月球探测器天文测角/单程无线电时间差分测距/差分测速导航方法

月球探测器高精度导航技术是确保月球探测任务顺利实施的关键技术之一。当前,大多数月球探测器都是利用地面无线电进行导航和控制,但存在可测控弧段短、易受干扰等局限性,且对于月球背面探测,存在无法直接测控的不足。针对上述问题,提出了一种新的基于天文测角/单程无线电差分测距/差分测速的月球探测器组合导航方法。该方法使用了天文星光角距、探测器接收到的来自地面站或中继星的单程无线电时间差分测距和时间差分多普勒测速3种量测信息,可有效抑制星上时钟和频谱仪的时间和频率测量误差。收敛后的平均位置和速度估计误差分别为902.7 m和0.12 m/s,最大的位置和速度估计误差分别为1 548.2 m和0.24 m/s。仿真分析结果表明该方法具有较高自主导航精度。     

Overloading of Landing Based on the Deformation of the Lunar Lander

Along with the progress of sciences and technologies, a lot of explorations are taken in many countries or organizations in succession. Lunar, the natural satellite of the earth, become a focus of the space discovery again recently because of its abundant resource and high value in use. Lunar exploration is also one of the most important projects in China. A primary objective of the probe in lunar is to soft-land a manned spacecraft on the lunar surface. The soft-landing system is the key composition of the lunar lander. In the overall design of lunar lander, the analysis of touchdown dynamics during landing stage is an important work. The rigid-flexible coupling dynamics of a system with flexible cantilevers attached to the main lander is analyzed. The equations are derived from the subsystem method. Results show that the deformations of cantilevers have considerable effect on the overloading of the lunar lander system.     

月地转移轨道精确轨道设计

以基于Lambert算法的快速轨道设计结果为初值,开展精确轨道设计研究.通过对月地返回飞行阶段的摄动项和量级分析,建立了月地转移轨道的动力学方程,提出了一种双向嵌套循环搜索算法,采用该算法求解同时满足两端约束条件的精确月地转移轨道.该算法以出月球影响球的时刻和位置、速度为中间变量,一方面采用前向数值积分和微分改正法搜索满足地球再入端的轨道,另一方面采用后向数值积分并进行倾角和近月距修正得到满足月球端的轨道,通过这种双向嵌套循环,使得两段轨道在月球影响球边界处的位置和速度连续,从而获得一条完整的满足两端约束条件的月地转移精确轨道.最后以2017年1月26日出月球影响球作为返回窗口,给出了具体的设计算例,并通过STK软件仿真验证了程序的设计结果.     

Back to the moon: the lure of lunar exploration

Interest in returning to the Moon is growing and has sparked plans for a NASA robotic sample return probe to the South Pole-Aitken basin. Japan and the European Space Agency also have plans for lunar probes and China is interested in expanding its new space program to the Moon.     

月球探测器姿态大角度机动的反作用轮控制

研究了月球探测器转速与控制力矩受限的姿态大角度机动问题。根据时间变尺度思想，提出了双回路反馈的姿态大角度机动控制方法。以某型月球控测器为例，对该方法进行了仿真验证。结果表明，利用该控制方法，可使探测器以期望的角速度转动，从而完成探测器的姿态大角度机动。     

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。     

The ARTEMIS Mission

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon??s Interaction with the Sun (ARTEMIS) mission is a spin-off from NASA??s Medium-class Explorer (MIDEX) mission THEMIS, a five identical micro-satellite (hereafter termed ??probe??) constellation in high altitude Earth-orbit since 17 February 2007. By repositioning two of the five THEMIS probes (P1 and P2) in coordinated, lunar equatorial orbits, at distances of ??55?C65 R _E geocentric (??1.1?C12 R _L selenocentric), ARTEMIS will perform the first systematic, two-point observations of the distant magnetotail, the solar wind, and the lunar space and planetary environment. The primary heliophysics science objectives of the mission are to study from such unprecedented vantage points and inter-probe separations how particles are accelerated at reconnection sites and shocks, and how turbulence develops and evolves in Earth??s magnetotail and in the solar wind. Additionally, the mission will determine the structure, formation, refilling, and downstream evolution of the lunar wake and explore particle acceleration processes within it. ARTEMIS??s orbits and instrumentation will also address key lunar planetary science objectives: the evolution of lunar exospheric and sputtered ions, the origin of electric fields contributing to dust charging and circulation, the structure of the lunar interior as inferred by electromagnetic sounding, and the lunar surface properties as revealed by studies of crustal magnetism. ARTEMIS is synergistic with concurrent NASA missions LRO and LADEE and the anticipated deployment of the International Lunar Network. It is expected to be a key element in the NASA Heliophysics Great Observatory and to play an important role in international plans for lunar exploration.     

