双目立体显示技术在月表形貌三维可视化中的应用

基于嫦娥二号探测器获得的地形及影像数据,将双目立体显示技术应用于月表形貌三维可视化中,构建了月球三维立体可视化系统。介绍了双目立体显示原理,并对月球三维立体可视化系统的具体实现进行了详细的介绍。首先论述了系统的设计方案及硬件环境;接着论述了月球海量地形数据的组织方式和实时渲染方法;最后采用离轴模型的双目立体显示方法,实现了舒适的立体效果。月球科普及科研应用表明,系统具有良好的实用价值。     

绕月探测工程CCD立体相机的实验室辐射定标

探月光学有效载荷系统含CCD立体相机与干涉成像光谱仪两台光学遥感器,CCD立体相机完成的科学目标主要是与激光高度计配合获取月球表面三维立体图像。文章主要叙述了三线阵立体相机的工作原理,定标内容、目的以及CCD裸片像元检测和整机的相对定标和绝对定标过程。     

月球的形状及其物理参数

本文简要评述了研究月球形状的一般理论和已取得的主要结论,包括对月球进行空间探测(包括Doppler跟踪和LLR观测)以来,在这一领域内发生的重大变化,它们涉及月球内部密度分布模型的建立,对月核大小限制的讨论,月球的弹性以及自转能量耗散等问题。最后,综合这一领域内已获得的研究成果,提出了一项有关选择月球物理参数采用值的建议。     

“寂寞嫦娥舒广袖”——“嫦娥”一号探月卫星研制进展顺利

我国第一颗探月卫星“嫦娥”一号目前正按计划进行研制。卫星各关键技术已获得突破性进展,初样卫星的研制工作进展顺利。它将在未来两年内,用长征三号甲运载火箭从西昌卫星发射中心发射升空。科学与工程目标我国探月卫星工程有四大科学目标: 一是获取月球表面三维立体影像。目前,世界上还没有覆盖整个月面的影像,如果我国获取全月面三维影像,则对于更好地了解月球的地质构造和演化历史     

从地面发射月球探测器的窗口选择

典型的月球探测器飞行轨道包括地球停泊轨道段、地月转移轨道段、月球卫星轨道段和着月轨道段。首先介绍了设计从地面发射月球探测器轨道典型的约束条件;然后,借助于二体假设,建立解析表达式,分析各种约束对窗口选择的影响,给出了各轨道段概略的飞行时间和粗窗口;最后,利用精确的探测器轨道动力学模型,计算精窗口,并给出了一则算例,所得结论可为月球探测器轨道发射、轨道设计提供依据。     

月球有“冰湖”吗

月球有“冰湖”吗据美国《航空周刊与空间技术》杂志报道，美国宇航局在１９９３年就制定了一项重返月球的计划，天文学家们试图建立月基天文台，使月球成为一个新的天文学基地，预计在２０１０年～２０３０年建成月球基地。１９９４年，美国发射了“克莱门汀”号无人驾驶...     

月球开发畅想曲(续)

四　开发月球矿物资源　　只要在月球上建立起强大的能源基地,开发月球上的矿物资源也就是轻而易举之事了。那么月球上都有哪些矿物资源呢?从阿波罗登月飞船取回的月岩分析可知,地球上有的元素月岩中都有,从月岩中就可以取出人类所需要的元素。在带回来的60余种月岩中,其?..     

月球激光测距的现状及可能的改进方法

月球激光测距 (LLR)代表了单光子探测技术的高峰 ,是国际激光测距界奋斗的目标。本文回顾了月球激光测距的现状以及它所特有的技术难度 ,同时介绍了我们为增加月球激光测距回波光子数所提出的一些可能的改进方法。特别介绍了在月球激光测距中利用月面反射器近旁的月面扩展源探测与计算大气倾斜量 ,进而对测月的激光束实施大气倾斜量实时改正这样一个全新的概念。最后介绍了云南天文台的激光测距系统以及它的近期工作目标。     

