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Characteristics of the lunar samples returned by the Chang'E-5 mission

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National Science Review 2022年第2期9卷 21-33页

作者： Chunlai Li Hao Hu Meng-Fei Yang Zhao-Yu Pei Qin Zhou Xin Ren Bin Liu Dawei Liu Xingguo Zeng Guangliang Zhang Hongbo Zhang Jianjun Liu Qiong Wang Xiangjin Deng Caijin Xiao Yonggang Yao Dingshuai Xue Wei Zuo Yan Su Weibin Wen Ziyuan Ouyang Key Laboratory of Lunar and Deep space Exploration National Astronomical Observatories Chinese Academy of Sciences Lunar Exploration and space Engineering Center Beijing institute of spacecraft System Engineering Department of Nuclear Physics China Institute of Atomic Energy State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences institute of Geochemistry Chinese Academy of Sciences

Forty-five years after the Apollo and Luna missions returned lunar samples,China’s Chang’E-5(CE-5)mission collected new samples from the mid-latitude region in the northeastern Oceanus Procellarum of the Moon.Our study shows that 95% of CE-5 lunar soil sizes are found to be within the range of 1.40-9.35 μm,while 95% of the soils by mass are within the size range of 4.84-432.27 μm.The bulk density,true density and specific surface area of CE-5 soils are 1.2387 g/cm~3,3.1952 g/cm~3 and 0.56 m~2/g,respectively.Fragments from the CE-5 regolith are classified into igneous clasts(mostly basalt),agglutinate and glass.A few breccias were also found.The minerals and compositions of CE-5 soils are consistent with mare basalts and can be classified as low-Ti/low-Al/low-K type with lower rare-earth-element contents than materials rich in potassium,rare earth element and phosphorus.CE-5 soils have high FeO and low Mg index,which could represent a new class of basalt.

关键词： Chang’E-5 lunar soils physical properties petrography mineralogy chemistry

In-flight calibration of the magnetometer on the Mars orbiter of Tianwen-1

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Science China(Technological sciences) 2023年第8期66卷 2396-2405页

作者： ZOU ZhuXuan WANG YuMing ZHANG TieLong WANG GuoQiang XIAO SuDong PAN ZongHao ZHANG ZhouBin YAN Wei DU Yang CHI YuTian CHENG Long WU ZhiYong HAO XinJun LI YiRen LIU Kai CHEN ManMing SU ZhenPeng SHEN ChengLong XU MengJiao GUO JingNan School of Earth and space sciences/Deep space Exploration Laboratory University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology/CAS Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China space Research institute Austrian Academy of SciencesGraz 8010Austria institute of space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518055China National Astronomical Observatories Chinese Academy of SciencesBeijing 100080China Shanghai institute of Satellite Engineering Shanghai 200240China institute of Deep space sciences Deep Space Exploration LaboratoryHefei 230026China

Mars orbiter magnetometer(MOMAG)is one of seven science payloads onboard Tianwen-1’s orbiter.Unlike most of the satellites,Tianwen-1’s orbiter is not magnetically cleaned,and the boom where placed the magnetometer’s sensors is not long enough.These pose many challenges to the magnetic field data processing.In this study,we introduce the in-flight calibration process of the Tianwen-1/MOMAG.The magnetic interference including spacecraft generated dynamic field and the slowlychanging zero offsets are cleaned in sequence.Then the calibrated magnetic field data are compared with the data from the Mars atmosphere and volatile Evolutio N(MAVEN).We find that some physical structures in the solar wind are consistent between the two data sets,and the distributions of the magnetic field strength in the solar wind are very similar.These results suggest that the in-flight calibration of the MOMAG is successful and the MOMAG provides reliable data for scientific research.

