Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.038
Yu Chen , Guangxing Wang , Massimo Menenti
This study retrieves high-resolution atmospheric water vapor fields by processing Global Navigation Satellite System (GNSS) data from Hong Kong Continuously Operating Reference Stations (CORS) and six International GNSS Service (IGS) stations. Using the GAMIT software, we derived Precipitable Water Vapor (PWV) and Zenith Tropospheric Delay (ZTD) during four distinct heavy rainfall events. Statistical analysis reveals a strong temporal correlation between PWV/ZTD variations and observed rainfall. Based on these results, we propose two quantitative thresholds for short-term rainfall prediction: a PWV change rate exceeding ±10 mm/h and a ZTD change rate surpassing ±40 mm/h. These thresholds provide reliable indicators for estimating precipitation probability and intensity, demonstrating the practical value of GNSS-derived atmospheric parameters in nowcasting applications. The consistency of our findings with previous studies further supports the applicability of the proposed thresholds in operational meteorology.
{"title":"Short-term rainfall forecasting using GNSS-derived PWV and ZTD variations: case studies of four Hong Kong rainstorm events","authors":"Yu Chen , Guangxing Wang , Massimo Menenti","doi":"10.1016/j.asr.2025.11.038","DOIUrl":"10.1016/j.asr.2025.11.038","url":null,"abstract":"<div><div>This study retrieves high-resolution atmospheric water vapor fields by processing Global Navigation Satellite System (GNSS) data from Hong Kong Continuously Operating Reference Stations (CORS) and six International GNSS Service (IGS) stations. Using the GAMIT software, we derived Precipitable Water Vapor (PWV) and Zenith Tropospheric Delay (ZTD) during four distinct heavy rainfall events. Statistical analysis reveals a strong temporal correlation between PWV/ZTD variations and observed rainfall. Based on these results, we propose two quantitative thresholds for short-term rainfall prediction: a PWV change rate exceeding ±10 mm/h and a ZTD change rate surpassing ±40 mm/h. These thresholds provide reliable indicators for estimating precipitation probability and intensity, demonstrating the practical value of GNSS-derived atmospheric parameters in nowcasting applications. The consistency of our findings with previous studies further supports the applicability of the proposed thresholds in operational meteorology.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3003-3021"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.10.059
Jin Byeong Lee, Jinzhen Han, Kwang Bae Kim, Min Su Kim, Hong Sik Yun
This study utilized several models to analyze thermohaline circulation. Specifically, it employed mean sea surface (MSS) models DTU21, CLS22, and SDUST2020 which were derived by averaging open-source sea surface height data observed via satellite altimetry over a specified period. Additionally, geoid models calculated from gravity field observation data WHU-SEPU-GOGR2022S, EGM2008, and XGM2019e_2159 were incorporated. These models were subsequently used to compute the mean sea surface height and geoid height, from which sea surface topography was derived to facilitate the analysis of geostrophic current patterns. Surface currents are tracked using surface floats, but the overall flow is difficult to capture due to the influence of specific areas, wind direction, water temperature, etc. In this study, we analyzed the geostrophic current, and the results showed that the sea surface topography in the East Sea was calculated to be 28.8 m on average, and the average velocity of the geostrophic current was calculated to be 2.07 cm/sec.