基于Blender的天文数据三维可视化

天文学是一门以观测为基础的古老学科,在不同波段的各种形式天文望远镜的观测已经积累了大量的数据,天文学领域对数据的处理与展示有着很高的要求与期望。目前有很多团队着力于开发天文数据的可视化分析工具和软件,同时,有很多其他领域的软件,通过整合和修改也可以应用到天文数据上。介绍了对三维建模软件Blender的工具包的再开发,结合其内置的Python API和BPY库,实现对常用天文数据三维数据单元(Data Cube)和N体模拟结果的实时静态和动态三维可视化。     

我国地基雷达观测月球的现状和研究进展

地基雷达观测可以提供太阳系天体目标的地形地貌、物理特征、轨道动力等信息。聚焦利用地基雷达天文技术开展月球观测的原理方法和科学意义,介绍了基于我国现有深空雷达上行装置、射电望远镜条件以及非相干散射雷达等系统,初步开展的特高频段(Ultra High Frequency,UHF)和X频段的地基雷达观测月球试验。通过月球反射回波的信号处理,获得了延迟、多普勒频移等参数,得到了一致的与近表层物质密度相关的月面雷达反射率,并得到了月球的左右旋圆极化率,反映了与波长同尺度的月球近表层结构。文章积累的数据处理经验将为我国的小行星预警、行星历表等地基雷达观测研究提供技术基础。     

嫦娥二号探测器在轨运行视景仿真系统的研究与实现

针对嫦娥二号探测器在轨运行阶段的仿真需求,充分发挥视景仿真的优势,利用嫦娥一号探测器获得的地形和影像数据、日地月嫦娥二号探测器星历数据,基于OSG(OpenScene Graph)设计了针对嫦娥二号任务的在轨运行视景仿真系统。论述了该系统的开发平台,系统总体框架,并对系统的实现进行了详细描述。论述了月球模型数据构建,嫦娥二号探测器构建,星历数据库构建与访问,仿真实体空间位置的实时更新,CCD立体相机探测过程的仿真,视点的控制等实现方法。仿真结果表明系统完全能满足嫦娥二号任务在轨运行仿真的要求,并已应用于嫦娥二号任务执行过程中。     

China's Lunar Exploration Program: Present and future

China launched its first lunar probe, Chang’E-1, at 6:05 p.m. (10:05 GMT), October 24, 2007. Chang’E-1 blasted off on a Long March 3A carrier rocket from the No. 3 launch tower in the Xichang Satellite Launch Center of southwestern Sichuan Province. China National Space Administration performed the lunar orbit injection maneuver for Chang’E-1 at 11:25 a.m. on November 5, 2007 (China Standard Time). Chang’E-1 was injected into the lunar orbit after the maneuver, and will begin to explore the moon in the following 1 year. It is the first step into its ambitious three-phase moon mission, marking a new milestone in the Chinese space exploration history.     

中国古历经朔数据的恢复及应用

中国元代的《授时历议》保存了44部古历的推朔参数及比验资料．借助古代朔望计算方法：1）恢复了诸历行用初年的天正经朔数值；2）修正了史载的错误数据．3）根据Meeus方法计算出经朔的理论值，并由此确定古历经朔的推步精度；4）尝试应用这些数据考察地球自转长期变化，得出日长变化为1．8ms／cy．     

Simulation of precise orbit determination of lunar orbiters

Based on the ongoing Chinese lunar exploration mission, i.e. the “Chang'e 1” project, precise orbit determination of lunar orbiters is analyzed for the actual geographical distribution and observational accuracy of the Chinese united S-band (USB) observation and control network as well as the very long baseline interferometry (VLBI) tracking network. The observed data are first simulated, then solutions are found after including the effects of various error sources and finally compared. We use the space data analysis software package, GEODYN, developed at Goddard Space Flight Center, NASA, USA. The primary error source of the flight orbiting the moon is the lunar gravity field. Therefore, the (formal) error of JGL165P1, i.e. the model of the lunar gravity field with the highest accuracy at present, is first discussed. After simulating the data of ranging and velocity measurement as well as the VLBI data of the time delay and time delay rate, precise orbit determination is carried out when the error of the lunar gravity field is added in. When the orbit is determined, the method of reduced dynamics is adopted with the selection of appropriate empirical acceleration parameters to absorb the effect of errors in the lunar gravity field on the orbit determination. The results show that for lunar missions like the “Chang'e 1” project, that do not take the lunar gravity field as their main scientific objective, the method of reduced dynamics is a simple and effective means of improving the accuracy of the orbit determination of the lunar orbiters.     

