Pub Date : 2025-02-15DOI: 10.1016/j.asr.2024.12.007
Ju Won Kim, Hongjae Kang
In this study, a thruster was developed by integrating a plasma reactor upstream of a catalyst bed and utilizing a plasma-arc jet to preheat the catalyst bed within 30 s. A plasma-assisted monopropellant thruster was designed for high-performance ionic monopropellants that require catalyst preheating. Hydroxyethylhydrazinium nitrate was selected as the monopropellant because of its easy synthesis and low adiabatic combustion temperature, which allow the use of conventional materials. Nitrogen or air (10 SLPM) was used as the plasma discharge gas, with a 20 kHz AC power supply generating plasma by passing 0.7 A current through the discharge gas. The Ru/LaAl2O3 catalyst bed was preheated using a plasma-arc jet with both nitrogen and air, reaching 763 K within 30 s. Subsequently, the propellant tank was pressurized to 0.4 MPa and 0.7 MPa to verify propellant decomposition under low and high mass flow rate conditions. The results confirmed the propellant decomposition under both nitrogen and air discharge conditions. This study demonstrates that the developed plasma-assisted monopropellant thruster offers a novel method for operating thrusters with high mass flow rates (> 1 g/s) during emergencies.
{"title":"Rapid startup of hydroxyethylhydrazinium nitrate ionic monopropellant thruster using rotating arc plasma jet","authors":"Ju Won Kim, Hongjae Kang","doi":"10.1016/j.asr.2024.12.007","DOIUrl":"10.1016/j.asr.2024.12.007","url":null,"abstract":"<div><div>In this study, a thruster was developed by integrating a plasma reactor upstream of a catalyst bed and utilizing a plasma-arc jet to preheat the catalyst bed within 30 s. A plasma-assisted monopropellant thruster was designed for high-performance ionic monopropellants that require catalyst preheating. Hydroxyethylhydrazinium nitrate was selected as the monopropellant because of its easy synthesis and low adiabatic combustion temperature, which allow the use of conventional materials. Nitrogen or air (10 SLPM) was used as the plasma discharge gas, with a 20 kHz AC power supply generating plasma by passing 0.7 A current through the discharge gas. The Ru/LaAl<sub>2</sub>O<sub>3</sub> catalyst bed was preheated using a plasma-arc jet with both nitrogen and air, reaching 763 K within 30 s. Subsequently, the propellant tank was pressurized to 0.4 MPa and 0.7 MPa to verify propellant decomposition under low and high mass flow rate conditions. The results confirmed the propellant decomposition under both nitrogen and air discharge conditions. This study demonstrates that the developed plasma-assisted monopropellant thruster offers a novel method for operating thrusters with high mass flow rates (> 1 g/s) during emergencies.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3982-3993"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402756","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.017
Zijian Wang , Zhongcheng Mu , Hang Zhou , Shufan Wu , Yixin Huang , Keke Zhang
Low Earth orbit (LEO) Mega-constellation networks (MCNs) with inter-satellite links (ISLs) are of great importance in terms of broadband communications. Compared to single-layer MCNs, multi-layer MCNs with inter-layer links (ILLs) bring better throughput and invulnerability at the cost of increased routing complexity. In this paper, for the first time, a theoretical analytic approach based on the non–homogeneous Poisson distribution is proposed to estimate the hop count between any two ground users for dual-layer MCNs with different ILL densities. Meanwhile, it is demonstrated that the establishment of ILLs reflects the dynamic features of ”small world” networks, which implies that introducing a small percentage of random connections to a regular network can significantly decrease the network diameter and the average shortest path length. Additionally, the uneven spatial distribution of hop count reduction is clarified. Results demonstrate that the implementation of ILLs effectively contributes to diminishing hop count. Remarkably, a mere 6% of ILLs leads to a substantial reduction of 22.3% in hop count for Starlink. These findings are helpful to the comprehension of constellation topological properties and provide valuable guidance for routing design and the deployment of ISLs.
