三层月壤模型的多通道微波辐射模拟与月壤厚度的反演

由月球表面数字高程试验性地构造了整个月球表面月壤厚度的分布.根据Clementine探月卫星的紫外-可见光光学数据,计算了整个月球表面月壤中FeO+TiO2含量分布,给出了整个月球表面月壤介电常数分布.由月球表层温度的观测结果以及月壤的导热特性,给出了月尘层与月壤层温度随纬度分布的经验公式.在这些条件的基础上,建立了月尘、月壤、月岩三层微波热辐射模型.由起伏逸散定理,模拟计算了该月球模型多通道辐射亮度温度.然后,以此辐射亮度温度模拟加随机噪声为理论观测值,按三层模型提出了月壤层厚度反演方法.由于高频通道穿透深度小,由高频通道的辐射亮度温度按照两层月尘-月壤微波热辐射模型反演月尘层与月壤层的物理温度,再由穿透深度较大的低频通道辐射亮度温度反演月壤层厚度.对于反演的相对误差也进行了讨论.      

月壤力学参数反求及试验验证

为了预测月球车的牵引特性并进行牵引控制,提出了一种基于线性最小二乘法的月壤力学参数估计算法,对内聚力和内摩擦角这两个关键的月壤力学参数进行反求.针对反映车轮土壤交互作用过程中轮刺效应的力学模型进行简化,建立了内聚力和内摩擦角的求解模型.将车轮与模拟月壤交互作用试验中的测量数据输入利用该算法编制的Matlab程序中,反求出模拟月壤的内聚力和内摩擦角,反求值与模拟月壤的实测值较为接近.试验验证结果表明该算法准确有效,且具有较好的稳定性和较快的运算速度,可用于月球车进行月壤力学参数的就位估计.      

月面钻进真空环境模拟装置的设计与验证

探月工程（三期）项目提出了在月面进行至少2 m深度的钻取采样任务,前期需要在地面进行模拟月面钻进过程热特性的研究,为此本文发明了一套月面真空环境模拟装置。根据模拟月壤钻进试验的要求,设计了一种可从底部抽气的三段式可多次拆装的真空罐结构。考虑到模拟月壤的颗粒大小和快速抽真空的要求,设计了一种筛网状具有多层过滤结构的月壤筒。根据在真空度不变的条件下可进行连续多次钻进试验的要求,设计了可从外部操作的具有缺齿结构的月壤筒转动机构。由真空度要求和可耐粉尘的特性要求,选取了三级扩散泵组。实验表明,在不放置模拟月壤的情况下,本环境模拟装置中的真空度可达10-1 Pa,在放置模拟月壤的情况下,真空度可达7 Pa,能够满足模拟月面钻进过程热特性试验的要求。此外,通过测量抽真空过程中真空度随时间的变化情况还得出了模拟月壤出气量曲线,对模拟月壤真空系统的实验应用具有重要价值。      

地球同步轨道长寿命卫星热控涂层太阳吸收率性能退化研究

文章介绍了15年地球同步轨道环境对卫星表面太阳吸收率性能影响的试验模拟研究,研究结果为长寿命卫星热设计及热控涂层选择和研制提供可靠依据;介绍自行研制的空间低能综合环境试验设备、太阳吸收率原位测试系统和空间低能综合环境模拟试验方法,并对航天器常用的S781白漆、SR107ZK白漆、F46镀银和OSR二次表面镜热控材料进行空间低能综合环境模拟试验,获得了这些热控涂层在地球同步轨道15年期间太阳吸收率性能退化模拟数据,与已有的飞行试验数据进行对比研究,取得满意的结果。     