关键词： magnetometer in-flight calibration Martian magnetic field Tianwen-1

Scalings for the Alfvén-cyclotron instability in a bi-kappa plasma

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地球与行星物理:英文版 2023年第6期7卷 631-639页

作者： YueQun Lou Xing Cao MingYu Wu BinBin Ni TieLong Zhang Shenzhen Key Laboratory of Numerical Prediction for space Storm Institute of Space Science and Applied TechnologyHarbin Institute of TechnologyShenzhen 518055China Key Laboratory of Solar Activity and space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Department of space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of sciences Center for Excellence in Comparative Planetology Hefei 230026China space Research institute Austrian Academy of SciencesGraz 8042Austria

The particle velocity distribution in space plasma usually exhibits a non-Maxwellian high-energy tail that can be well modeled by kappa distributions.In this study,we focus on the growth rates of the Alfvén-cyclotron instability driven by ion temperature anisotropy in a kappa plasma.By solving the kinetic linear dispersion equation,we explore the sensitivity of growth rates to the spectral indexκof a bi-kappa distribution under different plasma conditions,including a variety of plasma beta β_(hp) and temperature anisotropy A_(hp) values of hot protons.Furthermore,a concise,analytic scaling formula is derived that relates the dimensionless maximum growth rate to three independent variables:the spectral index and the plasma beta and temperature anisotropy of hot protons.Our results show that as theκ-value increases,the instability bandwidth narrows and the maximum growth rate increases significantly.For higherβ_(hp)and A_(hp)′the maximum instability undergoes a sharp increase as well.When our fits of dimensionless maximum growth rates are compared with solutions to kinetic linear dispersion theory,the results generally exhibit good agreement between them.Especially under the circumstances of largeκ-values and highβ_(hp)and A_(hp)′the scalings of maximum growth rates primarily accurately model the numerical solutions.Our analytic expressions can readily be used in large-scale models of the Earth’s magnetosphere to understand wave generation due to the Alfvén-cyclotron instability.

关键词： Alfvén-cyclotron instability kappa distribution kinetic linear dispersion theory scaling formula

The Mars orbiter magnetometer of Tianwen-1:in-flight performance and first science results

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Earth and Planetary Physics 2023年第2期7卷 216-228页

作者： YuMing Wang TieLong Zhang GuoQiang Wang SuDong Xiao ZhuXuan Zou Long Cheng ZongHao Pan Kai Liu XinJun Hao YiRen Li ManMing Chen ZhouBin Zhang Wei Yan ZhenPeng Su ZhiYong Wu ChengLong Shen YuTian Chi MengJiao Xu JingNan Guo Yang Du School of Earth and space sciences/Deep space Exploration Laboratory University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology/CAS Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China space Research institute Austrian Academy of SciencesGrazAustria institute of space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518055China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China institute of Deep space sciences Deep Space Exploration LaboratoryHefei 230026China Shanghai institute of Satellite Engineering Shanghai 201109China

The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars.Here we present its in-flight performance and first science results,based on its first one and one-half months’data.Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we report that the MOMAG magnetic field data are at the same level in magnitude,and describe the same magnetic structures with similar variations in three components.We recognize 158 clear bow shock(BS)crossings in these MOMAG data;their locations match well statistically with the modeled average BS.We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings.These BS crossings confirm the global shape of modeled BS,as well as the south-north asymmetry of the Martian BS.Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose.So far,MOMAG performs well,and provides accurate magnetic field vectors.MOMAG is continuously scanning the magnetic field surrounding Mars.Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.

关键词： Mars magnetic field Tianwen-1 magnetometer bow shock

Responses of the field-aligned currents in the plasma sheet boundary layer to a geomagnetic storm

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Earth and Planetary Physics 2023年第5期7卷 558-564页

作者： YuanQiang Chen MingYu Wu YangJun Chen SuDong Xiao GuoQiang Wang TieLong Zhang Shenzhen Key Laboratory of Numerical Prediction for space Storm Harbin Institute of TechnologyShenzhen 518055China Key Laboratory of Solar Activity and space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Chinese Academy of sciences Center for Excellence in Comparative PlanetologyHefei 230026China space Research institute Austrian Academy of SciencesGraz 8042Austria

Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the ground.As an important medium of momentum and energy transport among the solar wind,magnetosphere,and ionosphere,field-aligned currents(FACs)can also be strengthened in storm times.This study shows the responses of FACs in the plasma sheet boundary layer(PSBL)observed by the Magnetospheric Multiscale(MMS)spacecraft in different phases of a large storm that lasted from May 27,2017,to May 29,2017.Most of the FACs were carried by electrons,and several FACs in the storm time also contained sufficient ion FACs.The FAC magnitudes were larger in the storm than in the quiet period,and those in the main phase were the strongest.In this case,the direction of the FACs in the main phase showed no preference for tailward or earthward,whereas the direction of the FACs in the recovery phase was mostly tailward.The results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region,where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is evolving.Thus,the FACs are an important medium of energy transport between the tail and the ionosphere,and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.

