YF-79 远处的星辰
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美媒称歼20近战不敌F15战机 日本可用机炮击落 美国《国家利益》双月刊网站10月16日发表题为《中国的歼-20隐形战斗机对阵日本的F-15:谁会赢?》的文章,作者为凯尔·沟上,编译如下:   随着中国与日本间的紧张关系日益加剧,中国军机与日本军机之间的遭遇次数增多。在东中国海,多次发现中国空军的苏-27靠近日本飞机,导致以冲绳为基地的日本F-15战斗机紧急起飞。   这些遭遇似乎已成新常态,在可预见的将来,这种情况可能会继续下去——事实上,将持续至中国歼-20战斗机投入行动之际。作为中国第一种第五代战斗机,歼-20预计将于21世纪10年代末入役。   与此同时,日本仍在使用F-15J战斗机。尽管这是一种性能优异的战斗机,日本防卫省曾希望用F-22“猛禽”战斗机取而代之。但是,令日本感到遗憾的是,美国国会禁止“猛禽”战斗机出口,日本因找不到能真正替代F-15的战斗机而陷入困境。   日本于1981年接收首批F-15J战斗机。这种战斗机是授权三菱重工公司制造的,除电子对抗装置和雷达预警装置(美国政府拒绝出售这些装置)之外,在很大程度上与美国本国型号相同。这种机型最初装备AIM-9“响尾蛇”空对空导弹和半主动雷达制导AIM-7“麻雀”导弹——后来被AIM-120“阿姆拉姆”导弹取代。最后,在F-15J的武器中,还包括一门20毫米M61机炮。   日本共接收了223架F-15J,已因事故损失8架。   F-15J已长期服役。日本于21世纪初启动一项升级计划,然而,由于升级成本很高,每年只有不足10架飞机能够进行。在日本的F-15J中,只有大约一半接受了升级。   成都飞机工业集团生产的歼-20是一个令人感兴趣的谜团。作为中国第一种第五代战斗机的歼-20,于2011年首次披露。歼-20是一种双引擎单座隐形战斗机,据信略长于F-15J。其机身长而宽,用于储存武器和燃料。这种机型似乎有3个内部武器舱,两个较小的武器舱存放短程导弹,一个较大的武器舱存放远程空对空导弹和空对地武器。   歼-20的机头整流罩似乎很大,足以隐藏一台先进主动电子扫描阵列雷达,使之有能力发现遥远目标并用雷达制导导弹进行攻击。较新的原型机似乎装备了一套红外搜索跟踪系统和一套电子光学瞄准系统,用于进行空对地攻击。   歼-20的确切角色尚不可知。这种飞机似乎是为执行远程任务而制造的。歼-20可能会与俄罗斯制造的米格-31(一种特别关注于击落敌军空中加油机、空中预警控制飞机以及侦察和情报收集飞机等机型的高速(隐形)截击机)类似。另一种选择是,将其改装成一种远程中型轰炸机,类似于美国的F-111——能够打击冲绳和日本境内各个基地等目标。   为了便于讨论,让我们假设歼-20被装备成一种用于夺取空中优势的远程战斗机。在与F-15J对阵时,哪种飞机将获胜?   假设歼-20的设计人员成功缩小了这种飞机的雷达截面,F-15J在较远距离发现歼-20方面可能遇到麻烦。与此同时,F-15J缺乏隐形性意味着,借助于一台合格的雷达,歼-20将轻易发现这种日本战斗机。这对在进行超视距作战的F-15J可不是什么好兆头,尤其是如果歼-20装备“霹雳”-15导弹的话。   如果距离较近,F-15J可能占有优势。据称歼-20动力不足,至少就目前而言。众所周知,F-15系列战斗机具有无与伦比的近距离格斗能力。   最后一个考虑因素:尽管仍处于原型机阶段,迄今为止人们尚未看到歼-20装备加特林机炮。尽管空战专家在机炮之实用性这一问题上意见不一,但在近距离格斗中,F-15J用其M61加特林机炮快速发射炮弹的能力,也是派得上用场的。   在我们比较成都飞机工业集团生产的歼-10多用途战机和三菱重工生产的F-2战斗机时,近距离优势属于歼-10,远程优势属于F-2。在夺取空中优势战斗机方面,形势发生了转变。ATD-X战斗机(日本下一代战机)将于今年晚些时候上天,日本可以稍有放松。但无论如何,中国即将超越其宿敌、跨入第五代战斗机的世界,将对大国竞争态势产生重大影响。
腾讯新闻:科学家发现临近恒星有外星文明"戴森球"迹象 据国外媒体报道,KIC 8462852恒星系统位于1480光年之外,科学家在该系统中发现了奇怪的现象,一系列奇异的光波动现象无法用现有的理论进行解释,因此有理论指出,这可能是我们发现的外星人星际工程的证据。根据这个理论,当有一个巨大的物体通过恒星前方时,会导致恒星亮度发生微弱的改变,该方法也被用于发现系外行星,不过这次我们发现了不寻常的现象。暗示这可能是一个外星轨道建筑,运行在恒星周围的轨道上(即所谓“戴森球”)。 KIC 8462852恒星系统距离我们1480光年,这个距离其实不算太远,但我们目前的技术仍然无法抵达。开普勒望远镜从2009年开始就持续对目标恒星进行监视,寻找微弱的亮等变化,以此发现系外行星。这次公布的数据中,科学家发现了奇怪的地方,显然这不是一颗行星,恒星光信号波动的现象暗示有一个较大的物体通过了恒星盘面,有可能是外星人的能量站,或者说是超级油井。 从图中可以看出,一系列的光波动目前仍然无法解释,耶鲁大学科学家Tabetha Boyajian指出,我们从来没有见过这样的恒星信号,以为是探测器出现错误。但是检查之后,也没有发现问题,因此这个信号可能是真实的。如果这颗恒星被外星人利用,那么其周围会布满各种轨道建筑,以最大限度汲取光能。这就会导致恒星亮度发生改变,下降到原来20%的水平。该现象发现于2011年,每次活动呈现周期性,大约5至80天,这段光变曲线与其他恒星有所差别。 加州大学伯克利分校、搜寻地外文明研究所等机构也在推进地外文明搜寻,目前科学家建议我们应该寻找恒星周围的人造建筑。因为高级文明需要使用大量的能量,恒星上取之不尽的能量是可开采的。如果某个恒星系统被先进的外星文明殖民,那么会产生大量的中红外波长信号,由此可发现外星文明。(罗辑/编译)
