Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physica...Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physical properties can provide useful information on their origin,evolution,and hazard to human beings.However,it remains challenging to investigate small,newly discovered,near-Earth objects because of our limited observational window.This investigation seeks to determine the visible colors of near-Earth asteroids(NEAs),perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters.Observations were performed in the broadband BVRI Johnson−Cousins photometric system,applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory.We present new photometric observations of 84 near-Earth asteroids,and classify 80 of them taxonomically,based on their photometric colors.We find that nearly half(46.3%)of the objects in our sample can be classified as S-complex,26.3%as C-complex,6%as D-complex,and 15.0%as X-complex;the remaining belong to the A-or V-types.Additionally,we identify three P-type NEAs in our sample,according to the Tholen scheme.The fractional abundances of the C/X-complex members with absolute magnitude H≥17.0 were more than twice as large as those with H<17.0.However,the fractions of C-and S-complex members with diameters≤1 km and>1 km are nearly equal,while X-complex members tend to have sub-kilometer diameters.In our sample,the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_(J)<3.1.These bodies could have a cometary origin.C-and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous.展开更多
China has carried out four unmanned missions to the Moon since it launched Chang’E-1,the first lunar orbiter in 2007.With the implementation of the Chang’E-5 mission this year,the three phases of the lunar explorati...China has carried out four unmanned missions to the Moon since it launched Chang’E-1,the first lunar orbiter in 2007.With the implementation of the Chang’E-5 mission this year,the three phases of the lunar exploration program,namely orbiting,landing and returning,have been completed.In the plan of follow-up unmanned lunar exploration missions,it is planned to establish an experimental lunar research station at the lunar south pole by 2030 through the implementation of several missions,laying a foundation for the establishment of practical lunar research station in the future.China successfully launched its first Mars probe on 23 July 2020,followed in future by an asteroid mission,second Mars mission,and a mission to explore Jupiter and its moons.展开更多
The rapid increase of space debris population has posed serious threaten to the safety of human space activities and became a global issue.How to enhance the technical capabilities of space debris threat coping abilit...The rapid increase of space debris population has posed serious threaten to the safety of human space activities and became a global issue.How to enhance the technical capabilities of space debris threat coping ability is of great significance to the sustainable development of space activities,the further development,and utilization of outer space.In this paper,we describe space debris research progress of China on observation,collision avoidance,protection,mitigation,regulation,and standard during the last twenty years,and look forward to the future development direction of space debris.展开更多
The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should o...The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should optimally schedule surveillance tasks for the existing facilities to allocate re- sources in a manner that most significantly improves the ability to predict and detect events involving affected spacecrafts. This paper analyzes two criteria that mainly affect the performance of a scheduling scheme and introduces an artificial intelligence algorithm into the scheduling of tasks of the space debris surveillance network. A new scheduling algorithm based on the particle swarm optimization algorithm is proposed, which can be implemented in two different ways： individual optimization and joint optimiza- tion. Numerical experiments with multiple facilities and objects are conducted based on the proposed algorithm, and simulation results have demonstrated the effectiveness of the proposed algorithm.展开更多
A dynamic multi-beam resource allocation algorithm for large low Earth orbit(LEO)constellation based on on-board distributed computing is proposed in this paper.The allocation is a combinatorial optimization process u...A dynamic multi-beam resource allocation algorithm for large low Earth orbit(LEO)constellation based on on-board distributed computing is proposed in this paper.The allocation is a combinatorial optimization process under a series of complex constraints,which is important for enhancing the matching between resources and requirements.A complex algorithm is not available because that the LEO on-board resources is limi-ted.The proposed genetic algorithm(GA)based on two-dimen-sional individual model and uncorrelated single paternal inheri-tance method is designed to support distributed computation to enhance the feasibility of on-board application.A distributed system composed of eight embedded devices is built to verify the algorithm.A typical scenario is built in the system to evalu-ate the resource allocation process,algorithm mathematical model,trigger strategy,and distributed computation architec-ture.According to the simulation and measurement results,the proposed algorithm can provide an allocation result for more than 1500 tasks in 14 s and the success rate is more than 91%in a typical scene.The response time is decreased by 40%com-pared with the conditional GA.展开更多
An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time. Then, ...An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time. Then, the feedback control law based on Gauss’s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.展开更多
In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of ...In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of this architecture, is designed in detail. In order to describe the parallel activity, the state timeline is introduced to build the formal model of the planning system and based on this model, the temporal constraint satisfaction planning algorithm is proposed to produce the explorer’s activity sequence. With some key subsystems of the deep space explorer as examples, the autonomous mission planning simulation system is designed. The results show that this system can calculate the executable activity sequence with the given mission goals and initial state of the explorer.展开更多
Preface Space science is a discipline to study the universe,to investigate the fundamental process of molecules and atoms,and reveal,at the underlying roots,the laws of the external world.
