一种双层框架型腿式月球探测车方案

月球车的设计,就行进方式而言,多以轮式车为主。考虑到国外已有的车型及相关研究也多以轮式车为先,这里提出了一种双层框架型腿式车的设计方案,它兼具腿式车和轮式车的优点。文章建立了该型车的三维模型,并利用虚拟样机技术,构建起月球车的动力学仿真环境,并进行了控制算法和步态的设计,通过联合仿真,完成了此车的初步方案设计工作。     

月面巡视探测器立体相机共线方程的建立

为了准确提取月面巡视探测器探测区域的DEM并实现对月面巡视探测器的高精度定位,需要根据月面巡视探测器携带的立体相机的成像原理和配置情况,建立立体相机的共线方程。文章讨论了在水平和垂直方向旋转摄影条件下,月面巡视探测器桅杆上的立体相机的共线方程。     

月球表面热环境测量技术调研分析

月面热环境探测是我国探月工程中的一项必要工作,具有重要的工程和科学意义。文章从工程角度确定了月面热环境测量的主要物理参数,分析了现阶段我国探月工程中实现月面热环境测量的技术条件和要求;对国内外有关材料热物性测量技术进行了综合调研,了解了国内外关于开展行星表面热环境探测的技术及应用现状;在结合我国航天测量技术的基础上对月面热环境测量所涉及的关键技术进行了分析,并初步勾勒出我国探月工程中月面热环境测量装置的指标、任务和实现方案。     

直联式超燃实验台超声速燃气取样分析

在超燃冲压发动机实验中,燃烧室出口气体成份及分布是衡量燃烧情况的重要依据.笔者采用探针取样-色谱分析的方法,对于直联式超燃实验台不同工况下燃烧室出口气体进行了取样分析,总结了煤油燃烧比较完全、不完全以及基本未燃烧三种情况的典型气体分布规律.目前可测得的气体成份包括H2、O2、N2、CO、CO2、CH4和C2H4,进行成份分析与相应条件下燃烧室壁面静压分布比较,可进一步了解超声速燃烧的内部细节,为改进燃料掺混与燃烧提供参考数据.     

嫦娥三号巡视器-着陆器释放分离过程关键力学问题分析

针对嫦娥三号探测器两器释放分离过程几个关键力学问题,给出两器释放分离过程的主要风险点与影响参数,应用ADAMS建立两器释放分离全过程仿真模型,开展了全过程动力学仿真与相关试验。分析得到可适应安全释放分离要求的着陆器最大着陆姿态边界与关键性能参数,为两器释放分离提供了理论支撑与依据。     

嫦娥五号轻量化高精度上升器结构设计

针对嫦娥五号上升器结构面临的轻量化设计要求严苛、有效载荷接口精度要求极高和有效载荷指向变化预示精度要求很高的难题,提出至顶向下的结构轻量化设计方法,使得上升器结构自重降低到整器重量的6.2%(47.758 kg);建立压紧和精度保持功能分离、双坐标系分级实现高精度的结构设计方法,实现相关有效载荷的结构安装接口精度达到400 mm×400 mm区域平面度小于或者等于0.05 mm;探索出综合了有效载荷自身和安装结构耦合效应的有效载荷在轨指向变化预示方法,实现准确、高效、快速地对有效载荷指向变化进行角秒级高精度评估。这些方法支持完成中国月面无人自动采样返回任务,并最终促进中国航天器结构技术的发展。     

基于PE文件的病毒防治技术研究

本文提出了两种防范PE文件病毒的技术:一种是分析PE文件格式和病毒对PE文件的感染方式,通过PE自身文件结构的改进来防范病毒;另一种是基于PE文件自我完整性检查的计算机病毒的免疫方法,采用单向散列函数MD5算法抽取摘要,通过比较两个摘要值来判断是否存在病毒,如果存在病毒启用恢复程序来恢复文件。相对于传统的特征码匹配方法,这些技术不依靠病毒库,可以防范未知病毒。     

