空间动态目标间相对距离解算方法的改进

探讨了在地面光学测量条件下,直接解算空间动态目标间相对距离的方法,以避开首先解算两动态目标位置分量的要求,而有效地简化解算过程.在此基础上,对多台光学测量设备交会的观测数据,应用非线性递推估计,提供精确解算动态目标间相对距离量的方法,它不需按常规方法对观测方程进行线性化处理,有利于解算结果精度的提高,也减少了计算量.     

空间目标轨道确定专家系统

空间目标轨道确定专家系统的面向空间监测需求开发的大型交互式应用软件。它的功能面向空间监测和信息分析中广泛的业务需求，基础是轨道计算软件，数据库支持和一些辅助支持软件。本文详细地介绍了空间目标轨道确定专家系统软件的设计方案。     

The Climate Response to the Astronomical Forcing

Links between climate and Earth’s orbit have been proposed for about 160 years. Two decisive advances towards an astronomical theory of palæoclimates were Milankovitch’s theory of insolation (1941) and independent findings, in 1976, of a double precession frequency peak in marine sediment data and from celestial mechanics calculations. The present chapter reviews three essential elements of any astronomical theory of climate: (1) to calculate the orbital elements, (2) to infer insolation changes from climatic precession, obliquity and eccentricity, and (3) to estimate the impact of these variations on climate. The Louvain-la-Neuve climate-ice sheet model has been an important instrument for confirming the relevance of Milankovitch’s theory, but it also evidences the critical role played by greenhouse gases during periods of low eccentricity. It is recognised today that climatic interactions at the global scale were involved in the processes of glacial inception and deglaciation. Three examples are given, related to the responses of the carbon cycle, hydrological cycle, and the terrestrial biosphere, respectively. The chapter concludes on an outlook on future research directions on this topic.     

空间监视中设备级数据-目标对应关系确定方法

基于各测量弧段的方位、俯仰,通过数学变换和多项式拟合,实现以拟合系数为特征量表征该弧段的观测。进而通过比较观测值与理论值的拟合系数,完成数据-目标对应关系的确定,达到简化设备级数据-目标对应关系快速确定的目的。     

空间目标编目维持中的观测需求确定方法研究

针对空间目标探测中观测计划制定业务面临的目标观测需求确定问题,首先分析影响目标观测需求确定的因素,据此进行精度指标确定分析,然后结合一类目标,在进行“圈／站／天”组合精度分析的基础上,提出动态观测需求确定方法,并阐述其运行机制。     

An Experimental Determination of Distortion and Delay in the FM-FM Telemetry System of the Saturn Space Vehicle

The distortion of the FM-FM Saturn telemetry system for dc input (static error) has been the subject of many studies. The purpose of this correspondence is to measure the additional distortion (dynamic error) that results when the input signal is time-varying. A digital method is developed for measuring both the system delay and the system mean square error for various input signals.     

The Modelling of Background Noise in Astronomical Gamma Ray Telescopes

Gamma ray photons interact with matter through a wide variety of complex physical mechanisms, which can be readily imitated by other particle processes. Unfortunately since γ-ray telescopes are obliged to function in a hostile radiation environment above the earth's atmosphere the net result is low signal to noise observations and a corresponding loss in sensitivity. Consequently, understanding the generation of the systematic background noise is crucial if the full performance of a γ-ray instrument is to be realised. In the past it was not possible to reliably estimate the background levels in a fully quantitative manner; semi-empirical methods were employed. Although the basic underlying sources of the background noise were reasonably well understood, and the spectral intensities of the associated particles were reasonably well known, it was not possible to associate resultant noise components with the input source of that noise with any real degree of accuracy. The advent of sophisticated and accurate computer programmes capable of dependably representing the requisite particle physics processes and interactions coupled with the advances made in the context of high power/low cost computers has revolutionised the situation. The so-called ‘mass modelling’ technique is a truly physics-based approach, which takes the input particle spectra of the local radiation environment together with a computer representation of the mechanical structure and chemical composition of the instrumentation and associated spacecraft to trace the trajectories and interactions of all the incident particles throughout the system. All energy deposits from the various interactions and likewise those from the prompt and delayed secondary products are also accurately recorded. Subsequent energy discriminators and time coincidences can be applied to the event arrays with additional software to simulate on-board electronics systems. Internal spectral counting rates may be readily derived and analysed in terms of a wide variety of desired purposes. The impact of an accurate physics-based mass modelling technique has been to expand application of the procedure to effectively all the main aspects of a space γ-ray astronomy mission: instrument design; internal counting rates and spectral sensitivity estimates; optimisation of the design of the on-board processing electronics; operational planning and mission optimisation; estimation of radiation damage and its limitation; calibration planning and interpretation; the production of accurate instrumental response matrices; data analysis software; normalisation of astronomical results across instrument and instrumental degradation boundaries; and data archiving. This revised version was published online in June 2006 with corrections to the Cover Date.     

