Search Results (343)

Global water environment monitoring urgently requires remote sensing data with high temporal resolution and wide spatial coverage. However, current space-borne ocean color spectrometers still face a significant trade-off among spatial resolution, swath width, and system compactness, which limits the large-scale deployment of satellite constellations. To address this challenge, this study developed a lightweight high-resolution spectral imager (LHRSI) with a total mass of less than 25 kg and power consumption below 80 W. The visible (VIS) camera adopts an interleaved dual-field-of-view and detectors splicing fusion design, while the shortwave infrared (SWIR) camera employs a transmission-type focal plane with staggered detector arrays. Through the field-of-view (FOV) optical design, the instrument achieves swath widths of 207.33 km for the VIS bands and 187.8 km for the SWIR bands at an orbital altitude of 500 km, while maintaining spatial resolutions of 12 m and 24 m, respectively. On-orbit imaging results demonstrate that the spectrometer achieves excellent performance in both spatial resolution and swath width. In addition, preliminary analysis using index-based indicators illustrates LHRSI’s potential for observing chlorophyll-related features in water bodies. This research not only provides a high-performance, miniaturized spectrometer solution but also lays an engineering foundation for developing low-cost, high-revisit global ocean and water environment monitoring constellations. Full article

LuTan-1(LT-1) is the first Chinese civil L-band satellite constellation for geohazard observation, comprising LT-1A and LT-1B satellites. By employing interferometric altimetry and differential deformation measurement technologies, it achieves high-precision topographic mapping and establishes sub-millimeter-level deformation monitoring capabilities. To meet the high-precision measurement requirements for applications such as topographic surveying and deformation monitoring, this study systematically evaluates four categories of image quality metrics—geometric, radiometric, and polarimetric characteristics, as well as orbital and baseline quality—based on in-orbit test data from the twin satellites. The test results demonstrate that all image quality indicators of the LT-1 SAR satellites meet the design specifications, confirming that the imagery can provide robust spatial technical support for applications including geological hazard monitoring, land resource investigation, earthquake assessment, disaster prevention and mitigation, fundamental surveying and mapping, and forestry monitoring. Full article

Low-thrust propulsion systems have become mainstream for Low Earth Orbit (LEO) satellites due to their superior propellant efficiency, yet conventional low-thrust transfer strategies suffer from high computational costs and failure to achieve full orbital element convergence. To address these drawbacks, this paper proposes a novel semi-analytical three-phase low-thrust transfer strategy that leverages $J_2$ gravitational precession to realize convergence of all orbital elements for circular orbits. The core of the method lies in the design of two symmetric thrust arcs and an intermediate coasting period that utilizes $J_2$ precession. By solving the resulting polynomial equation, the strategy achieves simultaneous controlled convergence of the Right Ascension of the Ascending Node (RAAN) and the argument of latitude (AOL). Simulation results demonstrate that the proposed method achieves significant fuel savings compared to direct transfer strategies, while simultaneously achieving superior computational speed. Extensive validation via 100,000 Monte Carlo simulations confirms the method’s scope of applicability, and the sufficient conditions for the existence of a solution are provided. It is further found that the proposed method is particularly well-suited for missions involving medium-to-high inclination orbits and large RAAN gaps, such as constellation deployment. In conclusion, this strategy provides a fuel-efficient and computationally fast solution for low-thrust transfer, establishing the basis for the operational management of future large-scale space systems equipped with low-thrust propulsion. Full article

Automatic modulation recognition (AMR) plays a critical role in intelligent wireless communication systems, particularly under conditions with a low signal-to-noise ratio (SNR) and complex channel environments. To address these challenges, this paper proposes a three-branch fusion network that integrates complementary features from the time, frequency, and spatial domains to enhance classification performance. The model consists of three specialized branches: a multi-channel convolutional branch designed to extract discriminative local features from multiple signal representations; a bidirectional long short-term memory (BiLSTM) branch capable of capturing long-range temporal dependencies; and a vision transformer (ViT) branch that processes constellation diagrams to exploit global structural information. To effectively merge these heterogeneous features, a path attention module is introduced to dynamically adjust the contribution of each branch, thereby achieving optimal feature fusion and improved recognition accuracy. Extensive experiments on the two popular benchmarks, RML2016.10a and RML2018.01a, show that the proposed model consistently outperforms baseline approaches. These results confirm the effectiveness and robustness of the proposed approach and highlight its potential for deployment in next-generation intelligent modulation recognition systems operating in realistic wireless communication environments. Full article

