托福阅读机经背景:开普勒望远镜功成身殁

托福阅读机经背景：开普勒望远镜功成身殁

Planetary science

行星科学

Lost and found

失之东隅，收之桑榆

A successful piece of astronomical kit looks dead. But its mission continues

开普勒太空望远镜功成身殁，但其使命仍将延续。

So long, and thanks for all the facts

别了，感谢所有因你而来的事实

THE Kepler telescope was launched into space in 2009 to look for extrasolar planets, thosethat circle stars other than the sun. Since then it has spotted more than 2,700 potential alien worlds,including some that appear to be small, rocky and far enough from their stars for liquid water to existon the surface—rather like Earth, in other words, and thus, just possibly, hospitable to life. In doing soit made “exoplanet” research one of the busiest areas of astronomy. It also whetted planet-hunters’appetites. Originally meant to collect data for 3? years, last year its mission was extended until2016.

开普勒太空望远镜在2009年被送入太空，用于寻找太阳系外行星----即绕着太阳以外的恒星旋转的行星。自彼时起，开普勒太空望远镜共找出了2700多颗可能有外星生命存在的星球，包括一些似乎不大的岩态行星，且距其恒星的距离足以使其表面有液态水存在----换句话说，就像地球一样，然而这只是可能适宜生命生存而已。于是，开普勒太空望远镜使“系外行星”研究成为天文学中最为繁忙的一个领域，还刺激了“行星猎手”们的胃口。开普勒太空望远镜本来预计将运行三年半的时间来收集数据，但去年将其任务延长到2016年。

So it came as a blow when, on May 15th, the telescope’s minders at NASA announced thatthe device was in trouble. One of the three components, known as reaction wheels, that help keep itpointing in the right direction (specifically, at a patch of stars between the constellations Lyra andCygnus) had jammed.

所以，当NASA的开普勒太空望远镜的管理者在5月15日宣布该设备出现问题时，这对该领域是个不小的打击。开普勒太空望远镜的三个组件中有一个给卡住了，该组件叫做反力轮， 用于使望远镜保持朝向正确的方位。(明确来说，是朝向天琴座星云和天鹅座星云之间的一块星群)。

With its sole spare reaction wheel already damaged, things did not look good. After two weeksof trying, NASA’s boffins have been unable to restore Kepler to working order. Geoff Marcy, aplanet-hunter at University of California, Berkeley, expressed his angst by borrowing from W.H.Auden: “Kepler was my North, my South, my East and West,” he lamented online. This comes just

six months after COROT, a European telescope with a mission similar to Kepler’s, suffered acomputer failure from which it has yet to recover.

鉴于其唯一的备用反力轮已经损坏，情况似乎不太妙。经过两周的努力，NASA的技术人员仍无法使开普勒太空望远镜恢复正常工作。加州大学伯克利分校的“行星猎手”杰佛瑞?马西套用了W.H.奥登的一句诗来表达自己的不安：“开普勒曾经是我的东，我的西，我的南，我的北”(借自奥

登的“Funeral Blues”《葬礼蓝调》。译注)，他在网上哀叹道。刚刚六个月之前，科罗太空望远镜----欧洲的一台执行与开普勒望远镜类似任务的望远镜----由于其内部电脑故障，至今仍未恢复工作。

Life after death

身后事

Happily, there is plenty of science left to do. Big experiments collect such vast quantities ofdata these days that scientists cannot keep up. As a result, discoveries can be made long after atelescope has been decommissioned. Two papers, presented to the annual meeting of theAmerican Astronomical Society, held on June 2nd-6th in Indianapolis, show how.

幸运的是，还有许多科学研究在等着去做。在这段时间里，各项大型试验收集了海量的数据，多得让科学家们都来不及处理。结果，在天文望远镜退役后很长一段时间内都会有新的发现。在6月2日至6日在印第安纳波利斯召开的美国天文学会年会上发表的两篇论文便指明了要如何去做。

The first, by Mark Everett, of the National Optical Astronomy Observatory in Arizona, and hiscolleagues, concerns data gathered by Kepler to help astronomers nail down how common varioustypes of planet might be. Earlier results suggested that about 13% of the Milky Way’s stars hostEarth-size planets. A further 30% host so-called Super Earths, planets that are significantly biggerthan Earth but still rocky. All good news, in other words, for those hoping for signs of alien life.

