How far is far enough? Requirements derivation for planetary mobility systems

The origination of duration and distance requirements on planetary mobility systems (generally, rovers) are reviewed in detail. It is found that a ‘clean’ flow down from scientific objectives to requirement to capability is rarely presented. Rather, the historical record shows that the capability of emerging designs has been adopted post-hoc as a requirement, simple comparative superiority to predecessor missions has been invoked in competitive situations, or the requirement has been driven by capability of other elements of a mission architecture, such as delivery precision or astronaut life support. These deviations from the idealized systems engineering process have nonetheless resulted in missions that have generally been considered highly successful.     

大气行星波影响低频电波吸收变化的机制

本文根据冬季中低纬低电离层中、低频（ＬＦ）电波振幅扰动与高纬平流层中大气行昨波活动密切相关的观测事实，分析研究了可能引起低电离层对ＬＦ电波吸收变化诸因素的作用后，提出了一种能较好地解释观测现象的物理机制，大气行星波可通过两种方式改变大气离化率ｑ，因而引起低电离层中电子密度Ｎ扰动，进而改变由Ｎ大小决定的电离层电波吸收值，结果导致ＬＦ电波振幅发生相应变化。文中给出了描述这一物理计算公式和某些计算结果。     

Equilibrium positions on stationary orbits and planetary principal inertia axis orientations for the Solar System

We present a qualitative analysis in a phase space to determine the longitudinal equilibrium positions on the planetary stationary orbits by applying an analytical model that considers linear gravitational perturbations. We discuss how these longitudes are related with the orientation of the planetary principal inertia axes with respect to their Prime Meridians, and then we use this determination to derive their positions with respect to the International Celestial Reference Frame. Finally, a numerical analysis of the non-linear effects of the gravitational fields on the equilibrium point locations is developed and their correlation with gravity field anomalies shown.     

Planetary protection on international waters: An onboard protocol for capsule retrieval and biosafety control in sample return mission

Planetary protection has been recognized as one of the most important issues in sample return missions that may host certain living forms and biotic signatures in a returned sample. This paper proposes an initiative of sample capsule retrieval and onboard biosafety protocol in international waters for future biological and organic constituent missions to bring samples from possible habitable bodies in the solar system. We suggest the advantages of international waters being outside of national jurisdiction and active regions of human and traffic affairs on the condition that we accept the Outer Space Treaty. The scheme of onboard biological quarantine definitely reduces the potential risk of back-contamination of extraterrestrial materials to the Earth.     

Automated design architectures for co-orbiting spacecraft swarms for planetary moon mapping

This work describes the design and optimization of spacecraft swarm missions to meet spatial and temporal visual mapping requirements of missions to planetary moons, using resonant co-orbits. The algorithms described here are a part of Integrated Design Engineering and Automation of Swarms (IDEAS), a spacecraft swarm mission design software that automates the design trajectories, swarm, and spacecraft behaviors in the mission. In the current work, we focus on the swarm design and optimization features of IDEAS, while showing the interaction between the different design modules. In the design segment, we consider the coverage requirements of two general planetary moon mapping missions: global surface mapping and region of interest observation. The configuration of the swarm co-orbits for the two missions is described, where the participating spacecraft have resonant encounters with the moon on their orbital apoapsis. We relate the swarm design to trajectory design through the orbit insertion maneuver performed on the interplanetary trajectory using aero-braking. We then present algorithms to model visual coverage, and collision avoidance in the swarm. To demonstrate the interaction between different design modules, we relate the trajectory and swarm to spacecraft design through fuel mass, and mission cost estimations using preliminary models. In the optimization segment, we formulate the trajectory and swarm design optimizations for the two missions as Mixed Integer Nonlinear Programming (MINLP) problems. In the current work, we use Genetic Algorithm as the primary optimization solver. However, we also use the Particle Swarm Optimizer to compare the optimizer performance. Finally, the algorithms described here are demonstrated through numerical case studies, where the two visual mapping missions are designed to explore the Martian moon Deimos.     

火卫二地形地貌探测综述

火卫二（Deimos）是火星自然卫星之一，研究人员利用火星探测器对其地形地貌开展了大量研究。首先对火卫二的基本参数及起源假说进行了介绍，进而全面梳理了与火卫二相关的航天探测活动，重点对地形地貌探测活动进行了详细介绍，并对围绕火卫二地形地貌的研究成果进行了归纳分析，结果表明火卫二表面分布有撞击坑、风化层、明亮的反射物质及块状物，并存在物质移动。最后针对火卫二探测不全面的情况，给出了中国关于火卫二探测的建议。     

行星着陆轨迹优化技术研究进展

针对行星大气进入、动力下降过程动力学环境及约束条件等进行了分析,回顾了近年来行星着陆轨迹优化的研究现状。在此基础上,结合行星着陆轨迹优化技术在动力学特征、约束条件、不确定环境方面的特点,从非线性动力学的等价/近似变换技术、复杂约束条件下的最优轨迹快速求解技术、不确定条件下的能控/能达性分析技术三个方面,对行星着陆轨迹优化的关键技术进行了梳理。     

Electrostatic accelerometer with bias rejection for gravitation and Solar System physics

Radio tracking of interplanetary probes is an important tool for navigation purposes as well as for testing the laws of physics or exploring planetary environments. The addition of an accelerometer on board a spacecraft provides orbit determination specialists and physicists with an additional observable of great interest: it measures the value of the non-gravitational acceleration acting on the spacecraft, i.e. the departure of the probe from geodesic motion.     

行星车视觉导航与自主控制进展与展望

以视觉为主的行星车自主地形感知、导航、规划与控制系统是其安全高效探测的重要保障。本文通过对已成功开展和计划中的系列行星车任务导航与控制系统进行汇总，重点梳理了行星车多源地形感知、自主全局和局部导航、自主路径规划与控制等若干关键问题的进展情况，展望了未来自主化、智能化的发展趋势，并结合任务需求构建了行星车视觉导航与自主控制研究框架设想。     

The Planetary Laboratory for Image Analysis (PLIA)

The observation, characterization, and understanding of planetary atmospheres are key components of Solar System exploration. Their study requires, among other observations, the use of image data acquired from spacecrafts. The basic tasks that are generally used to work with planetary image data are: image navigation, projection, image processing, limb-darkening correction, composition of multiwavelength images and mosaicing. We illustrate the mathematical techniques required for the study of planetary images obtained from spacecrafts using as an example our own software package (PLIA). We present examples of analysis of Galileo SSI, Cassini ISS and Venus Express VIRTIS observations covering a large range of image peculiarities. The paper is organized as a guide for anyone willing to replicate one or several of the capabilities incorporated in the PLIA software. An open source version of PLIA for astronomical image processing is available.