Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evo...Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evolution,and image synthesis to compare directly with HST,LICIACube,ground-based and Lucy observations of the DART impact.Decomposing ejecta into(1)a highvelocity(~1600 m/s)plume exhibiting Na/K resonance,(2)a low-velocity(~1 m/s)conical component shaped by binary gravity and solar radiation pressure,and(3)meter-scale boulders,we quantify each component’s mass and momentum.Fitting photometric decay curves and morphological evolution yields size-velocity distributions and,via scaling laws,estimates of Dimorphos’bulk density,cratering parameters,and cohesive strength that agree with dynamical constraints.Photometric ejecta modeling therefore provides a robust route to constrain momentum enhancement and target properties,improving predictive capability for kinetic-deflection missions.展开更多
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
研究小行星的暴露年龄对于理解其形成与演化具有重要意义。双小行星重定向测试(Double Asteroid Redirection Test,DART)任务的实施,不仅验证了动能撞击技术偏转近地小行星轨道的可行性,也为研究小行星暴露年龄及其成因演化提供了宝贵...研究小行星的暴露年龄对于理解其形成与演化具有重要意义。双小行星重定向测试(Double Asteroid Redirection Test,DART)任务的实施,不仅验证了动能撞击技术偏转近地小行星轨道的可行性,也为研究小行星暴露年龄及其成因演化提供了宝贵机会。基于DART撞击前后地基望远镜获得的可见近红外光谱数据,对主星Didymos表面及次星Dimorphos溅射物开展暴露年龄研究。结果表明,Didymos表面的暴露年龄约为45.7万年,表明主星在约45.7万年前发生了一次较大规模的物质脱落事件。该事件对主星的表面年龄几乎没有影响,但重置了次星的表面年龄及主星的暴露年龄。Dimorphos溅射物与主星Didymos的表面成分相同,但风化程度较低,这表明在次星形成后,主星和次星表面受到强烈的太空风化作用,而次星内部物质受到的太空风化作用相对较弱。展开更多
This paper proposed an efficient method of image overlapping relationship analysis based on spatial index of KD tree fast search for disordered and large-scale asteroid images.In this study,the image data from asteroi...This paper proposed an efficient method of image overlapping relationship analysis based on spatial index of KD tree fast search for disordered and large-scale asteroid images.In this study,the image data from asteroid exploration missions such as Bennu,Vesta,and Ryugu were used for experiments,and the proposed image matching pairs determination algorithm was comprehensively compared with the corresponding modules of USGS ISIS in order to evaluate its performance in terms of efficiency and accuracy.The results show that when processing more than a thousand images,the proposed method greatly improves the efficiency of acquiring image matching pairs while ensuring the correctness of image overlapping relationships and accuracy of bundle adjustment.At the same time,according to the obtained image matching pairs,images that meet the requirements of Stereo Photoclinometry can be quickly selected,effectively improving the quality of 3D reconstruction models of asteroid images.展开更多
In a Nature Physics report published in late September 2024[1],a team of scientists and engineers at Sandia National Laboratories(Albuquerque,NM,USA)described the results of a laboratory experiment showing that a nucl...In a Nature Physics report published in late September 2024[1],a team of scientists and engineers at Sandia National Laboratories(Albuquerque,NM,USA)described the results of a laboratory experiment showing that a nuclear blast could create a burst of X-rays powerful enough to change the path of a large asteroid that might one day be on a collision course with Earth.展开更多
In the present study,we investigated the existence of arbitrary amplitude dust acoustic solitons by considering the Cairns distributed ions,negatively charged streaming dust grains along with(r,q)distributed electrons...In the present study,we investigated the existence of arbitrary amplitude dust acoustic solitons by considering the Cairns distributed ions,negatively charged streaming dust grains along with(r,q)distributed electrons in an un-magnetized dusty plasma.We used the pseudopotential technique to obtain the solitary wave solution.It is seen that the coexistence of rarefactive and compressive solitons is possible when ions and electrons are nonthermally distributed.We found that the soliton characteristics are strongly dependent on the choice of velocity distribution function through the nonthermal spectral indices r q,,a as well as on the ion and dust temperatures.For(r,q)distributed electrons,we found that the soliton amplitude increases(decreases)with smaller(higher)values of negative(positive)r.For Cairns distributed ions,we found a transition from negative to positive polarity solitary structures with the coexistence in between as the nonthermal parameter a increases.Our results gave a better explanation for the formation of dust acoustic solitary structures and their dependence on high and low energy particles in nonthermal distribution profiles in space environments.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
Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have no...Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have not been conducted for any meteorite fall events in China.On 2022 December 15 at 09:48 UT,meteoroid Tanxi was recorded by numerous cameras in populous northern Zhejiang.This event offers an opportunity to conduct the first systematic origin-tracing study for a meteorite fall event in China.The Tanxi meteorite was classified as an H6chondrite.This meteoroid entered the atmosphere with a velocity of 13.49 km s^(-1)and a slope of 69.52°.It most likely underwent a two-stage fragmentation process,with early fragmentation under a dynamic pressure of0.08 MPa,and main fragmentation under a dynamic pressure of 7.83 MPa.Before colliding with the Earth,the meteoroid’s heliocentric orbit had a semimajor axis of 2.363±0.107 au,an eccentricity of 0.584±0.019 and an inclination of 2.078±0.074°.A backward Dshevolution result of 5000 yr shows Tanxi’s orbit is most similar to a small near-Earth asteroid 2016 WV2.The source region analysis of the Tanxi fall indicates that the H chondrites could originate from two distinct reservoirs:the 3:1J mean motion resonance complex(51.2±3.7%)and the v6secular resonance region(41.6±2.9%).展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12272018)the National Key Basic Research Project(2022JCJQZD20600).
