Metallurgical performance evaluation of space-weathered Chang’e-5 lunar soil

Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.

First-round design of the flight scenario for Chang’e-2’s extended mission:take off from lunar orbit

Chang＇e-2, Chinese second lunar probe, was inserted into a 100 km altitude low lunar orbit on October 9th, 2010, its purpose is to continuously photograph the lunar surface and possibly chosen landing sites for future lunar missions. The probe will still carry considerable amount of propellant after completing all prescribed tasks in about six months. After the successful launch of Chang＇e-2, we began designing the probe＇s subsequent flight scenario, considering a total impulse of 1 100 m/s for takeoff from low lunar orbit and a maximum 3× 10^6 km distance for Earth-probe telecom- munication. Our first-round effort proposed a preliminary flight scenario that involves consecutive arrivals at the halo orbits around the Earth-Moon L1/L2 and Sun-Earth L1/L2 points, near-Earth asteroid flyby, Earth return, and lunar impact. The designed solution of Chang＇e-2＇s subsequent flight scenario is a multi-segment flight trajectory that serves as a reference for making the final decision on Chang＇e-2＇s extended mission, which is a flight to the Sun-Earth L2 point, and a possible scheme of lunar impact via Earth flyby after remaining at the Sun-Earth L2 point was also presented. The proposed flight trajectory, which possesses acceptable solution accuracy for mission analysis, is a novel design that effectively exploits the invariant manifolds in the circular restricted three-body problem and the patched-manifold-conic method.

Lunar Penetrating Radar onboard the Chang'e-3 mission

Lunar Penetrating Radar （LPR） is one of the important scientific instru- ments onboard the Chang＇e-3 spacecraft. Its scientific goals are the mapping of lunar regolith and detection of subsurface geologic structures. This paper describes the goals of the mission, as well as the basic principles, design, composition and achievements of the LPR. Finally, experiments on a glacier and the lunar surface are analyzed.

Rapid screening of Zr-containing particles from Chang’e-5 lunar soil samples for isotope geochronology:Technical roadmap for future study

New samples returned by China Chang’e-5(CE-5)mission offer an opportunity for studying the lunar geologic longevity,space weathering,and regolith evolution.The age determination of the CE-5 samples was among the first scientific questions to be answered.However,the precious samples,most in the micrometer size range,challenge many traditional analyses on large single crystals of zircon developed for massive bulk samples.Here,we developed a non-destructive rapid screening of individual zirconium-containing particle for isotope geochronology based on a Micro X-ray fluorescence analysis(μXRF).The selected particles were verified via scanning electron microscopy(SEM),3D X-ray microscopy(XRM),and focused ion beam scanning electron microscopy(FIB-SEM)techniques,which showed that zirconium-bearing minerals with several microns were precisely positioned and readily suitable for site-specific isotopic dating by second ion mass spectrometry(SIMS).Such protocol could be also appli-cable in non-destructively screening other types of particles for different scientific purposes.We there-fore proposed a correlative workflow for comprehensively studying the CE-5 lunar samples from single particles on nanometer to atomic scales.Linking various microscopic and spectromicroscopic instru-ments together,this workflow consists of six steps:(1)single-particle selection with non-destructive μXRF technique,(2)2D/3D morphological and structural characterization with a correlative submicron 3D XRM and nanoscale resolution FIB-SEM imaging methods,(3)SEM analysis of the surface morphology and chemistry of the selected particle,(4)a series of microscopic and microbeam analyses(e.g.,SEM,electron probe microanalysis,and SIMS)on the cross-section of the selected particle to obtain structural,mineralogical,chemical,and isotopic features from the micron to nanometer scale,(5)advanced 2D/3D characterization and site-specific sample preparation of thin foil/tip specimens on a microregion of inter-est in the selected particle with FIB-SEM technique,and(6)comprehensive analyses on the FIB-milled specimens at nanometer to atomic scale with synchrotron-based scanning transmission X-ray micro-scopy,analytic transmission electron microscopy,and atom probe tomography.Following this technical roadmap,one can integrate multiple modalities into a uniform frame of multimodal and multiscale cor-related datasets to acquire high-throughput information on the limited or precious terrestrial and extraterrestrial samples.