{"title":"Minimum hop path model for LEO mega constellation networks with inter-layer satellite links: A theoretical analytic approach","authors":"Zijian Wang , Zhongcheng Mu , Hang Zhou , Shufan Wu , Yixin Huang , Keke Zhang","doi":"10.1016/j.asr.2024.12.017","DOIUrl":"10.1016/j.asr.2024.12.017","url":null,"abstract":"<div><div>Low Earth orbit (LEO) Mega-constellation networks (MCNs) with inter-satellite links (ISLs) are of great importance in terms of broadband communications. Compared to single-layer MCNs, multi-layer MCNs with inter-layer links (ILLs) bring better throughput and invulnerability at the cost of increased routing complexity. In this paper, for the first time, a theoretical analytic approach based on the non–homogeneous Poisson distribution is proposed to estimate the hop count between any two ground users for dual-layer MCNs with different ILL densities. Meanwhile, it is demonstrated that the establishment of ILLs reflects the dynamic features of ”small world” networks, which implies that introducing a small percentage of random connections to a regular network can significantly decrease the network diameter and the average shortest path length. Additionally, the uneven spatial distribution of hop count reduction is clarified. Results demonstrate that the implementation of ILLs effectively contributes to diminishing hop count. Remarkably, a mere 6% of ILLs leads to a substantial reduction of 22.3% in hop count for Starlink. These findings are helpful to the comprehension of constellation topological properties and provide valuable guidance for routing design and the deployment of ISLs.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3994-4012"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402757","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.038
Erdem Onur Ozyurt, Alim Rustem Aslan
Star sensors serve as sophisticated instruments for determining spacecraft attitude, offering high accuracy to meet complicated scientific demands. However, their accuracy can be compromised by various sources of noise in the captured image, such as false stars arising from reflective objects or solar flares. Filtering out these false stars is essential for enhancing accuracy and reducing computational complexity. This study introduces an algorithm designed to identify and filter false stars while also estimating camera motion parameters, thus improving attitude determination performance. The algorithm operates by detecting isomorphic feature vectors via density-based clustering that is employed to discern false stars. Moreover, the variance in slope angles of true star pairs facilitates the derivation of an affine transformation matrix through a maximum likelihood estimator. It is a standalone algorithm that can be integrated into any star identification method to increase robustness to false stars while providing motion parameters to be used in recursive star identification algorithms to reduce complexity. The algorithm’s effectiveness is evaluated through experiments on 1000 pairs of time-sequential simulated star images, in which the sensor parameters are taken from the SharjahSat-1 project, while also taking position and brightness noise effects into account.
{"title":"False star filtering and camera motion estimation via density-based clustering","authors":"Erdem Onur Ozyurt, Alim Rustem Aslan","doi":"10.1016/j.asr.2024.12.038","DOIUrl":"10.1016/j.asr.2024.12.038","url":null,"abstract":"<div><div>Star sensors serve as sophisticated instruments for determining spacecraft attitude, offering high accuracy to meet complicated scientific demands. However, their accuracy can be compromised by various sources of noise in the captured image, such as false stars arising from reflective objects or solar flares. Filtering out these false stars is essential for enhancing accuracy and reducing computational complexity. This study introduces an algorithm designed to identify and filter false stars while also estimating camera motion parameters, thus improving attitude determination performance. The algorithm operates by detecting isomorphic feature vectors via density-based clustering that is employed to discern false stars. Moreover, the variance in slope angles of true star pairs facilitates the derivation of an affine transformation matrix through a maximum likelihood estimator. It is a standalone algorithm that can be integrated into any star identification method to increase robustness to false stars while providing motion parameters to be used in recursive star identification algorithms to reduce complexity. The algorithm’s effectiveness is evaluated through experiments on 1000 pairs of time-sequential simulated star images, in which the sensor parameters are taken from the SharjahSat-1 project, while also taking position and brightness noise effects into account.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 4035-4049"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402759","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.034