文摘Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evolution,and image synthesis to compare directly with HST,LICIACube,ground-based and Lucy observations of the DART impact.Decomposing ejecta into(1)a highvelocity(~1600 m/s)plume exhibiting Na/K resonance,(2)a low-velocity(~1 m/s)conical component shaped by binary gravity and solar radiation pressure,and(3)meter-scale boulders,we quantify each component’s mass and momentum.Fitting photometric decay curves and morphological evolution yields size-velocity distributions and,via scaling laws,estimates of Dimorphos’bulk density,cratering parameters,and cohesive strength that agree with dynamical constraints.Photometric ejecta modeling therefore provides a robust route to constrain momentum enhancement and target properties,improving predictive capability for kinetic-deflection missions.
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.
文摘研究小行星的暴露年龄对于理解其形成与演化具有重要意义。双小行星重定向测试(Double Asteroid Redirection Test,DART)任务的实施,不仅验证了动能撞击技术偏转近地小行星轨道的可行性,也为研究小行星暴露年龄及其成因演化提供了宝贵机会。基于DART撞击前后地基望远镜获得的可见近红外光谱数据,对主星Didymos表面及次星Dimorphos溅射物开展暴露年龄研究。结果表明,Didymos表面的暴露年龄约为45.7万年,表明主星在约45.7万年前发生了一次较大规模的物质脱落事件。该事件对主星的表面年龄几乎没有影响,但重置了次星的表面年龄及主星的暴露年龄。Dimorphos溅射物与主星Didymos的表面成分相同,但风化程度较低,这表明在次星形成后,主星和次星表面受到强烈的太空风化作用,而次星内部物质受到的太空风化作用相对较弱。
基金Space Optoelectronic Measurement and Perception Lab(LabSOMP-2023-07)the National Natural Science Foundation ofChina(42241147)+1 种基金the State Key Laboratory of Geo-Information Engineering(SKLGIE2021-Z-3-1)and the Open Program of Collaborativeinnovation Center of Geo-information(2023C002)。
文摘This paper proposed an efficient method of image overlapping relationship analysis based on spatial index of KD tree fast search for disordered and large-scale asteroid images.In this study,the image data from asteroid exploration missions such as Bennu,Vesta,and Ryugu were used for experiments,and the proposed image matching pairs determination algorithm was comprehensively compared with the corresponding modules of USGS ISIS in order to evaluate its performance in terms of efficiency and accuracy.The results show that when processing more than a thousand images,the proposed method greatly improves the efficiency of acquiring image matching pairs while ensuring the correctness of image overlapping relationships and accuracy of bundle adjustment.At the same time,according to the obtained image matching pairs,images that meet the requirements of Stereo Photoclinometry can be quickly selected,effectively improving the quality of 3D reconstruction models of asteroid images.
文摘In a Nature Physics report published in late September 2024[1],a team of scientists and engineers at Sandia National Laboratories(Albuquerque,NM,USA)described the results of a laboratory experiment showing that a nuclear blast could create a burst of X-rays powerful enough to change the path of a large asteroid that might one day be on a collision course with Earth.
文摘In the present study,we investigated the existence of arbitrary amplitude dust acoustic solitons by considering the Cairns distributed ions,negatively charged streaming dust grains along with(r,q)distributed electrons in an un-magnetized dusty plasma.We used the pseudopotential technique to obtain the solitary wave solution.It is seen that the coexistence of rarefactive and compressive solitons is possible when ions and electrons are nonthermally distributed.We found that the soliton characteristics are strongly dependent on the choice of velocity distribution function through the nonthermal spectral indices r q,,a as well as on the ion and dust temperatures.For(r,q)distributed electrons,we found that the soliton amplitude increases(decreases)with smaller(higher)values of negative(positive)r.For Cairns distributed ions,we found a transition from negative to positive polarity solitary structures with the coexistence in between as the nonthermal parameter a increases.Our results gave a better explanation for the formation of dust acoustic solitary structures and their dependence on high and low energy particles in nonthermal distribution profiles in space environments.
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 the National Key Research and Development Program of China(2023YFE0109900)the B-type Strategic Priority Research Program of Chinese Academy of Sciences(grant No.XDB 41000000)+4 种基金the National Natural Science Foundation of China(grant Nos.42273038,62227901,42073060 and 12150009)Space debris and NEO research project(No.KJSP2020020204)Youth Innovation Promotion Association CAS(2023332)the Science and Technology Project of Qinghai Province(2025-ZJ-T0)the Minor Planet Foundation of China.
文摘Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have not been conducted for any meteorite fall events in China.On 2022 December 15 at 09:48 UT,meteoroid Tanxi was recorded by numerous cameras in populous northern Zhejiang.This event offers an opportunity to conduct the first systematic origin-tracing study for a meteorite fall event in China.The Tanxi meteorite was classified as an H6chondrite.This meteoroid entered the atmosphere with a velocity of 13.49 km s^(-1)and a slope of 69.52°.It most likely underwent a two-stage fragmentation process,with early fragmentation under a dynamic pressure of0.08 MPa,and main fragmentation under a dynamic pressure of 7.83 MPa.Before colliding with the Earth,the meteoroid’s heliocentric orbit had a semimajor axis of 2.363±0.107 au,an eccentricity of 0.584±0.019 and an inclination of 2.078±0.074°.A backward Dshevolution result of 5000 yr shows Tanxi’s orbit is most similar to a small near-Earth asteroid 2016 WV2.The source region analysis of the Tanxi fall indicates that the H chondrites could originate from two distinct reservoirs:the 3:1J mean motion resonance complex(51.2±3.7%)and the v6secular resonance region(41.6±2.9%).
