Focusing on the key scientific questions of deep space exploration which include the origin and evolution of the solar system and its planets, disastrous impact on the Earth by the solar activities and small bodies, e...Focusing on the key scientific questions of deep space exploration which include the origin and evolution of the solar system and its planets, disastrous impact on the Earth by the solar activities and small bodies, extraterrestrial life, this paper put forward a propose about the roadmap and scientific objectives of China's Deep-space Exploration before 2030.展开更多
Previous research on deep-space networks based on delay-tolerant networking(DTN)has mainly focused on the performance of DTN protocols in simple networks;hence,research on complex networks is lacking.In this paper,we ...Previous research on deep-space networks based on delay-tolerant networking(DTN)has mainly focused on the performance of DTN protocols in simple networks;hence,research on complex networks is lacking.In this paper,we focus on network evaluation and protocol deployment for complex DTNbased deep-space networks and apply the results to a novel complex deep-space network based on the Universal Interplanetary Communication Network(UNICON-CDSN)proposed by the National Space Science Center(NSSC)for simulation and verification.A network evaluation method based on network capacity and memory analysis is proposed.Based on a performance comparison between the Licklider Transmission Protocol(LTP)and the Transmission Control Protocol(TCP)with the Bundle Protocol(BP)in various communication scenarios,a transport protocol configuration proposal is developed and used to construct an LTP deployment scheme for UNICON-CDSN.For the LTP deployment scheme,a theoretical model of file delivery time over complex deep-space networks is built.A network evaluation with the method proposed in this paper proves that UNICONCDSN satisfies the requirements for the 2020 Mars exploration mission Curiosity.Moreover,simulation results from a universal space communication network testbed(USCNT)designed by us show that the LTP deployment scheme is suitable for UNICON-CDSN.展开更多
eight planets,various asteroids and comets in the solar system.Amount of deep-space scientific experiments promoted people to understand about the origin and evolution of the universe.With the rapid developments of eq...eight planets,various asteroids and comets in the solar system.Amount of deep-space scientific experiments promoted people to understand about the origin and evolution of the universe.With the rapid developments of equipment and spacecraft with high-accuracy detector and long-term energy,more and more ambitious deep-space exploration plans have also been scheduled or under discussion about space resources utilization and space migration,e.g.,manned landing on the Mars,guard infrastructures on the Moon and human-flight to the edge of the solar system(>100 AU),etc.展开更多
This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from ...This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.展开更多
While approaching the target body, the deep-space probe is orbiting hyperbolically before the maneuver. We discuss the variation of perturbed hyperbolic orbit using the method similar to that used in elliptic orbit. E...While approaching the target body, the deep-space probe is orbiting hyperbolically before the maneuver. We discuss the variation of perturbed hyperbolic orbit using the method similar to that used in elliptic orbit. Ephemeris calculating and orbit control will benefit from the given analytical solution.展开更多
Delay/disruption-tolerant networking communications rely heavily on BP(Bundle Protocol),which uses the well-known approach of store-and-forward with optional custody transfer to deal with stressed communication enviro...Delay/disruption-tolerant networking communications rely heavily on BP(Bundle Protocol),which uses the well-known approach of store-and-forward with optional custody transfer to deal with stressed communication environments.The use of BP and its performance in deep-space communication has been the subject of debate.The accurate estimate of file delivery latency(i.e.,RTT(Round Trip Time))is essential for efficient transmission control,reliable delivery,and bandwidth usage optimization of a protocol.In this paper,we present a performance analysis of BP running over UDPCL/UDP over deep-space channels,focusing on the RTT estimate,in the presence of highly asymmetric channel rates.Analytical models are built for the RTT estimate of the BP/UDPCL transmissions considering the effect of delay caused by space channel-rate asymmetry,and,channel impairment.The models are validated by file transfer experiments using a PC-based testbed.It is found that a smaller bundle size(if smaller than a calculated threshold)results in a longer delay in custody acknowledgment transmission,and thus,a longer RTT.展开更多
