"牧羊人"魂归何处?

撞月地点位于月球南极卡比厄斯月坑的永久阴影区，科学家认为在月坑永久阴影区有可能存在水冰。水冰可能来自撞击月球的彗星。月球南极的卡比厄斯月坑大约位于南纬85度、东经310度。     

极区月壤和水冰形成演化机制及物理特性研究

月球极区独特的光照条件和表面环境特征是水富集和保存的理想场所,探测永久阴影区内的水冰对科学研究和开发利用月球资源具有重要的意义.综合调研了国际上在月球极区开展的理论研究和遥感探测成果,阐述了极区地质、表面光照条件和热环境特征.介绍了极区月壤和水的形成演化机制及水冰可能的赋存状态.系统梳理了国际上关于极区水冰的探测历程和...     

可持续性月球水资源提取利用设计与分析

月球极区水冰资源开发利用是月球基地建设和可持续性运行的重要支撑技术之一。在对月球南极永久阴影区的工作地点进行选址的基础上，调研了国内外月球极区水冰资源开发利用计划、实施方案和发展趋势。提出了一种可持续性月球极区含冰月壤水资源提取利用方案，由移动式基地载具、原位钻取机器人和可移动式反射镜组三部分组成，具有灵活布置以持续性开采阴影坑内水冰资源的能力。对所设计方案的物质流和能量流进行了计算建模，并进行了程序化分析。计算结果表明，通过提升太阳能传递效率、光电转换效率、热提取加热效率和水电解效率，初始水冰质量含量高于5.0%,可以显著减少系统任务的总能耗。方案设计与分析结果可为中国月球基地任务提供参考。     

“月球坑观测与感知卫星”将撞击月球

2009年6月,“月球坑观测与感知卫星”（LCROSS）将作为次要载荷与“月球勘测轨道器”（LRO）同时发射升空。1概述LRO与LCROSS是美国航空航天局（NASA）多项无人月球探测计划的第1项任务,主要目的是：研究、测绘和了解月球表面的情况,探测未来的潜在月球着陆点;勘察月球极地永久阴影区的水资源,验证“克莱门汀”（Clementine）和“月球勘探者”（LunarProspector）探测器对月球水冰的探测结果,为航天员重返月球作准备。     

月球水冰资源综合开发技术研究概况

水冰作为月球的重要资源，是未来月球科研站以及月球基地建设和运行的基本保障，开展月球水冰资源综合开发技术研究是目前各航天大国的关注热点之一。本文调研了有关月球水冰的探测和研究成果，阐述了月球水冰的赋存状态与分布特征，详细分析了月球水冰资源在开采提取、分离纯化、储存运输和分解利用等环节的技术方案，并简要评述了各个方案的优缺点。结合中国未来国际月球科研站的建设规划与美国以建立月球基地为目标的阿尔忒弥斯（Artemis）计划，评价分析了适宜开展月球水冰资源综合开发的地区和可行的技术方案，为中国在月球两极地区的水冰资源开发利用方案提供参考。     

月球两极存在大量冰态水

月球两极存在大量冰态水□□美国航宇局艾姆斯研究中心３月５日宣布说，根据迄今“月球勘探者”太空探测器对月球的初步探测，已有充分的证据表明，月球两极地区表层下面存在大量零散的冰块，且北极蕴藏的冰块数量约为南极的两倍。月球上有无可利用的大面积水资源对于未来...     

一片冰心在玉壶“月球勘探者”证实月球存在水冰

一片冰心在玉壶“月球勘探者”证实月球存在水冰□□１９９８年３月５日，美国航宇局的刘易斯研究中心，向新闻界公布了“月球勘探者”探测器获得的第一批月球探测结果，证实了月球上确实存在水冰，并初步测算出月面上水的总储量可能在１１×１０６ｔ～３．３×１０８ｔ之...     

月球上有多少水

早在20世纪60年代初，科学家就注意到在月球两极永久背阴的陨石坑中，可能存在着水冰，那是由彗星撞击带来的。     

以太阳风为源水分子在月球空间环境中的分布特征

近年来,越来越多的观测结果均显示月球上存在水.本文通过运用Monte-Carlo方法及基于能量守恒的有心力场中粒子轨道算法对水分子在近月表的输运过程进行建模,得到了水分子在近月表分布随时间演化的图像.模拟结果显示,分布在高纬地区的水分子较同经度的中低纬地区要多,这与目前探测得到的结论是一致的.同时,对最终进入永久阴影区的水分子的百分比进行了统计,在光解离常数为6.4×104s的情况下,有大约4.12%的水分子会被永久阴影区存储下来,这个比例与前人估算结果相吻合.      

月球永久阴影区着陆点选取要求的高分辨率极化SAR数据分析

月球两极永久阴影区(Permanently Shadowed Regions,PSR)全年没有直接光照,搜寻PSR内的月球水冰是"嫦娥七号"的主要任务之一.人类至今没有在PSR着陆,中国的"嫦娥七号"任务计划在PSR附近的太阳直射区域登陆,着陆器上携带的飞跃器将进入PSR进行采样与分析.如何选择登月点和取样点是该项任务...     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.     

