Space Astronomy in China： 2006-2008

In 2006 to 2008,the main activities in Chinese space astronomy focus on:(1)undertaking some missions set by CNSA,like HXMT,SMESE,wso/vv,SST,KUAFU,and so on;(2)drawing up a long-term plan of Chinese space astronomy.This paper summarizes in brief all these activities.     

中国空间天文40周年

过去40年中国空间天文学研究取得了巨大的发展.尤其是近10年内发射了数颗天文卫星,未来几年还将有一些天文卫星计划发射.本文简要回顾了国际空间天文学的发展历程.对中国空间天文学过去40年的发展进行了回顾和总结,包括1970年代第一颗天文卫星计划、气球空间天文探测、基于载人航天工程的空间天文实验以及天文卫星等.此外,介绍了...     

Status of the Stratospheric Observatory for Infrared Astronomy (SOFIA)

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint US/German project, is a 2.5-m infrared airborne telescope carried by a Boeing 747-SP that flies in the stratosphere at altitudes as high as 45,000 ft (13.72 km). This facility is capable of observing from 0.3 μm to 1.6 mm with an average transmission greater than 80% averaged over all wavelengths. SOFIA will be staged out of the NASA Dryden Flight Research Center aircraft operations facility at Palmdale, CA. The SOFIA Science Mission Operations (SMO) will be located at NASA Ames Research Center, Moffett Field, CA. First science flights began in 2010 and a full operations schedule of up to one hundred 8 to 10 hour-long flights per year will be reached by 2014. The observatory is expected to operate until the mid-2030s. SOFIA’s initial complement of seven focal plane instruments includes broadband imagers, moderate-resolution spectrographs that will resolve broad features due to dust and large molecules, and high-resolution spectrometers capable of studying the kinematics of atomic and molecular gas at sub-km/s resolution. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community and for future instrumentation development. The operational characteristics of the SOFIA first-generation instruments are summarized. The status of the flight test program is discussed and we show First Light images obtained at wavelengths from 5.4 to 37 μm with the FORCAST imaging camera. Additional information about SOFIA is available at http://www.sofia.usra.edu and http://www.sofia.usra.edu/Science/docs/SofiaScienceVision051809-1.pdf.     

一种校准空间蓄电池在不同加速度状态下电特性的装置CSCD

在飞行器发射升空之前,需对空间蓄电池进行一系列的测试。而地球上的环境和在太空中的环境存在很大的不同,尤其是太空的失重环境,在地球上很难长时间的模拟,以达到测试的目的。这样在地面上的测试数据可能与实际工作所得有所偏差。针对这种情况,文章提出了一种校准空间蓄电池在不同加速状态下电特性的装置。     

天基朗缪尔探针传感器设计与仿真

朗缪尔探针是进行空间等离子体电子密度和温度就位测量的重要仪器, 在电离层卫星探测和火箭探测中应用十分广泛. 传感器设计的合理与否是影响朗缪尔探针探测结果的关键因素之一. 朗缪尔探针传感器的结构本身比较简单, 但传感器的设计要受到多种物理条件及工程条件的限制, 其中, 有些限制条件相互制约甚至相互矛盾, 必须综合进行考虑. 从传感器形状、大小和表面材料的选取三个方面分析了朗缪尔探针的各种限制条件, 给出了一种原型朗缪尔探针的设计, 并通过仿真计算验证了该设计.     

The X-ray evolution of galaxies: implications for future X-ray observatories

The X-ray evolution of the luminosity of normal galaxies is primarily driven by the evolution of their X-ray binary populations. The imprints left by a cosmological evolution of the star formation rate (SFR) will cause the average X-ray luminosity of galaxies to appear higher in the redshift range 1–3. As reported by White and Ghosh [ApJ, 504 (1998) L31] the profile of X-ray luminosity with redshift can both serve as a diagnostic probe of the SFR profile and constrain evolutionary models for X-ray binaries. In order to observe the high redshift (z>3) universe in the X-ray band, it is necessary to avoid confusion from foreground field galaxies. We report on the predictions of these models of the X-ray flux expected from galaxies and the implications for the telescope parameters of future deep universe X-ray observatories.     