航天器大尺度部件折叠展开原理分析及应用

围绕航天器向大尺度、远距离发展所涉及的大尺度部件在轨展开技术中新工艺、新材料、新结构等，对现有航天器大尺度部件的折展机构进行了统计与分析，系统梳理了在轨航天器折展机构的技术参数、结构与组成等。介绍了折纸艺术、自回弹材料与记忆合金等新工艺、新材料在航天器太阳帆板、天线等大尺度部件上的应用。重点分析并梳理了新型结构的特性及其工作原理，包括：充气展开式、单轴旋转式、径向扩展式、单元重构式、延长伸展式等。最后，结合即将开展的载人登月与月球基地建设、太阳系探测等深空探测任务，对在轨航天器大尺度部件的折展结构与机构的发展趋势进行了展望。     

月尘静电迁移研究进展

月尘的静电悬浮和迁移是Apollo时期留下的最有争议的问题之一. 其既是研 究月球表面物质演化历史的重要线索, 也是探月工程必须考虑的重要因素. 月尘在月表环境下易因电子附着、光电效应、二次电子发射等过程带电, 并 在月球全球性静电场作用下发生迁移运动. 但目前对月尘静电迁移过程的认 识还不全面, 其主要原因在于对月尘静电特性的了解不够准确, 对静电迁移 过程的地面模拟不够充分以及对月球尘埃环境的探测较为缺乏. 未来需进一 步开展模拟月尘的研制, 月尘静电特性的分析, 静电迁移过程模拟以及尘埃 环境的探测等工作.      

悬浮月尘的遮挡模型

探月活动中,月表的尘埃会对太阳翼等光电器件的工作效率造成严重影响.基于附着月尘的遮挡模型,从立体空间的角度分析了悬浮月尘对工作器件的遮挡,提出了悬浮月尘的单粒度遮挡模型,利用月尘的平均粒度可计算在指定立体空间内,定量月尘造成的遮挡量;引入月尘的粒度分布函数,提出了悬浮月尘的多粒度遮挡模型,能够计算已知粒度分布函数的月尘在指定立体空间内造成的遮挡量;通过设计悬浮月尘遮挡的仿真实验,分别利用3种不同粒度大小的月尘进行实验,实验数据与悬浮月尘的单粒度、多粒度遮挡模型的理论计算值都较好吻合,实验结果证实了悬浮月尘遮挡模型的正确性与可靠性.      

紧凑型ECR等离子体原子氧束流源的研制

原子氧对低地球轨道航天器部件材料的侵蚀及其地面环境模拟日益受到国际航天界的重视.高速飞行的航天器与迎面的空间环境原子氧之间相互作用能量约为5eV,在此能量范围内,原子氧束流与材料表面相互作用的许多物理和化学问题尚待从实验上认真研究,因此必需建立地面环境模拟装置.本文根据电子回旋共振(ECR)原理,利用微波的同轴传输与耦合,采用永磁体构成轴向不对称磁镜场产生会切磁场,降低了常规设计的磁场强度,缩小了装置的尺寸,同时采用无电极放电,避免了重金属杂质导入等离子体,研制出紧凑型纯净原子氧中性束流源.该装置易与真空容器联接.联机运行结果表明该装置能够在10-1-10-3Pa的气压范围内稳定运行,通量密度达到3×1015atom/cm2@s,满足了原子氧环境地面模拟试验对装置小型化的要求.     

北京卫星环境工程研究所航天器试验装备事业部

<正>航天器试验装备事业部隶属于北京卫星环境工程研究所,主要从事空间真空热环境及特殊环境模拟试验设备的设计开发、产品研制、售后服务及咨询培训等。部组件级热真空试验设备我部研制的"神舟"系列部组件级热真空试验设备主要用于航天器部组件级产品的真空热试验,能够满足航天器零部件空间环境试验要求。     

新兴的人机与环境工程技术科学

围绕人-机-环境系统、飞行器环境控制和生命保障系统、环境模拟技术、空气调节技术4个方面,对国内外人机与环境工程科学研究进展情况作了综述;着重介绍了人-机-环境系统的计算机仿真、ECS制冷系统、航天器的生命保障系统、地面、空中及空间环境模拟技术、空气调节技术的最新发展方向和需要进一步研究的问题等,以期进一步推动该技术学科的研究和发展.     

