太阳风离子在月面的反射过程及对月面电场的影响

为探究月表磁异常区对太阳风离子产生反射的原理, 基于嫦娥二号卫星携带太阳风离子探测器的探测数据, 用单粒子模拟法反演太阳风离子运动, 并分析离子入射角和反射角的分布. 实验结果表明： 太阳风离子先被月壤向各方向大范围散射, 再被月面电场向天顶方向加速; 太阳风中, 月面有45~75 V电势, 该正电势对月面反射的太阳风离子有显著影响.     

Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite

Helium-3 (³He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the basis of the Apollo regolith samples, a linear relationship between ³He abundance and solar wind flux, optical maturity and TiO₂ content has been presented. China successfully launched its first lunar exploration satellite Chang-E 1 (CE-1) on October 24, 2007. A multi-channeled microwave radiometer was aboard the satellite with the purpose of measuring microwave thermal emission from the lunar surface layer. From the multi-channel brightness temperature (T_b) observed by CE-1, the global distribution of the regolith thickness was inverted from the multi-channel T_b, and was used to evaluate the total amount of ³He per unit area in the lunar regolith. The global inventory of ³He was estimated as being 6.6×10⁸ kg; 3.7×10⁸ kg for the lunar nearside and 2.9×10⁸ kg for the lunar farside.     

A non-terrestrial 16O-rich isotopic composition for the protosolar nebula

The discovery in primitive components of meteorites of large oxygen isotopic variations that could not be attributed to mass-dependent fractionation effects has raised a fundamental question: what is the composition of the protosolar gas from which the host grains formed? This composition is probably preserved in the outer layers of the Sun, but the resolution of astronomical spectroscopic measurements is still too poor to be useful for comparison with planetary material. Here we report a precise determination of the oxygen isotopic composition of the solar wind from particles implanted in the outer hundreds of nanometres of metallic grains in the lunar regolith. These layers of the grains are enriched in 16O by >20 +/- 4 per thousand relative to the Earth, Mars and bulk meteorites, which implies the existence in the solar accretion disk of reactions--as yet unknown--that were able to change the 17O/16O and 18O/16O ratios in a way that was not dependent strictly on the mass of the isotope. Photochemical self-shielding of the CO gas irradiated by ultraviolet light may be one of these key processes, because it depends on the abundance of the isotopes, rather than their masses.     

Developing space weathering on the asteroid 25143 Itokawa

Puzzlingly, the parent bodies of ordinary chondrites (the most abundant type of meteorites) do not seem to be abundant among asteroids. One possible explanation is that surfaces of the parent bodies become optically altered, to become the S-type asteroids which are abundant in the main asteroid belt. The process is called 'space weathering'-it makes the visible and near-infrared reflectance spectrum of a body darker and redder. A recent survey of small, near-Earth asteroids suggests that the surfaces of small S asteroids may have developing stages of space weathering. Here we report that a dark region on a small (550-metre) asteroid-25143 Itokawa-is significantly more space-weathered than a nearby bright region. Spectra of both regions are consistent with those of LL5-6 chondrites after continuum removal. A simple calculation suggests that the dark area has a shorter mean optical path length and about 0.04 per cent by volume more nanophase metallic iron particles than the bright area. This clearly shows that space-weathered materials accumulate on small asteroids, which are likely to be the parent bodies of LL chondrites. We conclude that, because LL meteorites are the least abundant of ordinary (H, L, and LL) chondrites, there must be many asteroids with ordinary-chondrite compositions in near-Earth orbits.     

核聚变与开发月球3 He资源的可行性研究

对开发月球^3He资源作为D-^3He聚变燃料的核聚变反应堆的经济技术和可行性进行了研究。对太阳风的参数分析与月球表层土中的^3He储量作了估计,对开采月球上^3He的可行性及D-^3He与D-T燃料的聚变能单位电价进行了比较。D-^3He聚变在经济上是可行的,它比通常的D-T为燃料的聚变电站更为安全、干净、可靠。     