空间碎片光谱特性获取与分析方法研究

空间碎片的反射光谱是碎片表面材料与太阳光谱共同作用的结果,能够反映碎片的材料性质,为空间碎片的光学特性研究提供依据. 将观测获得的空间碎片反射光谱进行预处理后,与已知空间材料样本的光谱进行比对,比较两者间光学特性差异,包括连续反射光谱曲线中的峰值、斜率、形态、特征窄波段、吸收谱线和多波段反射光谱间的成像差异、色指数、特征温度等,分辨碎片表面可能的材料,最终实现对空间碎片光学特性的研究.     

空间站机械臂研究

空间极端环境下, 大多数舱外活动必须借助于机械臂. 机械臂是国际空间站的主要组成部分, 其对空间站的在轨组装、外部维修以及运行起着至关重要的作用, 同时机械臂可以减少航天员在舱外的工作时间和频率. 通过对国际空间站成员国关于机械臂研究概况的介绍, 包括航天飞机机械臂、空间站机械臂、欧洲机械臂、日本实验舱机械臂以及德国机械臂, 为中国空间机械臂的设计提供参考.     

空间探测磁强计安装部件的力学特性分析

对某深空探测器中的有效载荷-高精度磁强计的安装部件进行了有限元分析,分别获取了磁强计安装部件在升空过程中承受40g加速度冲击载荷以及-180～75℃的极限温度情况下,在x,y,z方向上的最大应力和最大位移,给出了由于磁强计安装部件的变形而导致的三个探头在x,y,z方向上的偏转角度,采用扫频实验法分析了磁强计安装部件的频谱特性,为空间探测磁强计的设计提供了依据.     

空间物理过程时空协同探测的覆盖分析方法研究

针对空间物理过程时空协同探测任务的定量化探测覆盖分析需求, 在采用时空相关函数方法描述和分析空间物理时空过程的基础上, 提出一种基于θ-t_R覆盖图的探测覆盖分析方法. 通过分析不同设计方案在一定累计时间周期内的θ-t_R覆盖图, 根据其覆盖范围的不同选择所需要的设计方案. 采用该方法对两条共轨道面椭圆轨道的时空协同探测过程进行了定量的覆盖分析, 验证了该方法的有效性.     

基于解体事件的空间碎片轨道演化算法研究

针对航天器解体事件所生成的空间碎片的演化过程,进行了数学分析,确定了新生成的空间碎片的速度增量,在该增量作用下碎片轨道会发生变更,本文根据该增量得出了空间碎片在轨道变更后的轨道根数,分析了在大气阻力摄动作用下,空间碎片的数目和轨道分布的演化情况,给出了相关结果,结果表明此算法可行.     

First results of operational ionospheric dynamics prediction for the Brazilian Space Weather program

It is shown the development and preliminary results of operational ionosphere dynamics prediction system for the Brazilian Space Weather program. The system is based on the Sheffield University Plasmasphere–Ionosphere Model (SUPIM), a physics-based model computer code describing the distribution of ionization within the Earth mid to equatorial latitude ionosphere and plasmasphere, during geomagnetically quiet periods. The model outputs are given in a 2-dimensional plane aligned with Earth magnetic field lines, with fixed magnetic longitude coordinate. The code was adapted to provide the output in geographical coordinates. It was made referring to the Earth’s magnetic field as an eccentric dipole, using the approximation based on International Geomagnetic Reference Field (IGRF-11). During the system operation, several simulation runs are performed at different longitudes. The original code would not be able to run all simulations serially in reasonable time. So, a parallel version for the code was developed for enhancing the performance. After preliminary tests, it was frequently observed code instability, when negative ion temperatures or concentrations prevented the code from continuing its processing. After a detailed analysis, it was verified that most of these problems occurred due to concentration estimation of simulation points located at high altitudes, typically over 4000 km of altitude. In order to force convergence, an artificial exponential decay for ion–neutral collisional frequency was used above mentioned altitudes. This approach shown no significant difference from original code output, but improved substantially the code stability. In order to make operational system even more stable, the initial altitude and initial ion concentration values used on exponential decay equation are changed when convergence is not achieved, within pre-defined values. When all code runs end, the longitude of every point is then compared with its original reference station longitude, and differences are compensated by changing the simulation point time slot, in a temporal adjustment optimization. Then, an approximate neighbor searching technique was developed to obtain the ion concentration values in a regularly spaced grid, using inverse distance weighting (IDW) interpolation. A 3D grid containing ion and electron concentrations is generated for every hour of simulated day. Its spatial resolution is 1° of latitude per 1° of longitude per 10 km of altitude. The vertical total electron content (VTEC) is calculated from the grid, and plotted in a geographic map. An important feature that was implemented in the system is the capacity of combining observational data and simulation outputs to obtain more appropriate initial conditions to the ionosphere prediction. Newtonian relaxation method was used for this data assimilation process, where ionosonde data from four different locations in South America was used to improve the system accuracy. The whole process runs every day and predicts the VTEC values for South America region with almost 24 h ahead.     

