Overview of the New Horizons Science Payload

The New Horizons mission was launched on 2006 January 19, and the spacecraft is heading for a flyby encounter with the Pluto system in the summer of 2015. The challenges associated with sending a spacecraft to Pluto in less than 10 years and performing an ambitious suite of scientific investigations at such large heliocentric distances (>32 AU) are formidable and required the development of lightweight, low power, and highly sensitive instruments. This paper provides an overview of the New Horizons science payload, which is comprised of seven instruments. Alice provides moderate resolution (～3–10 Å FWHM), spatially resolved ultraviolet (～465–1880 Å) spectroscopy, and includes the ability to perform stellar and solar occultation measurements. The Ralph instrument has two components: the Multicolor Visible Imaging Camera (MVIC), which performs panchromatic (400–975 nm) and color imaging in four spectral bands (Blue, Red, CH₄, and NIR) at a moderate spatial resolution of 20 μrad/pixel, and the Linear Etalon Imaging Spectral Array (LEISA), which provides spatially resolved (62 μrad/pixel), near-infrared (1.25–2.5 μm), moderate resolution (λ/δ λ～240–550) spectroscopic mapping capabilities. The Radio Experiment (REX) is a component of the New Horizons telecommunications system that provides both radio (X-band) solar occultation and radiometry capabilities. The Long Range Reconnaissance Imager (LORRI) provides high sensitivity (V<18), high spatial resolution (5 μrad/pixel) panchromatic optical (350–850 nm) imaging capabilities that serve both scientific and optical navigation requirements. The Solar Wind at Pluto (SWAP) instrument measures the density and speed of solar wind particles with a resolution ΔE/E<0.4 for energies between 25 eV and 7.5 keV. The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) measures energetic particles (protons and CNO ions) in 12 energy channels spanning 1–1000 keV. Finally, an instrument designed and built by students, the Venetia Burney Student Dust Counter (VB-SDC), uses polarized polyvinylidene fluoride panels to record dust particle impacts during the cruise phases of the mission.     

离子发动机加速栅极腐蚀深度的DFF测量与数值模拟

使用聚焦深度表面测量(DFF)方法对加速栅极下游表面腐蚀深度进行了测量,并将测量结果与数值模拟结果进行了比较,所使用的数值方法为PIC-Monte Carlo方法.利用数值模拟程序对离子发动机栅极腐蚀进行了数值模拟.以氙为推进剂,栅极材料为钼.用蒙特卡罗方法模拟了氙离子与中性氙原子之间的电荷交换碰撞.模拟得到了加速栅极下游表面离子溅射腐蚀的深度分布,腐蚀模式与"Pits and grooves"模式相吻合.      

GPS抗干扰接收机空时二维自适应滤波算法的FPGA实现

传统的抗干扰接收机存在自由度有限、抗多径干扰能力弱等不足。针对这些不足,有人提出了空-时二维自适应滤波(STAP)算法。文章介绍了空-时二维自适应抗干扰算法的性能、特点以及Matlab仿真和FPGA实现情况。文章没有使用通常使用的多级维纳嵌套(MSNWF)逼近方法,而是尝试采用矩阵直接求逆的方法来求出自适应系数。通过仿真和实测,此方法达到了较好的效果。文章的研究成果对通信对抗、雷达对抗都有重要的参考价值。     

CCAR23部飞机HIRF防护适航验证方法研究

民用飞机为获得在高强辐射场环境中的运营许可,必须按照适航当局发布的高能电磁辐射场( HIRF )防护相关适航条款进行防护设计和适航验证。当前确定航空器内部 HIRF 环境主要通过试验方法和相似性评估法,具有工作量大、测试成本高等缺点。针对仅有 A 类显示系统的 CCAR23 部飞机首次使用数据推算方法,确定飞机内部 HIRF 环境电平,用于实现整机的 HIRF 防护适航验证;提出一套适用于 CCAR23 部飞机 HIRF防护适航验证的方法,分析该方法的关键技术及可行性。本文所提出的方法已应用于 Y12F 飞机 HIRF 防护适航验证的实际工程,有效降低了整机 HIRF 防护适航验证的复杂程度,节约了整机试验所需的测试成本,提高了试验效率,为民用航空器 HIRF 防护验证提供参考。     

地月平动点拟周期轨道探测器自主导航方法研究

地月L2点的拟周期轨道可以用于实现与月球背面的持续通信,具有重要的科学研究价值和广阔的应用前景。针对地月L2点探测器所处的弱稳定拟周期轨道,论证了基于日地月信息的自主导航方法的可行性,并进行了深入分析。首先,推导了会合坐标系下带有星历的精确导航动力学方程;其次,针对弱稳定轨道不同于近地强稳定轨道的特性,在基于日地月方位信息导航的基础上,提出了三种敏感器组合方案。使用迭代最小二乘方法给出导航仿真结果,并结合非线性可辨识性理论对这三种情况下历元状态的可辨识性及可辨识度进行分析。最后,仿真结果表明,使用日地月敏感器以及对地多普勒雷达可以满足历元状态的可辨识性、导航的收敛性以及系统经济性的要求。     