{"title":"Geostrophic current estimation of the East Sea of the Korean peninsula using recent MSS and geoid data","authors":"Jin Byeong Lee, Jinzhen Han, Kwang Bae Kim, Min Su Kim, Hong Sik Yun","doi":"10.1016/j.asr.2025.10.059","DOIUrl":"10.1016/j.asr.2025.10.059","url":null,"abstract":"<div><div>This study utilized several models to analyze thermohaline circulation. Specifically, it employed mean sea surface (MSS) models DTU21, CLS22, and SDUST2020 which were derived by averaging open-source sea surface height data observed via satellite altimetry over a specified period. Additionally, geoid models calculated from gravity field observation data WHU-SEPU-GOGR2022S, EGM2008, and XGM2019e_2159 were incorporated. These models were subsequently used to compute the mean sea surface height and geoid height, from which sea surface topography was derived to facilitate the analysis of geostrophic current patterns. Surface currents are tracked using surface floats, but the overall flow is difficult to capture due to the influence of specific areas, wind direction, water temperature, etc. In this study, we analyzed the geostrophic current, and the results showed that the sea surface topography in the East Sea was calculated to be 28.8 m on average, and the average velocity of the geostrophic current was calculated to be 2.07 cm/sec.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 2757-2772"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.026
Jiawei Chen, Xiang Lin, Yingguo Chen, Lei He, Yang Sun, Yingwu Chen
The scheduling of large-volume LEO Imaging data transmission tasks—involving data relay through inter-satellite links and ultimate downlink to ground stations—constitutes a complex optimization problem due to increasing satellite constellations, task volumes, and intricate operational constraints. While existing strategies have addressed aspects of this challenge, current sub-packet transmission models exhibit critical limitations by permitting defective and incomplete sub-packets to reach ground stations, incurring substantial resource overhead through invalid operations that significantly compromise system efficiency and profit margins. To overcome these deficiencies, we propose an integrated temporal graph convolutional network (TGCN) and advantage actor-critic (A2C) reinforcement learning framework that uniquely leverages TGNNs to model dynamic satellite contact networks, capturing multidimensional node feature representations and transitive relationships while accommodating partial observability constraints. Our constraint-aware A2C component incorporates penalty mechanisms that actively disincentivize defective sub-packet transmission through negative reward structuring. Rigorous experimental validation under extended 24-h scheduling horizons with complex constraints demonstrates our method’s superiority over heuristic and reinforcement learning baselines, achieving 37.43 % higher profit margins through elimination of invalid transmissions, without increasing computational time, and enhanced constraint satisfaction in resource-limited environments.
{"title":"A reinforcement learning strategy with temporal graph convolutional network for large-volume leo imaging data networked transmission","authors":"Jiawei Chen, Xiang Lin, Yingguo Chen, Lei He, Yang Sun, Yingwu Chen","doi":"10.1016/j.asr.2025.11.026","DOIUrl":"10.1016/j.asr.2025.11.026","url":null,"abstract":"<div><div>The scheduling of large-volume LEO Imaging data transmission tasks—involving data relay through inter-satellite links and ultimate downlink to ground stations—constitutes a complex optimization problem due to increasing satellite constellations, task volumes, and intricate operational constraints. While existing strategies have addressed aspects of this challenge, current sub-packet transmission models exhibit critical limitations by permitting defective and incomplete sub-packets to reach ground stations, incurring substantial resource overhead through invalid operations that significantly compromise system efficiency and profit margins. To overcome these deficiencies, we propose an integrated temporal graph convolutional network (TGCN) and advantage actor-critic (A2C) reinforcement learning framework that uniquely leverages TGNNs to model dynamic satellite contact networks, capturing multidimensional node feature representations and transitive relationships while accommodating partial observability constraints. Our constraint-aware A2C component incorporates penalty mechanisms that actively disincentivize defective sub-packet transmission through negative reward structuring. Rigorous experimental validation under extended 24-h scheduling horizons with complex constraints demonstrates our method’s superiority over heuristic and reinforcement learning baselines, achieving 37.43 % higher profit margins through elimination of invalid transmissions, without increasing computational time, and enhanced constraint satisfaction in resource-limited environments.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 2936-2955"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.016
