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31.
天线视角是航天测量船的一个重要指标,通过分析各种视角遮挡情况,列出相应的视角计算方法,为船用天线视角设计提供了依据。同时本文分析了针对视角遮挡问题在船舶设计阶段应采取的措施。  相似文献   
32.
    
Water masers are well-known to be variable on a variety of time scales, but only three Galactic H2O masers are known to flare to the level of 105–106 Jy (TB1017 K): Orion KL, W49N, and the recently discovered G25.65+1.05. Recently detected flaring activity of H2O maser in the massive star-forming region G25.65+1.05 gave us a unique opportunity to study the fine structure of H2O maser emission in the bursting state with extremely high space VLBI angular resolution. Observation of the source was carried out with ∼9 Earth diameter space-ground baseline within the framework of the RadioAstron project. H2O maser emission from two spectral features, including the bursting one, was detected in the experiment. Only ∼1% of the bursting H2O maser emission was detected on the space-ground baselines: it indicates the presence of a very compact spatial structure with a size of ∼25 μas, which corresponds to 0.05 AU or ∼5 solar diameters at the distance to the source of 2.08 kpc, and the brightness temperature of ∼3 × 1016 K. Analysis of the flux density as a function of the baseline length for the bursting H2O maser feature in the source shows that most of the emission comes from an extended “halo” structure, while the core of emission is very compact and has an extreme brightness temperature. These results are in agreement with the model of interacting maser clouds considered as the likely explanation of the nature of the burst in the source. Under the assumption of such a model, the beam size of maser emission is reduced while the brightness temperatures similar to the highest observed values are produced.  相似文献   
33.
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Submillimeter interferometry has the potential to image supermassive black holes on event horizon scales, providing tests of the theory of general relativity and increasing our understanding of black hole accretion processes. The Event Horizon Telescope (EHT) performs these observations from the ground, and its main imaging targets are Sagittarius A* in the Galactic Center and the black hole at the center of the M87 galaxy. However, the EHT is fundamentally limited in its performance by atmospheric effects and sparse terrestrial (u,v)-coverage (Fourier sampling of the image). The scientific interest in quantitative studies of the horizon size and shape of these black holes has motivated studies into using space interferometry which is free of these limitations. Angular resolution considerations and interstellar scattering effects push the desired observing frequency to bands above 500 GHz.
This paper presents the requirements for meeting these science goals, describes the concept of interferometry from Polar or Equatorial Medium Earth Orbits (PECMEO) which we dub the Event Horizon Imager (EHI), and utilizes suitable space technology heritage. In this concept, two or three satellites orbit at slightly different orbital radii, resulting in a dense and uniform spiral-shaped (u,v)-coverage over time. The local oscillator signals are shared via an inter-satellite link, and the data streams are correlated on-board before final processing on the ground. Inter-satellite metrology and satellite positioning are extensively employed to facilitate the knowledge of the instrument position vector, and its time derivative. The European space heritage usable for both the front ends and the antenna technology of such an instrument is investigated. Current and future sensors for the required inter-satellite metrology are listed. Intended performance estimates and simulation results are given.  相似文献   
34.
The Mariner 10 spacecraft made three flyby passes of Mercury in 1974 and 1975. It imaged a little less than half of the surface and discovered Mercury had an intrinsic magnetic field. This paper briefly describes the surface of Mercury as seen by Mariner 10 as a backdrop to the discoveries made since then by ground-based observations and the optimistic anticipation of new discoveries by MESSENGER and BepiColombo spacecraft that are scheduled for encounter in the next decade.  相似文献   
35.
推进剂液位检测技术研究及仪器设计   总被引:1,自引:0,他引:1  
通过对多种液位检测技术对比分析 ,提出一种利用超声波技术由储罐底部直接测量的方法 ,介绍了基于该方法的测量原理和仪器实现。此方法能够较好解决分界面明显的液位检测问题 ,但是对于一些气 -液界面模糊的介质的液位检测存在一定的问题 。  相似文献   
36.
    
An international effort dedicated to the science exploration of Jupiter system planned by ESA and NASA in the beginning of the next decade includes in-depth science investigation of Europa. In parallel to EJSM (Europa-Jupiter System Mission) Russia plans a Laplace-Europa Lander mission, which will include another orbiter and the surface element: Europa Lander. In-situ methods on the lander provide the only direct way to assess environmental conditions, and to perform the search for signatures of life. A critical advantage of such in situ analysis is the possibility to enhance concentration and detection limits and to provide ground truth for orbital measurements. The science mission of the lander is biological, geophysical, chemical, and environmental characterizations of the Europa surface. This review is dedicated to methods and strategies of geophysical and environmental measurements to be performed at the surface of Europa, and their significance for the biological assessment, basing on the concept of a relatively large softly landed module, allowing to probe a shallow subsurface. Many of the discussed methods were presented on the workshop “Europa Lander: Science Goals and Experiments” held in Moscow in February 2009. Methods and instruments are grouped into geophysical package, means of access to the subsurface, methods of chemical and structural characterization, and methods to assess physical conditions on the surface.  相似文献   
37.
Supergiant fast X-ray transients are a subclass of high mass X-ray binaries displaying a peculiar and still poorly understood extreme variability in the X-ray domain. These sources undergo short sporadic outbursts (LX∼LX 1036–1037 erg s−1), lasting few ks at the most, and spend a large fraction of their time in an intermediate luminosity state at about LX∼LX 1033–1034 erg s−1. The sporadic and hardly predictable outbursts of supergiant fast X-ray transients were so far best discovered by large field of view (FOV) coded-mask instruments; their lower luminosity states require, instead, higher sensitivity focusing instruments to be studied in sufficient details. In this contribution, we provide a summary of the current knowledge on supergiant fast X-ray transients and explore the contribution that the new space mission concept LOFT, the Large Observatory for X-ray Timing, will be able to provide in the field of research of these objects.  相似文献   
38.
天基与地基测量数据融合技术在靶场的应用   总被引:1,自引:0,他引:1  
随着GPS技术的发展,靶场的测控也在逐步由地基测控网过渡到天地结合的一体化综合测控网。如何将天基测量数据同靶场现有的高精度测量带测量数据融合处理,近年成为数据处理的热点话题。本文就某具体任务,对天基和地基测量数据融合技术的方法和工程应用作了详细介绍,给出了初步的结论,提出了天基测量数据在工程应用时应注意的问题和有待进一步分析的问题。  相似文献   
39.
对基于消息中间件的测量船测控信息交换模式进行研究,首先对消息中间件技术进行探讨,然后基于测量船应用需求,从测控信息交换体系结构、测控软件系统软件部署、测控消息流管理3个方面展开基于消息中间件的测量船测控信息交换模式设计.最后对基于该模式的测控信息交换的可靠性、实时性以及易管理性等优势进行了分析。  相似文献   
40.
船载设备测量数据处理结果的综合分析方法   总被引:1,自引:0,他引:1  
数据处理技术包括数据诊断与误差分析技术、数学建模与处理技术以及数值微分与弹(轨)道计算技术等,而测量误差分析与处理技术是数据处理技术的核心。如何分析和处理误差贯穿于数据处理的全过程,直接影响弹/轨道计算的精度。对误差的分析和处理是测量船数据处理工作中的重要内容。本文根据测量船数据处理实际情况介绍了测量船数据分析方法,并结合任务实例介绍了测量船误差分析和处理的详细过程。  相似文献   
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