关键词： field-aligned currents plasma sheet boundary layer geomagnetic storm

Olivine-norite rock detected by the lunar rover Yutu-2 likely crystallized from the SPA-impact melt pool

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National Science Review 2020年第5期7卷 913-920页

作者： Honglei Lin Zhiping He Wei Yang Yangting Lin Rui Xu Chi Zhang Meng-Hua Zhu Rui Chang Jinhai Zhang Chunlai Li Hongyu Lin Yang Liu Sheng Gou Yong Wei Sen Hu Changbin Xue Jianfeng Yang Jie Zhong Xiaohui Fu Weixing Wan Yongliao Zou Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong University Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory of space Active Opto-Electronics Technology Shanghai Institute of Technical Physics Chinese Academy of Sciences State Key Laboratory of Lunar and Planetary sciences Macau University of Science and Technology Beijing institute of space Mechanics and Electricity State Key Laboratory of space Weather National Space Science CenterChinese Academy of Sciences State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Key Laboratory of Electronics and Information Technology for space System National Space Science Center Chinese Academy of Sciences Xi'an institute of Optics and Precision Mechanics Chinese Academy of Sciences institute of Optics and Electronics Chinese Academy of Sciences

Chang’E-4 landed in the South Pole-Aitken (SPA) basin,providing a unique chance to probe the composition of the lunar interior.Its landing site is located on ejecta strips in Von Karman crater that possibly originate from the neighboring Finsen crater.A surface rock and the lunar regolith at 10 sites along the rover Yutu-2 track were measured by the onboard Visible and Near-Infrared Imaging Spectrometer in the first three lunar days of mission operations.In situ spectra of the regolith have peak band positions at 1and 2μm,similar to the spectral data of Finsen ejecta from the Moon Mineralogy Mapper,which confirms that the regolith’s composition of the landing area is mostly similar to that of Finsen ejecta.The rock spectrum shows similar band peak positions,but stronger absorptions,suggesting relatively fresh exposure.The rock may consist of 38.1±5.4%low-Ca pyroxene,13.9±5.1%olivine and 48.0±3.1%plagioclase,referred to as olivine-norite.The plagioclase-abundant and olivine-poor modal composition of the rock is inconsistent with the origin of the mantle,but representative of the lunar lower crust.Alternatively,the rock crystallized from the impact-derived melt pool formed by the SPA-impact event via mixing the lunar crust and mantle materials.This scenario is consistent with fast-cooling thermal conditions of a shallow melt pool,indicated by the fine to medium-sized texture (<3 mm) of the rock and the SPA-impact melting model[Icarus2012;220:730-43].

关键词： impact basin lunar interior composition visible and near-infrared spectra lunar rover Yutu-2 Chang’E-4 mission

Automatic calculation of the magnetometer zero offset using the interplanetary magnetic field based on the Wang-Pan method

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Earth and Planetary Physics 2022年第1期6卷 52-60页

作者： XiaoWen Hu GuoQiang Wang ZongHao Pan Chinese Academy of sciences Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China institute of space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518055China