Ali Haji Elyasi, Mohsen Nasseri, Peyman Badiei
Accurate land use/land cover (LULC) classification and projection are essential for sustainable environmental planning, but are challenged by the limited availability of high‑quality training samples and a reliance on static sampling methods. This study addresses these challenges by developing an automated dynamic sampling approach that integrates Spectral Angle Mapping (SAM) with Adaptive Otsu Threshold Fine‑Tuning (AOFT), coupled with a hyperparameter‑optimized Random Forest (RF) classifier in Google Earth Engine (GEE). The method enables accurate training‑sample migration from the base year (2004) to the target years (2014 and 2024), addressing a critical gap in dynamic sample generation. Results show that SAM–AOFT achieves over 91 % accuracy in training‑sample migration between time points, underscoring the robustness of the migration process, which is driven by key spectral bands and indices, including the blue and red bands and MNDWI. When applied to the complex Anzali Wetland Basin using Landsat imagery, the dynamic sampling approach significantly improved classification accuracy compared with the traditional method. For 2014 and 2024, the dynamic LULC maps demonstrated an absolute 7 % increase in Kappa and 6 % increase in overall accuracy compared to the static approach. Additionally, LULC projections for 2030, 2040, and 2050 were generated with a Cellular Automata–Markov (CA-Markov) model based on the dynamic approach demonstrated strong reliability (Kappa = 0.88–0.93). These projections reveal substantial LULC changes, including 30 % built‑up expansion and 27 % water‑body reduction by 2050 compared with 2024. Overall, the proposed method markedly enhances LULC classification accuracy and projection reliability, providing an effective tool for environmental monitoring.
{"title":"Proposing a novel optimized dynamic sampling approach for enhancing land use classification and projection accuracy","authors":"Ali Haji Elyasi, Mohsen Nasseri, Peyman Badiei","doi":"10.1016/j.asr.2025.11.016","DOIUrl":"10.1016/j.asr.2025.11.016","url":null,"abstract":"<div><div>Accurate land use/land cover (LULC) classification and projection are essential for sustainable environmental planning, but are challenged by the limited availability of high‑quality training samples and a reliance on static sampling methods. This study addresses these challenges by developing an automated dynamic sampling approach that integrates Spectral Angle Mapping (SAM) with Adaptive Otsu Threshold Fine‑Tuning (AOFT), coupled with a hyperparameter‑optimized Random Forest (RF) classifier in Google Earth Engine (GEE). The method enables accurate training‑sample migration from the base year (2004) to the target years (2014 and 2024), addressing a critical gap in dynamic sample generation. Results show that SAM–AOFT achieves over 91 % accuracy in training‑sample migration between time points, underscoring the robustness of the migration process, which is driven by key spectral bands and indices, including the blue and red bands and MNDWI. When applied to the complex Anzali Wetland Basin using Landsat imagery, the dynamic sampling approach significantly improved classification accuracy compared with the traditional method. For 2014 and 2024, the dynamic LULC maps demonstrated an absolute 7 % increase in Kappa and 6 % increase in overall accuracy compared to the static approach. Additionally, LULC projections for 2030, 2040, and 2050 were generated with a Cellular Automata–Markov (CA-Markov) model based on the dynamic approach demonstrated strong reliability (Kappa = 0.88–0.93). These projections reveal substantial LULC changes, including 30 % built‑up expansion and 27 % water‑body reduction by 2050 compared with 2024. Overall, the proposed method markedly enhances LULC classification accuracy and projection reliability, providing an effective tool for environmental monitoring.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 2807-2830"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.025
I.B. Ievenko
Stable auroral red (SAR) arcs are the consequence of interaction of energetic ions of the ring current with the plasmapause. The literature is dominated by the idea that SAR arcs are observed during the recovery phase of magnetic storms. Our previous studies of the subauroral luminosity at the Yakutsk meridian showed that auroral red arcs appear and/or brighten during the substorm expansion phase. This work presents for the first time the results of simultaneous observations with all-sky imagers of aurora dynamics at the Zhigansk station (CGMLat 62°, GMLon 196°) and formation of the SAR arc at the subauroral Maimaga station (CGMLat 58°, GMLon 202°). The event of February 15, 2018 with a minimum of SYM-H = −20 nT is considered, in which the red arc arose during the substorm growth phase after the IMF Bz southward turn. The longitudinal region of the expansion phase onset this substorm was located in the evening sector of 2000–2200 MLT.
