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Simulated Gravity Field Estimation for the Main Belt Comet 133p/Elst-pizarro Based on a Satellite-to-satellite Tracking Mode

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Research in Astronomy and Astrophysics 2023年第9期23卷 129-141页

作者： Shang-Biao Sun Jian-Guo Yan Wu-Tong Gao Bo Wang Zhen Wang Mao Ye jean-p.erre barriot State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Geodesy Observatory of Tahiti University of French PolynesiaBP 6570F-98702 FaaaTahitiFrench PolynesiaFrance

Most asteroids and comets are formed in the early stages of the solar system and therefore contain a wealth of information about their *** asteroid exploration mission planned in the coming years by China will likely target the celestial body named 133p/Elst-pizarro(estimated diameter of about 4 km).The orbit of this asteroid stays within the asteroid belt,but nevertheless,it displays a comet-like dust *** this study,we used differential tracking data between two simulated probes and the data from an Earth station to estimate 133p gravity field *** observation mode is similar to how the gravity field was estimated for large celestial objects in the GRAIL and GRACE missions,but here the object is the very small 133p *** compared the estimated gravity fields obtained for 133p from the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode,with only the Earth-based two-way range rate *** results show that the accuracy of the low-degree(4 degree and order)estimate of the gravity field is improved by one order of magnitude by using the satellite-to-satellite combined with the Earth-based two-way range-rate observation mode with respect to the Earthonly ***,another order of magnitude improvement in the gravity field solution is gained by decreasing the orbit altitude from 12 to 8 km.

关键词： gravitation-methods data analysis-celestial mechanics-comets general

A simulation experiment on the GM estimation for Comet 133p/Elst-pizarro

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Research in Astronomy and Astrophysics 2021年第1期21卷 158-164页

作者： Wu-Tong Gao Jian-Guo Yan Wei-Tong Jin Xuan Yang Chen Yang Mao Ye Fei Li jean-p.erre barriot l State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China China Academy of Space Technology Beijing 100094China Geodesy Observatory of Tahiti University of French PolynesiaBP 657098702 FaaaTahitiFrench Polynesia

In China’s asteroid mission to be launched around 2025,(7968)133 p/Elst-pizarro(hereafter 133 p)will be the second target,after a visit to asteroid(469219)Kamo’*** paper describes a simulation of precise orbit determination for the spacecraft around comet 133 p,as well as estimation of its gravitational parameter(GM)value and the solar radiation pressure coefficient Cr for the *** cometocentric distances of 200,150 and 100 km orbits are considered,as well as two tracking modes:exclusive two-way range-rate mode(Earth station to spacecraft)and combinations of two-way range-rate and local spacecraft onboard ranging to the *** to exclusive two-way range-rate,the introduction of local ranging observables improves the final GM uncertainties by up to one order of *** ephemeris error in the orbit of 133 p is also considered,and we show that,to obtain a reliable estimate of the GM for 133 p,this error cannot exceed a one km range.

关键词： celestial mechanics space vehicles comets:individual(133p/Elst-pizarro) methods:statistical

Reducing loss of significance in the computation of Earth-based two-way Doppler observables for small body missions

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Research in Astronomy and Astrophysics 2021年第8期21卷 75-90页

作者： Wei-Tong Jin Fei Li Jian-Guo Yan Xuan Yang Mao Ye Wei-Feng Hao Thomas paul Andert jean-p.erre barriot State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China State Key Laboratory of Satellite Navigation System and Equipment Technology Shijiazhuang 050200China Chinese Antarctic Center of Surveying and Mapping Wuhan UniversityWuhan 430079China Universitat der Bundeswehr München NeubibergBayern85579Germany University of French polynesia BP 6570F-98702 Faa'aTahitiFrench Polynesia

Two-way Doppler measurement is a typical Earth-based radiometric technique for interplanetary spacecraft navigation and gravity science *** most widely used model for the computation of two-way Doppler observables is Moyer’s differenced-range Doppler(DRD) formula,which is based on a Schwarzschild approximation of the Solar-System ***,the computation of range difference in DRD formula is sensitive to round-off errors due to approximate numbers defined by the norm IEEE754 in all *** paper presented two updated models and their corresponding detailed instructions for the computation of the two-way Doppler observables so as to impair the effects of this type of numerical *** two models were validated by two case studies related to the Rosetta mission—asteroid Lutetia flyby and comet 67 p/Churyumov-Gerasimenko orbiting *** these two cases,the numerical noise from the updated models can be reduced by two orders-of-magnitude in the computed two-way Doppler *** results showed an accuracy from better than 6 × 10^(-3) mm s^(-1) at 1 s counting time interval to better than 3 × 10^(-5) mm s^(-1) at 60 s counting time interval.