A Cosmic Microscope to Probe the Universe from Present to Cosmic Dawn:Dual-element Lowfrequency Space VLBI Observatory

A space-based Very Long Baseline Interferometry (VLBI) program, named as the Cosmic Microscope, is proposed to involve dual VLBI telescopes in the space working together with giant ground-based telescopes (e.g., Square Kilometre Array, FAST, Arecibo) to image the low radio frequency Universe with the purpose of unraveling the compact structure of cosmic constituents including supermassive black holes and binaries, pulsars, astronomical masers and the underlying source, and exoplanets amongst others. The operational frequency bands are 30, 74, 330 and 1670 MHz, supporting broad science areas. The mission plans to launch two 30-m-diameter radio telescopes into 2 000 km×90 000 km elliptical orbits. The two telescopes can work in flexibly diverse modes. (i) Space-ground VLBI. The maximum space-ground baseline length is about 100 000 km; it provides a high-dynamic-range imaging capacity with unprecedented high resolutions at low frequencies (0.3 mas at 1.67 GHz and 20 mas at 30 MHz) enabling studies of exoplanets and supermassive black hole binaries (which emit nanoHz gravitational waves). (ii) Space-space single-baseline VLBI. This unique baseline enables the detection of flaring hydroxyl masers, and more precise position measurement of pulsars and radio transients at mas level. (iii) Single dish mode, where each telescope can be used to monitor transient bursts and rapidly trigger follow-up VLBI observations. The large space telescope will also contribute in measuring and constraining the total angular power spectrum from the Epoch of Reionization. In short, the Cosmic Microscope offers astronomers the opportunity to conduct novel, frontier science.     

空间里的时间:微重力等环境下的生物节律研究

生物钟是地球上的生物为适应环境周期性变化经历长期演化而来的内在机制.在分子水平上受生物钟基因及其他相关基因的调节;在组织水平上,生物钟由主生物钟和外周生物钟组成.生物钟对于各种生物的生理、认知和行为等具有重要功能,是生物适应环境的决定因素之一.空间环境下的微重力、辐射、光照条件、社会性因素等与地面存在很大差异,这些因素均可能导致节律紊乱,影响生物的生理及环境适应性.因此,对地外生命的研究也应该考虑生物钟因素.对航天员而言,节律紊乱可引起睡眠障碍,并且对骨肌系统、神经系统、心血管系统及内分泌系统等造成不利影响,导致人的认知和工效水平下降.在未来空间生命探索以及航天员健康保障研究中,生物钟是一个不可忽视的重要因素.     

Planetary protection on international waters: An onboard protocol for capsule retrieval and biosafety control in sample return mission

Planetary protection has been recognized as one of the most important issues in sample return missions that may host certain living forms and biotic signatures in a returned sample. This paper proposes an initiative of sample capsule retrieval and onboard biosafety protocol in international waters for future biological and organic constituent missions to bring samples from possible habitable bodies in the solar system. We suggest the advantages of international waters being outside of national jurisdiction and active regions of human and traffic affairs on the condition that we accept the Outer Space Treaty. The scheme of onboard biological quarantine definitely reduces the potential risk of back-contamination of extraterrestrial materials to the Earth.     

空间电子辐射环境探测载荷测试定标试验平台研制

介绍了中国科学院国家空间科学中心新建成的空间电子辐射环境探测载荷测试定标试验平台.该平台由中、高能极弱流电子加速器以及内置多维真空转台的真空靶室试验终端组成,用于对星载空间电子辐射探测器进行地面加速器测试定标.重点描述了为得到中能极弱流均匀平行束,采用电子轨迹程序Egun对中能极弱流电子加速器进行的物理设计和模拟计算,给出球形结构电子枪在栅网孔不加栅网、加理想栅网和直径1mm孔栅网以及在不同加速管出口能量情况下,初聚系统和加速管以及经过二次扩束时输运段中电子轨迹的模拟结果.最终得出能够实现电子枪初始束流减弱8个数量级,获得满足测试定标试验需求的极弱流均匀平行电子束（在试验终端直径50mm靶上束流面密度为10⁵~10⁹cm^-2·s^-1）的结论.     