The auroral bulge were expanding eastward in the MLT postmidnight hours, where the SAR arc brightening was observed from the western horizon to the east. At the same time, there was also an eastward movement of the glow ledges on the polar edge of the arc, the rays (corona) appeared and the luminosity pulsations were detected in the vicinity of the diffuse aurora boundary in the 557.7 nm emission. The Swarm-B satellite measured subauroral electron temperature peaks at latitudes of the SAR arc near the meridian of observations during the growth and recovery phases of the substorm. We show a probable relationship of the observed luminosity dynamics to the series of magnetospheric phenomena in the plasmapause vicinity.
{"title":"Aurorae and SAR arc dynamics during the substorm event. Magnetospheric phenomena in the plasmapause vicinity","authors":"I.B. Ievenko","doi":"10.1016/j.asr.2025.11.025","DOIUrl":"10.1016/j.asr.2025.11.025","url":null,"abstract":"<div><div>Stable auroral red (SAR) arcs are the consequence of interaction of energetic ions of the ring current with the plasmapause. The literature is dominated by the idea that SAR arcs are observed during the recovery phase of magnetic storms. Our previous studies of the subauroral luminosity at the Yakutsk meridian showed that auroral red arcs appear and/or brighten during the substorm expansion phase. This work presents for the first time the results of simultaneous observations with all-sky imagers of aurora dynamics at the Zhigansk station (CGMLat 62°, GMLon 196°) and formation of the SAR arc at the subauroral Maimaga station (CGMLat 58°, GMLon 202°). The event of February 15, 2018 with a minimum of SYM-H = −20 nT is considered, in which the red arc arose during the substorm growth phase after the IMF Bz southward turn. The longitudinal region of the expansion phase onset this substorm was located in the evening sector of 2000–2200 MLT.</div><div>The auroral bulge were expanding eastward in the MLT postmidnight hours, where the SAR arc brightening was observed from the western horizon to the east. At the same time, there was also an eastward movement of the glow ledges on the polar edge of the arc, the rays (corona) appeared and the luminosity pulsations were detected in the vicinity of the diffuse aurora boundary in the 557.7 nm emission. The Swarm-B satellite measured subauroral electron temperature peaks at latitudes of the SAR arc near the meridian of observations during the growth and recovery phases of the substorm. We show a probable relationship of the observed luminosity dynamics to the series of magnetospheric phenomena in the plasmapause vicinity.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3386-3403"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.066
Xing-han Liu, Ming Zhu, Yi-fei Zhang, Tian Chen
Region coverage planning of the multiple stratospheric airship (MSA) system has attracted wide attention. With increasing requirements on the continuous coverage capability of the MSA system, existing methods are not sufficient for MSA continuous coverage missions and struggle to respond to complex environments when considering multiple objectives. Therefore, an adaptive gaining-sharing knowledge planner is proposed. First, an integrated model is established on the unique demands of the MSAs together with multiple mission objectives, including renewable energy, region coverage, and so on. Besides, a location potential map is designed to enhance the airships’ perception of environmental information under a rolling horizon planning framework, such as time-varying and non-uniform wind fields and forbidden areas. Then, to elevate the solving efficiency of complex constrained multi-objective problems, a novel adaptive gaining-sharing knowledge optimizer with adaptive population size reduction (AGSK-APSR) is proposed to obtain optimal control inputs. The trajectories achieve coverage rates of over in different simulation conditions within 24 h, with a decrease of in average waypoint wind speed and the minimum energy consumption. The proposed method realizes a reduction of in the comprehensive evaluation compared to the advanced AGSK optimization.