1 Introduction
Looking back to the 20th century, the science and technology have never influenced and changed all aspects of the people's lives as profoundly as they do today. With the birth of space tech... 1 Introduction
Looking back to the 20th century, the science and technology have never influenced and changed all aspects of the people's lives as profoundly as they do today. With the birth of space technology in late 1950s, space science emerged accompanying the space activities as a unique comprehensive discipline. Mankind started exploring various natural phenomenon and their laws in space by use of innovative spacecraft to reveal the mysteries of the universe. The space science research provides theoretical basis for mankind to understand the universe and develop application technologies, and drives the development of high and new technologies.……展开更多
Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses si...Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses significant challenges and requires an integrated approach.In this study,a unified requirement modeling approach is proposed based on unified architecture framework(UAF).Theoretical models are proposed which compose formalized descriptions from both topdown and bottom-up perspectives.Based on the description,the UAF profile is proposed to represent the SoS mission and constituent systems(CS)goal.Moreover,the agent-based simulation information is also described based on the overview,design concepts,and details(ODD)protocol as the complement part of the SoS profile,which can be transformed into different simulation platforms based on the eXtensible markup language(XML)technology and model-to-text method.In this way,the design of the SoS is simulated automatically in the early design stage.Finally,the method is implemented and an example is given to illustrate the whole process.展开更多
Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for...Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for studying the formation and evolution of the solar system,and even the origin of life on planet Earth.In this review,the formation,evolution processes and the internal characteristics of the asteroids and comets in the solar system are presented.The focus of this review is on the internal characteristics especially the dielectric properties of asteroids and comets by radar observations.On this basis,the possible internal structure of these celestial bodies is discussed.Combined with the existing theories,simulations and experiments,the possible internal structure of near-Earth asteroid 2016 HO_(3) is a monolith while structure of active asteroid 311P/PANSTARRS remains unknown.In 2025,China will launch Tianwen-2 asteroid-comet exploration mission to detect 2016 HO_(3) and 311P/PANSTARRS,which will carry a penetrating radar to observe the internal characteristics of these two objects.展开更多
China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar...China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.展开更多
Asteroid exploration is one of the most sophisticated missions currently being investigated. Gravity-assist trajectories have proven valuable in interplanetary missions such as the Pioneer, Voyager and Galileo. In thi...Asteroid exploration is one of the most sophisticated missions currently being investigated. Gravity-assist trajectories have proven valuable in interplanetary missions such as the Pioneer, Voyager and Galileo. In this paper, we design interplanetary trajectory for main belt asteroid exploration mission with the Mars gravity-assist (MGA) using “pork chop” plots and patched-conic theory and give some initial valuable trajectory parameters on main belt asteroid exploration mission with MGA.展开更多
The asteroid exploration opportunities are searched and calculated with launch dates in 2006 to2010, and with asteroid Ivar 1627 as the target, the spacecraft and its subsystems are designed and analyzed,and the trans...The asteroid exploration opportunities are searched and calculated with launch dates in 2006 to2010, and with asteroid Ivar 1627 as the target, the spacecraft and its subsystems are designed and analyzed,and the transfer trajectory is designed using △VEGA technology for the asteroid rendezvous. The design resultssatisfied the energy requirements for small explorers.展开更多