Generation of satellite tracking profile: Problems and validation algorithms

Recently, as a satellite mission becomes complicated, it has been required to generate the schedule of satellite antenna movements automatically without relying upon operator’s ad hoc knowledge. To generate the satellite antenna schedule autonomously, this paper first addresses geometrical problems associated with the antenna scheduling and mission planning problems that can be formulated from satellite navigation and antenna orientation information. Then, based on the solutions of the geometrical problems, a set of antenna azimuth and elevation angles that enables the antenna to point towards the desired ground station is obtained systematically. Using the computed azimuth and elevation angles, the satellite tracking profile (TP) is generated, and to validate it, TP validation algorithms are developed.     

Precise orbit determination using the batch filter based on particle filtering with genetic resampling approach

In this study, genetic resampling (GRS) approach is utilized for precise orbit determination (POD) using the batch filter based on particle filtering (PF). Two genetic operations, which are arithmetic crossover and residual mutation, are used for GRS of the batch filter based on PF (PF batch filter). For POD, Laser-ranging Precise Orbit Determination System (LPODS) and satellite laser ranging (SLR) observations of the CHAMP satellite are used. Monte Carlo trials for POD are performed by one hundred times. The characteristics of the POD results by PF batch filter with GRS are compared with those of a PF batch filter with minimum residual resampling (MRRS). The post-fit residual, 3D error by external orbit comparison, and POD repeatability are analyzed for orbit quality assessments. The POD results are externally checked by NASA JPL’s orbits using totally different software, measurements, and techniques. For post-fit residuals and 3D errors, both MRRS and GRS give accurate estimation results whose mean root mean square (RMS) values are at a level of 5 cm and 10–13 cm, respectively. The mean radial orbit errors of both methods are at a level of 5 cm. For POD repeatability represented as the standard deviations of post-fit residuals and 3D errors by repetitive PODs, however, GRS yields 25% and 13% more robust estimation results than MRRS for post-fit residual and 3D error, respectively. This study shows that PF batch filter with GRS approach using genetic operations is superior to PF batch filter with MRRS in terms of robustness in POD with SLR observations.     

A new approach to the telescope operation method for satellite tracking using a time synchronization technique

For the development of a telescope that is capable of precisely tracking satellites and high-speed operation such as satellite laser ranging, a special method of telescope operation is required. This study aims to propose a new telescope operation method and system configuration for the independent development of a mount and an operation system which includes the host computer. Considering that the tracking of a satellite is performed in real time, communication and synchronization between the two independent subsystems are important. Therefore, this study applied the concept of time synchronization, which is used in various fields of industry, to the communication between the command computer and the mount. In this case, communication delays do not need to be considered in general, and it is possible to cope with data loss. Above all, when the mount is replaced in the future, only the general communication interface needs to be modified, and thus, it is not limited by replacement in terms of the overall system management. The performance of the telescope operation method developed in this study was verified by applying the method to the first mobile SLR system in Korea. This study is significant in that it proposed a new operation method and system configuration, to which the concept of time synchronization was applied, for the observation system that requires an optical telescope.     

Lattice Boltzmann Flux Solver： An Efficient Approach for Numerical Simulation of Fluid Flows

A lattice Boltzmann flux solver （LBFS） is presented for simulation of fluid flows. Like the conventional computational fluid dynamics （CFD） solvers, the new solver also applies the finite volume method to discretize the governing differential equations, but the numerical flux at the cell interface is not evaluated by the smooth function approximation or Riemann solvers. Instead, it is evaluated from local solution of lattice Boltzmann equation （LBE） at cell interface. Two versions of LBFS are presented in this paper. One is to locally apply one-dimensional compressible lattice Boltzmann （LB） model along the normal direction to the cell interface for simulation of compressible inviscid flows with shock waves. The other is to locally apply multi-dimensional LB model at cell interface for simulation of incompressible viscous and inviscid flows. The present solver removes the drawbacks of conventional lattice Boltzmann method （LBM） such as limitation to uniform mesh, tie-up of mesh spacing and time interval, limitation to viscous flows. Numerical examples show that the present solver can be well applied to simulate fluid flows with non-uniform mesh and curved boundary.     

皮卫星星箭分离机构运动系统设计

为实现“皮星一号A”卫星无干涉分离,达到分离初始姿态要求,对皮卫星星箭分离机构运动系统进行了分析设计。首先,根据皮卫星与凸轮限位机构间的受力情况和能量守恒定理确定了凸轮轮廓尺寸和分离弹簧结构参数,在此基础上建立了星箭分离过程动力学模型,通过对动力学模型的数值计算确定满足无干涉分离条件的舱门扭簧弹性系数。星箭分离过程的仿真计算和试验校验了“皮星一号A”星箭分离机构可实现无干涉分离,皮卫星初始速度、角速率均满足所提出的各项初始分离姿态要求。