作者:蒋迅 圣荷西技术革新博物馆里的全尺寸“好奇号”模型 如果不出意外的话,“ 火星科学实验室 ” (“好奇号”) 预计在今年8月5日登陆火星的盖尔撞击坑,然后开展两年的科学研究。相比过去的火星探测漫游者“ 勇气号 ”(Spirit, MER-A)和“ 机遇号 ”(Opportunity, MER-B)两辆火星车,“好奇号”有什么进步?我们来看一看下面的对照表: compare 火星探测漫游者 ( MER ) 火星科学实验室 ( MSL ) 运载火箭 德尔塔Ⅱ运载火箭 宇宙神5型运载火箭 541 起飞质量 1,050公斤 3,600公斤 主要任物 7月飞行/3月地面 8月飞行/2年地面 搭载 5个仪器 (约9公斤) 10个仪器 (75公斤) 落地系统 原 火星拓荒者 技术/气球 引导进入/天空起重机 落地分解图 防热板直径 2.65 米 (8.5英尺) 4.5 米 (15英尺) 降落伞直径 8.5 米 (28英尺) 15.5 米 (51英尺) 落地通讯 火地直接通讯 + 超高频 火地直接通讯 + 超高频 地面通讯 火星轨道器中继 + 火地直接通讯 火星轨道器中继 + 火地直接通讯 火星车质量 170 公斤 775 公斤 绝热材料 SIRCA PICA 火星车电源 太阳能板/ 0.9度/火星日 放射性同位素热电机/2.5度/火星日 可达泛围 设计600 米,(实际达到数公里) 20 公里 降落椭圆范围 80 x 10-公里椭圆 20-公里直径圆 可达纬度 15 o S to 10 o N 60 o S to 60 o N 可达海拔 -1.3 公里 +2.0 公里 初始速度 19300公里/小时 (12000英里/小时) 21250公里/小时 (13200英里/小时) 落地时间长 6分钟 7分钟 成本 预算8.2亿美元 25亿美元 比较这两个探索任务我们可以很清楚地看到技术的进步:“火星科学实验室”的起飞质量是“火星 探测漫游者”的三倍;搭载仪器从5个增加到10个;火星车质量是以前的4.5倍;电源用核动力替代了太阳能板;设计可达泛围从600米增加到了20公里。当然花费也是火星探测漫游者的三倍。表中看不到还有很多。比如,再如大气层时的制导精度大为增加,使得火星车可以更准确地在指定地点降落;火星车上第一次安装了摄像机 (见: Curiosity's seventeenth camera: MARDI ),使人们可以看到火星车下降和落地时的场面,这使得观看这关键7分钟特别精彩;绝热材料的改进在以前的一篇文章里已经提到。绝热板的尺度是星际任务中最大的,降落伞的尺度也是最大的。 最为精彩的当然是火星车落地过程。这个过程分为进入、降落、落地三个过程。整个过程将持续7分钟,全部是火星车自行控制,JPL的人员甚至都不能“看到”火星车,因为它的信号传送到地球需要14分钟。这14分钟对JPL的人员将是一个煎熬的时 间。如果你有机会看实况转播,建议你不要错过。“火星科学实验室”落地过程开始将是在:美国西海岸时间2012年8月5日夜晚10:31;美国东海岸时间 2012年8月6日凌晨1:31;北京时间2012年8月6日中午1:31。现场直播提前两小时开始。相关阅读有: How Curiosity Will Land on Mars, Part 1: Entry How Curiosity Will Land on Mars, Part 2: Descent How Curiosity Will Land on Mars, Part 3: Skycrane and landing Challenges of Getting to Mars: Curiosity's Seven Minutes of Terror Behind JPL's '7 Minutes of Terror' video on risky rover landing Mars in a Minute: How Hard Is It to Land Curiosity on Mars? Mars in a Minute: How Do You Land on Mars? (three options) The Science of Curiosity: Seeking Signs of Past Mars Habitability 墙内看不到YouTube视频的读者可以直接到JPL的网上去看: http://www.jpl.nasa.gov/video/ 。 “火星科学实验室”的意义不仅在於它的科学意义,更是对新技术的检验。比如,“火星科学实验 室”的降落采用了天空起重机的新技术,因为火星探测漫游者采用的气球技术已经不能适用于它的搭载质量。但为了实现火星的载人之旅,显然火星科学实验室的搭载还是远远不够的。据估计,载人火星之旅必须有效搭载几十吨的物资。按照这个要求,我们可以看到目前运载火箭的推力远远不够,落地方式 (气球和天空起重机) 都不胜任,经费就更不用提了。人类还有生理上、心理上的问题要克服,还要避免强大的辐射。“火星科学实验室”的成功与否将是人类进军火星的重要一环。 尽管NASA对“好奇号”的落地充满信心,他们对存在的危险也是有足够的认识的。