A rocket launch can induce large-scale atmospheric disturbances,which have mainly been investigated in previous studies by using measurements of total electron content.In this study,we report the perturbation in very ...A rocket launch can induce large-scale atmospheric disturbances,which have mainly been investigated in previous studies by using measurements of total electron content.In this study,we report the perturbation in very low frequency(VLF)transmitter signals triggered by a rocket launch event,which,unlike total electron content measurements,is directly related to the D-region ionosphere.The perturbation in VLF measurements typically occurred~9 min after liftoff,resulting in an amplitude change of up to 2.82 dB,and it had a common period of~3.5-7 min.Moreover,the perturbation consisted of two isolated pulses,a feature notably different from previous measurements.Given the close correlation between the rocket launch and the VLF measurements,as well as the similarity between different propagation paths,these perturbations were likely caused by shock acoustic waves generated during the rocket launch because the periods were similar.展开更多
In this paper,we propose evaluation approaches for the spatial target localization precision based on the observation matrix conditional number.Three evaluation approaches for the spatial target localization precision...In this paper,we propose evaluation approaches for the spatial target localization precision based on the observation matrix conditional number.Three evaluation approaches for the spatial target localization precision are derived including relative condition numbers,absolute condition numbers,and volume condition numbers by properties of vectors and matrix norms.The theoretical analysis shows that the proposed methods are the upper certainty bound of the magnification of measurement error.Meanwhile,the proposed methods are able to account for variations of localization accuracy by exploiting geometric variations in the composition between the target and measurement stations.Finally,the proposed methods perform better,compared with the traditional evaluation methods.This is of great significance for the accuracy evaluation of high-precision measuring equipment,optimization of workstation layout and geometric configuration.Simulation experiments corroborate the effectiveness of the proposed methods.展开更多
As commercial mega-constellations such as SpaceX’s Starlink and Amazon’s Kuiper system rapidly expand,traditional Tracking,Telemetry,and Command(TT&C)architectures encounter unprecedented scalability challenges....As commercial mega-constellations such as SpaceX’s Starlink and Amazon’s Kuiper system rapidly expand,traditional Tracking,Telemetry,and Command(TT&C)architectures encounter unprecedented scalability challenges.Thus,a novel scheme design and capacity analysis framework is proposed for networked TT&C system serving large-scale Low Earth Orbit(LEO)satellite constellations.The networked TT&C architecture is designed to leverage Medium Earth Orbit(MEO)satellites to monitor LEO constellations,providing TT&C service for both normal and anomalous LEO satellites through inter-satellite links.A capacity decomposition framework is introduced,dividing system capacity into access capacity and anomaly-handling capacity.Through stochastic geometry and queuing theory models,the maximum number of LEO satellites that can be supported under various operational constraints is quantified.It is demonstrated by simulation results that for Starlink Phase 1,if the second-generation O3b mPower system is utilized for TT&C,the system can support up to 59,497 LEO satellites under a 30-second threshold of polling waiting time,and up to 50,761 satellites under a 10-minute threshold of anomaly-handling time in the steady state.The analysis provides critical design guidelines for the deployment and management of large-scale LEO constellations,highlighting the trade-offs between system capacity and operational constraints such as polling waiting time and anomaly-handling waiting time.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42188101,41874195,42074119,42274205,42461160256,U2541289,U25D9004,42130210 and 42025404)the National Key R&D Program of China(Grant No.2022YFF0503700)+2 种基金the Natural Science Foundation of Hubei Province,China(Grant No.2025AFA030)the Hubei Province Regional Science and Technology Innovation Plan Project(Grant No.2025EHA044)the Antarctic Zhongshan Ice and Space Environment National Observation and Research Station(Grant No.ZSNORS-20242603).
摘要A rocket launch can induce large-scale atmospheric disturbances,which have mainly been investigated in previous studies by using measurements of total electron content.In this study,we report the perturbation in very low frequency(VLF)transmitter signals triggered by a rocket launch event,which,unlike total electron content measurements,is directly related to the D-region ionosphere.The perturbation in VLF measurements typically occurred~9 min after liftoff,resulting in an amplitude change of up to 2.82 dB,and it had a common period of~3.5-7 min.Moreover,the perturbation consisted of two isolated pulses,a feature notably different from previous measurements.Given the close correlation between the rocket launch and the VLF measurements,as well as the similarity between different propagation paths,these perturbations were likely caused by shock acoustic waves generated during the rocket launch because the periods were similar.
基金supported by the National Natural Science Foundation of China(62203458)the Postgraduate Scientific Research Innovation Project of Hunan Province(CX20220024,CX20230014).
摘要In this paper,we propose evaluation approaches for the spatial target localization precision based on the observation matrix conditional number.Three evaluation approaches for the spatial target localization precision are derived including relative condition numbers,absolute condition numbers,and volume condition numbers by properties of vectors and matrix norms.The theoretical analysis shows that the proposed methods are the upper certainty bound of the magnification of measurement error.Meanwhile,the proposed methods are able to account for variations of localization accuracy by exploiting geometric variations in the composition between the target and measurement stations.Finally,the proposed methods perform better,compared with the traditional evaluation methods.This is of great significance for the accuracy evaluation of high-precision measuring equipment,optimization of workstation layout and geometric configuration.Simulation experiments corroborate the effectiveness of the proposed methods.
基金supported by the National Natural Science Foundation of China under Grant 62131012.
摘要As commercial mega-constellations such as SpaceX’s Starlink and Amazon’s Kuiper system rapidly expand,traditional Tracking,Telemetry,and Command(TT&C)architectures encounter unprecedented scalability challenges.Thus,a novel scheme design and capacity analysis framework is proposed for networked TT&C system serving large-scale Low Earth Orbit(LEO)satellite constellations.The networked TT&C architecture is designed to leverage Medium Earth Orbit(MEO)satellites to monitor LEO constellations,providing TT&C service for both normal and anomalous LEO satellites through inter-satellite links.A capacity decomposition framework is introduced,dividing system capacity into access capacity and anomaly-handling capacity.Through stochastic geometry and queuing theory models,the maximum number of LEO satellites that can be supported under various operational constraints is quantified.It is demonstrated by simulation results that for Starlink Phase 1,if the second-generation O3b mPower system is utilized for TT&C,the system can support up to 59,497 LEO satellites under a 30-second threshold of polling waiting time,and up to 50,761 satellites under a 10-minute threshold of anomaly-handling time in the steady state.The analysis provides critical design guidelines for the deployment and management of large-scale LEO constellations,highlighting the trade-offs between system capacity and operational constraints such as polling waiting time and anomaly-handling waiting time.