Liangke Huang , Peijie Zhu , Tengxu Zhang , Lin He , Wenhao Wu , Zixuan Ge , Hui Ai
Ground subsidence is a natural disaster that can cause severe consequences such as surface deformation and building collapse. With rapid economic growth, activities such as groundwater extraction, subway construction, and large-scale infrastructure projects have weakened the soil’s load-bearing capacity, resulting in subsidence issues for buildings and the ground. As the mechanism of land subsidence caused by the above factors is still unclear, it is necessary to conduct further study in a specific area. Intending to provide a scientific basis for successfully preventing and mitigating the potential risks associated with subsidence, we employed the Persistent Scatterer InSAR (PS-InSAR) technique for monitoring to precisely explore the causes, processes, and impacts of the subsidence. In this study, 14 Sentinel-1A terrain observations by progressive scans (TOPS) Synthetic Aperture Radar (SAR) images from January to December 2020 have been selected to investigate the spatiotemporal ground deformation in the specific Guangzhou and Foshan regions. Various analytical methods have been employed to investigate the significant deformation mechanism. Firstly, we analyzed characteristic points in industrial parks and urban areas. Subsequently, detailed investigations were conducted in three severely subsiding areas: Huadu, Nanhai, and Haizhu districts. Results demonstrate that the region’s surface deformation is highly heterogeneous; subsidence is primarily concentrated in urban areas and usually spreads outward from city centers. Additionally, numerous uplift regions were identified, with the maximum uplift rate exceeding 29 mm/yr. In particular, the highest rates of subsidence were found in Guangzhou’s Haizhu District, with annual average rates ranging from −28.3 mm/yr to −29.4 mm/yr, and significant seasonal fluctuations of nonlinear subsidence patterns have also been detected. Furthermore, comparative analysis of factors such as urban development (e.g., subway systems and artificial structures), rainfall, and industrial expansion in major subsidence areas indicates that subsidence in this region is primarily influenced by anthropogenic factors (such as industrial development and surface loading) as well as natural factors like rainfall and karst processes.
{"title":"Investigation of land subsidence in Guangdong Province, China, using PS-InSAR technique","authors":"Liangke Huang , Peijie Zhu , Tengxu Zhang , Lin He , Wenhao Wu , Zixuan Ge , Hui Ai","doi":"10.1016/j.asr.2024.12.034","DOIUrl":"10.1016/j.asr.2024.12.034","url":null,"abstract":"<div><div>Ground subsidence is a natural disaster that can cause severe consequences such as surface deformation and building collapse. With rapid economic growth, activities such as groundwater extraction, subway construction, and large-scale infrastructure projects have weakened the soil’s load-bearing capacity, resulting in subsidence issues for buildings and the ground. As the mechanism of land subsidence caused by the above factors is still unclear, it is necessary to conduct further study in a specific area. Intending to provide a scientific basis for successfully preventing and mitigating the potential risks associated with subsidence, we employed the Persistent Scatterer InSAR (PS-InSAR) technique for monitoring to precisely explore the causes, processes, and impacts of the subsidence. In this study, 14 Sentinel-1A terrain observations by progressive scans (TOPS) Synthetic Aperture Radar (SAR) images from January to December 2020 have been selected to investigate the spatiotemporal ground deformation in the specific Guangzhou and Foshan regions. Various analytical methods have been employed to investigate the significant deformation mechanism. Firstly, we analyzed characteristic points in industrial parks and urban areas. Subsequently, detailed investigations were conducted in three severely subsiding areas: Huadu, Nanhai, and Haizhu districts. Results demonstrate that the region’s surface deformation is highly heterogeneous; subsidence is primarily concentrated in urban areas and usually spreads outward from city centers. Additionally, numerous uplift regions were identified, with the maximum uplift rate exceeding 29 mm/yr. In particular, the highest rates of subsidence were found in Guangzhou’s Haizhu District, with annual average rates ranging from −28.3 mm/yr to −29.4 mm/yr, and significant seasonal fluctuations of nonlinear subsidence patterns have also been detected. Furthermore, comparative analysis of factors such as urban development (e.g., subway systems and artificial structures), rainfall, and industrial expansion in major subsidence areas indicates that subsidence in this region is primarily influenced by anthropogenic factors (such as industrial development and surface loading) as well as natural factors like rainfall and karst processes.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3507-3520"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402782","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.021