比如说火星上的风暴就可能影响火星车的著陆,而且天空起重机也是第一次使用,也增加了一个未知数。所以,“好奇号”有可能成功,也有可能失败。到现在这个时候,没有人能做什么新的努力。但不管是成功还是失败,它带来的影响将是巨大并深远。从历史上看,火星项目的失败都使人们对探索火星产生更强烈的愿望,经过艰苦的努力,最终是成功。从这一点上,笔者认为中国航天界不应该也不会因“ 萤火一号 ”的失利而后退。 现在很多人都说人类要到火星去,似乎人类离移民火星已经不远了其实,我们现在飞往火星甚至缺乏基本的技术。有不少人提出自愿单程去火星,真有壮士一去不复返的味道。但即使单程也谈何容易。 比较“火星科学实验室"和“火星探测漫游者”,我们既看到了进步,也看到了不足,更看到了方向。如果航天业的人士们想要有所创新的话,这是一块最好的领域。请阅读笔者以前发表的有关航天的博文: 移民火星已经不再“遥远” 参与“名字上月球”和“名字上火星”活动 MSL的火星车由华裔女孩命名,她仅仅是幸运吗? 从越南船民到国际一流航天工程设计师 ─ 陈惠女士 从美式足球职业运动员到NASA宇航员 从小学数学教师到NASA火箭工程师 她在太空中永生 ── 记美国印裔宇航员卡尔帕娜·乔拉 从校队的板凳队员到NASA工程师
http://www.nasa.gov/topics/earth/features/health-sapping.html New Map Offers a Global View of Health-Sapping Air Pollution 09.22.10 In many developing countries, the absence of surface-based air pollution sensors makes it difficult, and in some cases impossible, to get even a rough estimate of the abundance of a subcategory of airborne particles that epidemiologists suspect contributes to millions of premature deaths each year. The problematic particles, called fine particulate matter (PM 2.5 ), are 2.5 micrometers or less in diameter, about a tenth the fraction of human hair. These small particles can get past the body’s normal defenses and penetrate deep into the lungs. To fill in these gaps in surface-based PM 2.5 measurements, experts look toward satellites to provide a global perspective. Yet, satellite instruments have generally struggled to achieve accurate measurements of the particles in near-surface air. The problem: Most satellite instruments can't distinguish particles close to the ground from those high in the atmosphere. In addition, clouds tend to obscure the view. And bright land surfaces, such as snow, desert sand, and those found in certain urban areas can mar measurements. However, the view got a bit clearer this summer with the publication of the first long-term global map of PM 2.5 in a recent issue of Environmental Health Perspectives . Canadian researchers Aaron van Donkelaar and Randall Martin at Dalhousie University, Halifax, Nova Scotia, Canada, created the map by blending total-column aerosol amount measurements from two NASA satellite instruments with information about the vertical distribution of aerosols from a computer model.