新地平线号团队在《科学》杂志上发表了第一篇论文 New Horizons Publishes First Research Paper in 'Science,' Describing Numerous Pluto System Findings From Pluto’s unusual heart-shaped region to its extended atmosphere and intriguing moons, New Horizons has revealed a degree of diversity and complexity in the Pluto system that few expected in the frigid outer reaches of the solar system.The New Horizons team describes a wide range of findings about the Pluto system in its first science paper, released today. “The Pluto System: Initial Results from its Exploration by New Horizons,” led by mission Principal Investigator Alan Stern, appears as the cover story in the Oct. 16 issue of Science, just three months after NASA’s historic first exploration of the Pluto system in July. “The New Horizons mission completes our initial reconnaissance of the solar system, giving humanity our first look at this fascinating world and its system of moons,” said Jim Green, director of planetary science at NASA Headquarters in Washington. “New Horizons is not only writing the textbook on the Pluto system, it’s serving to inspire current and future generations to keep exploring—to keep searching for what’s beyond the next hill.” NASA’s New Horizons spacecraft reached a distance of 7,750 miles (12,500 kilometers) from Pluto’s surface during its July 14 closest approach, gathering so much data it will take almost another year to return to Earth. The data returned so far show a surprisingly wide variety of landforms and terrain ages on Pluto, as well as variations in color, composition and albedo (surface reflectivity). Team members also discovered evidence for a water-ice rich crust, multiple haze layers above the surface in Pluto’s atmosphere, and that Pluto is somewhat larger and a bit more ice rich than expected. “The Pluto system surprised us in many ways, most notably teaching us that small planets can remain active billions of years after their formation,” said Stern, with the Southwest Research Institute (SwRI) in Boulder, Colorado. “We were also taught important lessons by the degree of geological complexity that both Pluto and its large moon Charon display.” Some of the processes on Pluto appear to have occurred geologically recently, including those that involve the water-ice rich bedrock as well as the more volatile, and presumably more mobile, ices of the western lobe of Pluto’s “heart.” The diverse geology and apparent recent activity raise fundamental questions about how small planetary bodies remain active many billions of years after formation. The research suggests that other large worlds in the Kuiper belt -- such as Eris, Makemake, and Haumea -- could also have similarly complex histories that rival those of terrestrial planets such as Mars and Earth. The New Horizons team notes that Triton, likely a former Kuiper Belt planet captured by Neptune, was considered the best analog for Pluto prior to the July 14 flyby. The team now believes that the geologies of Triton and Pluto are more different than similar, but will know more as additional data are returned. New Horizons is part of NASA’s New Frontiers Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, designed, built, and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate. SwRI leads the science mission, payload operations, and encounter science planning.
