耐150 ℃太阳翼基板结构胶黏剂性能研究

介绍了一种J-159结构胶黏剂,用于太阳翼基板结构的板-芯胶接,重点进行了胶黏剂的力学性能、真空挥发性能、耐辐照性能研究,同时开展了典型件的制备及热真空循环试验。结果表明,J-159胶黏剂在150℃下各项力学性能保持率均56%,远高于常用的J-47胶黏剂,具有很好的耐高温性能。同时,真空挥发性能和耐带电粒子辐照性能满足航天器空间应用要求,制备的典型件在-105～+150℃热真空循环试验后,外观质量、胶接质量及其他性能均符合指标要求,能够满足卫星太阳翼基板耐150℃及以下空间环境的使用需求。     

Effects of Low Energetic Neutral Atoms on Martian and Venusian Dayside Exospheric Temperature Estimations

The heating of the upper atmospheres and the formation of the ionospheres on Venus and Mars are mainly controlled by the solar X-ray and extreme ultraviolet (EUV) radiation (λ = 0.1–102.7 nm and can be characterized by the 10.7 cm solar radio flux). Previous estimations of the average Martian dayside exospheric temperature inferred from topside plasma scale heights, UV airglow and Lyman-α dayglow observations of up to ∼500 K imply a stronger dependence on solar activity than that found on Venus by the Pioneer Venus Orbiter (PVO) and Magellan spacecraft. However, this dependence appears to be inconsistent with exospheric temperatures (<250 K) inferred from aerobraking maneuvers of recent spacecraft like Mars Pathfinder, Mars Global Surveyor and Mars Odyssey during different solar activity periods and at different orbital locations of the planet. In a similar way, early Lyman-α dayglow and UV airglow observations by Venera 4, Mariner 5 and 10, and Venera 9–12 at Venus also suggested much higher exospheric temperatures of up to 1000 K as compared with the average dayside exospheric temperature of about 270 K inferred from neutral gas mass spectrometry data obtained by PVO. In order to compare Venus and Mars, we estimated the dayside exobase temperature of Venus by using electron density profiles obtained from the PVO radio science experiment during the solar cycle and found the Venusian temperature to vary between 250–300 K, being in reasonable agreement with the exospheric temperatures inferred from Magellan aerobraking data and PVO mass spectrometer measurements. The same method has been applied to Mars by studying the solar cycle variation of the ionospheric peak plasma density observed by Mars Global Surveyor during both solar minimum and maximum conditions, yielding a temperature range between 190–220 K. This result clearly indicates that the average Martian dayside temperature at the exobase does not exceed a value of about 240 K during high solar activity conditions and that the response of the upper atmosphere temperature on Mars to solar activity near the ionization maximum is essentially the same as on Venus. The reason for this discrepancy between exospheric temperature determinations from topside plasma scale heights and electron distributions near the ionospheric maximum seems to lie in the fact that thermal and photochemical equilibrium applies only at altitudes below 170 km, whereas topside scale heights are derived for much higher altitudes where they are modified by transport processes and where local thermodynamic equilibrium (LTE) conditions are violated. Moreover, from simulating the energy density distribution of photochemically produced moderately energetic H, C and O atoms, as well as CO molecules, we argue that exospheric temperatures inferred from Lyman-α dayglow and UV airglow observations result in too high values, because these particles, as well as energetic neutral atoms, transformed from solar wind protons into hydrogen atoms via charge exchange, may contribute to the observed planetary hot neutral gas coronae. Because the low exospheric temperatures inferred from neutral gas mass spectrometer and aerobraking data, as well as from CO⁺ ₂ UV doublet emissions near 180–260 nm obtained from the Mars Express SPICAM UV spectrograph suggest rather low heating efficiencies, some hitherto unidentified additional IR-cooling mechanism in the thermospheres of both Venus and Mars is likely to exist. An erratum to this article can be found at     

向月球飞行轨道的若干特性研究

利用圆锥曲线拼接技术,研究从地球圆形停泊轨道飞向月球的轨道及月球卫星轨道的轨道特性.当地月转移轨道平面与月球轨道平面共面时,月心轨道和地月转移轨道射入条件的关系可用一组代数方程描述;不共面时,可用一组超越方程迭代求解.数字仿真得到了有益结论.      

太阳闪烁影响下的星际通信链路参数设计

针对太阳闪烁作用于星际通信链路而产生的幅度闪烁、频谱扩展、相位闪烁、时延扩展问题,提出一种适用于星际通信链路的参数设计方法。该方法根据通信链路与太阳的几何关系,计算太阳风中等离子体作用于无线电波的幅度统计特性、时间谱特性,将计算结果作为通信链路的频率选择、传输信号带宽设计、调制方式选择、锁相环路带宽设计的约束条件,并以某空间探测任务为例进行了S、X、Ka三种频段下的信号传输性能仿真分析,结果表明,在太阳闪烁指数m<0.3的情况下,采用Ka频段+8PSK调制相结合的方式,对于太阳闪烁的抵抗能力最强。该方法设计的参数能够降低太阳闪烁对通信链路的影响,可作为工程实际系统设计的参照。     