Jingge Liu , Alireza Arabameri , Chandan Surabhi Das , Pritam Sarkar
Gully erosion is one of the major global environmental threats that frequently affects semi-humid to arid Mediterranean regions and contributes to a wide range of ecological problems. Recognizing vulnerable areas to gully erosion and creating a comprehensive gully erosion susceptibility map (GESM) can assist in the lessening of land degradation and damage to numerous infrastructures. The primary goal of this research is to build a random subspace-based function tree (RSFT), i.e., an ensemble model, and compare it with other standard models such as Fisher’s linear discriminant analysis (FLDA), Nave Bayes tree (NBTree), J48 Decision Tree, and random forest (RF) models in order to identify which model generates the most accurate outcomes. Overall, a total number of 489 gully sites were utilised for modelling and validation purpose, with 377 (70 %) used for modelling and 112 (30 %) used for validation. Fourteen salient gully erosion conditioning factors (GECFs) were implemented for constructing the GESMs. The efficacy and significance of several GECFs were assessed through the random forest, or RF, model for gully erosion modelling. Using the GES maps, we computed the success rate curve (SRC) and prediction rate curve (PRC), as well as their areas under the curves (AUC). The AUC (SRC, PRC) scores for the RSFT model were 0.906 and 0.916, consequently, while the outcomes for the RF, NBTree, FLDA, and J48 models were 0.875 and 0.869, 0.861 and 0.859, 0.792 and 0.816, and 0.779 and 0.811. AUC findings indicated that the RSFT model delivered the most precise predictions, trailed by the RF, NBTree, FLDA, and J48 models. In terms of RMSE, each of the models performed adequately; however, RSFT exhibits the lowest RMSE values of all models, with 0.31 (training dataset) and 0.29 (validation dataset), which shows that RSFT is substantially more accurate than other models in forecasting gully erosionThus, the results of this research can be used by local managers and planners for environmental management. The results from our study suggests that all of the GESM models have high efficiency, and can be employed to formulate adequate measures for safeguarding of soil and water.
{"title":"An integrated approach for gully erosion susceptibility mapping and factor effect analysis","authors":"Jingge Liu , Alireza Arabameri , Chandan Surabhi Das , Pritam Sarkar","doi":"10.1016/j.asr.2024.12.021","DOIUrl":"10.1016/j.asr.2024.12.021","url":null,"abstract":"<div><div>Gully erosion is one of the major global environmental threats that frequently affects semi-humid to arid Mediterranean regions and contributes to a wide range of ecological problems. Recognizing vulnerable areas to gully erosion and creating a comprehensive gully erosion susceptibility map (GESM) can assist in the lessening of land degradation and damage to numerous infrastructures. The primary goal of this research is to build a random subspace-based function tree (RSFT), i.e., an ensemble model, and compare it with other<!--> <!-->standard models such as Fisher’s linear discriminant analysis (FLDA), Nave Bayes tree (NBTree), J48 Decision Tree, and random forest (RF) models in order to identify which model generates the most accurate outcomes. Overall, a total number of<!--> <!-->489 gully sites were utilised for modelling and validation purpose, with 377 (70 %) used for modelling and 112 (30 %) used for validation. Fourteen salient gully erosion conditioning factors (GECFs) were implemented for constructing the GESMs. The efficacy and significance of several GECFs were assessed through the random forest, or RF, model for gully erosion modelling. Using the GES maps, we computed the success rate curve (SRC) and prediction rate curve (PRC), as well as their areas under the curves (AUC). The AUC (SRC, PRC) scores for the RSFT model were 0.906 and 0.916, consequently, while the outcomes for the RF, NBTree, FLDA, and J48 models were 0.875 and 0.869, 0.861 and 0.859, 0.792 and 0.816, and 0.779 and 0.811. AUC findings indicated that the RSFT model delivered the most precise predictions, trailed by the RF, NBTree, FLDA, and J48 models. In terms of RMSE, each of the models performed adequately; however, RSFT exhibits the lowest RMSE values of all models, with 0.31 (training dataset) and 0.29 (validation dataset), which shows that RSFT is substantially more accurate than other models in forecasting gully erosionThus, the results of this research can be used by local managers and planners for environmental management. The results from our study suggests that all of the GESM models have high efficiency, and can be employed to formulate adequate measures for safeguarding of soil and water.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3451-3470"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402860","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.016
Jiahui Huang , Xiaoxing He , Shunqiang Hu , Feng Ming