基于光学数据的月壤介电常数的反演

摘要：月球元素含量的反演有利于了解月球物质成分的分布从而对月球矿产资源开发利用提供重要依据,对于月球科学的研究具有重要意义。本文利用LSCC数据和Clementine光学数据在全月球的角度上对月壤中FeO和TiO_2的含量进行反演,并基于回归分析建立介电常数和FeO和TiO_2含量总和的耦合关系,进而对介电常数进行反演,并与实测点的数据进行比较,验证了利用光学数据反演月壤元素含量以及通过回归分析反演介电常数的可行性,为月表反演的研究提供了新的思路。     

Terrestrial nitrogen and noble gases in lunar soils

The nitrogen in lunar soils is correlated to the surface and therefore clearly implanted from outside. The straightforward interpretation is that the nitrogen is implanted by the solar wind, but this explanation has difficulties accounting for both the abundance of nitrogen and a variation of the order of 30 per cent in the 15N/14N ratio. Here we propose that most of the nitrogen and some of the other volatile elements in lunar soils may actually have come from the Earth's atmosphere rather than the solar wind. We infer that this hypothesis is quantitatively reasonable if the escape of atmospheric gases, and implantation into lunar soil grains, occurred at a time when the Earth had essentially no geomagnetic field. Thus, evidence preserved in lunar soils might be useful in constraining when the geomagnetic field first appeared. This hypothesis could be tested by examination of lunar farside soils, which should lack the terrestrial component.     

Shoemaker crater as the source of most ejecta blocks on the asteroid 433 Eros

The loose material--regolith--on the surfaces of asteroids is thought to represent ballistically emplaced ejecta from impacts but the identification of source craters and the detailed study of the regolith modification have been hampered by the limited spatial resolution and area coverage of the few asteroids imaged by spacecraft. Here we report the results of global mapping of the asteroid 433 Eros from high-resolution images obtained by the NEAR-Shoemaker spacecraft. Based on the images and ejecta-emplacement models, we suggest that most large ejecta blocks on Eros originate from a relatively young 7.6-km-diameter crater. A large fraction of the ejecta from impacts pre-dating that crater has apparently been buried or eroded. The images also show evidence for the action of a variety of sorting environments for regolith particles after they are deposited on the surface.     

The modeling analysis of microwave emission from stratified media of non-uniform lunar cratered terrain surface for Chinese Chang-E 1 observation

In China’s first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness,and global evaluation of 3He content.To analyze the modeling of microwave radiative transfer from three-layered media of lunar surface,some factors,such as the cratered lunar surface roughness,scattering of regolith particulate medium with temperature profile,are discussed.Based on the statistics of the lunar cratered terrain and using Monte Carlo (MC) method,the cratered lunar surfaces are numerically generated.The triangulated network is utilized to divide the undulated lunar surface into discrete triangle meshes with the size 10 m as a digital surface topography.The reflectivities of each plane mesh are calculated,and the average reflectivity for all MC-realized lunar surfaces is obtained.It is found that under the spatial resolution of 30 km×30 km of Chang-E 1 radiometer observation,the lunar surface can be well modeled as a flat surface.It makes the predominance of the parameters,such as the regolith layer thickness and stratified structures,to be studied.Using the radiative transfer equation of stratified media with dense scatterers,the scattering coefficient of the regolith particulate medium is found negligible,and the emission is mainly governed by the absorptive property of the medium.Brightness temperature of multi-layered media,i.e.lunar soil,regolith layer with temperature profile and underlying rock media,are derived and calculated,and relevant main factors to affect the modeling and emission simulation are analyzed.     

月球探测的进展与我国月球探测的科学目标

在简述月球探测的历程与趋势的基础上,强调当代月球探测的总体目标为：(1)研究月球与地月系的起源和演化,特别是月球大气层与磁场的消失,矿物与岩石的分布和形成环境、月壤和内部层圈结构的形成以及月球演化的历程;(2)探测月球的资源、能源和特殊环境的开发利用及对人类社会长期可持续发展的支撑。我国不载人月球探测划分为绕、落及回三个阶段。为了全球性、整体性重新认识月球,绕月卫星探测的科学目标为获取全月面三维影像,探测14种有用元素的全球分布与丰度,探测月壤厚度并估算^3He资源量以及太阳活动对空间环境的影响。“落”为月球探测器软着陆就位探测和月球车巡视探测,建立月基光学、低频射电和极紫外天文观测平台。“回”为月球探测器软着陆就位探测和取样返回地面。     