Introduction to the TT&C Scheme for Chang’e⁃5 Mission

Chang’e-5 mission is China’s first lunar sample return mission.It contains several new flight phases compared with the previous lunar missions,such as the lunar take-off and orbit insertion phase,the rendezvous and docking phase,etc.Chang’e-5 mission is extremely complicated and full of new challenges.This paper sorts out the characteristics and the difficulties in telemetry,tracking,and command(TT&C)of Chang’e-5 mission.The main technical contribution is a reliable general design of the TT&C system,including the application of X-band TT&C in launch and early orbit phase(LEOP),multiple targets simultaneous TT&C in X-band,lunar surface benchmark calibration,high-precision and rapid orbit trajectory determination for the lunar surface take-off,remote guidance rendezvous and docking,the determination of the initial navigational value for the separation point of the Chang’e-5 orbiter and returner,and the design of the reentry measurement chain.Based on this scheme,a global deep space TT&C network and interplanetary reentry measurement chain have been established for China,and near-continuous TT&C support for China’s first extraterrestrial object sampling and return mission has been realized,ensuring reliable tracking,accurate measurement and accurate control.The global deep space network can provide TT&C support comparable to that of National Aeronautics and Space Administration(NASA)and European Space Agency(ESA)for subsequent lunar and deep space exploration missions.The techniques of rapid trajectory determination of lunar take-off and orbit entry,as well as high precision and remote guidance of lunar orbit rendezvous and docking can lay a technological foundation for the future manned lunar exploration missions and planetary sampling and return missions.

Development and characterization of the PolyU-1 lunar regolith simulant based on Chang’e-5 returned samples

Leading national space exploration agencies and private enterprises are actively engaged in lunar exploration initiatives to accomplish manned lunar landings and establish permanent lunar bases in the forthcoming years.With limited access to lunar surface materials on Earth,lunar regolith simulants are crucial for lunar exploration research.The Chang’e-5(CE-5)samples have been characterized by state-of-the-art laboratory equipment,providing a unique opportunity to develop a high-quality lunar regolith simulant.We have prepared a high-fidelity PolyU-1 simulant by pulverizing,desiccating,sieving,and blending natural mineral materials on Earth based on key physical,mineral,and chemical characteristics of CE-5 samples.The results showed that the simulant has a high degree of consistency with the CE-5 samples in terms of the particle morphology,mineral and chemical composition.Direct shear tests were conducted on the simulant,and the measured internal friction angle and cohesion values can serve as references for determining the mechanical properties of CE-5 lunar regolith.The PolyU-1 simulant can contribute to experimental studies involving lunar regolith,including the assessment of interaction between rovers and lunar regolith,as well as the development of in-situ resource utilization(ISRU)technologies.

Latest Scientific Results of China's Lunar and Deep Space Exploration(2022–2024)

China has successfully launched six lunar probes so far.From Chang'E-1 to Chang'E-4,they completed the circling,landing and roving exploration,of which Chang'E-4 was the first landing on the far side of the Moon in human history.Chang'E-5 was launched in December 2020,bringing back 1731 g of lunar soil samples.Through the detailed analysis of the samples,the scientists understand the history of late lunar volcanism,specifically extending lunar volcanism by about 800 million to 1 billion years,and proposed possible mechanisms.In addition,there are many new understandings of space weathering such as meteorite impacts and solar wind radiation on the Moon.China's first Mars exploration mission Tianwen-1 was successfully launched in July 2021.Through the study of scientific data,a number of important scientific achievements have been made in the topography,water environment and shallow surface structure of Mars.This paper introduces the main scientific achievements of Chang'E-4,Chang'E-5 and Tianwen-1 in the past two years,excluding technical and engineering contents.Due to the large number of articles involved,this paper only introduces part of the results.