Scaling analysis and model estimation of solar corona index

A monthly average solar green coronal index time series for the period from January 1939 to December 2008 collected from NOAA (The National Oceanic and Atmospheric Administration) has been analysed in this paper in perspective of scaling analysis and modelling. Smoothed and de-noising have been done using suitable mother wavelet as a pre-requisite. The Finite Variance Scaling Method (FVSM), Higuchi method, rescaled range (R/S) and a generalized method have been applied to calculate the scaling exponents and fractal dimensions of the time series. Autocorrelation function (ACF) is used to find autoregressive (AR) process and Partial autocorrelation function (PACF) has been used to get the order of AR model. Finally a best fit model has been proposed using Yule-Walker Method with supporting results of goodness of fit and wavelet spectrum. The results reveal an anti-persistent, Short Range Dependent (SRD), self-similar property with signatures of non-causality, non-stationarity and nonlinearity in the data series. The model shows the best fit to the data under observation.     

Stochastic particle acceleration by the forced interaction of relativistic current sheets

We address the problem of interacting relativistic current sheets in self-consistent kinetic plasma simulations within the framework of the Particle-In-Cell model. The interaction is enforced in head-on collisions of up to 10 current sheets at relativistic bulk speeds. The simulations are motivated by the general problem of Poynting flux dissipation in ‘striped wind’ configurations presumably governing the relativistic outflows pervasive in pulsar winds and gamma-ray bursts. We identify the generation of non-thermal particles and formation of a stable power-law shape in the particle energy distributions f(γ) dγ ∝ γ^−s dγ. In 1D, a spectral index s ∼ 2 is observed and attributed to a stochastic Fermi-type acceleration mechanism. In 2D, the generic index of s ∼ 3–4 is retained as in previous simulations of individual current sheets. Whereas in 2D the high energy cut-off is constrained by the limited dissipation of magnetic energy, in 1D the process converts the bulk motion of current sheets towards directed particle momentum of an exclusive class of non-thermal particles.     

Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary results

In the frame of the 2009 Mars Science Laboratory (MSL) mission a new sample preparation system (SPS) compatible with gas chromatography–mass spectrometry (GC–MS) has been developed for the in situ analysis of complex organic molecules in the Martian soil. The goal is to detect, if they exist, some of the key compounds that play an important role in life on Earth including carboxylic acids, amino acids and nucleobases.     

Concept options for the aerial survey of Titan

Various aerial platforms intended for long endurance survey of the Titan surface are presented. A few novel concepts are introduced, including a heated methane balloon and a balloon with a tethered wind turbine. All the concept options are predicted to have lower scientific payload fractions than the Huygens probe. It is concluded that the selection of the best aerial platform option depends on more accurate mass estimates and a clear decision on whether, or not, in situ surface composition measurements are required in conjunction with aerial remote sensing.     

Heterogeneous solid/gas chemistry of organic compounds related to comets,meteorites, Titan,and Mars: Laboratory and in lower Earth orbit experiments

To understand the evolution of organic molecules involved in extraterrestrial environments and with exobiological implications, many experimental programs in the laboratory are devoted to photochemical studies in the gaseous phase as well as in the solid state. The validity of such studies and their applications to extraterrestrial environments can be questioned as long as experiments conducted in space conditions, with the full solar spectrum, especially in the short wavelength domain, have not been implemented. The experiments that are described here will be carried out on a FOTON capsule, using the BIOPAN facility, and on the International Space Station, using the EXPOSE facility. Vented and sealed exposition cells will be used, which will allow us to study the chemical evolution in the gaseous phase as well as heterogeneous processes, such as the degradation of solid compounds and the release of gaseous fragments.     

基于LuGre模型的电液加载系统摩擦补偿

为了提高电液加载系统控制精度,针对摩擦问题提出了基于LuGre摩擦模型的前馈补偿方法.建立了用于摩擦仿真分析和补偿器设计的电液加载系统数学模型;通过实验获取并分析了相关的摩擦数据;基于实验数据进行LuGre模型参数辨识,把LuGre模型和辨识结果引入电液加载系统数学模型,并进行仿真结果与实际摩擦数据的对照,证明了LuGre摩擦模型的准确性.设计前馈补偿器,进行了实验对比,实验结果表明前馈补偿器可将摩擦产生的控制误差有效地降至未补偿时的30%左右.      

The ESA scientific programme

The ESA scientific programme has, so far, provided several significant astrophysics experiments and further important missions are scheduled for execution during the next decade. These missions are briefly summarised together with several astrophysics investigations presently under study.     

CoRoT and Kepler results: Solar-like oscillators

The space-borne observatories CoRoT (Convection Rotation and planetary Transits) and Kepler have provided photometric time series data of unprecedented precision for large numbers of stars. These data have revolutionized the fields of transiting exoplanets and asteroseismology. In this review some important asteroseismic results obtained using data from the CoRoT and Kepler space missions concerning stars that show solar-like oscillations are discussed. These results comprise, among others, measurements of the location of the base of the convection zone and helium second-ionization zone in main-sequence stars, the presence (or not) of core-helium burning in red-giant stars, as well as differential rotation in these stars.     

Return to Europa: Overview of the Jupiter Europa orbiter mission

Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.