This study systematically investigates the efficiency of RMLE and MLE algorithms for noise model identification using various information criteria and examines the influence of offsets on noise properties and velocity estimation. Through experimental analysis on simulated GNSS time series, we confirm that RMLE and MLE accurately discriminate among four different noise models using AIC, BIC, and BIC_tp information criteria. For time series longer than 15 years, RMLE is recommended as the default method, while MLE outperforms RMLE for short time series when the underlying noise model is FN, PL, or GGM. RMLE proves more sensitive to the RW component than the MLE algorithm, particularly with shorter time series (less than 10 years). We also confirm that the addition of offsets does not transform non-GGM optimal noise models into GGM noise models, further supporting that GGM noise models in GNSS time series are not an artifact and that residual offsets are not the underlying cause of GNSS position time series exhibiting GGMWN characteristics. For selected real GNSS time series without offsets from Extended Solid Earth Science ESDR System, we further confirm that PLWN and FNWN remain the primary noise processes best describing GNSS time series. A noteworthy discovery is the observation of more RW components (approximately 19.22 %) than in previous research with 15-year long-term GNSS time series using the RMLE algorithm. Additionally, we still find GGM as the optimal noise model in the vertical component, ensuring it is real and not an artifact. Furthermore, even with artificially induced frequent offsets, we observe that only about 0.35 % of sites’ optimal noise models change from non-GGMWN models to GGMWN, consistent with the simulated GNSS time series experiments.
{"title":"Impact of offsets on GNSS time series stochastic noise properties and velocity estimation","authors":"Jiahui Huang , Xiaoxing He , Shunqiang Hu , Feng Ming","doi":"10.1016/j.asr.2024.12.016","DOIUrl":"10.1016/j.asr.2024.12.016","url":null,"abstract":"<div><div>This study systematically investigates the efficiency of RMLE and MLE algorithms for noise model identification using various information criteria and examines the influence of offsets on noise properties and velocity estimation. Through experimental analysis on simulated GNSS time series, we confirm that RMLE and MLE accurately discriminate among four different noise models using AIC, BIC, and BIC_tp information criteria. For time series longer than 15 years, RMLE is recommended as the default method, while MLE outperforms RMLE for short time series when the underlying noise model is FN, PL, or GGM. RMLE proves more sensitive to the RW component than the MLE algorithm, particularly with shorter time series (less than 10 years). We also confirm that the addition of offsets does not transform non-GGM optimal noise models into GGM noise models, further supporting that GGM noise models in GNSS time series are not an artifact and that residual offsets are not the underlying cause of GNSS position time series exhibiting GGMWN characteristics. For selected real GNSS time series without offsets from Extended Solid Earth Science ESDR System, we further confirm that PLWN and FNWN remain the primary noise processes best describing GNSS time series. A noteworthy discovery is the observation of more RW components (approximately 19.22 %) than in previous research with 15-year long-term GNSS time series using the RMLE algorithm. Additionally, we still find GGM as the optimal noise model in the vertical component, ensuring it is real and not an artifact. Furthermore, even with artificially induced frequent offsets, we observe that only about 0.35 % of sites’ optimal noise models change from non-GGMWN models to GGMWN, consistent with the simulated GNSS time series experiments.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3397-3413"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403042","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 : 2025-02-15DOI: 10.1016/j.asr.2024.11.078
Swati Chowdhury, D. Bala Subrahamanyam, R.K. Choudhary
This study examines the impact of two tropical cyclones (Mora and Ockhi, 2017) over the Northern Indian Ocean on vertical total electron content (VTEC) over Trivandrum, by comparing data from similar periods in 2018 and 2019. To ensure accuracy, a precise data-screening method was implemented to exclude the potential effects of geomagnetic storms and other tropical cyclones on VTEC. Results showed a significant depletion in VTEC, ranging from 7% to 19%, which varied based on the intensity of the cyclones and their distance from the measurement site. The period analyzed coincided with the declining phase of the 24th solar cycle, during which VTEC naturally decreased from 2017 to 2019. The present analysis reports a sharp depletion in the VTEC during the passage of the cyclone, the first of its kind, emphasizing the TC-influence on the upper atmosphere, which was seen to extend even after the landfall.