Analysis of Chang’e-5 lunar core drilling process

Chang’e-5 explorer successfully acquired lunar regolith core samples from depths of greater than 1 m of lunar surface.This study analyzed the lunar core drilling process based on the telemetry data,image information,and returned samples to optimize the sampling device design and enhance the understanding of the lunar regolith.In particular,a prediction method for the projected drilling path and local terrain fitting of drilling dip angle was proposed based on the flight events recorded during the core drilling process and the image information acquired before,during,and after sampling.The results revealed that the drilling dip angle of Chang’e-5 was approximately2.3.,and the deviation of the drilling length and depth was less than 2 mm.For continuous drilling,a fusion method based on telemetry data and image information was applied to determine the demarcation point of drilling with and without the lunar soil.The position of the demarcation point implied that the drilling point remained at approximately 6 mm loose soil,thereby lagging the action of the force response.Additionally,a characteristic parameter comparison method was proposed for the lunar and ground drilling to analyze the status of the lunar soil.Furthermore,the analysis results revealed that the majority of the Chang’e-5 drilling samples were derived from 0–73.8 cm below the lunar surface and few samples were extracted below 73.8 cm,as the drilling encountered several rocky regions.Moreover,the drilling point exhibited two prominent stratification variations at~28.7 cm and~70 cm below the lunar surface.Ultimately,the preliminary relationship between sample dissected position in soft tube and drilling displacement was analyzed.The segmented estimation results can support research on subsurface lunar soil.

Scheme design of the CHANG＇E-5T1 extended mission

Flight schemes for the CHANG＇E-5T1 extended mission are investigated in this paper.In the flight scheme and trajectory design, the remaining propellant of the CHANG＇E-5T1 mission is utilized. The CHANG＇E-5T1 mission is firstly introduced with feasible flight goals derived based on the terminal trajectory and satellite status. The flight schemes are designed to include a lunar return and the libration points in the Sun-Earth/Moon and Earth-Moon systems, with an emphasis on the Earth-Moon triangle libration point thus far unexplored. Secondly, three schemes are proposed for the CHANG＇E-5T1 extended mission with different flight goals. The direct libration point orbit transfer and injection method is adopted to solve the issue in the transfer trajectory design.Furthermore, an innovative concept is proposed to transfer from the Earth-Moon collinear libration point to the triangle point using the Sun-Earth/Moon libration point. Finally, the merits and drawbacks of the three schemes are discussed in terms of flight time, control energy and frequency, flight distance, and goal value. As a result, the scheme including a lunar return and the Earth-Moon L2 libration point is selected for the CHANG＇E-5T1 extended mission. A flight to the Earth-Moon libration point is achieved, replicating the achievement of the ARTEMIS mission.

Data preprocessing and preliminary results of the Moon-based Ultraviolet Telescope on the CE-3 lander

The Moon-based Ultraviolet Telescope （MUVT） is one of the payloads on the Chang＇e-3 （CE-3） lunar lander. Because of the advantages of having no at- mospheric disturbances and the slow rotation of the Moon, we can make long-term continuous observations of a series of important celestial objects in the near ultra- violet band （245-340 nm）, and perform a sky survey of selected areas, which can- not be completed on Earth. We can find characteristic changes in celestial brightness with time by analyzing image data from the MUVT, and deduce the radiation mech- anism and physical properties of these celestial objects after comparing with a phys- ical model. In order to explain the scientific purposes of MUVT, this article analyzes the preprocessing of MUVT image data and makes a preliminary evaluation of data quality. The results demonstrate that the methods used for data collection and prepro- cessing are effective, and the Level 2A and 2B image data satisfy the requirements of follow-up scientific researches.