{"title":"Adaptive gaining-sharing knowledge region coverage planning for multi-stratospheric airships in complex environments","authors":"Xing-han Liu, Ming Zhu, Yi-fei Zhang, Tian Chen","doi":"10.1016/j.asr.2025.11.066","DOIUrl":"10.1016/j.asr.2025.11.066","url":null,"abstract":"<div><div>Region coverage planning of the multiple stratospheric airship (MSA) system has attracted wide attention. With increasing requirements on the continuous coverage capability of the MSA system, existing methods are not sufficient for MSA continuous coverage missions and struggle to respond to complex environments when considering multiple objectives. Therefore, an adaptive gaining-sharing knowledge planner is proposed. First, an integrated model is established on the unique demands of the MSAs together with multiple mission objectives, including renewable energy, region coverage, and so on. Besides, a location potential map is designed to enhance the airships’ perception of environmental information under a rolling horizon planning framework, such as time-varying and non-uniform wind fields and forbidden areas. Then, to elevate the solving efficiency of complex constrained multi-objective problems, a novel adaptive gaining-sharing knowledge optimizer with adaptive population size reduction (AGSK-APSR) is proposed to obtain optimal control inputs. The trajectories achieve coverage rates of over <span><math><mrow><mn>99</mn><mspace></mspace><mo>%</mo></mrow></math></span> in different simulation conditions within 24 h, with a decrease of <span><math><mrow><mn>5.02</mn><mspace></mspace><mo>%</mo></mrow></math></span> in average waypoint wind speed and the minimum energy consumption. The proposed method realizes a reduction of <span><math><mrow><mn>10.17</mn><mspace></mspace><mo>%</mo></mrow></math></span> in the comprehensive evaluation compared to the advanced AGSK optimization.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3732-3753"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.067
Sheng Gao , Wei Zhang , Ting Li , Zhaoguang Wang
An adaptive fixed-time fault-tolerant prescribed performance control strategy for space manipulators trajectory tracking considering bounded external disturbances, parametric uncertainties, and input saturations is proposed in this paper. An improved prescribed performance function (PPF) is investigated to achieve better performance. The PPF and nonsingular fast terminal sliding mode control are used for solving actuator faults and saturations. Adaptive radial bias function neural networks are employed for approximation to effectively compensate for lumped uncertainties including unknown disturbances, parametric uncertainties, and system dynamics. Lyapunov theory is employed for a rigorous theoretical analysis of practical fixed-time stability and for realising the prescribed performance. The effectiveness of the proposed controller is demonstrated through numerical simulations. The proposed controller provides superior trajectory tracking performance while ensuring strong robustness against actuator faults and complex disturbances.
{"title":"Adaptive neural networks-based fixed-time fault-tolerant control for space manipulator with prescribed performance and input saturations","authors":"Sheng Gao , Wei Zhang , Ting Li , Zhaoguang Wang","doi":"10.1016/j.asr.2025.11.067","DOIUrl":"10.1016/j.asr.2025.11.067","url":null,"abstract":"<div><div>An adaptive fixed-time fault-tolerant prescribed performance control strategy for space manipulators trajectory tracking considering bounded external disturbances, parametric uncertainties, and input saturations is proposed in this paper. An improved prescribed performance function (PPF) is investigated to achieve better performance. The PPF and nonsingular fast terminal sliding mode control are used for solving actuator faults and saturations. Adaptive radial bias function neural networks are employed for approximation to effectively compensate for lumped uncertainties including unknown disturbances, parametric uncertainties, and system dynamics. Lyapunov theory is employed for a rigorous theoretical analysis of practical fixed-time stability and for realising the prescribed performance. The effectiveness of the proposed controller is demonstrated through numerical simulations. The proposed controller provides superior trajectory tracking performance while ensuring strong robustness against actuator faults and complex disturbances.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3754-3768"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.022
Lalida Tantiparimongkol , Ming Shen , Peng-qi Gao , Xiao-zhong Guo , Huan-huan Yu , Jia-wei Li , Jia-lang Ding , Yu-ting Chu , Ran Duan , You Zhao
Space debris detection and monitoring are increasingly critical due to the accelerated growth of orbital debris, particularly in low-Earth orbit (LEO). Most existing detection systems are complex and remain inaccessible for civilian or academic research. This study presents a conceptual radar design model that integrates a phased-array radio astronomy receiver, developed at the National Astronomical Observatories, Chinese Academy of Sciences, as the receiving element. The quasi-monostatic phased-array architecture is designed to enable debris detection at altitudes of up to 1,000 km. A feasibility analysis was conducted by optimising radar parameters and modelling system components, including transmit antenna configuration, waveform design, and digital signal processing functions. The results demonstrate detection capability for spherical debris as small as 6-cm in diameter at 1,000 km altitude, with extended performance for sub-10 cm debris within LEO up to 2,000 km. Cataloguing potential was further assessed utilising two-line element (TLE) data of representative LEO objects. The study contributes an accessible space monitoring infrastructure in support of global space sustainability.