An age-colour relationship for main-belt S-complex asteroids

Asteroid collisions in the main belt eject fragments that may eventually land on Earth as meteorites. It has therefore been a long-standing puzzle in planetary science that laboratory spectra of the most populous class of meteorite (ordinary chondrites, OC) do not match the remotely observed surface spectra of their presumed (S-complex) asteroidal parent bodies. One of the proposed solutions to this perplexing observation is that 'space weathering' modifies the exposed planetary surfaces over time through a variety of processes (such as solar and cosmic ray bombardment, micro-meteorite bombardment, and so on). Space weathering has been observed on lunar samples, in Earth-based laboratory experiments, and there is good evidence from spacecraft data that the process is active on asteroid surfaces. Here, we present a measurement of the rate of space weathering on S-complex main-belt asteroids using a relationship between the ages of asteroid families and their colours. Extrapolating this age-colour relationship to very young ages yields a good match to the colour of freshly cut OC meteorite samples, lending strong support to a genetic relationship between them and the S-complex asteroids.     

Glassy particles in lunar fines

Most of the Apollo 11 glassy particles differ from those generated by terrestrial volcanism, by meteoritic impacts, or by the condensation of the parent bodies of meteorites. Some of the particles may have been formed by the action of solar flares on the lunar surface.     

利用相比率影像方法研究月球月谷Schroteri区域

我们利用月球侦察轨道器（LRO）的窄角相机（NAC）数据,使用一种新的光学遥感方法—相比率影像法,来评估月表亚分辨率尺度的粗糙度.我们用该方法对月面谷Vallis Schrteri地区的三维相比率影像进行分析后发现,在月面谷侧面上风化物的复杂运动模式与撞击坑并无关联,而是由风化物和岩屑形成的,而非冲击熔融.     

月壤工程地质特性综述

根据国内外的最新研究成果,综述了近年来月壤工程地质力学特性研究的新进展.首先简述了月壤的矿物特征与化学成分,分析了月壤的级配、颗粒形态与孔隙率等物理性质;然后总结了月壤的变形特性与强度特征,阐述了目前模拟月壤的主要类别,及其内摩擦角、弹性参数等力学参数的研究成果;最后指出月壤研究中存在的问题,即模拟月壤试验必须注意环境变量(如弱重力)及化学成分对于工程地质性质的影响,同时应加强对月壤动力性质方面的研究.     

月球表面光度行为的地域依赖性分析

月球表面光度行为描述了月表物质反射的太阳光随入射、出射和太阳相角的变化,它取决于月壤颗粒的粒径和形状、孔隙度、粗糙度等物理特性和矿物成分等化学性质．本文利用嫦娥一号干涉成像光谱仪（IIM）2A级辐亮度数据,基于太阳相角一辐亮度二维直方图统计,可将月球表面划分为两种光度行为迥异的地域类型,二者FeO含量分别与月海和高地的值大致吻合．高地（阿波罗16号着陆点）和月海（澄海）区域的IIM数据验证了该划分方法的合理性．本文提出的直接依据IIM2A级数据太阳相角一辐亮度二维直方图的划分方法,可以避免FeO含量划分月表光度单元中由于后期数据处理过程引入的误差．     

Isotopic enhancements of 17O and 18O from solar wind particles in the lunar regolith

Differences in isotopic abundances between meteorites and rocks on Earth leave unclear the true composition of the gas out of which the Solar System formed. The Sun should have preserved in its outer layers the original composition, and recent work has indicated that the solar wind is enriched in 16O, relative to Earth, Mars and bulk meteorites. This suggests that self-shielding of CO due to photo-dissociation, which is a well understood process in molecular clouds, also led to evolution in the isotopic abundances in the early Solar System. Here we report measurements of oxygen isotopic abundances in lunar grains that were recently exposed to the solar wind. We find that 16O is underabundant, opposite to an earlier finding based on studies of ancient metal grains. Our result, however, is more difficult to understand within the context of current models, because there is no clear way to make 16O more abundant in Solar System rocks than in the Sun.     