第一篇论文的作者是亚利桑那州国家光学天文台的马克?埃弗雷特及其同事，论文与开普勒太空望远镜收集到的数据有关，这些数据让天文学家能够明确各种常见类型的行星是什么样子的。早期的研究结果认为银河系的恒星中有13%拥有与地球大小相当的行星。另有30%的恒星拥有所谓的“超级地球”，即那些远大于地球，但仍为岩石态的行星。换句话说，对于那些期待找到外星生命迹象的人来说都是利好消息。

But Dr Everett thinks that those numbers may be too high. Kepler scans hundreds of thousandsof stars, hunting for the tiny but regular dips in brightness which occur when a planet passes in frontof its parent star. Astronomers can estimate the size of a star from its brightness and its colour. Oncethat is known, they can estimate the radius of a transiting planet from the amount of dimming itcauses.

但是埃弗雷特博士认为这些数字或许过高了。开普勒太空望远镜扫掠了数十万颗恒星，从中寻找微小但亮度却周期性减弱的恒星，当有行星从其母恒星面前飞过时会出现该现象。天文学家能够从一个恒星的亮度及颜色来估计其大小。一旦知道了恒星的大小，他们便可以根据亮度衰减量估计出该凌日行星的半径。

Dr Everett and his team used ground-based telescopes to make detailed measurements of thesizes of 268 stars identified by Kepler as being orbited by planets. They found that Kepler

underestimated how big the stars were. Sometimes the underestimates were small. But one in fourstars seems to be larger by 35% or more.

埃弗雷特博士及其团队使用陆基天文望远镜对开普勒太空望远镜发现的268颗有行星环绕的恒星的大小进行了详细的测量。他们发现开普勒太空望远镜低估了这些恒星的大小。有时该低估量并不大，但是有四分之一的恒星似乎要比估计值至少大35%。

That matters, because the size of a planet is calculated from the size of its parent star and theamount of dimming observed. If the star is bigger, therefore, so too are its planets. In other words,some of the Super Earths identified by Kepler may in fact be gas giants, more akin to Neptune andUranus.

这一点很重要，因为行星的大小是根据其母恒星的大小及观测到的亮度衰减量计算得来的。因此，如果该恒星比估算的要大，那么其行星也会估算值要大。换句话说，开普勒太空望远镜发现的“超级地球”中有一些实际上可能是巨型气体行星，与海王星和天王星更为类似。

Bigger stars’ “habitable zones”, in which temperatures are low enough for liquid water, and life,to exist, are also farther from a star system’s centre. So some planets Kepler deemed far enoughfrom their parent star to be sufficiently cool may in fact not be. (Admittedly, some others, previouslyconsidered too far to contain any water other than ice, could be balmier than thought.)

较大恒星的“宜居带”(带内的温度较低，足以使液态水及生命存在)也离恒星星系的中心更远。所以有些被开普勒太空望远镜认作离其母恒星的距离足以使其足够凉爽的行星在实际上并非如此。(不可否认，其它一些之前被认为距离过远只能有固态水存在的行星要比想象的更宜人一些。)

The second paper, by John Gizis at the University of Delaware, reports the discovery not of astrange new planet, but of a strange new star. W1906+40, as it is known, is a cool dwarf that suffersfrom regular temper tantrums. Roughly once a week it flares, its temperature rising from around2,000°C to 7,700°C in a matter of minutes, before slowly cooling off again.

第二篇论文的作者是特拉华大学的约翰?吉吉斯，该文报道的发现并非是一个奇怪的新行星，而是一颗怪异的新恒星。该恒星被称为W1906+40，是一颗温度较低，但会定期爆发的矮星。该星大约每周会出现一次耀斑，其温度几分钟便会从约2000°C升至 7700°C，然后便会慢慢冷却，直至再次爆发。

Flares like these have never before been seen in such a small, cool star. Dr Gizis hopes thatstudying them will help astronomers understand the whims and fancies of the powerful magneticfields that all stars, including the sun, generate, and which are presumed to produce the flares.

类似这样的耀斑从来没有在这样一个温度较低的小型恒星上见到过。吉吉斯博士希望对其进行研究会有助于天文学家了解所有恒星，包括太阳产生的强力磁场的奇特之处，该磁场也被认为是产生耀斑的原因。

Even if Kepler cannot be mended, planet-hunters need not despair. Earlier this year NASAconfirmed that in 2017 it plans to launch the Transiting Exoplanet Survey Satellite, a successor toKepler which will search the entire sky, rather than merely a part of it, and look for exoplanets

nearest to Earth. Until then, though, astronomers will be poring over Kepler’s back catalogue, wheremany discoveries still lurk.

即使开普勒太空望远镜无法修复，“行星猎手”们也不必绝望。今年早些时候NASA确认了其计划于2017年发射系外凌日行星观测卫星，这是开普勒太空望远镜的继任者，将会对整个宇宙进行搜寻----而非仅仅囿于宇宙中的一部分----来寻找离地球最近的系外行星。然而在此之前，天文学家们还要继续钻研开普勒太空望远镜以前的数据，这些数据也可能带来许多重大发现。

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