A prototype based on digital radio technology with associated open-loop Doppler signal processing techniques has been developed to measure a spacecraft's line-of-sight velocity. The prototype was tested in China&#...A prototype based on digital radio technology with associated open-loop Doppler signal processing techniques has been developed to measure a spacecraft's line-of-sight velocity. The prototype was tested in China's Chang'E-1 lunar mission relying on S-band telemetry signals transmitted by the sat-ellite,with results showing that the residuals had a RMS value of ～3 mm/s (1σ ) using 1-sec integration,which is consistent with the Chinese conventional USB (Unified S-Band) tracking system. Such preci-sion is mainly limited by the short-term stability of the atomic (e.g. rubidium) clock at the uplink ground station. It can also be improved with proper calibration to remove some effects of the transmission media (such as solar plasma,troposphere and ionosphere),and a longer integration time (e.g. down to 0.56 mm/s at 34 seconds) allowed by the spacecraft dynamics. The tracking accuracy can also be in-creased with differential methods that may effectively remove most of the long-term drifts and some of the short-term uncertainties of the uplink atomic clock,thereby further reducing the residuals to the 1 mm/s level. Our experimental tracking data have been used in orbit determination for Chang'E-1,while other applications (such as the upcoming YH-1 Mars orbiter) based on open-loop Doppler tracking will be initiated in the future. Successful application of the prototype to the Chang'E-1 mission in 2008 is believed to have great significance for China's future deep space exploration.展开更多
随着第六代移动通信系统(6th generation mobile communication system, 6G)通信技术的发展,空天地一体化网络(Spaceair-ground integrated network, SAGIN)作为6G的重要组成部分,旨在实现卫星、空中平台与地面系统的无缝互联,在应急通...随着第六代移动通信系统(6th generation mobile communication system, 6G)通信技术的发展,空天地一体化网络(Spaceair-ground integrated network, SAGIN)作为6G的重要组成部分,旨在实现卫星、空中平台与地面系统的无缝互联,在应急通信、环境监测、智能交通等领域展现出巨大的潜力.然而,SAGIN具有异构结构、链路动态性高、资源分布广泛等特征,给网络的高效管理与优化带来巨大的挑战.近年来,人工智能(Artificial intelligence, AI)技术凭借强大的感知、学习与自主决策能力应用于通信网络,为SAGIN的智能演进提供了新契机.本文首先系统介绍SAGIN网络架构的基本组成与关键特征,并梳理当前主流AI技术在网络优化中的主要技术体系与适配优势,包括机器学习、图神经网络以及强化学习.其次,本文深入探讨了AI技术在SAGIN中智能资源管理、移动性管理与路由优化、空中平台路径规划、任务卸载与计算协同等典型场景中的应用与最新进展.最后,本文总结了AI技术应用在SAGIN网络中面临的挑战并展望了AI与SAGIN融合发展的未来方向.本文概述了AI技术在SAGIN网络中应用的优势与进展,旨在为AI赋能的SAGIN研究与应用发展提供技术参考.展开更多
文摘Focusing on the key scientific questions of deep space exploration which include the origin and evolution of the solar system and its planets, disastrous impact on the Earth by the solar activities and small bodies, extraterrestrial life, this paper put forward a propose about the roadmap and scientific objectives of China's Deep-space Exploration before 2030.
基金supported by the Strategic leading project of the Chinese Academy of Sciences (Grant No. XDA15014603)。
文摘Previous research on deep-space networks based on delay-tolerant networking(DTN)has mainly focused on the performance of DTN protocols in simple networks;hence,research on complex networks is lacking.In this paper,we focus on network evaluation and protocol deployment for complex DTNbased deep-space networks and apply the results to a novel complex deep-space network based on the Universal Interplanetary Communication Network(UNICON-CDSN)proposed by the National Space Science Center(NSSC)for simulation and verification.A network evaluation method based on network capacity and memory analysis is proposed.Based on a performance comparison between the Licklider Transmission Protocol(LTP)and the Transmission Control Protocol(TCP)with the Bundle Protocol(BP)in various communication scenarios,a transport protocol configuration proposal is developed and used to construct an LTP deployment scheme for UNICON-CDSN.For the LTP deployment scheme,a theoretical model of file delivery time over complex deep-space networks is built.A network evaluation with the method proposed in this paper proves that UNICONCDSN satisfies the requirements for the 2020 Mars exploration mission Curiosity.Moreover,simulation results from a universal space communication network testbed(USCNT)designed by us show that the LTP deployment scheme is suitable for UNICON-CDSN.