载人小行星探测目标选择与轨道优化设计

针对2020-2040年载人小行星探测任务,研究了探测目标选择与轨道优化设计问题。首先,针对已编目的近地小行星,综合考虑绝对星等、燃料消耗等多方面因素与约束,给出了适合载人探测任务的候选小行星序列;然后,构建了载人小行星探测任务轨道的设计模型,采用参数优化算法对探测轨道进行了设计;进一步,为了获得最优探测轨道,利用主矢量原理对探测轨道进行了优化。该研究可为载人小行星探测任务设计提供有价值的参考。     

Halo轨道族延拓方法及特性研究

对Halo轨道周期和运动范围等特性的研究是平动点任务设计的首要前提。针对大幅值Halo轨道和完整Halo轨道族的应用需求及其数值计算问题,面向当前应用广泛的地月系和日-地月系共线平动点,基于延拓法研究了圆型限制性三体问题下的Halo轨道族数值计算和运动学特性,给出了Halo轨道族延拓计算方法。数值仿真了族参数选择对轨道族计算的影响,得到了地月系和日-地月系共线平动点的大范围南北Halo轨道族,同时给出了轨道族的轨道周期变化和空间位置变化特性。研究结果表明,固定延拓步长下,L1点Halo轨道族应选择会合坐标系x坐标作为族参数,L2点Halo轨道族应选择y方向速度或者周期T作为族参数。方法适用于任意三体系统平动点的周期轨道族计算,特别是对其中的状态转移矩阵简单修改后可用于完整力模型下的Halo轨道（族）的数值设计。     

火星探测接近段的光学自主导航研究

目前光学自主导航技术已成为深空探测计划中的重点研究对象. 已有研究, 多侧重于光学自主导航技术在深空探测巡航段或是对小行星探测接近段中的应用, 而关于大行星探测接近段光学自主导航技术的研究比较少. 结合中国即将开展的火星探测计划, 研究了探测器在火星探测接近段中利用火星进行光学自主导航的整个过程, 提出了适用于接近段的动力学模型、光学观测模型及自主导航滤波算法. 通过对自主导航系统的可观测性分析, 证明了仅利用火星光学信息进行自主导航的可行性. 仿真计算结果表明, 在接近段, 整个光学自主导航的持续时间约为40h. 在自主导航的最后5h内, 滤波结果稳定, 探测器的总体位置误差在40km以内, 速度误差在0.25m·s-1以内. 计算结果的精度满足实际任务需求, 对中国火星探测计划具有直接的参考价值.      

基于多冲量能耗估算的小推力任务窗口搜索

针对小推力轨道设计中任务窗口参数具有范围跨度大、非连续性强、对设计结果影响显著等特点,提出了一种基于多冲量能耗估算的任务窗口搜索方法.该方法基于多冲量轨道和小推力轨道的能耗一致性,先由朗伯特两冲量轨道经过数次迭代扩展快速获得多冲量轨道,再通过多冲量轨道能耗估算对任务区间进行全局栅格搜索,最终得到任务窗口的可行区域.仿真结果表明:1)该方法同时适用于交会和飞越任务;2)同朗伯特两冲量相比,它与小推力轨道能耗的一致性更强;3)同Sims和Flanagan最优多冲量相比,计算时间缩短了1～2个量级,计算效率显著提高.地球—火星交会任务的仿真应用表明,该方法只需8.59s即可获得任务窗口的可行区域,进而快速给出小推力最优转移轨道,验证了该方法的有效性.     

模拟月壤可行驶性的离散元数值分析

基于模拟月壤扫描电镜显微照片,建立土颗粒的几何模型,提出不规则形状颗粒群系统的生成策略,构建模拟月壤颗粒间接触的简化本构模型,并利用量纲分析法和双轴压缩试验离散元模拟,建立土宏观力学特性与细观模型参数的关系,结合模拟月壤的三轴压缩试验数据确定离散元模型参数.在月球重力环境下,对轮-土交互作用进行离散元模拟,推导土壤推力的细观表达式,定性分析不同滑转率时土颗粒的动态行为,定量分析模拟月壤的可行驶性.研究结果表明,土壤推力随滑转率的提高而增大;当车轮以高滑转率行驶时,土壤推力相对行驶时间存在瞬态和稳态2个阶段,并且瞬态值高于稳态值.     

火星空间环境磁场探测研究——高精度磁强计

萤火一号卫星将对火星空间环境磁场实施探测。火星磁场对火星弓激波、磁鞘、电离层、大气等绝大多数空间环境效应都具有重要影响,萤火一号对火星磁场的探测是通过搭载于其上的科学载荷磁强计来实现的。此磁强计在工作原理及具体设计上,考虑了火星轨道严酷的工作环境和科学目标所需的测量要求。通过装星前的地面标定测试,验证了萤火一号磁强计可以在-130～75℃温度范围内测量±256nT以内的磁场,分辨率可达到0.01 nT,带宽内总噪声小于0.03 nT,能够满足萤火一号对火星空间环境探测的需求。