卡西尼号即将再次略过土星卫星伊赛拉德斯 NASA's Cassini spacecraft will wrap up its time in the region of Saturn's large, icy moons with a series of three close encounters with Enceladus starting Wednesday, Oct. 14. Images are expected to begin arriving one to two days after the flyby, which will provide the first opportunity for a close-up look at the north polar region of Enceladus. Wednesday’s flyby is considered a moderately close approach for Cassini, which will pass at an altitude of 1,142 miles (1,839 kilometers) above the moon's surface. Closest approach to Enceladus will occur at 6:41 a.m. EDT (3:41 a.m. PDT). The spacecraft’s final two approaches will take place in late October and mid-December. During Cassini’s early-mission encounters with the moon, the northern terrain of Enceladus was masked by wintry darkness. Now that the summer sun is shining on the high northern latitudes, scientists will be looking for signs of ancient geological activity similar to the geyser-spouting, tiger-stripe fractures in the moon's south polar region. Features observed during the flyby could help them understand whether the north also was geologically active at some time in the past. "We've been following a trail of clues on Enceladus for 10 years now," said Bonnie Buratti, a Cassini science team member and icy moons expert at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "The amount of activity on and beneath this moon's surface has been a huge surprise to us. We're still trying to figure out what its history has been, and how it came to be this way." Since Cassini's 2005 discovery of continually-erupting fountains of icy material on Enceladus, the Saturn moon has become one of the most promising places in the solar system to search for present-day habitable environments. Mission scientists announced evidence in March that hydrothermal activity may be occurring on the seafloor of the moon's underground ocean. In September they broke news that its ocean -- previously thought to be only a regional sea -- was, in fact, global.
The Impact of Craters 冥王星上的陨石坑 Hello! It’s Kelsi Singer again from the New Horizons science team to talk about one of my favorite planetary geologic features –impact craters. They may just look like holes in the ground, but amazingly, craters can give us all sorts of useful clues to a planet’s history.There are many ways scientists investigate a planet they’re seeing for the first time, and this is one example. With a flyby mission you can’t probe the ice on the surface or analyze samples, so you have other methods to determine a planet’s makeup and age – and gain insight into how it involved into the world it is today. Analyzing craters can help us understand the age of a planet’s surface. A surface with more craters indicates that it’s older, geologically, than a less-cratered surface. Pluto displays many good examples of this concept. Any guesses as to which parts of Pluto mission scientists think are younger? If you went with the informally named Sputnik Planum – the left half of Pluto’s “heart” feature – as a young geologic unit, then you are on the right track. So far we have not identified any obvious craters on Sputnik Planum. We can also try to put an actual date on a surface (e.g., that a given surface is 1 billion years old), but this is more difficult because it requires some knowledge of how often impactors (chunks of space debris) of a certain size hit the surface to make craters. Age-dating based on craters is complicated by a number of other factors as well. I will highlight one big issue here: How one “sees” craters is affected by lighting over the planet’s surface. Just like on Earth, the lighting on Pluto and Charon changes both with latitude and over the course of the day. When the sun is directly overhead, there are very few shadows cast and it is hard to see topography, but that overhead lighting makes it much easier to see dark or bright markings. The opposite is true when the sun hits the surface at a shallow angle near sunrise or sunset: topography is easy to see, but bright and dark colorations are often washed out. Because New Horizons flew by Pluto so quickly (in just a few hours out of Pluto’s day, which is 6.4 Earth days), our highest-resolution pictures were all taken under the same lighting conditions. The northern latitudes of Pluto and Charon have the sun mostly overhead, while near the equator the sun hits the surface at an angle. This gives the effect that craters in the north look flatter and have stronger dark/bright contrasts, while craters near the equator look more 3-D. There are many other complicating factors, such as variable image resolutions and variable surface erosion or degradation. Even fragments of surface material ejected while creating a “primary” crater can pose a problem because they may litter the surface and make smaller, so-called “secondary craters” that influence crater statistics. We are taking all of these factors into account as we map Pluto and Charon’s craters and mine this data to learn more about the history and evolution of these amazing, mysterious worlds.