The geostationary orbit (GEO), a finite one-dimensional longitudinal resource, has emerged as a critical research focus driven by the rapid development of global communication systems. This scarcity motivates current research efforts toward multi-satellite collocation within single longitudinal slots. This article investigates the optimization design problem of configurations at fixed longitudes in GEO. First, a kinematic model describing the relative fixed-point motion of geostationary satellites was established. Subsequently, the long-term stability conditions of these fixed-point configurations under $J_2$ perturbations were analyzed, with collocation flight stability and passive flight safety formulated as design constraints. The particle swarm optimization (PSO) algorithm was employed to design circular and straight-line spatial configurations, and their corresponding Kepler orbital elements were numerically simulated. Comparative analysis confirmed that circular configurations demonstrate superior stability compared to straight-line configurations. Full article

As humanity prepares for prolonged space missions and future extraterrestrial settlements, developing reliable and resilient food-production systems is becoming a critical priority. Space agriculture, the cultivation of plants beyond Earth (particularly on the Moon and Mars), faces a constellation of interdependent environmental, biological, and engineering challenges. These include limited solar radiation, elevated ionizing radiation, large thermal variability, non-Earth atmospheric pressures, reduced gravity, regolith substrates with low nutrient-holding capacity, high-CO₂/low-O₂ atmospheres, pervasive dust, constrained water and nutrient availability, altered plant physiology, and the overarching need for closed-loop, resource-efficient systems. These stressors create an exceptionally challenging environment for plant growth and require tightly engineered agricultural systems. This review examines these constraints by organizing them across environmental differences, resource limitations, biological adaptation, and operational demands, emphasizing their systemic interdependence and the cascading effects that arise when one subsystem changes. By integrating findings from planetary science, plant biology, space systems engineering, biotechnology, robotics, and controlled-environment agriculture (CEA), the review outlines current limitations and highlights emerging strategies such as regolith utilization, advanced hydroponics, crop selection and genetic engineering, and the use of robotics, sensors, and artificial intelligence (AI) for monitoring and automation. Finally, the article underscores the broader relevance of space–agriculture research for terrestrial food security in extreme or resource-limited environments, providing a structured foundation for designing resilient and sustainable agricultural systems for space exploration and beyond. Full article

This article interrogates the theoretical articulations of the body–space nexus through the formulation of an alternative methodological framework. It advances the premise that body and space cannot be reduced to physical parameters or representational models; rather, they are continually reconstituted through experience, perception, cultural contexts, and relational processes. Against the backdrop of fragmented spatial, phenomenological, and socio-political readings of space, Joseph Kosuth’s “One and Three Chairs” [1965] is posited as a conceptual compass, while semiotic instruments are mobilized as analytical devices. Within this constellation, the body–space relation is examined through a trialectical configuration that couples three relational modalities—distance, togetherness, and plurality—with three representational dimensions: object, image, and definition. The analysis shows how each modality delineates a distinct regime of bodily–spatial interaction and exposes the ways in which these regimes become manifest within architectural experience, social production, and conceptual potential. Within this framework, the notion of the flesh of space is advanced to describe space as a relational field in which bodies, materials, images, and definitions become mutually entangled. The principal contribution of this study lies in advancing a methodological orientation that transcends normative metrics and reductionist representational paradigms, thereby enabling body–space relations to be apprehended through relational dynamics and multilayered processes of signification. In doing so, this article provides a critical ground for rethinking architectural epistemology from a more flexible, experiential, and plural perspective, and proposes a transferable analytical scaffold for future case-based and design-oriented research. Full article