Ariane 5 GTO debris mitigation using natural perturbations

GTO objects can potentially collide with operative satellites in LEO and GEO protected regions. Internationally accepted debris mitigation guidelines require that these objects exit these protected regions within 25?years, e.g. by re-entering and burning up in Earth’s atmosphere. In this paper, an inventory of the GTO debris generated from Ariane 5 launches in the period 2012–2017 is provided, and it is expected that none of these objects will re-enter within 25?years. For future launches, natural perturbations can be exploited to increase compliance with mitigation guidelines without the use of extra propellant or complex de-orbiting systems, which is attractive from an economic point of view. The lifetime of GTO objects is very sensitive to initial conditions and some environmental and body-related parameters, mainly due to the effect of solar gravity on the perigee altitude. As a consequence, the lifetime of a specific GTO object cannot be predicted accurately, but its probability of re-entering in less than 25?years can be estimated with proper accuracy by following a statistical approach. By propagating the orbits of over 800,000 simulated Ariane 5 GTO objects, it was found that the launch time leading to the highest probability of compliance with debris mitigation guidelines for GEO launches from Kourou corresponds to about 2 PM local time, regardless of the date of launch, which leads to compliance rates ranging from 60 to 100%. Current practice is to launch at around 5–9?PM, so a change in procedures would be required in order to reach a higher degree of compliance with debris mitigation guidelines, which was predicted to be on average below 20% for the objects generated in the period 2012–2017.     

Mesosphere/lower thermosphere wind regime parameters using a newly installed SKiYMET meteor radar at Kazan (56°N, 49°E)

New meteor radar (MR) horizontal wind data obtained during 2015–2018 at Kazan (56°N, 49°E) are presented. The measurements were carried out with a state-of-the-art SKiYMET meteor radar. Monthly mean vertical profiles of zonal and meridional components of the prevailing wind speeds, also amplitudes and phases of the components of diurnal (DT) and semidiurnal tide (SDT) winds are displayed as contour plots for a mean calendar year over the four recent years and compared with distributions of these parameters provided by the previous multiyear (1986–2002) meteor radar (MR) measurements at Kazan and by the recent HWM07 empirical model. The analysis shows that the SKiYMET zonal and meridional prevailing wind speeds are generally in good agreement, sharing the same seasonal features, with the earlier MR seasonal winds. Comparisons with the HWM07 model are not favourable: eastward solstitial cells as modelled are significantly larger, >30?m/s compared to 15–20?m/s. Also, reversal lines are too variable with height, and the positions of modelled cells (positive and negative) are unlike those of either MRs at Kazan or other MLT radars. Both MR systems provide the large SDT amplitudes, approximately 30?m/s and vertical wavelengths, approximately 55?km, for both components at middle latitudes in winter. They also show the well known strong SDT September feature (heights 85–100?km, the vertical wavelength ～55–60?km), and the weak summer SDT for 80–91?km. HWM07 shows unrealistic amplitudes and phases above 90?km by height and month: minimal amplitudes in equinoxes and no September feature.The weak DT of middle to high latitudes provide similar amplitude and phase structures from both MRs, 1986–2002 and 2015–2017: largest amplitudes (10–12 or 8–10?m/s) for the evanescent meridional tide in summer, peaking in late July; weakest (0–2, 2–4?m/s) at 80 to 92–96?km, when the tide is vertically propagating (January, February, November, December) with a vertical wavelength near 40?km. Again, HWM07 differs in amplitude and phase structures: showing peak amplitudes in equinoxes: April, 15?m/s at 88?km; October, 21?m/s at 89?km.Coupling of the MR wind parameters with the ERA5 wind parameters is studied for a case in 2016. It is shown that the prevailing winds and DT amplitudes and phases of both datasets can be simply linked together, but that the ERA5 SDT amplitudes are significantly underestimated at the top model levels of the ERA5 reanalysis project.