The global atmospheric static stability(N2)in the middle atmosphere and its relation to gravity waves(GWs)were investigated by using the temperature profiles measured by the Sounding of the Atmosphere using Broadband ...The global atmospheric static stability(N2)in the middle atmosphere and its relation to gravity waves(GWs)were investigated by using the temperature profiles measured by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument from 2002 to 2018.At low latitudes,a layer with enhanced N2 occurs at an altitude of^20 km and exhibits annual oscillations caused by tropopause inversion layers.Above an altitude of^70 km,enhanced N2 exhibits semiannual oscillations at low latitudes caused by the mesosphere inversion layers and annual oscillations at high latitudes resulting from the downward shift of the summer mesopause.The correlation coefficients between N2 and GW amplitudes can be larger than 0.8 at latitudes poleward of^40°N/S.This observation provides factual evidence that a large N2 supports large-amplitude GWs and indicates that N2 plays a dominant role in maintaining GWs at least at high latitudes of the middle atmosphere.This evidence also partially explains the previous results regarding the phase changes of annual oscillations of GWs at high latitudes.展开更多
The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magne...The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magnetic field turning and produce SXI count maps with a 5-minute integration time.By making assumptions about the magnetopause shape,we find the magnetopause standoff distance from the count maps and compare it with the one obtained directly from the magnetohydrodynamic(MHD)simulation.The root mean square deviations between the reconstructed and MHD standoff distances do not exceed 0.2 RE(Earth radius)and the maximal difference equals 0.24 RE during the 25-minute interval around the southward turning.展开更多
This paper reports the use of a specialized, mesoscale, numerical weather prediction （NWP） system and a satellite imaging and prediction system that were set up to support the CLAMS （Chesapeake Lighthouse and Aircr...This paper reports the use of a specialized, mesoscale, numerical weather prediction （NWP） system and a satellite imaging and prediction system that were set up to support the CLAMS （Chesapeake Lighthouse and Aircraft Measurements for Satellites） field campaign during the summer of 2001. The primary objective of CLAMS was to validate satellite-based retrievals of aerosol properties and vertical profiles of the radiative flux, temperature and water vapor. Six research aircraft were deployed to make detailed coincident measurements of the atmosphere and ocean surface with the research satellites that orbited overhead. The mesoscale weather modeling system runs in real-time to provide high spatial and temporal resolution for forecasts that are delivered via the World Wide Web along with a variety of satellite imagery and satellite location predictions. This system is a multi-purpose modeling system capable of both data analysis/assimilation and multi-scale NWP ranging from cloud-scale to larger than regional scale. This is a three-dimensional, non-hydrostatic compressible model in a terrain-following coordinate. The model employs advanced numerical techniques and contains detailed interactive physical processes. The utility of the forecasting system is illustrated throughout the discussion on the impact of the surface-wind forecast on BRDF （Bidirectional Reflectance Distribution Function） and the description of the cloud/moisture forecast versus the aircraft measurement.展开更多
At present,the moon and Mars are the main focus of deep space exploration,scientific pursuits are the initial goal,and extensive cooperation leads to a greater prospect.China has made many scientific achievements and ...At present,the moon and Mars are the main focus of deep space exploration,scientific pursuits are the initial goal,and extensive cooperation leads to a greater prospect.China has made many scientific achievements and built considerable infrastructure through its lunar and Mars exploration activities.In the future,China will continue to carry out deep space exploration activities with scientific goals as the driving force,develop the International Lunar Research Station,explore the sun,inner planets and asteroids,discover exoplanets and build an asteroid defence system.In order to support future deep space exploration missions,China will construct an integrated communication,navigation and remote sensing constellation and develop heavy-lift launch vehicles.China offers a wide range of opportunities for cooperation,upholds the central role of Committee on the Peaceful Uses of Outer Space(UNCOPUOS),and welcomes all countries in the world to participate in deep space exploration activities.展开更多
基金funded by the China National Space Administration(KJSP2023020105)supported by the National Key R&D Program of China(Grant No.2023YFA1608100)+2 种基金the NSFC(Grant No.62227901)the Minor Planet Foundationsupported by the Egyptian Science,Technology&Innovation Funding Authority(STDF)under Grant No.48102.
