design of fluid components in long-term system engineering. [ABSTRACT FROM AUTHOR]

This article introduces the design and development of a space environment monitoring unit embedded in the versatile experimental assembly for electronic components outside the China space station's Wentian laboratory cabin module. A newly designed comprehensive detection system is being used for the first time in this kind of detector. The sensor head of the instrument includes a silicon telescope (composed of two silicon semiconductors) for measuring the LET spectrum and radiation dose rate, a typical chip for monitoring a single-event upset, and a CR-39 plastic nuclear track detector for detecting heavy ion tracks. The two silicon sensors stacked up and down are used for measuring the LET spectrum, which ranges from 0.001 to 100 MeV·cm2/mg. A sensor charge allocation method is adopted to divide the detection range into four cascaded levels, each achieving different detection ranges separately and then concatenated together, while traditional detection methods need multiple sets of probes to achieve the same dynamic range. At the same time, using the two sensors mentioned above, the silicon absorption dose rate under two different shielding thicknesses can be obtained through calculation, ranging from 10−5 to 10−1 rad (Si)/h. Multiple calibration methods are applied on the ground. The preliminary in-orbit detection results are provided and compared with the simulation results obtained using the existing space environment model, and we analyze and discuss their differences. [ABSTRACT FROM AUTHOR]

A satellite laser ranging (SLR) system uses lasers to measure the range from ground stations to space objects with millimeter-level precision. Recent advances in SLR systems have increased their use in space surveillance and tracking (SST). The problem we are addressing, the precise orbit determination (POD) using one-dimensional range observations within a single arc, is challenging owing to infinite solutions because of limited observability. Therefore, general orbit determination algorithms struggle to achieve reasonable accuracy. The proposed algorithm redefines the cost value for orbit determination by leveraging residual tendencies in the POD process. The tendencies of residuals are quantified as R-squared values using Fourier series fitting to determine velocity vector information. The algorithm corrects velocity vector errors through the grid search method and least squares (LS) with a priori information. This approach corrects all six dimensions of the state vectors, comprising position and velocity vectors, utilizing only one dimension of the range observations. Simulations of three satellites using real data validate the algorithm. In all cases, the errors of the two-line element data (three-dimensional position error of 1 km and velocity error of 1 m/s, approximately) used as the initial values were reduced by tens of meters and the cm/s level, respectively. The algorithm outperformed the general POD algorithm using only the LS method, which does not effectively reduce errors. This study offers a more efficient and accurate orbit determination method, which improves the safety, cost efficiency, and effectiveness of space operations. [ABSTRACT FROM AUTHOR]

Stellar ultraviolet (UV) emission serves as a crucial indicator for estimating magnetic activity and evaluating the habitability of exoplanets orbiting stars. In this paper, we present a straightforward method to derive stellar photospheric UV emission for F to M main-sequence stars. By using PARSEC models, we establish relations between near-UV (NUV) and far-UV (FUV) magnitudes from the Galaxy Evolution Explorer, NUV magnitudes from the China Space Station Telescope, and stellar effective temperatures and Gaia blue photometer–red photometer colors for different metallicities. Together with the observed sample, we find that for NUV emission, the photospheric contribution to the observed flux is less than 20% for M stars, around 10%–70% for K stars, and in a range from 30% to 85% for G and F stars. For FUV emission, the photospheric contribution is less than 10−6 for M stars, below 10−4 for K stars, around 10−4–10% for G stars, and between 6% and 50% for F stars. Our work enables the simple and effective determination of stellar excess UV emission and the exploration of magnetic activity. [ABSTRACT FROM AUTHOR]

Long-duration spaceflight creates a variety of stresses due to the unique environment, which can lead to compromised functioning of the skeletal and immune systems. However, the mechanisms by which organisms respond to this stress remain unclear. The present study aimed to investigate the impact of three different gravitational loadings (microgravity, 1/6 g [lunar gravity], and 1 g) on the behavior, bone, thymus, and spleen of mice housed for 25–35 days in the International Space Station. The bone density reduction under microgravity was mostly recovered by 1 g but only partially recovered by 1/6 g. Both 1 g and 1/6 g suppressed microgravity-induced changes in some osteoblast and osteoclast marker gene expression. Thymus atrophy induced by microgravity was half recovered by both 1 g and 1/6 g, but gene expression changes were not fully recovered by 1/6 g. While no histological changes were observed due to low gravity, alterations in gene expression were noted in the spleen. We found that in bone and thymus, lunar gravity reduced microgravity-induced histological alterations and partially reversed gene expression changes. This study highlighted organ-specific variations in responsiveness to gravity, serving as an animal test for establishing a molecular-level gravity threshold for maintaining a healthy state during future spaceflight. [ABSTRACT FROM AUTHOR]