关键词： methods:numerical space vehicles planets and satellites:general

Illumination and regolith temperature at China's next candidate lunar landing site Shackleton crater

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Science China Earth Sciences 2023年第2期66卷 417-429页

作者： Zhen ZHONG Jianguo YAN Huaiyu HE Qiling WEN Deyun LIU jean-p.erre barriot School of physics and Electronic Science Guizhou Normal UniversityGuiyang550025China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan430079China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing100029China Beijing Spacecraft Manufacturing Co. LtdBeijing100094China Observatory Geodetic de Tahiti BP 657098702Faa’aTahitiFrench Polynesia

This study focuses on the illumination and temperature at China’s next lunar candidate landing site Shackleton *** used the NASA’s SpICE system to evaluate the terrain obscuration effect on real-time illumination;the resulting illumination map resembles previous studies,validating the methodologies used in our *** addition,we estimated an accumulated illumination map for the period of likely rover *** map indicates the illuminated inner wall of the Shackleton crater is close to 27%of the whole,meaning that the rover will likely receive solar radiation during its *** the real-time illumination and the distributed 1-D thermal diffusion model,we continuously evaluated the regolith temperature for more than 20 years to stabilize the temperature,and selected the temperature of the end time as the initial value used in a thermal study set for July 20,2023 and May 8,*** results indicate the temperature in the permanent shadow region remains nearly constant,thus validating the stability of our estimated initial *** results also indicate that the surface temperature is more sensitive to transient illumination,but the subsurface temperature is more likely to be associated with the accumulated *** difference indirectly implies that the conductivity of the lunar regolith is *** locations receiving more solar radiation show a temperature larger than the threshold(~112 K)of ice *** permanently shadowed regions can be as cold as 25 K,and such extreme coldness is a hazard to the *** are suitable temperature locations which have a warm surface but cold subsurface to preserve water *** further ensure normal rover movement,we provided a map of suitable temperature sites and found that these locations exist not only in the Shackleton crater’s inner wall,but also outside the *** suggested four trade-off sampling sites with suitable temperatures and gradual slopes.

关键词： Real-time illumination Regolith temperature Shackleton crater Map of landing site

同方期刊数据库

小行星433-Eros土壤厚度分布和表面强度估计

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地球物理学进展 2017年第6期32卷 2353-2359页

作者：刘威鄢建国李斐 jean-p.erre barriot 武汉大学测绘遥感信息工程国家重点实验室武汉430079 法属波利尼西亚大学法国波利尼西亚98709

根据Near探测器飞跃433-Eros小行星时观测得到的重力数据分析,在433-Eros小行星外侧边缘处存在轻微的负布格异常现象(Garmier et al.,2002).本文借鉴Geissler在Ida小行星上的结论,认为该异常是由其表面撞击过程中高速溅射物聚集效应产生... 详细信息

根据Near探测器飞跃433-Eros小行星时观测得到的重力数据分析,在433-Eros小行星外侧边缘处存在轻微的负布格异常现象(Garmier et al.,2002).本文借鉴Geissler在Ida小行星上的结论,认为该异常是由其表面撞击过程中高速溅射物聚集效应产生的.文中计算表明:在合理范围内调整模型Z参数和强度p参数,Eros上高速溅射物将聚集在其表面边缘外侧,这与Geissler实验结论是一致的.计算结果同时表明433-Eros行星表面的土壤层厚度以及布格异常数值与433-Eros表面物质的强度相关,通过这一相关性,可以约束433-Eros表面的强度参数p及其土壤层分布.取Z模型中Z参数为2.5时,我们估计出Eros表面物质的强度值大约为106pa,土壤层的堆积情况是全球平均堆积厚度约为30 m,Eros边缘末端处厚度为50 m.

关键词： 433-Eros 布格异常溅射物聚集效应土壤厚度分布表面强度

基于改进彗星星历的67p/Churyumov-Gerasimenko的三阶重力场模型

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中国科学：物理学、力学、天文学 2023年第5期53卷 135-149页

作者：高梧桐鄢建国王波杨婉羚李斐 jean-p.erre barriot 武汉大学测绘遥感信息工程国家重点实验室武汉430079 Geodesy Observatory of Tahiti University of French PolynesiaFaa’a Tahiti F-98702French Polynesia

本文解算了Rosetta彗星探测任务的主要目标——彗星67p/Churyumov-Gerasimenko的重力场模型.与以往模型的主要区别是,本文使用了JpL团队最新解算的67p星历模型,该彗星星历在很大程度上得到了改进.67p的改进星历能够对其GM值的解算产生... 详细信息

本文解算了Rosetta彗星探测任务的主要目标——彗星67p/Churyumov-Gerasimenko的重力场模型.与以往模型的主要区别是,本文使用了JpL团队最新解算的67p星历模型,该彗星星历在很大程度上得到了改进.67p的改进星历能够对其GM值的解算产生一定的影响,这一影响与67p通过近日点由于彗星喷发造成的质量损失处于同一水平.新的彗星重力场解算结果表明,67p重力异常比过去的模型更加显著.从2.65 km的参考球上看,新的重力场模型最大重力异常值约为0.9±0.03 mGal,较大的异常值表明了该彗星内部质量分布不均一的特性,这可能是由于高孔隙率和分层的彗核结构导致的.