{"title":"First observational investigation on the temporal trends of Vertical Total Electron Content (VTEC) over an equatorial station: Discerning the impacts of Mora and Ockhi – Two tropical cyclones in 2017","authors":"Swati Chowdhury, D. Bala Subrahamanyam, R.K. Choudhary","doi":"10.1016/j.asr.2024.11.078","DOIUrl":"10.1016/j.asr.2024.11.078","url":null,"abstract":"<div><div>This study examines the impact of two tropical cyclones (Mora and Ockhi, 2017) over the Northern Indian Ocean on vertical total electron content (VTEC) over Trivandrum, by comparing data from similar periods in 2018 and 2019. To ensure accuracy, a precise data-screening method was implemented to exclude the potential effects of geomagnetic storms and other tropical cyclones on VTEC. Results showed a significant depletion in VTEC, ranging from 7% to 19%, which varied based on the intensity of the cyclones and their distance from the measurement site. The period analyzed coincided with the declining phase of the 24th solar cycle, during which VTEC naturally decreased from 2017 to 2019. The present analysis reports a sharp depletion in the VTEC during the passage of the cyclone, the first of its kind, emphasizing the TC-influence on the upper atmosphere, which was seen to extend even after the landfall.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3651-3660"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403147","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.002
Da Song , Hong-bo Cai , Shen Wang , Jing Wang
Impact flashes on the moon are caused by high-speed collisions of celestial bodies with the lunar surface. The study of the impacts is critical for exploring the evolutionary history and formation of the Moon, and for quantifying the risk posed by the impacts to future human activity. Although the impacts have been monitored from the Earth by a few projects in past 20 years, the events occurring on the lunar far side have not been explored systematically so far. We here present an end-to-end image simulator dedicated to detecting and monitoring the impacts from space, which is useful for future mission design. The simulator is designed for modularity and developed in the Python environment, which is mainly composed of four components: the flash temporal radiation, the background emission, the telescope and the detector used to collect and measure the radiation. Briefly speaking, with a set of input parameters, the simulator calculates the flash radiation in the context of the spherical droplet model and the background emission from the lunar surface. The resulting images are then generated by the simulator after considering a series observational effects, including the stray light, transmission of the instrument, point spread function and multiple kinds of noise caused by a CCD/CMOS detector. The simulator is validated by comparing the calculation with the observations taken on the ground. The modular design enables the simulator to be improved and enhanced by including more complex physical models in the future, and to be flexible for other future space missions.