月球探测器飞越多小天体的拓展任务设计

为充分利用月球探测任务完成后的探测器,提出控制其从环绕月球或地球的轨道出发开展多个小天体飞越探测拓展任务。结合月球探测任务完成后的探测器飞行状态,重点分析了逃逸月球或地球的能量需求,以及小天体飞越探测的其他必要条件,如小天体亮度、星载设备能力约束等。研究了小天体目标确定和转移轨道设计方法,针对小天体目标众多引起的搜索空间和计算量大、多目标序列优化复杂等问题,设计了小天体目标多层择优搜索算法。以嫦娥五号为例,搜索得到了多个可行的小天体飞越探测方案,结果表明在给定约束下可以交会最多5个小天体,包括尺寸较大的小行星12923。研究结论可直接用于嫦娥五号拓展任务,并为后续月球和小天体探测任务提供有益参考和借鉴。

Chang’E-2 satellite asymmetric-descent orbit control technology

To accomplish high-resolution imaging of the preselected landing area, it was necessary for the Chang＇E-2 mission to perform orbital maneuvering on the far side of the moon to meet the conditional height requirement of the imaging area. Engine shutdown would be executed invisibly on the back side of the moon if the descent maneuver mode opposite to the target perilune or the fuel optimal maneuver mode was used. To ensure the satellite safety, the project collectivety required that the engine shutdown should be designed to be executed in the domestic segmental arcs and meet the requirement of satellite emergency treatment simultaneously. Accordingly, the asymmetric-descent orbit control technology was adopted by offsetting the ma- neuver point, which obtained the orbit control parameters of finite-thrust mode with an iteration algorithm and modified the results with target perilune drift estimation. The Chang＇E-2 satellite declined to the target of 100 km×l5 km orbit successfully on 26 October 2010, and has been flying for 32 circles in the experimental orbit to accomplish the preselected landing area imaging. This paper describes the mechanism and realization method of the asymmetric-descent orbit control technology and evaluates the maneuver effect with the actual mission data.

Mineral chemistry and 3D tomography of a Chang’E 5 high-Ti basalt:implication for the lunar thermal evolution history

In December 2020, Chang’E-5(CE-5), China’s first lunar sample return mission, successfully collected samples totaling 1731 g from the northern Oceanus Procellarum. The landing site was located in a young mare plain, a great distance from those of Apollo and Luna missions. These young mare basalts bear critical scientific significance as they could shed light on the nature of the lunar interior(composition and structure) as well as the recent volcanism on the Moon. In this article, we investigated a CE-5 basalt sample(CE5 C0000 YJYX065) using a combination of state-of-art techniques, including high resolution X-ray tomographic microscopy(HR-XTM), energy dispersive X-ray spectroscopy(EDS)-based scanning electron microscope(SEM), and electron probe microanalysis(EPMA) to reveal its 3 D petrology and minerology.Our results show that this sample has a fine-to medium-grained subophitic texture, with sparse olivine phenocrysts setting in the groundmass of pyroxene, plagioclase, ilmenite and trace amounts of other phases. It has an extremely high ilmenite modal abundance(17.8 vol%) and contains a significant amount(0.5 vol%) of Ca-phosphate grains. The mineral chemistry is in excellent agreement with that of Apollo and Luna high-Ti basalts. The major phase pyroxenes also display strong chemical zoning with compositions following the trends observed in Apollo high-Ti basalts. Based on current data, we came to the conclusion that CE5 C0000 YJYX065 is a high-Ti mare basalt with a rare earth element(REE) enriched signature. This provides a rigid ground-truth for the geological context at the CE-5 landing site and clarifies the ambiguity inferred from remote sensing surveys.

Method for differential phase delay resolution of phase referencing VLBI technique and its experimental verification

The phase referencing Very Long Baseline Interferometry(VLBI)technique is a newly developed tool to measure the angular position of a deep space exploration probe in the plane-of-the-sky.Through alternating observations between the probe and a nearby reference radio source,their accurate relative angular separation can be obtained from the radio images generated by this technique.To meet the requirements of the current orbit determination software,differential delay should be firstly derived from those radio images.A method to resolve the differential phase delay from the phase referencing VLBI technique is proposed in this paper,and as well the mathematical model for differential phase ambiguity resolution is established.This method is verified with practical measurement data from the Chang’E-3 mission.The differential phase delay between the Chang’E-3 lander and rover was derived from the phase referencing VLBI measurements,and was then imported into the Shanghai astronomical observatory Orbit Determination Program(SODP)to calculate the position of the rover relative to the lander on the lunar surface.The results are consistent with those acquired directly from radio images,indicating that the differential phase ambiguity has been correctly resolved.The proposed method can be used to promote applications of the phase referencing VLBI technique in future lunar or deep space explorations,and more accurate orbit determination becomes promising.