Following recommendations from the 2023–2032 Planetary Science and Astrobiology Decadal Survey, we propose a novel Uranus exploration mission that is centered on using constellations of small spacecraft to observe the Uranus system. Using the method of patched conics and system-level design, we present a Pre-Phase A mission concept to launch a 4500 kg spacecraft on a Jupiter–Uranus gravity assist transfer trajectory with a transfer time of six years, having the spacecraft arrive at Uranus in 2039 after launching in 2033. To maintain the quality of data collection while minimizing mass, we propose that the spacecraft will be composed of a carrier spacecraft with a 3848 kg wet mass, which would be used primarily for communications and orbital transfers, and a constellation of CubeSats with a combined wet mass of 640 kg, which would house the instrumentation. In this paper, we discuss the feasibility of the proposed mission concept and we demonstrate that a CubeSat constellation mission to Uranus can be not only viable but also a fuel and cruise time optimization opportunity, delivering 16 exploration spacecraft to Uranus in six years. Full article

In 2023, the detection rate of porcine rotavirus (PoRV) surpassed that of porcine epidemic diarrhea virus (PEDV) for the first time, establishing PoRV as the predominant pathogen responsible for viral diarrhea in pigs. To systematically investigate the epidemiology and molecular characteristics of PoRV in Southwest China, a total of 196 diarrheal clinical samples were collected from 29 large-scale pig farms across the region during 2024–2025. RT-qPCR results revealed a high PoRV positivity rate of 57.14% (112/196) with group A porcine rotavirus (PoRVA) being the most prevalent at 46.43%, representing the predominant group. Genotyping and phylogenetic analysis of the VP4 and VP7 genes indicated that the P genotype P[13] was most prevalent (77.78%, 21/27), while the major G genotypes were G4 (39.28%) and G9 (35.71%). The most common G/P combinations were G9P[13] and G4P[13]. Furthermore, a PoRV strain was successfully isolated and identified through whole-genome sequencing, indirect immunofluorescence assay (IFA), and transmission electron microscopy (TEM). The isolate was designated RVA/Pig-wt/SCLS-JW/2024/G1P[7], with a whole-genome constellation of G1-P[7]-I5-R1-C1-M1-A8-N1-T1-E1-H1. The structural proteins VP1-4 and VP6-7, along with nonstructural genes NSP1 and NSP5, shared high sequence identity with porcine strains, whereas the nonstructural genes NSP2–NSP4 clustered more closely with human rotaviruses. These findings indicate a higher prevalence of PoRV in southwestern China compared to other regions; the dominant circulating genotypes have shifted to G9 and G4; the isolated G1P[7] strain is relatively rare in China and might be a genetic recombinant of human and porcine rotaviruses. This study provides valuable data and theoretical support for understanding the current epidemiology of PoRV, and facilitates vaccine development and the formulation of prevention and control strategies. Full article

As optical networks continue to evolve toward higher speed and larger capacity, conventional security mechanisms relying on optoelectronic conversion are facing increasing limitations. The optical photonic firewall, as an emerging optical-layer security device, enables direct inspection in the optical domain, making its core technology—All-Optical Pattern Matching (AOPM)—a focal point of current research. This review provides a comprehensive survey of AOPM systems. It first introduces the main components of AOPM, namely symbol matching and system architectures, and analyzes their representative implementations. For low-order modulation formats such as OOK and BPSK, the review highlights matching schemes enabled by semiconductor optical amplifier (SOA) and highly nonlinear fiber (HNLF) logic gates, as well as their potential for reconfigurable extension. Building upon this foundation, the paper focuses on systems for high-order modulation formats including QPSK, 8PSK, and 16QAM, covering dimensionality-reduction-based approaches (e.g., PSA-based phase compression, squarer-based phase multiplication, constellation-mapping-based format conversion), direct symbol matching methods (e.g., phase interference, generalized XNOR, real-time Fourier transform correlation), and reconfigurable designs for multi-format adaptability. Furthermore, the review discusses optimization challenges under non-ideal conditions, such as noise accumulation, phase misalignment, and phase-locking-free operation. Finally, it outlines future directions in robust high-order modulation handling, photonic integration, and AI-driven intelligent matching, offering guidance for the development of optical-layer security technologies. Full article

