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The author:(作者)hpmailerpublished in(发表于) 2013/12/1 20:48:51 Expert interpretation of Chang-third design
Xinhuanet, Beijing, December 1 (reporter Wang Min)-Chang the third probe, is China's first "leg" of the spacecraft, a Chinese spacecraft of extraterrestrial objects are first used to attempt a soft landing. "Three girls" looks like, compared with the earlier Chang, first, second, what are the characteristics of, is how to design it? Reporters interviewed the relevant experts of the China Aerospace Science and Technology Corporation.
Configuration design – four-legged six rounds
According to reports, the "three girls" has four legs six wheels are Lander and visiting players (commonly known as "Rover") combination. Different from the goddess, first, second, to become immortal, not satellites, third in the name, is the first "leg" of the spacecraft.
Designer Yang Jianzhong, Director of the aerospace science and technology group introduced, that combination configuration, are determined by the characteristics of its mandate. Chang-there are two main third mission, is to achieve Lunar soft landing, the second is the implementation of moon patrol reconnaissance. This requires both falling on the lunar surface, can independently animated. Break down tasks to two probes to help accelerate the development pace.
Fall months ago, toured as a payload is mounted on the lander itself does not work. During the entire flight, power dropped and the implementation of a soft landing in the early, are done by the lander. After months, both compatible with visiting collector on the surface, becoming two separate detectors, in months of efforts to detect their mandates.
Lander contains 11 sub-system, one of the most distinctive is the landing cushion system, embodied in the four "Chinese leg" shape. It is understood that the soft landing approach in other countries there are three main types: first, balloon bounce, landing is the second-leg, and the third is an aerial cable car. Each option has advantages and disadvantages. Chang-third soft landing missions, air bag type does not meet the weight requirement, cranes are more complex leg meets mission needs, guarantee the stability of landing. Under General, selection of Chang e, third-leg landing.
Contains 8 system for inspection, one of the most distinctive are the move system. From the appearance point of view, is visited by 6 wheels.
Visiting Vice President of China Aerospace Science and technology group designers introduce Jia Yang, mobile solution has three main visits abroad: crawler, legs and wheeled. Crawler visits like the robots in the movie, its biggest advantage is that small pressure, through strong, but its weakness is encountered stone-easily get stuck, unable to move. -Leg visit is walking on a flat surface, but more complex to control, can't just sit on the floor. Wheel you can avoid these shortcomings.
In addition, due to the weight of the detector limit to become immortal, the third must be "downsizing", integrated, compact design, you must also ensure the reliability of the system. Only in this way can guarantee that it is a robust probe.
Path design – an unprecedented
Prior to this, Chang e, path to reach the Moon, the first and the second successful exploration has been done. Because the tasks needed to become immortal, the third path design to be based on the previous one, and greatly enhances the risk and difficulty. It 15 kilometres in recent months to be powered down, went on to achieve Lunar soft landing, then the lunar surface inspection survey.
This 15 km drive down is based on parabolic line decreases. Probes from the 1.7 km/s relative velocity gradually reduced to 0, the process is driven by detector independently to complete, almost zero possibility of manual intervention. When from the lunar surface 100 meters, detectors to hover, photographing the lunar surface, avoiding obstacles, searching for landing sites.
Engineers on the ground, the process for the first time, there are two major risks. Is the key equipment that is newly developed, including GNC systems (guidance, navigation and control systems), and China's first new space for 7,500 n variable thrust engine. Second soft landing the topography of the area there was a degree of uncertainty.
Probe after Lunar soft landing, the lander separated and inspections should be carried out, achieving shooting each other. Lander largely fixed in one place, visit requires from the Lander's "walk" down, Moon patrol reconnaissance. Path of the lunar surface, but also to "tele-operated" and "patrol independently control the" combination of technical means.
In addition to ground remote-operation, inspections can also use computers, processes the images, identify obstacles, plan out relatively close to local path, control the movement of their own. At this time, visiting is an autonomous mobile robot.
Functional design – to ensure that the lunar surface survival
Unlike Earth, the surface of the Moon larger temperature difference between day and night, at the high temperature to 120 degrees Celsius, temperature is low at lingxia180sheshidu. Also, alternating day and night of the Moon cycle is longer, which gives "three girls" brings a great deal of difficulty to the lunar surface survival.
Lander of the China Aerospace Science and technology group of thermal control subsystem designer Liu Zijun, Director of "tuck", "make" and "open air" and other familiar concept explanation of control design. Chang, third, there is a multi-layer insulation components, known as "blanket", bi-directional, and external high-temperature heat from inside, cold outside when heat from leaking.
Cold "three girls" or "stove". "Stove" mainly isotope nuclear sources, it can radiate. Designers have designed the gravity-driven two fluid circuits, heat when you need to import the cabin, cut heat transfer when not needed.
To the months of daylight, Rainbow Bay temperature quickly rise to 90 degrees Celsius, on the Moon's surface, cooling only heat radiation. Designers are detectors designed several thermal, thermal escape device.
With these means and methods, "three girls" could properly protect themselves and survive on the surface, which can be used to carry scientific payloads for the work. At present, the lander carries mainly, moon base EUV camera camera binoculars, topography, there are some on the lunar surface, moon dust to measure engineering loads. Patrol has mainly carried radar, panoramic camera, infrared spectrometer, and Lunar laser particle induced x-ray spectrometers, carry out scientific exploration tasks. Through them, scientists will be the subsequent accumulation of lunar exploration data, ordinary people can have a better understanding of the universe.