月尘环境效应及地面模拟技术

介绍了月球尘的特点及其对探月活动的影响。在分析月球尘环境及其对月面探测器污染、磨损、阻塞、静电效应的基础上,对月球尘环境模拟技术、月球尘扬尘及其运动学和动力学规律、月球尘效应防护及试验评价方法等研究方向和重点提出了一些初步看法。针对研究内容的需求,梳理出一台完整的月球尘地面模拟试验设备应具备真空、温度、太阳风、太阳紫外、月球尘、月面电场、月面磁场等环境因素。在此基础上,设计了一种月球尘地面模拟试验装置方案,并对月球尘环境效应试验方法进行了初步讨论。为月球探测后期任务条件保障建设及相关研究工作提供参考。     

Instrument study of the Lunar Dust eXplorer (LDX) for a lunar lander mission

One of the highest-priority issues for a future human or robotic lunar exploration is the lunar dust. This problem should be studied in depth in order to develop an environment model for a future lunar exploration. A future ESA lunar lander mission requires the measurement of dust transport phenomena above the lunar surface. Here, we describe an instrument design concept to measure slow and fast moving charged lunar dust which is based on the principle of charge induction. LDX has a low mass and measures the speed and trajectory of individual dust particles with sizes below one micrometer. Furthermore, LDX has an impact ionization target to monitor the interplanetary dust background. The sensor consists of three planes of segmented grid electrodes and each electrode is connected to an individual charge sensitive amplifier. Numerical signals were computed using the Coulomb software package. The LDX sensitive area is approximately 400 cm². Our simulations reveal trajectory uncertainties of better than 2° with an absolute position accuracy of better than 2 mm.     

Moon surface radiation environment analysis for February 1956 solar event conditions

The radiation environment on the surface of the Moon presents a new source of particles resulting from the interaction of incoming solar protons and galactic cosmic rays with the lunar regolith. Here we present a study of the fluence profile of primary and secondary particles on the top 1 m layer of lunar regolith for the spectrum of one of the hardest spectrum solar event, that of February 1956. Different regolith compositions and their influence in proton and neutron production and backscattering is considered, as well as the nature of the backscattered radiation. Simple geometry Monte Carlo simulations have been used also for calculating regolith shielding properties, and it is shown that a layer of at least 50 cm regolith is needed for significantly reducing the dose levels received by astronauts in a hypothetical lunar habitat.     

Plasma electron temperature variability in lunar surface potential and in electric field under average solar wind conditions

The Moon is immersed in plasma environment. The most interesting challenge of the lunar plasma– field environment is that it is alternatively dominated by the extended but variable outer atmosphere of the Earth – the magnetosphere – and by the extended but highly variable solar atmosphere – the solar wind. Understanding the plasma environment and its interaction with the lunar surface will be beneficial to both manned and robotic surface exploration activities and to scientific investigations. Presented is a preliminary map of variations of lunar surface electric potential over the day side and night side using probe equations and a discussion on dust dynamics in this E-field structure using the data from Electron Reflectometer in Lunar Prospector spacecraft during 1998–1999. On the day side, potential is around 5 V and on the night side it reaches up to −82 V. On the night side region, only highly energetic electrons can overcome this large negative potential. The variation at electron temperature (T_e) strongly reflects in the surface potential. The potential reaches to a value of −82 V for T_e = 58 eV. Surface charging causes the electrostatic transport of charged dust grains. Dust grain size of 0.1 μm shows a levitation height of 4.92 m on lunar day side, 748 m on terminator region and 3.7 km on the night side. The radius of maximum sized grain to be lofted, R_max, peaks at the terminator region (R_max = 0.83 μm). At the transition region dust levitation is almost absent. This region is most suited for exploration activities as the region is free from hazards caused by lunar dust.     