NASA’s Most Adorable Model Spaceships By Betsy Mason November 30, 2011 | 6:30 am | Categories: Space View as gallery The list of NASA's accomplishments is long and impressive, which is probably why one of its most remarkable feats is so often overlooked: the extreme cuteness of its scale models. From lunar landers and rovers to satellites space stations, NASA's engineers built tiny replicas and concept representations that will melt your heart. Here are some of our favorites. Above: Apollo Lunar Lander 1963 The design for the Apollo lunar excursion module went through several stages, some cuter than others. The image above shows the lander at peak cuteness. Even without the miniature astronaut, fake moon rock and starry sky, this scale model would elicit motherly coos from space geeks. This concept was known as a "bug." Apollo Lunar Lander 1964 By 1964 the design of the lunar excursion module had entered another phase of adorability. This model almost looks like it has eyes and ears and is afraid of the surface of the moon. Mercury Capsule The Mercury capsule design above, called "shape B," was fairly close to the final design of the real capsule. This loveable little 1958 model shows how the astronaut would be positioned inside, including the individually fitted couch . Below is a model of "shape A." Space Station Concept Early concepts for a space station also resulted in super-cute models. The one shown above from 1963 is probably our favorite, but the one below from 1966 has a tiny astronaut doll in it. Viking Lander This little model of a Viking lander, shown here at NASA's Langley Research Center in 1973, is almost as cute as the engineer pretending to tend to it as he poses for the photo. Nuclear-Powered Spacecraft This 1959 model of a piloted nuclear-powered spacecraft looks like a gumball machine or some kind of game. Posing it hovering above a fake extraterrestrial surface with Earth in the background seems almost calculated specifically to enhance the ship's cuteness. The model below from 1964 only has an earnest-looking NASA employee to help it out, and is consequently not as cute. Lunar Rover Lunar rovers are almost always adorable, but the one above from 1975 has seats that look like the lawn chairs of the time and even has a remote control. But where are the photos of scientists steering it over a mini moon surface with astronaut dolls at the controls? There's no way that didn't happen. The model below from 1990 looks like part of a Lego set, and it has dolls and a moonscape (some of which was made from real lunar surface images) to make it more precious. Jupiter Rocket This 1959 model of the Jupiter vehicle might not be the cutest, but it has a monkey on it, so I couldn't resist including it. The squirrel monkey, named Baker, would ride a real Jupiter rocket into space along with a rhesus macaque named Able to be the first astromonkeys to return safely to Earth. Sadly, Able died from a reaction to surgical anesthesia a few days later. But Baker lived for another 25 years. Mars Expedition Vehicle This 1961 image from the NASA archive is labeled simply "electric space vehicle model for 8 man mars expedition." The photographer really went all out on this one, with the model of Earth in the foreground and the bow-tied man staring off into space, probably at Mars. Orbiting Solar Observatory One of NASA's top scientists, Nancy Roman, poses in 1962 with a little model of the Orbiting Solar Observatory. Roman looks like your favorite science teacher combined with your doting grandmother, and is definitely cuter than the model. Roman had her hand in many important satellite projects, including the Hubble Space Telescope and the Cosmic Background Explorer. Gemini Capsule This 1963 image shows a model of the Gemini capsule attached to a parawing , which was a self-inflating flexible airfoil NASA considered using to help land the capsule before dropping it in favor of a parachute in 1964. Just picture this little guy gliding down to land in your swimming pool. Biosatellite NASA's Biosatellite program sent three capsules into orbit with various plants and organisms to study the effects of space on living things. This model from around 1968 is of the third launch, which put a pig-tailed monkey named Bonnie into orbit. The model monkey in the image above looks a lot happier than Bonnie probably was -- the month-long mission was shortened to nine days when Bonnie's health started to suffer. Skylab This 1967 model of the Skylab space station isn't that cute until you notice the tiny astronauts inside the orbital workshop. I might have overlooked them if it wasn't for the one standing next to the model for scale. Apollo Lunar Lander 1961 Just like the wooden toys your parents probably played with, the early lunar excursion model shown above is adorably simplistic. In some ways it might even be cuter than the more advanced models at the beginning of this gallery. The early models of a 1961 lunar vehicle and a 1962 Apollo re-entry vehicle below are also lovably simple. View as gallery Images: NASA
这次,美国业已报废的“高层大气研究卫星”坠落地球,使得 NASA 再次成为人们关注的焦点。 在众多外国机构名称中,NASA 的汉译也许是分歧最大的一个,华人世界有多个不同的简称版本,如航天局、太空署、宇航局、航宇局等。昨天笔者百度了一下,相关结果最多的是“美国宇航局”,,接下来是“美国太空署”,然后是“美国航天局”,相关结果最少的大概是“美国航宇局”。 从字面上来看,NASA(National Aeronautics and Space Administration)可直译为“(美国)国家航空航天局”,因此,“美国航宇局”也许是最贴切的简称了。不过,从媒体曝光以及 NASA 多个下属机构的研究领域来看,“航天”的比重似乎更大些。