This paper presents the findings related to the design solution options for a next-generation C-band Synthetic Aperture Radar (SAR) mission, developed to address the Harmonized User Needs (HUN) in Earth observation (EO) data as defined by several departments of the Government of Canada. The work analyses various mission solution options, including multi-satellite constellations, and their performance to evaluate feasibility and assess their compliance with the HUN as well as minimize the associated lifecycle costs, technical risks, implementation schedule, and programmatic challenges. This mission concept contributes to the advancement of space-based surveillance solutions aligned with Canada’s long-term strategic objectives to ensure service continuity for Earth Observation and national security applications. Systematic user needs analysis helped to reveal the importance of high-resolution (1–5 m), enhanced interferometric, polarimetric SAR interferometry (PolInSAR) and other capabilities. Two satellite constellation configurations are proposed: (1) a three-medium-satellite setup with a tandem pair, and (2) a five-large-satellite system incorporating tandem and optimal orbits. Employing High-Resolution Wide Swath (HRWS) imaging modes and full polarimetric capability. Performance simulations indicate low Noise Equivalent Sigma Zero (NESZ) with wide swath width fully addresses driving needs for sea ice and ocean monitoring, covering most of the Canadian areas of interest, with the revisit time of less than 4–6 hours. Orbit optimization ensures high revisit rates, enabling novel interferometric SAR (InSAR) capabilities with observations separated by only a few hours. This mission concept, considering two options with three medium and with five large satellites, respectively, offers a flexible, scalable, and strategically impactful solution for Earth Observation (EO) service continuity and technological leadership for Canada until 2050 and beyond. Full article

Recent progress in laboratory medicine provides powerful tools for the detailed evaluation of cardiovascular risk in military populations. This study aimed to characterize cardiometabolic biomarker profiles across four Polish military groups through chemometric analysis. The study included 392 participants (336 men, 56 women, aged 19–56 years). In total, 23 serum biomarkers from lipid, metabolic, hepatic, hormonal, and bone axes, and lactate dehydrogenase (LDH) were analyzed. Random forest (RF) modeling and effect-size profiling identified group-specific signatures. Group 4 (exposed to extreme acceleration forces and ionizing radiation) exhibited a systemic stress and metabolic-load profile with higher N-terminal pro-B-type natriuretic peptide (NT-proBNP, 36.7 ± 48.2 pg/mL) and calcium (Ca, 10.4 ± 0.88 mg/dL), and lower parathyroid hormone (PTH, 15.4 ± 10.1 pg/mL) and C-terminal telopeptide of type I collagen (β-CTX, 0.22 ± 0.19 ng/mL). Group 2 (exposed to fuels and exhaust gases) and group 3 (exposed to vibration, noise, ionizing radiation) showed an atherogenic–hepatometabolic axis with elevated apolipoprotein B (apoB, 1.04 ± 0.31; 0.97 ± 0.29 g/L), non-high-density lipoprotein cholesterol (N-HDL, 151.0 ± 46.7; 147.0 ± 41.4 mg/dL), and alanine aminotransferase (ALT). Group 1 (exposed to a biological hazard) displayed higher glucose (Glu, 96.0 ± 25.6 mg/dL) and triglycerides (TG, 151.0 ± 113.0 mg/dL) with lower magnesium (Mg, 2.03 ± 0.27 mg/dL). RF modeling confirmed these constellations. This study was exploratory in nature, providing a foundation for future longitudinal research. These findings provide a rationale for tailored cardiovascular surveillance, although causal inference is limited by the cross-sectional design. Full article