Production of high fidelity lunar agglutinate simulant

As space faring nations consider manned and unmanned missions to the Moon, there is a growing need to develop high fidelity lunar regolith simulants that can accurately reproduce the properties and behavior of lunar regolith. Such simulants will be employed to verify the performance of equipment, mechanisms, structures and processes to be used on the lunar surface. One of the significant limitations of current terrestrial-based simulants, such as the popular mare simulant, JSC-1A, is the lack of agglutinates. This paper investigates the production of a lunar mare agglutinate simulant based on JSC-1A. A modified plasma processing technique was used to expose the JSC-1A regolith simulant to high temperatures and transform it to predominantly a glassy phase. Detailed characterization results are presented to confirm that the agglutinate simulant material produced during this investigation reasonably satisfies the primary requirements of an agglutinate simulant such as amorphous/crystalline content, particle size, morphology, vesicular structure, chemistry, and presence of nanophase elemental Fe.     

The lunar dust pendulum

An analytic model for the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum is presented. It is shown that the dust grain executes oscillatory trajectories, and an expression is derived for the period of oscillation. Simulations used to verify the analytic expression also show that because the trajectories are unstable, dust grains are either ejected from the crater’s vicinity or deposited into the crater forming “dust ponds.” The model also applies to other airless bodies in the solar system, such as asteroids, and predicts that under certain conditions, particularly near lunar sunset, oscillating dust “canopies” or “swarms” will form over negatively charged craters.     

模拟月壤研制的初步设想

模拟月壤是月球样品的地球化学复制品，作者总结世界上已有的5种模拟月壤JSC-1，MLS．1，MLS-2，MKS-1和FJS-1的研制过程、方法与基本理化性质，认为系列化模拟月壤研制对中国首次月球探测有重要意义，在此基础上，作者提出系列化模拟月壤研制的基本思路．     

Gas permeability and flow characterization of simulated lunar regolith

Recent discoveries of water ice trapped within lunar topsoil (regolith) have placed a new emphasis on the recovery and utilization of water for future space exploration. Upon heating the lunar ice to sublimation, the resulting water vapor could theoretically transmit through the lunar regolith, to be captured on the surface. As the permeability of lunar regolith is essential to this process, this paper seeks to experimentally determine the permeability and flow characteristics of various gas species through simulated lunar regolith (SLR). Two different types of SLR were compacted and placed into the permeability setup to measure the flow-rate of transmitted gas through the sample. Darcy’s permeability constant was calculated for each sample and gas combination, and flow characteristics were determined from the results. The results show that Darcy’s permeability constant varies with SLR compaction density, and identified no major difference in permeable flow between the several tested gas species. Between the two tested SLR types, JSC-1A was shown to be more permeable than NU-LHT under similar conditions. In addition, a transition zone was identified in the flow when the gas pressure differential across the sample was less than ∼40 kPa.     

Electrostatic particle collection in vacuum

Lunar grains accumulate charges due to solar-based ionizing radiations, and the repelling action of like-charged particles causes the levitation of lunar dust. The lunar dust deposit on sensitive and costly surfaces of investigative equipment is a serious concern in lunar explorations. Inspired by electrostatic precipitators (ESPs), the Electrostatic Lunar Dust Collector (ELDC) was proposed for collecting already charged lunar dust particles to prevent the lunar dust threat. As the conditions for terrestrial counterparts are not valid in the lunar environment, equations developed for terrestrial devices yield incorrect predictions in lunar application. Hence, a mathematical model was developed for the ELDC operating in vacuum to determine its collection efficiency. The ratios of electrical energy over potential energy, kinetic energy over potential energy and the ratio of ELDC dimensions were identified to be the key dimensionless parameters. Sensitivity analyses of the relevant parameters showed that depending on ELDC orientation, smaller particles would be collected more easily at vertical orientation, whereas larger particles were easier to collect in a horizontal ELDC configuration. In the worst case scenario, the electrostatic field needed to be 10 times stronger in the vertical mode in order to adequately collect larger particles. The collection efficiency was very sensitive to surface potential of lunar dust and it reached the maximum when surface potential was between 30 and 120 V.