{"title":"Preliminary design and analysis of a radar system model based-on a phased-array RF astro-receiver for space debris detection and tracking","authors":"Lalida Tantiparimongkol , Ming Shen , Peng-qi Gao , Xiao-zhong Guo , Huan-huan Yu , Jia-wei Li , Jia-lang Ding , Yu-ting Chu , Ran Duan , You Zhao","doi":"10.1016/j.asr.2025.11.022","DOIUrl":"10.1016/j.asr.2025.11.022","url":null,"abstract":"<div><div>Space debris detection and monitoring are increasingly critical due to the accelerated growth of orbital debris, particularly in low-Earth orbit (LEO). Most existing detection systems are complex and remain inaccessible for civilian or academic research. This study presents a conceptual radar design model that integrates a phased-array radio astronomy receiver, developed at the National Astronomical Observatories, Chinese Academy of Sciences, as the receiving element. The quasi-monostatic phased-array architecture is designed to enable debris detection at altitudes of up to 1,000 km. A feasibility analysis was conducted by optimising radar parameters and modelling system components, including transmit antenna configuration, waveform design, and digital signal processing functions. The results demonstrate detection capability for spherical debris as small as 6-cm in diameter at 1,000 km altitude, with extended performance for sub-10 cm debris within LEO up to 2,000 km. Cataloguing potential was further assessed utilising two-line element (TLE) data of representative LEO objects. The study contributes an accessible space monitoring infrastructure in support of global space sustainability.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3654-3669"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.045
Bushra Ansari, Sanat K. Biswas
This work focuses on target tracking using GNSS-Reflectometry (GNSS-R) with NavIC-L5 multipath signals. After receiving the satellite signal, signal acquisition plays a crucial role in both Positioning, Navigation, and Timing (PNT) applications and reflectometry applications. In this study, we derive an expression for the Doppler frequency bound of NavIC-L5 multipath signals, which significantly improves signal acquisition efficiency. A grid-based analysis is performed to compute the Doppler frequencies for various surface target points within the NavIC service region. The estimated Doppler frequency bound significantly reduces the signal acquisition time by 70 % and 60 % for static and moving receiver scenarios, respectively, compared to acquisition using GPS Doppler bounds. Specifically, the Doppler frequency bound is found to be 0.55 kHz for a static receiver and 3.7 kHz for a moving receiver onboard a Low Earth Orbit (LEO) satellite travelling at 7.78 km/s. Furthermore, this work explores the application of GNSS-R for target tracking by leveraging bistatic range observations. The target location is estimated by optimizing three sets of bistatic ranges derived from multiple GNSS transmitters and a single receiver. The difference between the direct and reflected path lengths serves as a key observation for target tracking. Additionally, Position Dilution of Precision (PDOP) analysis is conducted to assess the accuracy of target localization using the GNSS-R technique. The Doppler bound calculation presented in this work is used to define the Doppler search range while performing the signal acquisition. It also helps to reduce the processing time for NavIC multipath signal acquisition during the GNSS-R analysis.