新华网北京12月1日电(记者王敏)嫦娥三号探测器，是我国第一个“有腿”的航天器，也是中国人首次用来尝试地外天体软着陆的航天器。“三姑娘”长什么样，与此前的嫦娥一号、二号相比有什么特点，是如何设计出来的？记者采访了中国航天科技集团的有关专家。
构型设计—— 四腿六轮
据介绍，“三姑娘”有四条腿六个轮子，是着陆器和巡视器(俗称“月球车”)的组合体。与嫦娥一号、二号不同，嫦娥三号在名称上不叫卫星而叫器，是我国第一个“有腿”的航天器。
航天科技集团主任设计师杨建中介绍，这样的组合构型，是由其任务特点决定的。嫦娥三号任务主要有两个，一是实现月面软着陆，二是实施月面巡视勘察。这需要它既能落到月面上，还能自主动起来。将任务分解给两个探测器，有助于加快研制进度。
落月之前，巡视器作为一个载荷被安装在着陆器上，本身并不工作。整个前期飞行、动力下降以及实施软着陆过程，都是由着陆器完成的。到月面后，二者互相配合，将巡视器释放到月面上，成为两个独立的探测器，各自在月面开展探测任务。
着陆器包含11个分系统，其中最有特色的当属着陆缓冲分系统，又集中体现在四条“中国腿”的外形上。据了解，其他国家的软着陆方式主要有三种：一是气囊弹跳式，二是着陆腿式，三是空中吊车式。每种方案都有优缺点。就嫦娥三号软着陆任务来讲，气囊式不能满足重量要求，吊车式又比较复杂，腿式能满足任务需要，保证着陆的稳定性。综合之下，嫦娥三号选用了腿式着陆。
巡视器包含8个分系统，其中最有特色的当属移动分系统。从外形上看，就是巡视器的6个轮子。
中国航天科技集团巡视器副总设计师贾阳介绍，国外巡视器的移动方案主要有三种：履带式、腿式和轮式。履带式巡视器就像电影里的机器人瓦力，它最大的优点是压强小、通过性强，但它的弱点是遇到石块等容易被卡住不能动弹。腿式巡视器在平缓的地面行走尚可，但控制起来比较复杂，弄不好一下子就坐到地上。轮式则能避免上述方式的缺点。
此外，由于探测器的重量限制，嫦娥三号必须“瘦身”，进行集成化、小型化设计，还必须保证系统的可靠性。只有这样，才能保证它是一个健壮的探测器。
路径设计——前所未有
此前，嫦娥一号和二号对到达月球的路径已经做了先期的成功探索。由于任务需要，嫦娥三号的路径设计还要在此前基础上更进一层，且难度和风险大大增强。它要在近月点15公里处进行动力下降，接着实现月面软着陆，然后再进行月面巡视勘察。
这15公里的动力下降，是以抛物线下降。探测器的相对速度要从1.7公里/秒逐渐减为0，过程主要靠探测器自主来完成，人工干预的可能性几乎为零。距月面100米处时，探测器还要悬停，对月面进行拍照，避开障碍物，寻找着陆点。
对于地面工程人员来说，这一过程尚属首次，存在两大风险。一是关键设备都是新研制的，包括GNC系统(制导、导航与控制系统)和我国首台全新的7500牛变推力空间发动机。二是软着陆区域的地形地貌存在一定程度的不确定性。
等到探测器在月面实现软着陆后，着陆器和巡视器还要进行分离，实现互相拍摄。着陆器基本固定在一个位置，巡视器则需要从着陆器上“走”下来，进行月面巡视勘察。在月面路径中，还涉及到“地面遥操作”和“巡视器自主控制”相结合的技术手段。
除了地面遥操作外，巡视器也可以利用计算机，对图像进行处理、识别障碍，规划出相对较近的局部路径，控制自身的移动。这时候，巡视器就是一个自主移动的机器人了。
功能设计——确保月面生存
不同于地球，月球表面昼夜温差较大，温度高时有120摄氏度，温度低时在零下180摄氏度。而且，月球的昼夜交替周期也较长，这给“三姑娘”的月面生存带来了很大的难度。
中国航天科技集团着陆器热控分系统主任设计师刘自军用“盖被子”“生炉子”和“开空调”等熟知的概念解释热控设计。嫦娥三号上有一个多层隔热组件，也就是所谓的“被子”，可以双向隔热，外部高温时候热量不能往里传，外部寒冷时候里面热量不能往外漏。
寒冷时“三姑娘”还得“生炉子”。“炉子”主要是同位素核源，它能够持续放热。设计师们还设计了重力驱动的两项流体回路，在需要的时候将热量导入舱内，不需要的时候切断传热途径。
到了月昼时，虹湾温度迅速升高至90摄氏度，在月球表面，散热的方式只有热辐射。设计师们在探测器上精心设计了几个散热面，可以把设备发出的热量散出去。
有了这些手段和方法，“三姑娘”便能很好地保护自我，在月面上生存下来，从而用携带的科学载荷进行工作。目前，着陆器主要携带了极紫外相机、月基望远镜、地形地貌相机，还有一些对月面、月尘进行测量的工程载荷。巡视器主要携带了测月雷达、全景相机、红外光谱仪和粒子激发X射线谱仪，开展相应的科学探测任务。通过它们，科学家们将为后续的月球探测积累数据，普通百姓也可以更好地认识宇宙。
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