First Results from ARTEMIS, a New Two-Spacecraft Lunar Mission: Counter-Streaming Plasma Populations in the Lunar Wake

We present observations from the first passage through the lunar plasma wake by one of two spacecraft comprising ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon??s Interaction with the Sun), a new lunar mission that re-tasks two of five probes from the THEMIS magnetospheric mission. On Feb 13, 2010, ARTEMIS probe P1 passed through the wake at ??3.5 lunar radii downstream from the Moon, in a region between those explored by Wind and the Lunar Prospector, Kaguya, Chandrayaan, and Chang??E missions. ARTEMIS observed interpenetrating proton, alpha particle, and electron populations refilling the wake along magnetic field lines from both flanks. The characteristics of these distributions match expectations from self-similar models of plasma expansion into vacuum, with an asymmetric character likely driven by a combination of a tilted interplanetary magnetic field and an anisotropic incident solar wind electron population. On this flyby, ARTEMIS provided unprecedented measurements of the interpenetrating beams of both electrons and ions naturally produced by the filtration and acceleration effects of electric fields set up during the refilling process. ARTEMIS also measured electrostatic oscillations closely correlated with counter-streaming electron beams in the wake, as previously hypothesized but never before directly measured. These observations demonstrate the capability of the comprehensively instrumented ARTEMIS spacecraft and the potential for new lunar science from this unique two spacecraft constellation.     

月球着陆器软着陆状态跳跃半主动控制

 将磁流变阻尼器应用到月球着陆器着陆机构中,进行减震与缓冲。考虑到着陆初始姿态角的不定和月面斜角的未知,建立起着陆器软着陆动力学模型。基于磁流变液在高速流与长冲程时的阻尼特性,分析了磁流变阻尼器的力学特性。应用安全角面的概念定义安全着陆所要求的着陆初始姿态角与月面斜角之间的关系,建立状态跳跃控制策略,实现软着陆半主动控制。通过与某型被动控制的着陆器进行对比分析,研究了半主动控制。研究结果表明：当允许的最大加速度响应不超过8g时,磁流变半主动状态跳跃控制的安全角面为理想安全角面的0.977 4,是被动控制安全角面的4.2倍,最大加速度变化的相对标准差为被动控制的0.59;而且当着陆初始姿态角以及月面斜角很大时,月球着陆器姿态角变化少,保证月球着陆器平稳着陆。     

新一代载人月面着陆器发展趋势研究

月面着陆器是实现载人探月任务的重要组成部分,从任务规划和着陆器参数两个方面对早期美国阿波罗计划中的月面着陆器（ LM）、苏联N1-L3登月计划中的月面着陆器（ L3登月系统）以及最近美国星座计划中的月面着陆器（ Altair）的相关情况进行了分析,并从任务需求、月面环境和研究经费及基础设施方面对LM与Altair月面着陆器进行详细比较,通过比较分析总结出新一代载人月面着陆器将沿着提高乘员运送能力、扩大到达范围、延长航天员生活时间及功能模块化的方向发展,并提出研制新一代月面着陆器应着重解决着陆器推进、结构、着陆障碍检测及缓冲以及月尘防护等关键技术。     

面向月球基地设备交互场景的目标检测与路径规划算法研究

随着国际月球科研站计划的快速推进,针对月球基地相关技术的研究受到了广泛关注。面向月球基地场景下不同的设备间进行自主接触式交互这一应用背景展开研究。考虑不同的设备在进行自主接触式交互时,需要准确地完成相互识别,并且规划出畅行无阻且较优的行进路线以保证往返活动顺利进行,基于Webots搭建了月球基地仿真环境进行目标检测和路径规划相关实验。以前后配备高精度RGB相机的交互设备为载体实现基于TPH-YOLOv5月球基地场景下的目标检测。此外,设计并实现了交互设备在月球基地场景下基于双向快速扩展随机树（Bidirectional RTT）的路径规划算法,以保证交互设备在月球基地环境下的相关工作顺利进行。仿真结果显示,该目标检测及路径规划算法能够实现预期功能。     

月面特征稀疏环境下的视觉惯性SLAM方法

月球车在执行科学探测任务过程中,其自身的高精度定位是一项亟需解决的关键问题。针对在特征稀疏的月面环境下的定位问题,提出一种视觉惯性融合的SLAM方法,将视觉测量与惯性传感器的信息利用位姿图优化方法融合,实现高精度的联合定位。针对特征稀疏环境下的前端视觉数据关联误差较大的问题,提出了一种基于四元树的光流跟踪算法,能够有效地跟踪鲁棒的特征点,提升了关键帧之间相对位姿估计的准确性。并且针对月面环境特有的恒星无穷远点干扰问题,提出一种高效的恒星点剔除算法,能够有效改善无穷远点导致的定位精度下降的问题。搭建了一套模拟月面环境的计算机仿真系统,并构建了多个月面环境视觉惯性SLAM仿真数据集,在不同的模拟月面场景下进行定位性能仿真验证,仿真测试结果表明本文算法的鲁棒性更强,具有更高的定位准确度。     