关键词： 67p/Churyumov-Gerasimenko 重力场彗星精密定轨内部结构

One-pot Microwave-Assisted Synthesis of Graphene/Layered Double Hydroxide(LDH) Nanohybrids

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Nano-Micro Letters 2015年第4期7卷 332-340页

作者： Sunil p.Lonkar jean-Marie Raquez philippe Dubois Laboratory of polymeric and Composite Materials Center of Innovation and Research in Materials and PolymersUniversity of Mons Department of Chemical Engineering The Petroleum Institute

A facile and rapid method to synthesize graphene/layered double hydroxide(LDH)nanohybrids by a microwave technique is *** synthesis procedure involves hydrothermal crystallization of Zn–Al LDH at the same time in situ reduction of graphene oxide(GO)to *** microstructure,composition,and morphology of the resulting graphene/LDH nanohybrids were *** results confirmed the formation of nanohybrids and the reduction of graphene *** growth mechanism of LDH and in situ reduction of GO were *** LDH sheet growth was found to prevent the scrolling of graphene layers in resulting *** electrochemical properties exhibit superior performance for graphene/Zn–Al LDH hybrids over pristine *** present approach may open a strategy in hybridizing graphene with multimetallic nano-oxides and hydroxides using microwave method.

关键词： Graphene LDHs Nanostructures Microwave Composite materials

Integrating multiple electromagnetic data to map spatiotemporal variability of soil salinity in Kairouan region, Central Tunisia

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Journal of Arid Land 2022年第2期14卷 186-202页

作者： Besma ZARAI Christian WALTER Didier MICHOT jean p MONTOROI Mohamed HACHICHA University of Carthage National Research Institute of Rural EngineeringWater and Forestry LR16INRGREF02Non-Conventional Water ValorizationAriana 2080Tunisia National Institute of Agronomy Tunis University of CarthageNicolle 1082Tunisia SAS Mixed Research Unit Soil Agro and Hydrosystem SpatializationINRAENational Research Institute for AgricultureFood and the EnvironmentRennes 35000France Bondy Research and Development Institute Bondy 93140France

Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions,which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from *** soil recovery involving drainage of shallow saline groundwater and the removal of soil salts by natural rainfall or by irrigation are good strategies for the reclamation of salty *** develop suitable management strategies for salty soil reclamation,it is essential to improve soil salinity assessment pro cess/mechanism and to adopt new approaches and techniques.T his study mapped a recovered area of 7200 m2 to assess and verify variations in soil salinity in space and time in K airouan region in Central Tunisia,taking into account the thickness of soil *** electromagnetic conductivity meters(EM38 and EM31)were used to measure the electrical conductivity of saturated soil-paste extract(ECe)and apparent electrical conductivity(E Ca).Multiple linear regression was established between ECe and ECa,and it was revealed that ECa-EM38 is optimal for E Ce prediction in the surface *** maps demonstrated that the spatial structure of soil salinity in the region of interest was relatively unchanged but varied *** in salinity at the soil surface was greater than that at a *** findings can not only be used to track soil salinity variations and their significance in the field but also help to identify the spatial and temporal features of soil salinity,thus improving the efficiency of soil management.

关键词： electrical conductivity soil salinity saturated paste extract apparent electrical conductivity multiple linear regression Tunisia

Energetics and thermodynamic stability of potential Fe (II) -hexa-aza-active sites for O_(2) reduction in pEM fuel cells

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SusMat 2022年第6期2卷 731-748页

作者： Vassili p.Glibin jean-pol Dodelet Gaixia Zhang Department of Chemical and Biochemical Engineering University of Western OntarioLondon OntarioCanada Institut National de la Recherche Scientifique(INRS) Energie Materiaux Telecommunications Research CentreVarennesQuebecCanada Department of Electrical Engineering Ecole de Technologie Superieure(ETS)1100rue Notre-Dame OuestMontrealQuebec H3C 1K3Canada

We present here a thermodynamic assessment of the stability behavior in acid environment at 298 and 353 K(80◦C)of two iron(II)hexa-aza-macrocyclic complexes and of an hexa-aza-iron-based site(Fe^(II)N_((4+2))/C)that should potentially be active for the oxygen reduction reaction in proton exchange membrane(pEM)fuel *** calculations of the equilibrium constant(K c)for the demetallation reaction indicate that the iron(II)-hexa-aza-macrocyclic complexes and Fe^(II)N_((4+2))/C are chemically stable in an acid medium at 298 and 353 *** with two other potential model sites(Fe^(II)N_((4+2))/C and Fe II N(2+2)/C)that were thought to be present in the same Fe-based catalysts,K c of Fe^(II)N_((4+2))/C is two to three orders of magnitude smaller at 353 K,and three to four orders of magnitude smaller at 298 K,than K c for Fe^(II)N_((4+2))/C or Fe II N(2+2)/C,revealing the great chemical stability of Fe^(II)N_((4+2))/*** this work,we discuss about a novel proposition that the two catalytic sites active in these Fe-based catalysts are Fe II N_(4)/C and Fe^(II)N_((4+2))/*** proposition is in agreement with the durability behavior of these catalysts in pEM fuel cells and also with their known physico-chemical *** origin of the fast and slow decay behaviors of the different sites,which are active at the Fe–N–C-based cathode of pEM fuel cells,is also discussed.

关键词： active site fuel cell oxygen reduction reaction thermodynamic stability