一种改进的空间目标接近分析快速算法

Alfano-Negron(1993)提出的空间目标接近分析算法将最小相对距离及其对应时刻和进出误差椭球时刻的求解问题均转化为插值多项式求根问题.A-N算法在判断三次多项式根的存在性、筛选合理实根时存在缺陷,可能导致多余计算.由A-N算法提出的准则不能直接计算插值时间步长并可能导致丢根,对此根据多项式插值误差理论提出了一种自适应的插值时间步长选取方法.相比原始A-N算法,完善后的A-N算法计算结果更加可靠.与精确的逐秒比较结果相比,改善后的A-N算法计算速度远高于逐秒比较,具有较高精度,更适合于有实时计算要求的任务.     

国内外深空探测器精密定轨软件研究综述及WUDOGS简介

深空探测器精密定轨软件系统的研制在深空探测活动中是一个非常重要的环节,一直受到各大航天机构的重视。针对国内外深空探测器精密定轨软件平台的研究现状,重点介绍了具有代表性的美国JPL(Jet Propulsion Laboratory,喷气推进实验室)的DPTRAJ/ODP(Double Precision TRAJectory program/Orbit Determination Program,双精度轨道程序/定轨程序)和MONTE(Mission analysis,Operations,and Navigation Toolkit Environment,任务分析、操作和导航工具箱环境),GSFC(Goddard Space Flight Center,戈达德航天飞行中心)的GEODYN-II以及法国CNES(Centre National dEtudes Spatiales,国家空间研究中心)的GINS(Géodésie par Intégrations Numériques Simultanées,同步数值积分大地测量)软件系统,对这些软件的结构与功能进行了总结。之后对武汉大学自主研制的深空探测器精密定轨软件系统WUDOGS(Wuhan University Deep space Orbit determination and Gravity recovery System,武汉大学深空探测器精密定轨与重力场解算软件系统)的主要模块与功能进行了介绍,通过与GEODYN-II的交叉对比验证,表明:对于探测器的轨道预报,WUDOGS与GEODYN-II的1个月位置差异小于0.3mm,2d位置差值小于5×10~(-3) mm;双程测距、双程测速的理论计算值和GEODYN-II的差值RMS(Root Mean Square,均方根)分别在0.06mm,0.002mm/s的水平;WUDOGS目前已初步具备了月球和火星探测器精密定轨能力。最后对WUDOGS的下一步发展方向进行了展望。     