Crewed outer-space missions require adequate motor capacity among astronauts, whose sensorimotor system is disturbed by microgravity. Stressors other than microgravity, e.g., sleep loss, confinement, and high workload, characterize the living experience in space and potentially affect motor performance. However, the evidence of these stressors remains elusive. We recruited twelve taikonauts from the China Space Station to conduct a motor timing task that minimized the effect of microgravity on motor performance. Participants showed a remarkable increase in motor timing variance during spaceflight, compared to their pre- and post-flight performance and that of ground controls. Model-based analysis revealed that their timing deficits were driven by increased central noise instead of impaired motor execution. Our study provides evidence that nonspecific stressors can profoundly affect motor performance during spaceflight. [ABSTRACT FROM AUTHOR]

Extended-duration human spaceflight necessitates a better understanding of the physiological impacts of microgravity. While the ground-based microgravity simulations identified low intensity vibration (LIV) as a possible countermeasure, how cells may respond to LIV under real microgravity remain unexplored. In this way, adaptation of LIV bioreactors for space remains limited, resulting in a significant gap in microgravity research. In this study, we introduce an LIV bioreactor designed specifically for the usage in the International Space Station. Our research covers the bioreactor's design process and evaluation of the short-term viability of cells encapsulated in hydrogel-laden 3D printed scaffolds under 0.7 g, 90 Hz LIV. An LIV bioreactor compatible with the operation requirements of space missions provides a robust platform to study cellular effects of LIV under real microgravity conditions. [ABSTRACT FROM AUTHOR]

It is essential to provide high-integrity navigation information for safety-critical applications. Global navigation satellite systems (GNSSs) play an important role in these applications because they can provide global, high-accuracy, all-weather navigation services. Therefore, it has been a hot topic to improve GNSS integrity performance. This paper focuses on an initial proposal of the next-generation BeiDou Navigation Satellite System (BDS) integrity subsystem, with the aim of providing high-quality and global integrity services for the BDS. This paper first reviews the current status of the third-generation BDS integrity service. Following this, this paper proposes a space–ground integrated integrity monitoring design for the BDS that integrates the traditional ground-based integrity monitoring method, the advanced satellite autonomous integrity monitoring (A-SAIM) method, and the augmentation from low-earth-orbit (LEO) satellites. Specifically, this work offers an initial design of the A-SAIM method, which considers both single-satellite autonomous integrity monitoring and multi-satellite joint integrity monitoring. In addition, this work describes two different ways to augment BDS integrity with LEO satellites, i.e., (a) LEO satellites act as space monitoring stations and (b) LEO satellites act as navigation satellites. Simulations are carried out to validate the proposed design using CAT-I operation in civil aviation as an example. Simulation results indicate the effectiveness of the proposed design. In addition, simulation results suggest that if the fault probability of LEO satellites is worse than 1 × 10−4, LEO satellites can contribute more to BDS integrity performance improvement by acting as space monitoring stations; otherwise, it would be better to employ LEO satellites to broadcast navigation signals. The results also suggest that after taking LEO satellites into account, the global coverage of CAT-I can be potentially improved from 67% to 99%. This work is beneficial to the design of the next-generation BDS integrity subsystem. [ABSTRACT FROM AUTHOR]