基于虚拟天文台的HXMT卫星数据检索发布系统设计与实现

目前,国际上诸多天文项目均遵循虚拟天文台（Virtual Observatory,VO）标准协议开发各天文数据检索发布系统,对外公开发布数据,并对数据资源进行VO注册,从而使用户通过虚拟天文台门户网站即可访问获取不同天文项目的数据集.硬X射线调制望远镜（HXMT）卫星项目也将虚拟天文台技术引入HXMT卫星数据检索发布系统的设计与实现过程中,既满足HXMT卫星数据发布需求,又将HXMT卫星数据融入虚拟天文台环境,实现国际天文数据的共享共用.系统提出了符合虚拟天文台规范的体系架构,并选取SCS锥形检索、VOTable数据格式等虚拟天文台标准协议加以实现,采用MVC模式、SSH框架以及各种J2EE技术进行软件研发,提供检索访问、浏览下载和可视化功能.实践和应用结果表明,系统在解决天文数据资源互操作、共享发布、检索访问及异构应用集成方面均具有可操作性,对我国空间天文卫星数据检索发布系统的研制具有参考意义.     

Implementation of cartographic symbols for planetary mapping in geographic information systems

The steadily growing international interest in the exploration of planets in our Solar System and many advances in the development of space-sensor technology have led to the launch of a multitude of planetary missions to Mercury, Venus, the Earth's moon, Mars and various Outer-Solar System objects, such as the Jovian and Saturnian satellites. Camera instruments carried along on these missions image surfaces in different wavelength ranges and under different viewing angles, permitting additional data to be derived, such as spectral data or digital terrain models. Such data enable researchers to explore and investigate the development of planetary surfaces by analyzing and interpreting the inventory of surface units and structures. Results of such work are commonly abstracted and represented in thematic, mostly geological and geomorphological, maps. In order to facilitate efficient collaboration among different planetary research disciplines, mapping results need to be prepared, described, managed, archived, and visualized in a uniform way. These tasks have been increasingly carried out by means of computer-based geographic information systems (GIS or GI systems) which have come to be widely employed in the field of planetary research since the last two decades. In this paper we focus on the simplification of mapping processes, putting specific emphasis on a cartographically correct visualization of planetary mapping data using GIS-based environments. We present and discuss the implementation of a set of standardized cartographic symbols for planetary mapping based on the Digital Cartographic Standard for Geologic Map Symbolization as prepared by the United States Geological Survey (USGS) for the Federal Geographic Data Committee (FGDC). Furthermore, we discuss various options to integrate this symbol catalog into generic GI systems, and more specifically into the Environmental Systems Research Institute's (ESRI) ArcGIS environment, and focus on requirements for symbol definitions in the field of planetary mapping. A symbology of this type can be embedded into any modular GIS environment capable in dealing with external stand-alone as well as database-driven management of symbol sets. Using such a uniform GIS-based symbol catalog will give the research community access to map results already cartographically elaborated, enabling them to create digital maps as a secondary data source in subsequent studies.     