首次在嫦娥五号月壤中鉴定出铁陨石碎片类型

Lunar soil preserves numerous fragments of meteorites impacting on the Moon,providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years.Here we report the first discovery of an iron meteorite fragment from the Chang’e-5 lunar soil,which consists mainly of martensite(quenched from taenite),kamacite,and schreibersite,with a trace of pentlandite.The meteorite fragment is Ni-and P-rich,S-poor,and based on its mineral chemistry and bulk composition,can be classified into the IID-group,a rare and carbonaceous group of iron meteorite originating in the outer Solar System.This meteorite fragment experienced only limited partial melting followed by fast cooling,suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith.Alternatively,it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite.Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils,thus shedding light on the dynamic evolution of the Solar System.

撞击过程对月表氧逸度的改造:来自嫦娥五号月壤中撞击玻璃珠的启示

Lunar materials are overall more reducing compared with their terrestrial counterparts,but the mechanism remains to be elucidated.In this study,we present a possible explanation for the changes in redox state of the lunar regolith caused by impact events,based on our investigations of the impact glass beads from Chang’e-5 mission.These glass beads contain iron metal grains and show concentration gradients of FeO and K_(2)O(with or without Na_(2)O)from their rims to centers.The compositional profiles exhibit errorfunction-like shapes,which indicates a diffusion-limited mechanism.Our numerical modeling results suggest that the iron metal grains on the surface of the glass beads were generated through the reduction of FeO by elemental K and(or)Na produced during the impact events.Meanwhile,the iron metal grains inside the bead may have formed due to oxygen diffusion driven by redox potential gradients.Furthermore,our study suggests that impact processes intensify the local reducing conditions,as evidenced by the presence of calcium sulfide particles within troilite grains that coexist with iron metal grains on the surface of the glass beads.This study provides insights into the oxygen diffusion kinetics during the formation of iron metal spherules and sheds light on the changes in redox conditions of lunar materials caused by impact events.

基于嫦娥五号月球样品的月壤残余内摩擦角预测

随着人类探月工程的快速发展,月球基地建设以及月表资源开发利用有望更快实现,合理预测月壤工程力学性质对于未来深层次探月工程意义重大,我国嫦娥五号返回月球样品为研究月壤工程力学特性提供了直接的实测材料。然而,月球样品极其珍贵,难以满足传统土工试验测试.为了应对这一科学挑战,本研究从无损分析月球样品颗粒属性入手,使用高精度X-射线μCT扫描、三维白光干涉、原子力显微镜等无损测试手段,分析了不同类型月壤颗粒的三维多尺度形态、弹性力学和摩擦属性等指标.在此基础上,基于颗粒材料宏微观物理力学理论和数值模型尝试预测了嫦娥五号采样处月壤残余内摩擦角。本研究为基于月球样品信息跨尺度分析月壤工程力学性质提供了可行思路。

嫦娥五号月壤中首次发现蒸发沉积成因的蓝辉铜矿

由于缺乏磁场和大气的保护,月球表面持续受到陨石和微陨石的轰击.撞击引起的气化沉积作用是月表典型的改造过程,该过程往往伴随独特矿物相的产生(如纳米金属铁以及铁硅化合物).研究团队通过对嫦娥五号月壤进行细致的扫描电子显微镜观察,在纯铁颗粒以及玻璃质表面发现了具有典型气相沉积特征的含铜组分,进一步通过透射电子显微镜以及电子能量损失谱确认了这些含铜沉积物为蓝辉铜矿这是首次在月壤中发现此类矿物.本研究提供了月表硫化物发生气化沉积的直接证据,揭示了月表撞击过程引起的气相组分迁移及其对月表物质的显著改造效应.同时,嫦娥五号月壤中蓝辉铜矿的发现进一步拓宽了人们对月表复杂矿物组成的认识.