A new retrieval approach for obtaining vertical profiles of the aerosol extinction coefficient from measurements of scattered solar light in the limb-viewing geometry made by the Ozone Mapper and Profiler Suite Limb Profiler (OMPS-LP) instrument is presented. In contrast to many other published limb-scatter retrievals, our new algorithm does not employ normalization by a limb measurement at an upper tangent height. Instead, the measured limb radiances are normalized to solar irradiance. The main advantage of this approach is an almost complete elimination of the dependence of the retrieval results on the prior aerosol extinction profile used in the retrieval. This makes the retrieval better suited for the analysis of observation scenes with highly elevated aerosol plumes, such as those that occurred after the Hunga Tonga–Hunga Ha′apai volcanic eruption in January 2022. The results from the new approach were compared to the vertical profiles of the aerosol extinction coefficients retrieved from the Stratospheric Aerosol and Gas Experiment III on the International Space Station (SAGE III/ISS) and the Optical Spectrograph and InfraRed Imaging System (OSIRIS). In general, agreement within 25 % between the different data products was observed in the 18–23 km altitude range, although larger differences were seen after very strong volcanic eruptions and wildfires. In comparison with OSIRIS, larger differences are seen at high southern latitudes (above 60° S). The new data product was used to investigate the evolution of the aerosol plume after the Hunga Tonga–Hunga Ha′apai volcanic eruption. [ABSTRACT FROM AUTHOR]

The development of eye pathology is a serious concern for astronauts who spend time in deep space. Microgravity is a major component of the spaceflight environment which could have adverse effects on ocular health. The use of centrifugation to exert forces that partially or fully mimic Earth-level gravity in space is a possible countermeasure to mitigate the effects of microgravity on the eye. Therefore, we subjected mice on the International Space Station (ISS) to microgravity (0 G) or artificial gravity by centrifugation at 0.33 G, 0.67 G, and 1 G, and then performed RNA sequencing (RNA-seq) on optic nerve and retinal tissue after returning them to Earth alive. We find that the microgravity environment induces transcriptomic changes in the optic nerve and retina consistent with an increased oxidative stress load, inflammation, apoptosis, and lipid metabolic stress. We also find that adding artificial gravity on board the ISS attenuates the transcriptomic response to microgravity in a dose-dependent manner. Such attenuation may effectively protect from and mitigate spaceflight-induced detrimental effects on ocular tissue. [ABSTRACT FROM AUTHOR]

The Calorimetric Electron Telescope, CALET, is an astroparticle physics mission installed on the International Space Station, ISS. The primary objective of the mission is studying the details of galactic cosmic-ray acceleration and propagation, and searching for the possible nearby sources of high-energy electrons and dark matter signatures. The CALET experiment measure the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays to 10 TeV and nuclei to 1000 TeV. The detector is an all-calorimetric instrument with a total vertical thickness of 30 radiation lengths and fine imaging capability, optimized for the measurement of the electron and positron (all-electron) spectrum well into the TeV energy region. It consists of a charge detector (CHD) with two layers of segmented plastic scintillators for the identification of cosmic-rays via a measurement of their charge over the range Z = 1 ∼ 40 , a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). The instrument was launched on August 19, 2015 to the ISS and installed on the Japanese Experiment Module-Exposed Facility. Since the start of operation in October, 2015, CALET has been collecting scientific data without any major interruption for more than eight years. The number of triggered events over 10 GeV is nearly 1.97 billion events as of November 30, 2023. In this paper, we present the results of the CALET mission so far, including the all-electron energy spectrum, the spectra of protons and other nuclei, gamma-ray observations, as well as the characterization of on-orbit performance. Some results on the electromagnetic counterpart search for LIGO/Virgo gravitational wave events and the observations of solar modulation and gamma-ray bursts are also included. [ABSTRACT FROM AUTHOR]

We present the latest precision measurements of the fluxes of all charged cosmic elementary particles, protons, electrons, antiprotons and positrons based on the first 10 years of data collected by the Alpha Magnetic Spectrometer on the International Space Station. These unique results, obtained with the same detector and with unprecedented precision in the uncharted energy range, provide precise experimental information and reveal new properties of cosmic charged elementary particles. In the absolute rigidity range of 60 to 525 GV, the antiproton-to-proton flux ratio is constant and the antiproton flux and proton flux have identical rigidity dependence. This behavior indicates an excess of high-energy antiprotons compared with traditional predictions of secondary antiprotons produced from the collision of cosmic rays. More importantly, from 60 to 525 GV, the antiproton flux and positron flux also show identical rigidity dependence. The positron-to-antiproton flux ratio is independent of energy, with its value of 2 established with percent-level accuracy. This unexpected observation suggests a common origin of high-energy antiprotons and positrons in the cosmos. [ABSTRACT FROM AUTHOR]