{"title":"An image simulator of lunar far-side impact flashes captured from the Earth-Moon L2 point","authors":"Da Song , Hong-bo Cai , Shen Wang , Jing Wang","doi":"10.1016/j.asr.2024.12.002","DOIUrl":"10.1016/j.asr.2024.12.002","url":null,"abstract":"<div><div>Impact flashes on the moon are caused by high-speed collisions of celestial bodies with the lunar surface. The study of the impacts is critical for exploring the evolutionary history and formation of the Moon, and for quantifying the risk posed by the impacts to future human activity. Although the impacts have been monitored from the Earth by a few projects in past 20 years, the events occurring on the lunar far side have not been explored systematically so far. We here present an end-to-end image simulator dedicated to detecting and monitoring the impacts from space, which is useful for future mission design. The simulator is designed for modularity and developed in the Python environment, which is mainly composed of four components: the flash temporal radiation, the background emission, the telescope and the detector used to collect and measure the radiation. Briefly speaking, with a set of input parameters, the simulator calculates the flash radiation in the context of the spherical droplet model and the background emission from the lunar surface. The resulting images are then generated by the simulator after considering a series observational effects, including the stray light, transmission of the instrument, point spread function and multiple kinds of noise caused by a CCD/CMOS detector. The simulator is validated by comparing the calculation with the observations taken on the ground. The modular design enables the simulator to be improved and enhanced by including more complex physical models in the future, and to be flexible for other future space missions.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 4061-4079"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402761","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 : 2025-02-15DOI: 10.1016/j.asr.2024.12.019
Layue Li , Wei Zhan , Changyun Chen , Yujiao Niu
On September 5, 2022, a Ms 6.8 earthquake struck the Xianshuihe fault zone, a large-scale left-lateral strike-slip fault zone on the southeastern margin of the Tibetan Plateau, filling the Moxi seismic gap and resulting in significant economic losses and casualties. To clarify the seismogenic process and mechanism of this earthquake, we conducted a comprehensive and in-depth analysis on the stress–strain accumulation characteristics preceding the Ms 6.8 Luding earthquake based on the Global Positioning System (GPS) data and focal mechanism solutions. Our results reveal that the epicenter area of the Luding earthquake underwent long-term NWW-SEE directed compression and NEE-SWW directed tension, and gradually accumulates strain energy predominantly through shear deformation, with a sinistral shear strain rate of 3.4 × 10−8/a, which is associated with regional tectonic movement. Additionally, the focal area of the Luding earthquake exhibited a high accumulation of strain energy prior to the rupture, with a maximum locking depth of approximately 15.6 km. The Moxi section, where the Luding earthquake occurred, is likely approaching the late stage of its seismogenic cycle. The tectonic stress analysis further confirms that the mainshock of the Luding earthquake was primarily triggered by tectonic shear stress. These findings suggest that the Ms 6.8 Luding earthquake was a normal release of strain energy accumulated on a NW-striking strike-slip fault, mainly driven by the regional tectonic stress field resulting from the India-Eurasia plate convergence and the resistance from the rigid Sichuan Basin.
{"title":"Interseismic strain accumulation of the 2022 Ms 6.8 Luding earthquake (Tibet) and discussion of the seismogenic mechanism","authors":"Layue Li , Wei Zhan , Changyun Chen , Yujiao Niu","doi":"10.1016/j.asr.2024.12.019","DOIUrl":"10.1016/j.asr.2024.12.019","url":null,"abstract":"<div><div>On September 5, 2022, a <em>M</em>s 6.8 earthquake struck the Xianshuihe fault zone, a large-scale left-lateral strike-slip fault zone on the southeastern margin of the Tibetan Plateau, filling the Moxi seismic gap and resulting in significant economic losses and casualties. To clarify the seismogenic process and mechanism of this earthquake, we conducted a comprehensive and in-depth analysis on the stress–strain accumulation characteristics preceding the <em>M</em>s 6.8 Luding earthquake based on the Global Positioning System (GPS) data and focal mechanism solutions. Our results reveal that the epicenter area of the Luding earthquake underwent long-term NWW-SEE directed compression and NEE-SWW directed tension, and gradually accumulates strain energy predominantly through shear deformation, with a sinistral shear strain rate of 3.4 × 10<sup>−8</sup>/a, which is associated with regional tectonic movement. Additionally, the focal area of the Luding earthquake exhibited a high accumulation of strain energy prior to the rupture, with a maximum locking depth of approximately 15.6 km. The Moxi section, where the Luding earthquake occurred, is likely approaching the late stage of its seismogenic cycle. The tectonic stress analysis further confirms that the mainshock of the Luding earthquake was primarily triggered by tectonic shear stress. These findings suggest that the <em>M</em>s 6.8 Luding earthquake was a normal release of strain energy accumulated on a NW-striking strike-slip fault, mainly driven by the regional tectonic stress field resulting from the India-Eurasia plate convergence and the resistance from the rigid Sichuan Basin.