The light of the night sky: Astronomical,interplanetary and geophysical

Summary We bring together our general results in two figures. Figure 14 portrays the resolution of the light of the night sky into its three principal components based on a series of zenith observations extending over a year at the two stationse: Fritz Peak in Colorado, U.S.A., (latitude N 39°.9, longitude W 105°.5) and Haleakala in Hawaii, U.S.A. (latitude N 20°.7, longitude W 156°.3). The observations are from a current study by Roach and Smith (1964a) using photometers centered on wavelength 5300 Å. With respect to sidereal time the airglow continuum is a constant. The two Milky Way traverses are conspicuous features of the integrated starlight curves. The variation of the zodiacal light is the result of the variable ecliptic latitude of the zenith throughout the year. A refined analysis of the data, not shown in the plot, gives a further variation of the zodiacal light as a function of - _bd, the differential ecliptic longitude between the zenith and the sun. The zodiacal light is the brighter of the three components except when the Milky Way is in the zenith. The zodiacal light tends to be systematically brighter toward the horizon so that it is definitely the most prominent of the three for the sky as a whole.The interrelationships of the constituents of the light of the night sky are shown from a different point of view in Figure 15 where the ordinate is logarithm of the surface brightness and the abscissa is logarithm of the distance or extent. Moving downward in the plot the features of the night sky appear below the line corresponding to the end of twilight. The brightness of the nightglow, the zodiacal light and gegenschein, the integrated starlight and galactic light are comparable (on the logarithm scale) but one is impressed with the vastly different linear distances in connection with the several phenomena. The nightglow is a terrestrial phenomenon having a thickness of about one atmospheric scale height (log R 7). The zodiacal light is an interplanetary phenomenon with a characteristic dimension of one astronomical unit (log R 13). The integrated starlight from our galaxy has a characteristic maximum dimension of some 30 kpc (log R 23). Finally the extra galactic nebulae which collectively contribute much less than 1% of the light of the night sky are at distances as much as log R 28. They can be photographed individually in spite of the competition of the sky background and in spite of the hazard of extinction by intervening dust.In the preparation of this report the writer has been impressed with the confluence of several circumstances that make possible the observation of the universe in the visible part of the spectrum. Any one of several contingencies might have made such observations impossible.Let us consider the matter of contrast. The prime example here is the bright (but beautiful!) day sky which prohibits serious daytime study of the astronomical sky. There follows, during a diurnal terrestrial rotation the period of twilight which under the best of circumstances lasts a little less than 1 1/2 hours but which, during the local summer, in the vicinity of polar regions persists all night. The obliquity of the ecliptic is sufficient to make a stimulating annual sequence of seasons but small enough to keep the twilight period of reasonable duration over a good portion of the earth.A hazard narrowly averted is that due to the interplanetary dust cloud leading to the zodiacal light. The concentration of dust is very small indeed (Figure 10) so that an increase by a factor often would be trivial in terms of the constitution of the solar system. But such an increase would result in a night sky so bright (average zodiacal light 2000 S₁₀ (vis) instead of 200) that the Milky Way would be difficult to see and the airglow difficult to measure. The aesthetic gain in a rather spectacular zodiacal light pattern over the sky would hardly compensate for the loss from the absence of the details of our galactic universe. The effect of such an enhanced zodiacal light would correspond to that experienced in a planetarium when the operator adjusts the rheostats to bring on dawn and the celestial objects disappear.A permanent twilight that would have the same effect would be due to the hydroxyl nightglow if (a) it were concentrated in the visible part of the spectrum rather than in the near infra red or if (b) the human eyes were sensitive in the near infrared.The narrow escape from the cosmic ignorance that would have resulted from a situation in which the observer found himself in a less favorable environment is well illustrated by the zone of avoidance of extra galactic nebulae in the vicinity of the Milky Way plane. If our galaxy were not highly flattened so that its extent perpendicular to the plane is sufficiently small to permit an observational window outward we would not have been able to photograph the extra-galactic objects and we would have been content with a rather restricted concept of a universe consisting of a single galaxy. The same dire result would have occurred if the sun to which our planet is attached were more deeply embedded in the galactic dust near the galactic center. Thus we find compensation for our non-central location.There can be little doubt that human ingenuity would in time have overcome any or all of the above circumstances as the radio astronomers have done by changing the exploring frequency so as to avoid the difficulties. But this would have taken time, especially in the absence of the stimulation of the knowledge gained by visual and photographic observations. It is likely that the time lag would have been sufficient that the present review could not have been written by the present author. It may be conjectured whether other astronomers on other planets are as fortunate or whether, after all, this is the best of all possible worlds.Contribution number 73. The report was written while the author was a Senior Specialist at the East-West Center of the University of Hawaii — on leave of absence from the Central Radio Propagation Laboratory of the U.S. National Bureau of Standards, Boulder, Colo., U.S.A.

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Determination of the Equivalence Principle Violation Signal for the MICROSCOPE Space Mission: Optimization of the Signal Processing

The MICROSCOPE space mission aims at testing the Equivalence Principle (EP) with an accuracy of 10^?15. The test is based on the precise measurement delivered by a differential electrostatic accelerometer on-board a drag-free microsatellite which includes two cylindrical test masses submitted to the same gravitational field and made of different materials. The experiment consists in testing the equality of the electrostatic acceleration applied to the masses to maintain them relatively motionless at a well-known frequency. This high precision experiment is compatible with only very little perturbations. However, aliasing arises from the finite time span of the measurement, and is amplified by measurement losses. These effects perturb the measurement analysis. Numerical simulations have been run to estimate the contribution of a perturbation at any frequency on the EP violation frequency and to test its compatibility with the mission specifications. Moreover, different data analysis procedures have been considered to select the one minimizing these effects taking into account the uncertainty about the frequencies of the implicated signals.     