Iron and nickel cosmic ray nuclei play a key role in the understanding of the acceleration and propagation mechanisms of charged particles in our Galaxy. In fact, iron and nickel are the most abundant nuclei among the heavy elements and provide favorable conditions for a low background measurement thanks to the negligible contamination from spallation of higher mass elements. CALET, operating on the ISS since 2015, has excellent capabilities of charge discrimination up to nickel and can measure the energy of cosmic ray nuclei thanks to a lead tungstate calorimeter providing a direct and precise measurement of heavy charged nuclei spectra. In this contribution, a direct measurement of iron and nickel nuclei spectra in the energy range from 10 GeV/n to 2 TeV/n and from 8.8 GeV/n to 240 GeV/n, respectively is presented. More than five years of data collected by CALET were used. A detailed study of systematic uncertainties is also illustrated. The measured spectra are compared with the ones measured by other experiments and are compatible with a single power law fit in the energy region from 50 GeV/n to 2 TeV/n and from 20 GeV/n to 240 GeV/n for iron and nickel respectively. Also, the ratio between nickel and iron spectra is reported. [ABSTRACT FROM AUTHOR]

A measurement of the cosmic ray anisotropy on the arrival directions of elementary particles (electrons, positrons and protons) has been performed in galactic coordinates by the Alpha Magnetic Spectrometer onboard the International Space Station. The analysis is based on the sample of events collected in the first 10 years of data taking. The results are consistent with isotropy for all cosmic ray species and upper limits on the dipole amplitude have been computed. In particular, 95 % credible interval upper limits of δ < 1.50 % and δ < 0.34 % are obtained for positrons and electrons, respectively, above 16 GeV. On the other hand, the upper limit to the dipole anisotropy of protons above 200 GV is found to be δ < 0.30 %. [ABSTRACT FROM AUTHOR]

The precision measurements of the cosmic-ray positron and electron fluxes collected by the Alpha Magnetic Spectrometer on the International Space Station during first ten years of operations are presented. The positron flux exhibits complex energy dependence. It is described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which dominates at low energies, and a new source term, which dominates at high energies and is associated with either dark matter or astrophysical origin. The positron source term also manifest itself in the measured electron spectrum. This is the first indication of the existence of an identical charge symmetric source term both in the positron and in the electron spectra. If confirmed with a higher level of confidence, these observations might suggest the existence of new physics. [ABSTRACT FROM AUTHOR]

The two primary material requirements for a crewed habitat or spacecraft to operate beyond low earth orbit (LEO) include effective radiation shielding against the space radiation and secondary neutron environment and sufficient structural and thermal integrity. In this context it is mandatory to study the effect of long duration space environment on any proposed multifunctional radiation shielding material. In this paper we discuss two radiation shielding composite architectures and their long duration performance in LEO. Samples were flown on NASA's The Materials International Space Station Experiment (MISSE) platform and their structural, optical, and radiation shielding capabilities were characterized pre and post flight. Results showed composite architecture can be key in determining expected damage irrespective of sample placement orientation on the space station. A surface layer with a protective or sacrificial coating can be instrumental in minimizing property degradation even when exposed to orientations with high estimated sun hours and high fluence of atomic oxygen. Plain Language Summary: To live and work on planetary surfaces, beyond confines of the international space station in low earth orbit, humans and equipment have to be protected from the damaging effects of space radiation. Developing multifunctional materials as a countermeasure to the radiation environment is one such approach. Multifunctionality is key in mass optimization such that a single material can provide protection against radiation, micrometeoroid impact, thermal extremes, etc to name a few hazards. It is imperative to understand the interaction of shielding materials with the space environment and characterize the performance after long duration exposure. This paper addresses the development of such a multifunctional composite and discusses their performance after interaction with the low earth orbit space environment. Key Points: Multifunctional radiation shielding composites with plasma boron coating demonstrated high specific strength and neutron attenuationPost long duration exposure to low earth orbit environment resulted in degradation of mechanical properties due to ultraviolet and atomic oxygen exposureRadiation shielding capability and optical properties showed no degradation after long duration low earth exposure [ABSTRACT FROM AUTHOR]