文摘Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physical properties can provide useful information on their origin,evolution,and hazard to human beings.However,it remains challenging to investigate small,newly discovered,near-Earth objects because of our limited observational window.This investigation seeks to determine the visible colors of near-Earth asteroids(NEAs),perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters.Observations were performed in the broadband BVRI Johnson−Cousins photometric system,applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory.We present new photometric observations of 84 near-Earth asteroids,and classify 80 of them taxonomically,based on their photometric colors.We find that nearly half(46.3%)of the objects in our sample can be classified as S-complex,26.3%as C-complex,6%as D-complex,and 15.0%as X-complex;the remaining belong to the A-or V-types.Additionally,we identify three P-type NEAs in our sample,according to the Tholen scheme.The fractional abundances of the C/X-complex members with absolute magnitude H≥17.0 were more than twice as large as those with H<17.0.However,the fractions of C-and S-complex members with diameters≤1 km and>1 km are nearly equal,while X-complex members tend to have sub-kilometer diameters.In our sample,the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_(J)<3.1.These bodies could have a cometary origin.C-and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous.
基金Supported by National Key R&D Program of China(2020YFE0202100)Beijing Municipal Science and Technology Commission(Z181100002918003)。
文摘China has carried out four unmanned missions to the Moon since it launched Chang’E-1,the first lunar orbiter in 2007.With the implementation of the Chang’E-5 mission this year,the three phases of the lunar exploration program,namely orbiting,landing and returning,have been completed.In the plan of follow-up unmanned lunar exploration missions,it is planned to establish an experimental lunar research station at the lunar south pole by 2030 through the implementation of several missions,laying a foundation for the establishment of practical lunar research station in the future.China successfully launched its first Mars probe on 23 July 2020,followed in future by an asteroid mission,second Mars mission,and a mission to explore Jupiter and its moons.
文摘The rapid increase of space debris population has posed serious threaten to the safety of human space activities and became a global issue.How to enhance the technical capabilities of space debris threat coping ability is of great significance to the sustainable development of space activities,the further development,and utilization of outer space.In this paper,we describe space debris research progress of China on observation,collision avoidance,protection,mitigation,regulation,and standard during the last twenty years,and look forward to the future development direction of space debris.
基金funded by the National Natural Science Foundation of China (Grant No. 11503044)by the Young Researcher Grant of National Astronomical Observatories, Chinese Academy of Sciences
文摘The increasing number of space debris has created an orbital debris environment that poses increasing impact risks to existing space systems and human space flights. For the safety of in-orbit spacecrafts, we should optimally schedule surveillance tasks for the existing facilities to allocate re- sources in a manner that most significantly improves the ability to predict and detect events involving affected spacecrafts. This paper analyzes two criteria that mainly affect the performance of a scheduling scheme and introduces an artificial intelligence algorithm into the scheduling of tasks of the space debris surveillance network. A new scheduling algorithm based on the particle swarm optimization algorithm is proposed, which can be implemented in two different ways： individual optimization and joint optimiza- tion. Numerical experiments with multiple facilities and objects are conducted based on the proposed algorithm, and simulation results have demonstrated the effectiveness of the proposed algorithm.
基金This work was supported by the National Key Research and Development Program of China(2021YFB2900603)the National Natural Science Foundation of China(61831008).
文摘A dynamic multi-beam resource allocation algorithm for large low Earth orbit(LEO)constellation based on on-board distributed computing is proposed in this paper.The allocation is a combinatorial optimization process under a series of complex constraints,which is important for enhancing the matching between resources and requirements.A complex algorithm is not available because that the LEO on-board resources is limi-ted.The proposed genetic algorithm(GA)based on two-dimen-sional individual model and uncorrelated single paternal inheri-tance method is designed to support distributed computation to enhance the feasibility of on-board application.A distributed system composed of eight embedded devices is built to verify the algorithm.A typical scenario is built in the system to evalu-ate the resource allocation process,algorithm mathematical model,trigger strategy,and distributed computation architec-ture.According to the simulation and measurement results,the proposed algorithm can provide an allocation result for more than 1500 tasks in 14 s and the success rate is more than 91%in a typical scene.The response time is decreased by 40%com-pared with the conditional GA.
文摘An impulse feedback control law to change the mean orbit elements of spacecraft around asteroid is presented. First, the mean orbit elements are transferred to the osculating orbit elements at the burning time. Then, the feedback control law based on Gauss’s perturbation equations of motion is given. And the impulse control for targeting from the higher circulation orbit to the specified periapsis is developed. Finally, the numerical simulation is performed and the simulation results show that the presented impulse control law is effective.