雷达波束驻留模式下空间碎片数量的置信区间估计

碎片数量估计是空间碎片环境统计特征描述的重要内容之一,对于空间碎片环境模型验证、航天器碰撞风险分析以及碎片数量增长趋势预测有重要意义.针对波束指向正东、正南任意仰角的雷达波束驻留(Beam-park)模式(天顶指向是波束指向仰角为90°时的特例),给出了一种估计碎片数量置信区间的方法.对于给定轨道高度范围内一个具有穿越雷达波束可能性(即雷达散射截面足够大,且轨道倾角相对测站纬度足够大)的碎片,将其是否真正穿越波束这一随机事件用(0-1)分布来建模,根据所采集的轨道高度和倾角数据,计算出该轨道高度范围内碎片穿越波束的平均概率,进而采用中心极限定理来估计碎片数量的置信区间.仿真结果表明了方法的有效性.     

Physical characterization of the deep-space debris WT1190F: A testbed for advanced SSA techniques

We report on extensive ${\mathit{BVR}}_c{I}_c$ photometry and low-resolution ($\lambda /\mathrm{\Delta }\lambda ～250$) spectroscopy of the deep-space debris WT1190F, which impacted Earth offshore from Sri Lanka, on 2015 November 13. In spite of its likely artificial origin (as a relic of some past lunar mission), the case offered important points of discussion for its suggestive connection with the envisaged scenario for a (potentially far more dangerous) natural impactor, like an asteroid or a comet.Our observations indicate for WT1190F an absolute magnitude $R_c={32.45}_{\pm 0.31}$, with a flat dependence of reflectance on the phase angle, such as ${\mathit{dR}}_c/d?～{0.007}_{\pm 2}$?mag?deg^?1. The detected short-timescale variability suggests that the body was likely spinning with a period twice the nominal figure of $P_{\mathrm{flash}}={1.4547}_{\pm 0.0005}\mathrm{s}$, as from the observed lightcurve. In the ${\mathit{BVR}}_c{I}_c$ color domain, WT1190F closely resembled the Planck deep-space probe. This match, together with a depressed reflectance around 4000 and 8500 Å may be suggestive of a “grey” (aluminized) surface texture.The spinning pattern remained in place also along the object fiery entry in the atmosphere, a feature that may have partly shielded the body along its fireball phase perhaps leading a large fraction of its mass to survive intact, now lying underwater along a tight ($～1\times 80$?km) strip of sea, at a depth of 1500?m or less.Under the assumption of Lambertian scatter, an inferred size of ${216}_{\pm 30}/\sqrt{\alpha /0.1}$?cm is obtained for WT1190F. By accounting for non-gravitational dynamical perturbations, the Area-to-Mass ratio of the body was in the range $(0.006?\mathit{AMR}?0.011)$?m²?kg^?1.Both these figures resulted compatible with the two prevailing candidates to WT1190F’s identity, namely the Athena II Trans-Lunar Injection Stage of the Lunar Prospector mission, and the ascent stage of the Apollo 10 lunar module, callsign “Snoopy”. Both candidates have been analyzed in some detail here through accurate 3D CAD design mockup modelling and BRDF reflectance rendering to derive the inherent photometric properties to be compared with the observations.     

Overview of the Solar Polar Orbit Telescope Project for Space Weather Mission

The Solar Polar ORbit Telescope (SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections (CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun. The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star (ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13th Five-Year Plan period of 2016-2020.     

空间站机械臂转位系统动力学建模及特性分析

为分析空间站在应用机械臂转位过程中的动力学特性,采用矢量力学方法推导了考虑偏心量的空间站转位系统动力学模型.使用有限元方法描述柔性臂的弹性变形,应用Newton-Euler法建立空间站机械臂转位系统转动方程,并采用Lagrange法建立柔性臂振动方程;针对柔性机械臂末端带有大负载的特点,将末端弹性变形引起的负载角速度从负载绝对角速度中分离,应用约束模态展开法对动力学方程进行降阶.提出了构造降维矩阵的方法以便于利用空间动力学模型研究机械臂平面转位问题;分析了空间站舱体转位过程中系统的转动惯量、偏心量发生变化的特性.数值仿真结果表明:空间站在转位过程中,系统总体相对于系统质心的转动惯量变化巨大,且偏心量变化范围甚至已超出了空间站核心舱的几何范围.结论可为空间站的控制系统设计提供理论参考.