文摘eight planets,various asteroids and comets in the solar system.Amount of deep-space scientific experiments promoted people to understand about the origin and evolution of the universe.With the rapid developments of equipment and spacecraft with high-accuracy detector and long-term energy,more and more ambitious deep-space exploration plans have also been scheduled or under discussion about space resources utilization and space migration,e.g.,manned landing on the Mars,guard infrastructures on the Moon and human-flight to the edge of the solar system(>100 AU),etc.
文摘This paper proposed an optimal algorithm using the sun line-of-sight vector to improve the probe attitude estimation accuracy in deep-space mission.Firstly,the elaborate analysis of the attitude estimation error from vector observations was done to demonstrate that the geometric relation between the reference vectors is an important factor which influences the accuracy of attitude estimation.Then,with introduction of the sun line-of-sight vector,the attitude quaternion obtained from the star-sensor was converted into a pair of mutually perpendicular reference vectors perpendicular to the sun vector.The normalized weights were calculated according to the accuracy of the sensors.Furthermore,the optimal attitude estimation in the least squares sense was achieved with the quaternion estimation method.Finally,the results of simulation demonstrated the validity of the proposed optimal algorithm based on the practical data of the Deep Impact mission.
基金the National Natural Science Foundation of China(Grant No.2000028416).
文摘While approaching the target body, the deep-space probe is orbiting hyperbolically before the maneuver. We discuss the variation of perturbed hyperbolic orbit using the method similar to that used in elliptic orbit. Ephemeris calculating and orbit control will benefit from the given analytical solution.
基金supported by the National Natural Science Foundation of China(Nos.91338201,91438109,61401507).
文摘Delay/disruption-tolerant networking communications rely heavily on BP(Bundle Protocol),which uses the well-known approach of store-and-forward with optional custody transfer to deal with stressed communication environments.The use of BP and its performance in deep-space communication has been the subject of debate.The accurate estimate of file delivery latency(i.e.,RTT(Round Trip Time))is essential for efficient transmission control,reliable delivery,and bandwidth usage optimization of a protocol.In this paper,we present a performance analysis of BP running over UDPCL/UDP over deep-space channels,focusing on the RTT estimate,in the presence of highly asymmetric channel rates.Analytical models are built for the RTT estimate of the BP/UDPCL transmissions considering the effect of delay caused by space channel-rate asymmetry,and,channel impairment.The models are validated by file transfer experiments using a PC-based testbed.It is found that a smaller bundle size(if smaller than a calculated threshold)results in a longer delay in custody acknowledgment transmission,and thus,a longer RTT.
基金Supported by the Innovation Research Plan of CAS,the National Natural Science Foundation of China (Grant Nos. 10973031 and 40904006)the CAS Key Research Program (Grant No. KJCX2-YW-T13-2), and Beijing Aerospace Command and Control Center
文摘A prototype based on digital radio technology with associated open-loop Doppler signal processing techniques has been developed to measure a spacecraft's line-of-sight velocity. The prototype was tested in China's Chang'E-1 lunar mission relying on S-band telemetry signals transmitted by the sat-ellite,with results showing that the residuals had a RMS value of ～3 mm/s (1σ ) using 1-sec integration,which is consistent with the Chinese conventional USB (Unified S-Band) tracking system. Such preci-sion is mainly limited by the short-term stability of the atomic (e.g. rubidium) clock at the uplink ground station. It can also be improved with proper calibration to remove some effects of the transmission media (such as solar plasma,troposphere and ionosphere),and a longer integration time (e.g. down to 0.56 mm/s at 34 seconds) allowed by the spacecraft dynamics. The tracking accuracy can also be in-creased with differential methods that may effectively remove most of the long-term drifts and some of the short-term uncertainties of the uplink atomic clock,thereby further reducing the residuals to the 1 mm/s level. Our experimental tracking data have been used in orbit determination for Chang'E-1,while other applications (such as the upcoming YH-1 Mars orbiter) based on open-loop Doppler tracking will be initiated in the future. Successful application of the prototype to the Chang'E-1 mission in 2008 is believed to have great significance for China's future deep space exploration.