The space-borne fluxgate magnetometer(FGM)requires regular in-flight calibration to obtain its zero offset.Recently,Wang GQ and Pan ZH(2021a)developed a new method for the zero offset calibration based on the properties of Alfvén waves.They found that an optimal offset line(OOL)exists in the offset cube for a pure Alfvén wave and that the zero offset can be determined by the intersection of at least two nonparallel OOLs.Because no pure Alfvén waves exist in the interplanetary magnetic field,calculation of the zero offset relies on the selection of highly Alfvénic fluctuation events.Here,we propose an automatic procedure to find highly Alfvénic fluctuations in the solar wind and calculate the zero offset.This procedure includes three parts:(1)selecting potential Alfvénic fluctuation events,(2)obtaining the OOL,and(3)determining the zero offset.We tested our automatic procedure by applying it to the magnetic field data measured by the FGM onboard the Venus Express.The tests revealed that our automatic procedure was able to achieve results as good as those determined by the Davis-Smith method.One advantage of our procedure is that the selection criteria and the process for selecting the highly Alfvénic fluctuation events are simpler.Our automatic procedure could also be applied to find fluctuation events for the Davis-Smith method.

关键词： fluxgate magnetometer in-flight calibration zero offset highly Alfvénic fluctuations automatic procedure

Contribution of the Chinese Meridian Project to space environment research:Highlights and perspectives

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Science China Earth sciences 2023年第7期66卷 1423-1438页

作者： Chi WANG Jiyao XU Libo LIU Xianghui XUE Qinghe ZHANG Yongqiang HAO Gang CHEN Hui LI Guozhu LI Bingxian LUO Yajun ZHU Jiangyan WANG State Key Laboratory of space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China School of Earth and space sciences University Science and Technology of ChinaHefei 230026China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China School of Earth and space sciences Peking UniversityBeijing 100191China Department of space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Key Laboratory of Science and Technology on Environmental space Situation Awareness National Space Science CenterChinese Academy of SciencesBeijing 100190China

The Chinese Meridian Project(CMP)is devoted to establishing a comprehensive ground-based monitoring network for China’s space weather research.CMP is a major national science and technology infrastructure project with the participation of more than 10 research institutions and universities led by the National space Science Center of the Chinese Academy of sciences.CMP is planned to be constructed in two phases:CMP phasesⅠandⅡ.The first phase(CMP-Ⅰ)started construction in2008 and completed in 2012,after which it entered the operation stage.The 10-year observation of CMP-Ⅰhas made significant scientific discoveries and achievements in the research fields of the middle and upper atmospheric fluctuations,metal layers in the mesosphere and lower thermosphere,ionospheric disturbances and irregularities,geomagnetic disturbances,and influences of solar activity.The review summarizes the main observations and research achievements,space weather forecast modeling and methods based on CMP-Ⅰover the past 10 years,and presents a future extension perspective along with the construction of CMP-Ⅱ.

关键词： Chinese Meridian Project Ground-based observation network space weather Solar-terrestrial physics

A multi-frame sparse self-learning PWC-Net for motion estimation in satellite video scenes

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Science China(Information sciences) 2023年第9期66卷 213-225页

作者： Tengfei WANG Yanfeng GU Shengyang LI School of Electronics and Information Engineering Harbin Institute of Technology Technology and Engineering Center for space Utilization Chinese Academy of Sciences University of Chinese Academy of sciences

Motion estimation is an important approach to acquiring motion information of all targets in satellite video while it provides the ability to real-time monitor the Earth observation region. Compared with the case in computer vision, motion estimation in satellite video has to face two main difficulties: the large scale of observation and numerous weak targets of low signal-to-noise ratio. In this paper, a multi-frame sparse self-learning PWC-Net(MSSPWC-Net) is proposed to implement motion estimation of the weak targets in satellite video. To overcome the shortage that the existing PWC-Net fails to extract motion information from numerous weak targets, motion consistency and sparse self-learning are introduced to modify the pyramid,warping, and cost volume convolutional neural networks(CNN) network(PWC-Net). The motion consistency between neighboring frames as a multi-frame framework is mainly used to improve the accuracy of motion estimation of the weak targets, and sparse self-learning is adopted to deal with the case that labeled samples in satellite video are insufficient to train PWC-Net. Numerical experiments are conducted on 4 real satellite video datasets. Experimental results demonstrate that the proposed MSSPWC-Net achieves the excellent performance of motion estimation of the weak targets in satellite video and outperforms the state-of-the-art methods.

关键词： satellite video scenes motion estimation small blurry targets