Climate-related studies need information about the distribution of stratospheric aerosols, which influence the energy balance of the Earth's atmosphere. In this work, we present a merged dataset of vertically resolved stratospheric aerosol extinction coefficients, which is derived using data from six limb and occultation satellite instruments: SAGE (Stratospheric Aerosol and Gas Experiment) II on ERBS (Earth Radiation Budget Satellite), GOMOS (Global Ozone Monitoring by Occultation of Stars) and SCIAMACHY (Scanning Imaging Spectrometer for Atmospheric Chartography) on Envisat, OSIRIS (Optical Spectrograph and InfraRed Imaging System) on Odin, OMPS (Ozone Monitor Profiling Suite Limb Profiler) on Suomi NPP, and SAGE III on the ISS (International Space Station). The merging of aerosol profiles is performed via the transformation of the aerosol datasets from individual satellite instruments to the same wavelength (750 nm) and their de-biasing and homogenization by adjusting the seasonal cycles. After such homogenization, the data from individual satellite instruments are in good agreement. The merged aerosol extinction coefficient is computed as the median of the adjusted data from the individual instruments. The merged time series of vertically resolved monthly mean aerosol extinction coefficients at 750 nm is provided in 10° latitudinal bins from 90° S to 90° N, in the altitude range from 8.5 to 39.5 km. The time series of the stratospheric aerosol optical depth (SAOD) is created via the integration of aerosol extinction profiles from the tropopause to 39.5 km ; it is also provided as monthly mean data in 10° latitudinal bins. The created aerosol climate record covers the period from October 1984 until December 2023, and it is intended to be extended in the future. The merged CREST aerosol dataset (v2) is available at 10.57707/fmib2share.dfe14351fd8548bcaca3c2956b17f665 (Sofieva et al., 2024a). It can be used in various climate-related studies. [ABSTRACT FROM AUTHOR]

Leveraging the photometric data of the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX), we construct mean/median spectral energy distributions (SEDs) for unique bright quasars in redshift bins of 0.2 and up to z ≃ 3 , after taking the GALEX non-detection into account. Further correcting for the absorption of the intergalactic medium, these mean/median quasar SEDs constitute a surprisingly redshift-independent mean/median composite SED from the rest-frame optical down to ≃ 500   A ˚ for quasars with bolometric luminosity brighter than 10 45.5 erg s − 1 . Moreover, the mean/median composite quasar SED is plausibly also independent of black hole mass and Eddington ratio, and suggests similar properties of dust and gas in the quasar host galaxies since cosmic noon. Both the mean and median composite SEDs are nicely consistent with previous mean composite quasar spectra at wavelengths beyond ≃ 1000   A ˚ , but at shorter wavelengths, are redder, indicating, on average, less ionizing radiation than previously expected. Through comparing the model-predicted to the observed composite quasar SEDs, we favor a simply truncated disk model, rather than a standard thin disk model, for the quasar central engine, though we request more sophisticated disk models. Future deep ultraviolet facilities, such as the China Space Station Telescope and the Ultraviolet Explorer, would prompt revolutions in many aspects, including the quasar central engine, production of the broad emission lines in quasars, and cosmic reionization. [ABSTRACT FROM AUTHOR]

