卫星无线传能系统主动电场屏蔽效能分析

针对无线传能系统宽频段电场辐射屏蔽的需求,建立了采用主动屏蔽方式的无线传能系统屏蔽效能分析电路模型。推导出主动屏蔽激励源可由无线传能系统电压激励源控制。给出了空间点位置和面位置屏蔽效能计算公式,通过对激励电压源进行傅里叶变换后提取关注频段电压分量可实现对宽频段屏蔽效能的分析。通过仿真分析证明了方法的有效性,屏蔽效能与空间位置有关,同时受限于传输效率的约束。通过调节压控电压源的压控系数可以在传输效率损失相对较小的情况下实现关注位置电场辐射的有效屏蔽。最后通过实验验证了无线传能系统主动屏蔽方式屏蔽效能分析方法的正确性和工程可应用性。     

卫星天线在热真空试验中的全场变形测量技术

为真实卫星天线在卫星地面实验站进行了热变形测量的需求,利用卫星天线小模型,进行测试技术研究,用电子散斑干涉技术,在无特殊隔振的条件下,进行全场动态变形测量,获得了全场变形的信息,结果表明,该项技术完全有可能用于真空卫星天线热变形时实时测量。     

卫星天线抗静电技术研究的进展

论述了卫星天线的主要电环境：地球同步轨道和低高度极轨空间环境;卫星天线表面充电的危害性; 抗静电膜的发展水平。已研制出了导电膜＋ Ｋａｐｔｏｎ（聚酰亚胺） ＋ 温控漆的复合结构抗静电膜和加有氧化锡的可溶性高聚物涂层。通过环境效应试验、抗静电膜对天线电性能影响的试验和模拟极光充电环境下的充放电评估实验, 证明抗静电膜符合天线性能要求, 并可以有效控制天线表面的充电电位     

星载合成孔径雷达的分辨特性

较全面和详细地论述了星载合成孔径雷达（ＳＡＲ）的分辨特性;导出了距离分辨率、方位分辨率和辐射分辨率的定量关系式;阐述了多种辐射分辨率定义的内涵,并对其错误概率进行了比较;介绍了ＳＡＲ图像的分辨体积和可懂度的概念,并且完成了ＳＡＲ图像分辨特性的方形等效。这些论述对于ＳＡＲ图像质量的评估和比较,以及系统参数的折衷设计具有重要意义。     

卫星成形反射面天线波束赋形的研究

采用单馈成形反射面天线,将天线口面分为多个栅格,通过优化栅格的场的相位分布对中国版图进行波束赋形。在优化过程中附加了相位限制条件,以保证反射面的表面连续,并与阵馈抛物反射面天线的赋形效果作了分析比较,说明单馈成形反射在天线在波束赋形中是可取的,该单馈成形反射面天线有其实用价值。     

基于中继测量的环月探测器定轨能力分析

嫦娥四号月球探测拟首次实现月球背面的软着陆,测控与数传依赖地月L2平动点的中继卫星,并有望获取四程测量与星间测量数据。对基于中继测量的环月探测器测定轨能力进行了仿真分析,结果表明,中继卫星可较好地实现环月探测器连续跟踪;在定轨能力方面,中继卫星自身轨道精度是制约环月探测器定轨精度的重要因素,当跟踪弧段达到5h以上时,定轨精度趋于稳定,但轨道精度较中继卫星的轨道精度相差1个量级;对于星间链路测量,除中继卫星自身的轨道精度外,星钟的稳定性是制约定轨精度的另一个重要因素,如果辅助以每天1h的地基跟踪亦可实现优于百m的定轨精度。     

低轨航天器天基测控方法研究

我国的航天器测控主要依赖地基测控系统实施,随着民用和军用需求的不断增加,太空运行的低轨航天器数量越来越多.仅依赖地基测控系统满足这些航天器的测控需求越来越困难,费用也越来越高.探索新的、有效且经济的测控模式势在必行.天基测控技术是航天器测控发展的方向,研究和应用天基测控技术具有重要的实用价值,可以解决困扰我国航天领域多年的测控资源紧张问题.在分析美国NASA数据与中继卫星系统相关技术的基础上,提出了我国低轨航天器天地基测控模式,讨论了该模式的运行原理,设计了该模式的仿真系统,分析了应用该模式需解决的关键技术问题,通过基于设计的仿真系统对提出的测控模式进行了验证.验证结果表明了提出的天地基测控模式可行,可以满足低轨航天器的测控需求.      