基于数学形态学的月海圆形撞击坑自动识别方法

撞击坑是月球表面最为常见的地质单元,是研究月球地质演化历史的重要对象,也是月球地质定年的基本依据,因此撞击坑识别具有重要意义.本文根据嫦娥一号采集的月球CCD图像,基于数学形态学方法对撞击坑进行自动识别提取研究.在CCD图像中,撞击坑边缘的灰度变化明显,梯度较大,由此可以计算获取撞击坑的边缘形态;一般情况下,依据图像灰度梯度突变,通过边缘检测得到的撞击坑边缘比较粗糙、不连续,而且有断口和小洞.根据数学形态学的基本思想——用具有一定形态的结构元素去量度和提取图像中的对应形状,对识别出来的边缘作进一步处理,可得到较光滑、连续的撞击坑边缘弧,从而能方便地拟合出撞击坑边缘,并获得撞击坑的直径与位置.用数学形态学进行撞击坑识别与提取的主要步骤是：首先对CCD影像计算灰度的梯度,得到梯度图像,然后进行二值化,再使用数学形态学分离出边缘,最后用圆形对撞击坑进行拟合并计算出撞击坑的位置和直径.本文分别对月海和月陆地区进行撞击坑识别实验,结果表明,我们设计的算法能够识别的最小撞击坑直径为10个像素.其中月海区域撞击坑识别准确可靠;而月陆区域岩性差异大、地形起伏,造成CCD图像背景变化较大,其识别效果相对差一些,有待进一步改善.     

Domination of heliosheath pressure by shock-accelerated pickup ions from observations of neutral atoms

The solar wind blows an immense magnetic bubble, the heliosphere, in the local interstellar medium (mostly neutral gas) flowing by the Sun. Recent measurements by Voyager 2 across the termination shock, where the solar wind is slowed to subsonic speeds before entering the heliosheath, found that the shocked solar wind plasma contains only approximately 20 per cent of the energy released by the termination shock, whereas energetic particles above approximately 28 keV contain only approximately 10 per cent; approximately 70 per cent of the energy is unaccounted for, leading to speculation that the unmeasured pickup ions or energetic particles below 28 keV contain the missing energy. Here we report the detection and mapping of heliosheath energetic ( approximately 4-20 keV) neutral atoms produced by charge exchange of suprathermal ions with interstellar neutral atoms. The energetic neutral atoms come from a source approximately 60 degrees wide in longitude straddling the direction of the local interstellar medium. Their energy spectra resemble those of solar wind pickup ions, but with a knee at approximately 11 keV instead of approximately 4 keV, indicating that their parent ions are pickup ions energized by the termination shock. These termination-shock-energized pickup ions contain the missing approximately 70 per cent of the energy dissipated in the termination shock, and they dominate the pressure in the heliosheath.     

月表虹湾地区辉石及橄榄石含量反演

月表成分定量分布是月球探测中重要的一个科学问题．为了建立月表虹湾地区辉石与橄榄石的含量反演模型,本文在深入分析理解月表主要矿物的光谱特性的基础上,首先使用LSCC实测矿物数据,根据辉石、橄榄石在300-2600nm波谱范围的吸收特征分布,通过MGM模型计算19个采样点的光谱数据的5个吸收特征,每个吸收特征有吸收中心（Center）、吸收宽度（FWHM）、吸收强度（Strength）这3个吸收特征参数,利用多元回归分析建立矿物反演模型．由于缺乏月表实测数据,本文弓1入M^3高光谱数据利用Hapke辐射传输模型制作模拟混合矿物光谱对模型性能进行检验．最后,将反演模型应用于嫦娥三号月球车的首选着陆点一虹湾地区,得到其矿物含量分布图．实验表明利用MGM模型拟合分析的方法进行高光谱遥感矿物识别是一种可行的研究方法．     

TJ 1模拟月壤承载特性物理模型试验研究

借助现代土力学试验技术研究月壤工程特性,是解决月球上岩土工程问题的一个可行方法.室内载荷物理模型试验是研究土体承载特性的重要方法.本研究自行设计加工了一套可以实现加载速率控制的加载装置,采用试验材料为Tongji-1(简称TJ-1)模拟月壤,对4种不同尺寸的圆盘载荷板进行加载速率控制条件下的载荷模型试验,同时测定了基底土压力分布.试验结果表明:在相同载荷板条件下,TJ-1模拟月壤的地基极限承载力和变形模量随加载速率的增加而增加;在相同加载速率条件下,TJ-1模拟月壤的地基极限承载力和变形模量随载荷板尺寸增加而增加;加载时基底中心土压力最大.