Synopsis: Horizons in Guidance Computer Component Technology

An extensive survey of semiconductor and memory component manufacturers conducted by the Electronics Research Center of NASA and industry has resulted in estimates of the state of the art of components available to designers of on-board guidance and control computers for long-term, deep-space missions for the 1970-1972 period. The vehicle for the survey was the mission requirements for the synchronous satellite, lunar orbiter, Mars orbiter, and Jupiter fly-by solar probe missions.     

深空探测着陆器数字化设计及着陆性能影响因素

以对称分布四腿悬架式月球着陆器为研究对象,建立了着陆器软着陆过程六自由度动力学模型并改进了月壤摩擦系数模型;在以上动力学模型基础上,以月球着陆器为例编制了着陆器软着陆六自由度动力学分析程序,利用该程序分析了探测器全机月面软着陆性能,重点研究了动力学模型中的月面等效弹性系数、月面摩擦系数和月面倾斜角度等参数对探测器着陆性能的影响。研究表明上述影响因素对着陆器着陆缓冲性能影响显著,通过对以上参数的合理选择可以有效缓解月球探测器月面软着陆的着陆冲击过载。     

Synthesis and characterization of geopolymer from lunar regolith simulant based on natural volcanic scoria

In this study, a new GVS（Ground Volcanic Scoria） lunar regolith simulant was produced. The similarity between GVS and lunar soil was proved by comparison with Apollo lunar soil samples and other commercial lunar soil simulants. Then, GVS lunar regolith simulant was investigated as the source material for preparing geopolymer to produce building material for lunar colony construction. To study the possibility of preparing geopolymer from GVS lunar regolith simulant and the optimum activator formu...     

不同粒径分布模拟月壤承压特性试验研究

月壤的承压特性决定月面巡视探测器的行驶阻力和沉陷,是影响月面可通过性的主要特征之一。为了得出不同粒径分布的模拟月壤在巡视器地面载荷和月面载荷下的承压特性,通过压板试验获取了3种不同粒径分布模拟月壤的承压性能曲线与参数。分析表明:粒径分布对模拟月壤承压性能影响大,粒径粗且分布均匀的JLU-1模拟月壤承压能力最强,其次为JLU-3模拟月壤,而粒径细且分布窄的JLU-2模拟月壤承压能力最弱;3种模拟月壤的变形指数在其他模拟月壤的范围内,松软状态时接近月壤值,在小载荷作用且松软状态时变形指数小于1;3种模拟月壤的内聚模量在其他模拟月壤的范围内,但大于月壤值;松软状态时3种模拟月壤的摩擦模量在其他模拟月壤的范围内,中密和密实状态下均大于月壤值。研究结果对月面探测器行走机构的仿真和路径规划具有参考意义。     

基于月面LTE基站OFDM测距的巡视器定位

针对目前的月面定位技术中成本高、观测时间长以及缺少可用定位信息的问题,开展了基于长期演进（LTE）基站的月面定位技术的研究,并引入了LTE技术,通过在月面布设基站为月面巡视器的实时定位提供了可行基础。提出了一种基于因子图优化的月面定位方法,通过融合月面基站的正交频分复用（OFDM）测距信息和巡视器自身的惯性导航信息,利用有限的月面基础设施,在较低成本的硬件条件下实现了月面巡视器的准确定位。仿真实验结果显示,该月面定位方法具有良好的准确性和鲁棒性。     

月球探测器与地球轨道卫星测控通信干扰分析

对月球探测器的测控通信,通信距离遥远,信号空间损耗大,地面站接收机灵敏度高,因此更易受到外来信号干扰的影响。本文根据卫星网络间同频干扰计算方法,分析月球探测器测控通信下行链路受地球轨道卫星发射信号的干扰问题,主要包括月球探测器受地球静止轨道卫星（GEO）和地球非静止轨道卫星（NGSO）的干扰分析。在此基础上实现了仿真,计算其受干扰的可能性。     

载人登月轨道月面可达区域分析

全月面到达是21世纪以来载人登月研究的主要目标之一。影响月面可达区域的因素有很多,而阳光入射角约束和转移轨道约束是主要因素。首先分析了不同纬度区域阳光入射角规律,其次建立了一种适于月面可达区域分析的双二体圆锥曲线拼接算法,分析了自由返回轨道和混合轨道月面可达区域,并计算了变轨策略及其速度增量关系,为未来实现载人登月月面着陆区选择提供参考。