{"title":"Target localisation using GNSS-R and Doppler bound estimation for NavIC-L5 reflected signal: a simulation-based approach","authors":"Bushra Ansari, Sanat K. Biswas","doi":"10.1016/j.asr.2025.11.045","DOIUrl":"10.1016/j.asr.2025.11.045","url":null,"abstract":"<div><div>This work focuses on target tracking using GNSS-Reflectometry (GNSS-R) with NavIC-L5 multipath signals. After receiving the satellite signal, signal acquisition plays a crucial role in both Positioning, Navigation, and Timing (PNT) applications and reflectometry applications. In this study, we derive an expression for the Doppler frequency bound of NavIC-L5 multipath signals, which significantly improves signal acquisition efficiency. A grid-based analysis is performed to compute the Doppler frequencies for various surface target points within the NavIC service region. The estimated Doppler frequency bound significantly reduces the signal acquisition time by 70 % and 60 % for static and moving receiver scenarios, respectively, compared to acquisition using GPS Doppler bounds. Specifically, the Doppler frequency bound is found to be <span><math><mrow><mo>±</mo></mrow></math></span>0.55 kHz for a static receiver and <span><math><mrow><mo>±</mo></mrow></math></span>3.7 kHz for a moving receiver onboard a Low Earth Orbit (LEO) satellite travelling at 7.78 km/s. Furthermore, this work explores the application of GNSS-R for target tracking by leveraging bistatic range observations. The target location is estimated by optimizing three sets of bistatic ranges derived from multiple GNSS transmitters and a single receiver. The difference between the direct and reflected path lengths serves as a key observation for target tracking. Additionally, Position Dilution of Precision (PDOP) analysis is conducted to assess the accuracy of target localization using the GNSS-R technique. The Doppler bound calculation presented in this work is used to define the Doppler search range while performing the signal acquisition. It also helps to reduce the processing time for NavIC multipath signal acquisition during the GNSS-R analysis.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"77 3","pages":"Pages 3706-3717"},"PeriodicalIF":2.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.asr.2025.11.034
Tieding Lu , Yang Zhang , Zhiping Chen , Wen Xie , Jianghe Chen , Ruchao Tan , Haiqing He , Kaiyun Lv
Global Ionospheric Maps (GIM) serve as an essential data product for investigating ionospheric responses to solar activity and mitigating ionospheric delays in navigation positioning. However, the uneven distribution of ground-based GPS stations, particularly the scarcity of stations over oceanic regions, results in substantially degraded accuracy in GIM products derived solely from ground-based GPS observations. To address this limitation, this study pioneers the integration of HaiYang-2 (HY-2) series observations with a latitude-dependent systematic bias calibration scheme, establishing a new global ionospheric TEC model that combines multi-altimetry satellite and GPS observations. Comparative analyses with conventional GPS-only TEC models demonstrate significant improvements in both stability and accuracy for GIM and Differential Code Bias (DCB) products. These findings provide valuable references for future TEC retrieval and global ionospheric modeling over oceanic regions using HY-2 series observations. Compared with the GIM products obtained from GPS-only observations, the mean model RMS, MAR, and RMSE of the GIM products from the proposed model are reduced by 40.64 %, 11.53 %, and 17.78 %, respectively, with the GIM products of the Chinese Academy of Sciences (CAS) as the reference. The mean STD and RMSE of the satellite DCB products are reduced by 2.73 % and 12.13 %, respectively, while the mean STD and MAE of the station DCB products are reduced by 8.00 % and 5.23 %. Additionally, the accuracy of DCB in the Southern Hemisphere, where station distribution is sparse, is significantly improved by 14.64 % after integrating multi-source altimetry satellite observations. Taking the measurements from five GPS stations that were not involved in the global ionospheric TEC modeling as references, the mean RMSE of the GIM products from the proposed model is reduced by 23.77 % and 14.72 % compared with those of the GIM products of CAS and GPS-only, respectively.
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