A K-M-N on-orbit service network architecture and its mission scheduling problem are proposed and studied, in which K space service stations and M service spacecraft are scheduled to service for N target spacecraft. The service spacecraft, which are initially docked with the space service station in the geosynchronous region, set off through orbital maneuver to conduct servicing operation for one or multiple target spacecraft upon receiving the service command. A mission scheduling strategy of on-orbit service for the target GEO spacecraft is proposed based on space service stations, in which the service spacecraft are scheduled to serve all target spacecraft with the lowest cost of fuel for the orbital transfers. As the mission scheduling for such a K-M-N GEO on-orbit service network is NP-hard, a hybrid simulated annealing optimization algorithm is put forward based on a mechanism of dynamic reverse processing of encoding and decoding to solve this problem. Four numerical case studies are presented and their results are compared with those from the literature to demonstrate the effectiveness of the approach. A series of different network model simulations and Mann-Kendall tests prove that multispace service stations can significantly reduce total fuel consumption for transfers, and the initial layout is also very important. Besides, the initial distribution of the service spacecraft also has an impact on total fuel. However, the quantitative impact of the service spacecraft is uncertain and needed to be analyzed on a specific basis, sometimes increasing the quantity of service spacecraft can reduce the total fuel, sometimes it has no effect, sometimes it may even cause negative effect when the number of service spacecraft is too large and unreasonable. Practical Applications: On-orbit servicing (OOS), refers to the execution of space operations through the exterior vehicle activities of astronauts, robots or both to extend the mission life of a spacecraft or improve the ability of a spacecraft to perform on-orbit missions. With the development of relevant enabling technologies, OOS will become a business which can be implemented commercially and in a large scale, in which one or multiple space service stations, as the space resource storage warehouse of the satellites in orbit, run in the earth orbit for a long time, and the service spacecraft will provide service to the target spacecraft in turn after completing the rendezvous and docking. In the process of servicing, the service spacecraft will return to the space service station for the replenishment when its resource is insufficient. In this paper, on-orbit service network scheduling based on space service station is studied, which is NP-hard. A hybrid simulated annealing optimization algorithm is put forward based on a mechanism of dynamic reverse processing of encoding and decoding to solve this problem. The researches in this paper are of great significance to the scale design and scheduling of on-orbit services in the future, meanwhile have a certain appeal for the relevant operational research scholars. [ABSTRACT FROM AUTHOR]

The annular flow payload is among the first batch of space science experimental projects carried out on the Fluid Physics Rack of the China Space Station. This paper provides a detailed introduction to the development of the payload, ground validation, and in orbit experiments. The payload, sized 320 mm × 200 mm × 220 mm, includes an annular flow model and supports supply (24 V, 12 V, and 5 V), communication, and data transmission. A multi-functional heating column in the annular flow model was designed, allowing for the column to operate in fixed, rotating, and lifting scenarios. In the first round, 96 sets of space experiments covering volume ratio ranges from 0.45 to 1.06 were carried out. The annular flow liquid surface state, temperature oscillation, and infrared temperature field evolution were obtained. Mode decomposition shows the oscillatory convection of the m = 4 travelling wave, and contains m = 3, m = 6, and m = 8 waves. [ABSTRACT FROM AUTHOR]

The electromagnetic method is widely used in mineral exploration, geothermal resource exploration, and deep earth structure detection. To improve the resolution and positioning accuracy of magnetotelluric surveys for targets beneath cover, it is essential to utilize forward modeling. This approach allows for a better understanding of the capabilities and limitations of MT in resolving features of different scales. In this paper, we employ forward modeling using the finite element method to simulate a series of continuous fault zones ranging from 100 m to 400 m in width, with varying lengths and dips. These fault zones represent conductive fluid pathways that could be associated with different scales and depths. The forward modeling provides the necessary data and method testing to assess the effectiveness of MT surveys in identifying and resolving such features. Our findings demonstrate that a station spacing of 400 m is optimal for resolving fault zones of various widths. For narrower faults (approximately 100 m), extending the survey line to 12 km or more significantly improves the deep structural inversion of the bounding faults, while an 8 km survey line suffices for wider faults (400 m). However, the vertical extent of these features is less well constrained, with deeper faults appearing broader and inversion depths being notably shallower than actual depths. These results highlight the need for careful interpretation of inversion anomalies, especially when supplementary data from other geophysical methods are lacking. Misinterpretation can lead to inaccurate resource assessments and exploration potential. [ABSTRACT FROM AUTHOR]