PROBA-3 mission and the Shadow Position Sensors: Metrology measurement concept and budget

PROBA-3 is a space mission of the European Space Agency that will test, and validate metrology and control systems for autonomous formation flying of two independent satellites. PROBA-3 will operate in a High Elliptic Orbit and when approaching the apogee at 6·10⁴ Km, the two spacecraft will align to realize a giant externally occulted coronagraph named ASPIICS, with the telescope on one satellite and the external occulter on the other one, at inter-satellite distance of 144.3 m. The formation will be maintained over 6 hrs across the apogee transit and during this time different validation operations will be performed to confirm the effectiveness of the formation flying metrology concept, the metrology control systems and algorithms, and the spacecraft manoeuvring. The observation of the Sun’s Corona in the field of view [1.08;3.0]R_Sun will represent the scientific tool to confirm the formation flying alignment. In this paper, we review the mission concept and we describe the Shadow Position Sensors (SPS), one of the metrological systems designed to provide high accuracy (sub-millimetre level) absolute and relative alignment measurement of the formation flying. The metrology algorithm developed to convert the SPS measurements in lateral and longitudinal movement estimation is also described and the measurement budget summarized.     

Towards the automated operations of large distributed satellite systems. Part 2: Classifications and tools

Recent developments have seen a trend towards larger constellations of spacecraft, with some proposals featuring constellations of more than 10.000 satellites. While similar concepts for large constellations already existed in the past, traditional satellite deployments hardly ever feature groups of more than 100 satellites. This trend towards considerably larger satellite numbers originates from non-traditional design and operations of spacecraft by non-traditional space companies. The evolution in the space sector, precipitated by new players, is often referred to as “Space 4.0” or “New Space”. It necessitates a rethinking of the way satellites and satellite constellations are planned, designed, and operated. New operational paradigms are needed to enable automatic, optimal task definition, and scheduling in a holistic approach.This is the second of two companion papers that investigate the operations of distributed satellite systems. This second article investigates the classification of distributed satellite systems and evaluates commercial tools for automated spacecraft operations, whereas the first article performed a survey of conventional and “new space”operations of spacecraft constellations.Classification metrics for constellations are derived and evaluated with respect to their informative value concerning the operation, the automation, and the scalability of the constellation. The proposed classification system is applied to the Dove and RapidEye constellation and allows for a comparison between the presented automation approaches. Commercial tools for automated spacecraft operations are evaluated for several mission task elements, such as orbit control, orbit maintenance, and collision avoidance. Subsequently, the trends, benefits, and standardization needs for operational automation are identified.     

First spaceborne demonstration of BeiDou-3 signals for GNSS reflectometry from CYGNSS constellation

The full constellation of Chinese Global Navigation Satellite System (GNSS) BeiDou-3 has been deployed completely and started fully operational service. In addition to providing global Positioning, Navigation and Timing (PNT) services, the BeiDou-3 satellites transmissions can also be used as the sources of illumination for Earth Observation (EO) with a bistatic radar configuration. This innovative EO concept, known as GNSS reflectometry (GNSS-R), allows to measure the Earth surface characteristics at high resolution via the reflected L-band radar signals collected by a constellation of small, low cost and low Earth orbiting satellites. For the first time in orbit, earth reflected BeiDou-3 signal has been detected from the limited sets of raw data collected by the NASA’s Cyclone GNSS (CYGNSS) constellation. The feasibility of spaceborne BeiDou-3 reflections on two typical applications, including sea surface wind and flooding inundation detection, has been demonstrated. The methodology and results give new strength to the prospect of new spaceborne GNSS-R instruments and missions, which can make multi-GNSS reflectometry observations available to better capture rapidly changing weather systems at better spatio-temporal scales.