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3414-3426"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402846","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 : 2025-02-15DOI: 10.1016/j.asr.2024.11.074
Mengmeng Li , Xingyu Zhou , Qianxin Wang , Kai Li , Ming Gao , Tong Cheng , Han Zhang
Low Earth Orbit (LEO) satellites play a vital role in fields of gravity field recovery, meteorological detection, and Precise Point Positioning (PPP) of augmented Global Navigation Satellite Systems (GNSS), which makes the precise orbit determination (POD) of LEO satellites the key to their mission-execution. Ambiguity resolution (AR) is an effective method to improve the orbit accuracy of LEO satellites, among which the Single Difference (SD) AR method requires GNSS hardware bias products. Besides, Track-to-Track (T2T) AR and Single Difference Track-to-Track (SDT2T) AR can be used as the alternative methods in the scenarios without any GNSS bias products. In this study, the reduced dynamic POD (RDPOD) of the GRACE-FO and SWARM constellations from day 001 to 150 of 2020 was performed using the SD AR, T2T AR and SDT2T AR methods. The results showed that the performance of T2T AR is inferior to that of SDT2T AR and SD AR due to the gradual variability in the phase fractional bias of satellites and receivers. By analyzing the relationship between the success rate of T2T AR and the time interval between adjacent ambiguities, it is found that the success rate of T2T AR is higher when the time interval is within 30 min. Therefore, it can be assumed that the fractional cycle biases of the receivers remains constant within 30 min because the performance of T2T AR highly depends on the stability of the fractional cycle biases of the receivers. With impacts caused by the receiver fractional biases eliminated, SDT2T AR significantly outperforms T2T AR and achieves comparable performance with SD AR. Therefore, in the cases that GNSS bias products are unavailable, SDT2T AR is recommended as the preferred option for single LEO POD.
{"title":"Performance assessment of multiple ambiguity resolution methods in single LEO precision orbit determination","authors":"Mengmeng Li , Xingyu Zhou , Qianxin Wang , Kai Li , Ming Gao , Tong Cheng , Han Zhang","doi":"10.1016/j.asr.2024.11.074","DOIUrl":"10.1016/j.asr.2024.11.074","url":null,"abstract":"<div><div>Low Earth Orbit (LEO) satellites play a vital role in fields of gravity field recovery, meteorological detection, and Precise Point Positioning (PPP) of augmented Global Navigation Satellite Systems (GNSS), which makes the precise orbit determination (POD) of LEO satellites the key to their mission-execution. Ambiguity resolution (AR) is an effective method to improve the orbit accuracy of LEO satellites, among which the Single Difference (SD) AR method requires GNSS hardware bias products. Besides, Track-to-Track (T2T) AR and Single Difference Track-to-Track (SDT2T) AR can be used as the alternative methods in the scenarios without any GNSS bias products. In this study, the reduced dynamic POD (RDPOD) of the GRACE-FO and SWARM constellations from day 001 to 150 of 2020 was performed using the SD AR, T2T AR and SDT2T AR methods. The results showed that the performance of T2T AR is inferior to that of SDT2T AR and SD AR due to the gradual variability in the phase fractional bias of satellites and receivers. By analyzing the relationship between the success rate of T2T AR and the time interval between adjacent ambiguities, it is found that the success rate of T2T AR is higher when the time interval is within 30 min. Therefore, it can be assumed that the fractional cycle biases of the receivers remains constant within 30 min because the performance of T2T AR highly depends on the stability of the fractional cycle biases of the receivers. With impacts caused by the receiver fractional biases eliminated, SDT2T AR significantly outperforms T2T AR and achieves comparable performance with SD AR. Therefore, in the cases that GNSS bias products are unavailable, SDT2T AR is recommended as the preferred option for single LEO POD.</div></div>","PeriodicalId":50850,"journal":{"name":"Advances in Space Research","volume":"75 4","pages":"Pages 3870-3890"},"PeriodicalIF":2.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143402867","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}
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