Aims Methods Results Conclusions Therapeutic drug monitoring for astronauts faces limitations in conventional blood sampling and sample management onboard the international space station. Here, we explore the feasibility of dried blood spot (DBS) collection during parabolic flights (PF) to overcome these constraints.We assessed the feasibility of blood deposition on blotting paper for preanalytical aspects in a PF using synthetic blood. Subsequently, DBS sampling validation was carried out in another PF campaign. Twenty volunteers participated in a pharmacokinetic study on caffeine and its metabolite, paraxanthine, conducted during parabolic flights. After >18 h caffeine washout, coffee (115 mg), tea (30 mg) or dark chocolate (11 mg) were ingested by the participants. DBS samples were collected at baseline, during weightlessness and post‐flight. Caffeine and paraxanthine were analysed using liquid chromatography–tandem mass spectrometry (LC‐MS/MS). Genotyping for cytochrome P450‐1A2 (CYP1A2) was performed and a metabolic ratio by area under the curve for caffeine and paraxanthine (AUCPAX/AUCCAF) for CYP1A2 was determined. A user experience survey was also conducted.Full in‐flight pharmacokinetic study was feasible in seventeen volunteers with three unable to perform the sampling due to motion sickness. Nineteen participants (twelve males and seven females) completed pharmacokinetic profiles, with repeated pharmacokinetic studies for six participants. CYP1A2 genotyping resulted in eight ultrarapid, eleven intermediate, and one poor metabolizer. Among the women, four were on oestrogen contraceptives, a known inhibitor of CYP1A2, and were considered as poor metabolizers. Expected differences in kinetic profiles, consistent with consumption habits, the ingested dose and the genotypic/phenotypic information, were observed. The mean caffeine AUC for coffee, tea and chocolate were 9419 ng.h.mL−1 (95% confidence interval [CI]: 6222–12 616, n = 10), 6917 ng.h.mL−1 (95% CI: 2729–11 105), n = 7) and 3039 ng.h.mL−1 (95% CI: 1614–4142, n = 12), respectively. The mean paraxanthine AUC were 10 566 ng.h.mL−1 (95% CI: 6242–14 890, n = 10), 4011 ng.h.mL−1 (95% CI: 2305–5716, n = 7) and 3638 ng.h.mL−1 (95% CI: 1589–40 859, n = 12), respectively. The mean metabolic ratio in oestrogen‐treated women was 0.53 (95% CI: 0.35–0.71) compared to 1.19 (95% CI: 0.99–1.33) in others. The mean metabolic ratio was 1.02 (95% CI: 0.81–1.23, n = 15) on the ground and 1.10 (95% CI: 0.70–1.41, n = 13) during the parabolic flights, with no significant difference observed between the two conditions. Overall participants were satisfied with the usability of the method.DBS collection was safe, stable, feasible and well accepted in weightlessness. This method would offer valuable insights into human metabolism adaptation during long‐term spaceflight, addressing space pharmacology challenges. [ABSTRACT FROM AUTHOR]

In response to the costly and error-prone manual satellite tracking on the International Space Station (ISS), this paper presents a deep neural network (DNN)-based robotic visual servoing solution to the automated tracking operation. This innovative approach directly addresses the critical issue of motion decoupling, which poses a significant challenge in current image moment-based visual servoing. The proposed method uses DNNs to estimate the manipulator's pose, resulting in a significant reduction of coupling effects, which enhances control performance and increases tracking precision. Real-time experimental tests are carried out using a 6-DOF Denso manipulator equipped with an RGB camera and an object, mimicking the targeting pin. The test results demonstrate a 32.04% reduction in pose error and a 21.67% improvement in velocity precision compared to conventional methods. These findings demonstrate that the method has the potential to improve efficiency and accuracy significantly in satellite target tracking and capturing. [ABSTRACT FROM AUTHOR]

• Infiltration rates under low gravities were agreed with 1G based predictions. • The air entrapped little in fine porous media may have prevented the infiltration rate reduction. • The infiltration theory is applicable to fine uniform porous media under low gravities. The applicability of the theory of water infiltration in porous media under low gravities is controversial. We evaluated the hypothesis that infiltration under low gravities can be simulated from horizontal infiltration experiments under 1G. Parabolic flights provided low gravity conditions, assuming in the space station (µG), on the moon (0.19 G), and Mars (0.38 G). We measured infiltration rates in uniform particle-size porous media. No significant differences existed between infiltration rates under low gravities and ground-based predictions, i.e. the 1G condition. The air was entrapped little in this study, which may have prevented the infiltration rate reduction reported in previous studies. We concluded that the current infiltration theory adequately simulated water infiltration in fine uniform porous media under low gravity conditions. [ABSTRACT FROM AUTHOR]