基于连续同伦算法的天基仅测角初定轨方法

要进一步提高天基短弧初定轨的精度,在观测资料精度较高的情况下,仅考虑二体问题是不够的,还应考虑轨道摄动的影响。因此,基于无摄初轨的单位矢量法原理和矢量斜分解方法,给出了考虑摄动的天基仅测角初定轨单位矢量法。针对天基仅测角观测条件方程组求解过程中易出现迭代不收敛或收敛到平凡解的问题,引入连续同伦算法求解观测条件方程组,提出了单星观测方式下的空间目标天基仅测角初定轨方法,并通过数值仿真算例验证了该算法在较大范围的收敛性和数值稳定性。     

Space, security in the forefront

The Washington Watch column reports on President Bush's recently announced human space flight program, which includes new policies for returning the shuttle to flight, finishing the International Space Station by 2010, and developing a new space vehicle to return to the Moon; challenges in the airline industry; and selection of a helicopter for use by the President.     

Space Weather in the Equatorial Ionosphere

The ‘scintillations’ observed on signals received in the equatorial region from GPS satellites are due to plasma instabilities in the F region of the ionosphere, also detected as spread F. These instabilities give rise to depletions of ionisation or ‘bubbles’. The occurrence of these events and their relation to the equatorial electrojet are reviewed. Possibilities of short-term forecasting are examined with particular attention to problems encountered in modelling the equatorial electrojet. This revised version was published online in August 2006 with corrections to the Cover Date.     

STEREO Space Weather and the Space Weather Beacon

The Solar Terrestrial Relations Observatory (STEREO) is primarily a solar and interplanetary research mission, with one of the natural applications being in the area of space weather. The obvious potential for space weather applications is so great that NOAA has worked to incorporate the real-time data into their forecast center as much as possible. A subset of the STEREO data will be continuously downlinked in a real-time broadcast mode, called the Space Weather Beacon. Within the research community there has been considerable interest in conducting space weather related research with STEREO. Some of this research is geared towards making an immediate impact while other work is still very much in the research domain. There are many areas where STEREO might contribute and we cannot predict where all the successes will come. Here we discuss how STEREO will contribute to space weather and many of the specific research projects proposed to address STEREO space weather issues. The data which will be telemetered down in the Space Weather Beacon is also summarized here. Some of the lessons learned from integrating other NASA missions into the forecast center are presented. We also discuss some specific uses of the STEREO data in the NOAA Space Environment Center.     

天文光谱测速导航技术与应用思考

随着我国航天技术的发展,航天器对导航系统的精度、自主性、实时性等综合性能需求越来越高。天文光谱测速导航作为近年来提出的新型自主导航技术,具有直接获取航天器速度信息且实时性好、测速精度高等特点,具有广阔的应用前景。在梳理近年来天文光谱测速导航研究进展的基础上,结合天文光谱测速导航的特点,深入思考并提出了若干天文光谱测速导航技术应用组合。基于当前航天任务的需求和研究的难点,结合国内外技术趋势和我国实际工程需求,指出了天文光谱测速导航技术未来的重点研究方向及内容。天文光谱测速导航为我国航天探测工程任务导航提供了一条崭新的技术途径,对天文光谱测速导航技术的持续研究将有力促进我国航天领域导航技术的发展,提升天文导航理论研究能力和工程研制技术水平。     

J. Andersen (ed.), Transactions of the International Astronomical Union,Volume XXIIIB

Space Science Reviews -     

Space robotics in the '90s

This article describes the use of robots to perform work in space. In particular, telerobotics, which uses human operators to control the movement and operation of the robots, are explored. The relationship between the human operator and the robot is very complex but these systems are being used to explore planetary surfaces and will also be used in the construction of the space station. Research being conducted at NASA facilities is described, providing a picture of the future of space robotics.     

大圆距离及大圆航向的计算

在飞机选型中对各机型进行性能分析、经济性评估或编制飞行计划软件时,常需要根据航段两端点的经纬度坐标计算该航段的大圆距离及航向,在沿大圆航线飞行时也需要知道航路上各点的真航向及磁航向。本文用矢量方法导出了根据起止点的经纬度坐标计算该航段大圆距离及大圆航向的公式以及沿大圆航线飞行时根据给定点的经度计算其纬度和真航向的公式,并且用算例做了验证,结果表明这些公式是正确的。