New Horizons Sampling ‘Space Weather’ on Approach to Pluto As NASA’s New Horizons spacecraft approaches the Pluto system, its space plasma (also called charged particle) instruments —SWAP and PEPSSI — have already been taking measurements and assessing the space weather environment in the Kuiper Belt near Pluto. “Results from those measurements are being radioed to the ground and our team is already learning new things about the distant environment near Pluto’s orbit, 3 billion miles from Earth,” says New Horizons Principal Investigator Alan Stern, from Southwest Research Institute, Boulder, Colo. The solar wind consists mainly of protons and electrons, but also has trace amounts of ions of helium and oxygen that New Horizons detects. Typical solar wind speeds at Pluto’s orbit distance range from 350-500 kilometers per second (about 750,000-1 million miles per hour); typical densities of the solar wind near Pluto’s orbit are about 6,000 particles per cubic meter – about a 1,000 times less than the solar wind at Earth. For comparison, the Earth’s atmosphere at its surface is one hundred billion-billion times denser.“For some unknown reason, the Sun has been blowing less hard over the past decade and a half, and we are seeing the weakest solar wind of the space age,” says New Horizons co-investigator Dave McComas, also of SwRI, who leads the SWAP instrument team. “A weaker solar wind means that the size of the region where the solar wind interacts with the planet’s escaping atmosphere is expanded beyond our earlier predictions.” Added New Horizons co-investigator Fran Bagenal, from University of Colorado, Boulder: “This means that New Horizons may cross the interaction boundary between the solar wind and Pluto’s atmosphere up to dozens of Pluto radii [and several hours] before its closest approach on July 14, creating a scientific bonanza for studies of the composition and escape rate of Pluto’s atmosphere!”
冥王星地表地质的情况 New Horizons remains healthy and on course for its prime Pluto system science in July!As I write these words I am flying to a dress-rehearsal simulation (called a “sim”) of the closest approach portion of the Pluto flyby. About 40 science team members are involved—atmospheric scientists, geologists, geochemists, planetary astronomers and space physics experts. This is the second of three such multiday sims that the science team is doing to prepare for the flyby in July. But this is far from the only type of flyby simulation we’re doing across the project. There are also sims to practice optical navigation to home in on Pluto, sims to practice searching for hazards on approach, sims to handle possible instrument and spacecraft anomalies, and more. Some sims only involve a handful of people, some (like the one I’m headed to) are much larger; but all involve practice datasets that scientists and engineers retrieve, reduce and analyze as a part of the practice. In total, several dozen mission sims have already been completed over the past few years. Now that we’re on early approach, we have just a few left. Hard to believe, but we’re almost finished training for encounter operations! Right now, just as when I wrote in January, the SWAP, PEPSSI and SDC instruments are taking daily science data—measuring the charged particle and dust environment of space near Pluto’s orbit. And now, the LORRI long-focal-length camera aboard New Horizons has started imaging the Pluto system for navigation purposes. This has yielded a few dozen images of Pluto and Charon — which still remain just dots in the distance — against star fields. Despite the low-resolution imagery of Pluto and Charon when we are still so far out (well over 100 million miles), these images help us triangulate the distance to our targets more accurately than any other navigation technique we have. Of course, the images are getting better as we get closer, and by April, they will begin to reveal Pluto as a tiny globe a few pixels across, rotating in the far distance, by then just 70 million miles or so away. Last month, I wrote about the Pluto atmospheric science we plan to do during the flyby, and promised that this month I’d preview the surface geology, geophysics and composition measurements we’re planning. But before I tell you what we’ll be doing to explore these aspects of the Pluto system, I want to tell you the basics of what we know about Pluto’s surface geology and composition, and what we know about Charon’s too. Unfortunately, it isn’t much. We know that Pluto’s surface is, on average, extremely reflective, like freshly driven snow. We also know that surface has very large markings with greatly varying reflectivities and various shades of red to neutral color. We know the surface ices are dominated by molecular nitrogen, and that hydrocarbons like methane and ethane are present, as is carbon monoxide ice. We also know that the proportions of all of these ices vary as Pluto rotates and shows us different terrains. We don’t know much else, because we can’t see enough detail from Earth to determine the planet’s geology, how cratered it is, or any signs of ongoing geophysical or geologic activity. That has to wait for New Horizons in July. We know even less about Charon. Its surface is about half as reflective as Pluto’s, but still reflective enough to be indicative of ices, as opposed to dark soils like on the Moon and Mars. We know that Charon’s surface is not tinged red like Pluto, but is neutrally colored. And we know that Charon is covered primarily in water ice, with hints of ammonium hydrates laced into the surface. Like Pluto, our current lack of spatial resolution prevents us from knowing much more.