文摘In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of this architecture, is designed in detail. In order to describe the parallel activity, the state timeline is introduced to build the formal model of the planning system and based on this model, the temporal constraint satisfaction planning algorithm is proposed to produce the explorer’s activity sequence. With some key subsystems of the deep space explorer as examples, the autonomous mission planning simulation system is designed. The results show that this system can calculate the executable activity sequence with the given mission goals and initial state of the explorer.
文摘Preface Space science is a discipline to study the universe,to investigate the fundamental process of molecules and atoms,and reveal,at the underlying roots,the laws of the external world.
文摘 1 Introduction
Looking back to the 20th century, the science and technology have never influenced and changed all aspects of the people's lives as profoundly as they do today. With the birth of space technology in late 1950s, space science emerged accompanying the space activities as a unique comprehensive discipline. Mankind started exploring various natural phenomenon and their laws in space by use of innovative spacecraft to reveal the mysteries of the universe. The space science research provides theoretical basis for mankind to understand the universe and develop application technologies, and drives the development of high and new technologies.……
基金Fifth Electronic Research Institute of the Ministry of Industry and Information Technology(HK07202200877)Pre-research Project on Civil Aerospace Technologies of CNSA(D020101)+2 种基金Zhejiang Provincial Science and Technology Plan Project(2022C01052)Frontier Scientific Research Program of Deep Space Exploration Laboratory(2022-QYKYJHHXYF-018,2022-QYKYJH-GCXD-001)Zhiyuan Laboratory(ZYL2024001)。
文摘Model-based system-of-systems(SOS)engineering(MBSoSE)is becoming a promising solution for the design of SoS with increasing complexity.However,bridging the models from the design phase to the simulation phase poses significant challenges and requires an integrated approach.In this study,a unified requirement modeling approach is proposed based on unified architecture framework(UAF).Theoretical models are proposed which compose formalized descriptions from both topdown and bottom-up perspectives.Based on the description,the UAF profile is proposed to represent the SoS mission and constituent systems(CS)goal.Moreover,the agent-based simulation information is also described based on the overview,design concepts,and details(ODD)protocol as the complement part of the SoS profile,which can be transformed into different simulation platforms based on the eXtensible markup language(XML)technology and model-to-text method.In this way,the design of the SoS is simulated automatically in the early design stage.Finally,the method is implemented and an example is given to illustrate the whole process.
基金supported by the National Natural Science Foundation of China(Grant No.12473063,12461160265,and 62227901)Shenzhen Science and Technology Innovation Commission(Grant No.20231121103211001)+5 种基金the Opening Fund of the Key Laboratory of Lunar and Deep Space Exploration,Chinese Academy of Sciences(No.LDSE202005)the Shenzhen University 2035 Program for Excellent Research(Grant No.2024C009)China National University Student Innovation&Entrepreneurship Development Program(No.202410590011)Natural Science Foundation of Guangdong Province(No.2024A1515011275)the Shenzhen Municipal Government Investment Project(No.2106_440300_04_03_901272)the team“Searching For Subglacial Water On Mars With Orbiting Ground Penetrating Radars”of the International Space Science Institute(ISSI).
文摘Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for studying the formation and evolution of the solar system,and even the origin of life on planet Earth.In this review,the formation,evolution processes and the internal characteristics of the asteroids and comets in the solar system are presented.The focus of this review is on the internal characteristics especially the dielectric properties of asteroids and comets by radar observations.On this basis,the possible internal structure of these celestial bodies is discussed.Combined with the existing theories,simulations and experiments,the possible internal structure of near-Earth asteroid 2016 HO_(3) is a monolith while structure of active asteroid 311P/PANSTARRS remains unknown.In 2025,China will launch Tianwen-2 asteroid-comet exploration mission to detect 2016 HO_(3) and 311P/PANSTARRS,which will carry a penetrating radar to observe the internal characteristics of these two objects.
基金Supported by National Key Research and Development Program of China(2020YFE0202100)。
文摘China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.
文摘Asteroid exploration is one of the most sophisticated missions currently being investigated. Gravity-assist trajectories have proven valuable in interplanetary missions such as the Pioneer, Voyager and Galileo. In this paper, we design interplanetary trajectory for main belt asteroid exploration mission with the Mars gravity-assist (MGA) using “pork chop” plots and patched-conic theory and give some initial valuable trajectory parameters on main belt asteroid exploration mission with MGA.