Dynamical History of the Earth–Moon System

Differential equations describing the tidal evolution of the earth's rotation and of the lunar orbital motion are presented in a simple close form. The equations differ in form for orbits fixed to the terrestrial equator and for orbits with the nodes precessing along the ecliptic due to solar perturbations. Analytical considerations show that if the contemporary lunar orbit were equatorial the evolution would develop from an unstable geosynchronous orbit of the period about 4.42 h (in the past) to a stable geosynchronous orbit of the period about 44.8 days (in the future). It is also demonstrated that at the contemporary epoch the orbital plane of the fictitious equatorial moon would be unstable in the Liapunov's sense, being asymptotically stable at early stages of the evolution. Evolution of the currently near-ecliptical lunar orbit and of the terrestrial rotation is traced backward in time by numerical integration of the evolutional equations. It is confirmed that about 1.8 billion years ago a critical phase of the evolution took place when the equatorial inclination of the moon reached small values and the moon was in a near vicinity of the earth. Before the critical epoch t _cr two types of the evolution are possible, which at present cannot be unambiguously distinguished with the help of the purely dynamical considerations. In the scenario that seems to be the most realistic from the physical point of view, the evolution also has started from a geosynchronous equatorial lunar orbit of the period 4.19 h. At t < t _cr the lunar orbit has been fixed to the precessing terrestrial equator by strong perturbations from the earth's flattening and by tidal effects; at the critical epoch the solar perturbations begin to dominate and transfer the moon to its contemporary near-ecliptical orbit which evolves now to the stable geosynchronous state. Probably this scenario is in favour of the Darwin's hypothesis about originating the moon by its separation from the earth. Too much short time scale of the evolution in this model might be enlarged if the dissipative Q factor had somewhat larger values in the past than in the present epoch. Values of the length of day and the length of month, estimated from paleontological data, are confronted with the results of the developed model.     

Lunisolar effect on the trigger of earthquakes

Dealing with moon theory and tidal dynamics and checking lists of earthquake data one can take the following two observations: 1) The first extreme proxigean spring tide in the new millennium happened on 2005 January 10, in new moon phase, and half a synodic month earlier, when the Moon was full on 2004 December 26, the Christmas Tsunami was triggered in the Indian Ocean. The next extreme tide in new moon phase will occur after one Saros cycle, on 2023 January 21. 2) The second observation is connected with the lunar evection anomaly. The time between the Whitsun Quake in China on 2008 May 12 and the Christmas Tsunami amounts to 1233 days. On the other hand, three lunar evectional cycles take 3 × U_e = 3 × 411.8 = 1235 days. These observations hint at lunisolar structures in the earthquake distribution. In the present treatise we will reveal such structures by composing lunisolar ephemerides and earthquake Tables. In particular, we use Student's t‐test and show that there is a significant relationship between the beat period U_e and the earthquake statistics (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

‘Direct’ evidence for water (H2O) in the sunlit lunar ambience from CHACE on MIP of Chandrayaan I

Direct detection of water in its vapour phase in the tenuous lunar environment through in situ measurements carried out by the Chandra’s Altitudinal Composition Explorer (CHACE) payload, onboard the Moon Impact Probe (MIP) of Chandrayaan I mission vindicates the presence of water on the surface of the moon in form of ice at higher lunar latitudes inferred from IR absorption spectroscopy, (especially that of OH), by the Moon Mineralogy Mapper (M³) of Chandrayaan I. The quadrupole mass spectrometer based payload, CHACE, sampled the lunar neutral atmosphere every 4 s with a broad latitudinal (∼40°N to 90°S, with a resolution of ∼0.1°) and altitudinal (from 98 km up to impact on the lunar surface with a resolution of ∼0.25 km) coverage in the sunlit side of the moon for the first time. These two (CHACE and M³) complementary experiments are shown to collectively provide unambiguous signatures for the distribution of water in solid and gaseous phases in Earth’s moon.     

Feasibility of spectro-photometry in X-rays (SPHINX) from the moon

Doing space Astronomy on lunar surface has several advantages. We present here feasibility of an All Sky Monitoring Payload for Spectro-photometry in X-rays (SPHINX) which can be placed on a lander on the moon or in a space craft orbiting around the moon. The Si–PIN photo-diodes and CdTe crystals are used to detect solar flares, bright gamma bursts, soft gamma-ray repeaters from space and also X-ray fluorescence (XRF) from lunar surface. We present the complete Geant4 simulation to study the feasibility of such an instrument in presence of Cosmic Diffused X-Ray Background (CDXRB). We find that the signal to noise ratio is sufficient for moderate to bright GRBs (above 5 keV), for the quiet sun (up to 100 keV), solar flares, soft gamma-ray repeaters, X-ray Fluorescence (XRF) of lunar surface etc. This is a low-cost system which is capable of performing multiple tasks while stationed at the natural satellite of our planet.