〔新浪体育〕乌兹记者讽国足仅佩兰一个海归 中国不可能赢 新浪体育讯 亚洲杯国足与乌兹别克斯坦的小组第二场比赛即将打响。与中国的百人媒体大军相比,乌兹别克斯坦仅仅有10名记者来到了澳大利亚,其中还包括4名摄影。但对手媒体却有足够的底气和霸气,乌兹别克斯坦《国际足球》杂志主编阿卜杜哈米托夫告诉新浪体育,“中国队不可能战胜乌兹别克斯坦,我们有无数海归和经验丰富的球员,你们只有一个海归,那就是主教练佩兰。” 阿卜杜哈米托夫是乌兹别克斯坦资深足球专家,曾采访了三届亚洲杯。对于明天的中乌之战,阿卜杜哈米托夫摇摇头说中国队不可能获胜,“球队中9名球员参加过上届亚洲杯,又有很多在欧洲踢球的球员,中国队呢?从名单上看只有一个,那就是你们的法国主教练佩兰。比赛中乌兹别克斯坦队的经验将起到重要作用,我觉得中国队的最大问题是缺乏经验。”   在预测比赛结果时,阿卜杜哈米托夫说,“可能会是2-1,乌兹别克斯坦获胜。”他进一步分析说,“乌兹别克斯坦和中国都是欧洲风格的球队,这场比赛会很接近,但最终获胜的是我们。主教练卡西莫夫告诉我,我们的首发阵容不会有任何变化,这些队员在一起打了很多比赛,彼此之间的配合很默契。而且第一场也赢了球,没必要进行更换球员。”   阿卜杜哈米托夫专门给记者展示了乌兹别克斯坦报纸转载的《球童帮助王大雷》的电子版文章,笑着说,“那场比赛也真是运气,如果沙特队打进点球,沙特就赢了。”
【14-07-13】【转载】新人首贴 凤凰:波音公司的新产品 美国的载人火星计划终于迈出了实质性的一步,国外媒体报道称,美国宇航局(NASA)近日已经与波音公司签订了价值28亿美元的合同,用于设计建造迄今最大的运载火箭——SLS。 据了解,SLS是一款比执行登月任务的“土星5号”火箭更加庞大的人类航天器,其将拥有丰富的载重配比和扩展性。 按计划,SLS火箭将在2017年进行首次飞行测试。初期将提供77吨载重,但事实上根据任务的需要,SLS在装备多级扩展组件之后最大可实现超过140吨的运载能力。 因此,NASA认为SLS将成为下一阶段人类前往包括火星在内的更遥远宇宙空间的得力工具,这意味着我们也有可能在对于小行星的一系列探索活动中见到它的身影。图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4图片来自:http://tieba.baidu.com/mo/q/checkurl?url=http%3A%2F%2Fxiangce.baidu.com%2Fpicture%2Falbum%2Flist%2Fd91920b5d7f3008611bb0cf30cf1856098df0df2&urlrefer=1b89c418cbc9409a038a178e3b19a8d4
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