Very-Low Earth Orbit Synthetic Aperture Radar (VLEO SAR) satellites, defined as SAR satellites operating at orbital altitudes 350 km or below, offer distinct technical advantages compared to conventional SAR satellites. Equipped with a high-resolution SAR payload, the Haishao-1 (HS-1) satellite was successfully launched on 4 December 2024. According to publicly available information, the HS-1 satellite represents the world’s first VLEO SAR satellite and has successfully demonstrated 1-m resolution Stripmap mode imaging with continuous azimuth coverage. Through an analysis of the HS-1 satellite’s system parameters and imaging results, this paper comprehensively explores the advantages of VLEO SAR satellites over traditional orbit SAR satellites, particularly in terms of enhanced resolution, reduced payload costs, and improved constellation deployment capabilities. VLEO SAR satellites possess significant advantages, including the potential for higher-resolution imagery and lower-cost payload designs, positioning them for extensive application prospects in fields such as space-based military reconnaissance, natural resource surveying, and natural disaster monitoring. Full article

Background: The intersection between oncology and intensive care has shifted from predominantly end-of-life care to a therapeutic bridge that can preserve anticancer trajectories in carefully selected patients. Yet, criteria separating benefit from futility remain fragmented. Objective: This paper seeks to map contemporary evidence (2015–2025) on outcomes after Intensive Care Unit (ICU) admission in adults with cancer and to identify clinical constellations in which ICU-level care still changes prognosis. Methods: PRISMA-ScR scoping review (PCC framework). PubMed search (2015–2025), dual screening, standardized extraction; narrative/thematic synthesis across six clusters (hematologic, solid tumors, sepsis/non-COVID-19 infection, COVID-19/viral pneumonia, novel/targeted-therapy toxicities, end-of-life/aggressive ICU) were used. No meta-analysis given heterogeneity. Results: Seventy-three studies (>170,000 ICU admissions) were included, mostly cohort designs across 27 countries. ICU mortality ranged 8–72% (weighted mean ≈ 41%); hospital ≈ 38%; 90-day ≈ 46%; 1-year ≈ 62%. About one third of ICU survivors resumed systemic therapy. Benefit concentrated in early admissions, single-organ failure, controlled/remission disease, postoperative/elective monitoring, and reversible treatment-related toxicities (e.g., ICI pneumonitis, CAR-T CRS/ICANS). Futility clustered around ≥3 organ supports, RRT > 7 days, refractory/progressive disease, and ECOG ≥ 3. Sepsis outcomes averaged 45–55% ICU mortality but improved with rapid recognition and source control; COVID-19 mortality was particularly high in hematologic malignancies early in the pandemic, with subsequent declines post-vaccination. Conclusions: In modern oncologic practice, ICU care changes prognosis when the acute physiological insult is reversible and cancer control remains plausible; conversely, high organ-support burden and refractory disease define practical futility thresholds. These signals support time-limited ICU trials, earlier ICU involvement for sepsis/irAEs, and embedded palliative care to align intensity with goals. Full article

The rapid expansion of Low Earth Orbit (LEO) satellite constellations necessitates the development of multi-band antennas that are not only high-performing but also low-cost, lightweight, and highly reliable for mass production. This paper addresses this need by proposing a novel shared-aperture reflectarray antenna for simultaneous S-band and X-band operation. The design is based on a single-layer architecture that co-integrates two electromagnetically distinct resonant elements—a cross-dipole for the S-band and a diamond-ring slotted patch for the X-band—onto a single 1.52 mm thick Rogers RO3003 substrate. This approach achieves a high frequency ratio of 4:1 while ensuring independent phase control and high isolation for each band through an optimized geometry, circumventing the complexity and reliability issues of conventional multilayer systems. A prototype with dimensions of 260 × 364 mm² was fabricated and experimentally validated in an anechoic chamber. It achieved a measured peak gain of 7.99 dBi at 1.996 GHz for the S-band and 17.99 dBi at 7.94 GHz for the X-band, respectively. The results confirm the viability of the proposed design, demonstrating a structurally simple, easily manufacturable, and cost-effective alternative to complex multilayer systems, making it a promising candidate for next-generation LEO satellite communication platforms. Full article