文摘The asteroid exploration opportunities are searched and calculated with launch dates in 2006 to2010, and with asteroid Ivar 1627 as the target, the spacecraft and its subsystems are designed and analyzed,and the transfer trajectory is designed using △VEGA technology for the asteroid rendezvous. The design resultssatisfied the energy requirements for small explorers.
基金This work was supported by the National Natural Science Foundation of China(grants 41831073 and 41874182).
文摘The global atmospheric static stability(N2)in the middle atmosphere and its relation to gravity waves(GWs)were investigated by using the temperature profiles measured by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument from 2002 to 2018.At low latitudes,a layer with enhanced N2 occurs at an altitude of^20 km and exhibits annual oscillations caused by tropopause inversion layers.Above an altitude of^70 km,enhanced N2 exhibits semiannual oscillations at low latitudes caused by the mesosphere inversion layers and annual oscillations at high latitudes resulting from the downward shift of the summer mesopause.The correlation coefficients between N2 and GW amplitudes can be larger than 0.8 at latitudes poleward of^40°N/S.This observation provides factual evidence that a large N2 supports large-amplitude GWs and indicates that N2 plays a dominant role in maintaining GWs at least at high latitudes of the middle atmosphere.This evidence also partially explains the previous results regarding the phase changes of annual oscillations of GWs at high latitudes.
基金support from the UK Space Agency under Grant Number ST/T002964/1partly supported by the International Space Science Institute(ISSI)in Bern,through ISSI International Team Project Number 523(“Imaging the Invisible:Unveiling the Global Structure of Earth’s Dynamic Magnetosphere”)。
文摘The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magnetic field turning and produce SXI count maps with a 5-minute integration time.By making assumptions about the magnetopause shape,we find the magnetopause standoff distance from the count maps and compare it with the one obtained directly from the magnetohydrodynamic(MHD)simulation.The root mean square deviations between the reconstructed and MHD standoff distances do not exceed 0.2 RE(Earth radius)and the maximal difference equals 0.24 RE during the 25-minute interval around the southward turning.
文摘This paper reports the use of a specialized, mesoscale, numerical weather prediction （NWP） system and a satellite imaging and prediction system that were set up to support the CLAMS （Chesapeake Lighthouse and Aircraft Measurements for Satellites） field campaign during the summer of 2001. The primary objective of CLAMS was to validate satellite-based retrievals of aerosol properties and vertical profiles of the radiative flux, temperature and water vapor. Six research aircraft were deployed to make detailed coincident measurements of the atmosphere and ocean surface with the research satellites that orbited overhead. The mesoscale weather modeling system runs in real-time to provide high spatial and temporal resolution for forecasts that are delivered via the World Wide Web along with a variety of satellite imagery and satellite location predictions. This system is a multi-purpose modeling system capable of both data analysis/assimilation and multi-scale NWP ranging from cloud-scale to larger than regional scale. This is a three-dimensional, non-hydrostatic compressible model in a terrain-following coordinate. The model employs advanced numerical techniques and contains detailed interactive physical processes. The utility of the forecasting system is illustrated throughout the discussion on the impact of the surface-wind forecast on BRDF （Bidirectional Reflectance Distribution Function） and the description of the cloud/moisture forecast versus the aircraft measurement.
文摘At present,the moon and Mars are the main focus of deep space exploration,scientific pursuits are the initial goal,and extensive cooperation leads to a greater prospect.China has made many scientific achievements and built considerable infrastructure through its lunar and Mars exploration activities.In the future,China will continue to carry out deep space exploration activities with scientific goals as the driving force,develop the International Lunar Research Station,explore the sun,inner planets and asteroids,discover exoplanets and build an asteroid defence system.In order to support future deep space exploration missions,China will construct an integrated communication,navigation and remote sensing constellation and develop heavy-lift launch vehicles.China offers a wide range of opportunities for cooperation,upholds the central role of Committee on the Peaceful Uses of Outer Space(UNCOPUOS),and welcomes all countries in the world to participate in deep space exploration activities.
