美国航天探测器揭示彗星状况

US Space Probe to Reveal Comet's Secrets

美国航天探测器揭示彗星状况

 

A U.S. spacecraft is completing a five-and-a-half month voyage to a distant comet and could create celestial¹ fireworks when it crashes into it Monday, America's Independence Day. Scientists want to know what a comet's nucleus² is made of and believe the best way to find out is to blast a hole in one.

 

The target is the comet Tempel 1, 431 million kilometers away. As NASA puts it, meeting it head on at such a great distance is like threading a needle.

 

Tempel 1 is typical of the comets that emerge from the so-called Kuiper belt of objects orbiting beyond the planet Neptune³ and swing around the sun.

 

NASA scientist Tom Morgan describes a comet as a big dirty snowball in space, a glowing collection of ice, rocks, dust, and gases whose interior composition is intriguing⁴.

 

Morgan: What we're interested in is the source of the dust and gas that forms the coma⁵, which is a small core of ices, organic compounds, and dust called the nucleus. These objects are of interest to us because they are literally⁶ the leftover⁷ building blocks of our solar system.

 

Knowing the makeup⁸ of a comet would provide information about the chemistry and physics of the solar system as it formed 4.5 billion years ago.

 

The United States and Europe have a fleet of spacecraft going to various comets to understand them better. Just last year, for example, the U.S. Stardust satellite collected samples as it passed through dust ejected by comet Wild 2 and will be the first to return such matter to Earth for study. The European Rosetta craft is enroute to deposit instruments on the surface of comet Wirtanen in 2014.

 

The U.S. Deep Impact mission is unique among space projects. The head of NASA's Solar System Division, Andrew Dantzler, says the spacecraft will send a 372-kilogram copper⁹ missile to penetrate¹⁰ a comet's surface.

 

Dantzler: Deep Impact's rendezvous¹¹ in space with Tempel 1 will be the first time a spacecraft has ever touched the surface of a comet. In fact, the impactor will penetrate the comet's surface, blowing material away from the surface of the comet and revealing the mysteries of the interior of the nucleus.

 

It all takes place on Monday when the Deep Impact spacecraft releases the projectile¹² while it is flying in the comet's path. The spacecraft is then to execute a deflecting¹⁴ maneuver¹⁵ to get out of the way shortly before the comet smashes into the projectile at a relative speed of 37,000 kilometers per hour.

 

Before its demise¹⁶, the missile is to transmit the sharpest pictures ever of a comet. Cameras on the mothership are to return views of the excavation¹⁷ from above and photograph the structure beneath the surface. Deep Impact project manager Rick Grammier says the three orbiting U.S. space telescopes and many ground observatories¹⁸ worldwide will also be trained on the event, which could be bright enough to be seen.

 

Rick Grammier: So we expect to provide some great fireworks for all our observatories.

 

Mission scientists do not know how spectacular the space collision will be. If the comet is mostly a pile of rocks held together loosely by ice, the resulting crater¹⁹ could be shallow and wide, with a lot of material thrown out. If it is mostly ice, then the hole would be deeper and narrower with less material ejected. Or the impactor could be swallowed without a significant hole if the material is soft and fluffy²⁰. The mission's chief investigator²¹, Michael A'Hearn of the University of Maryland, says the crater could be anywhere from centimeters to dozens of meters deep.

 

Michael A'Hearn: The problem is there are no data on the interior. That's what we hope to solve with Deep Impact. A related question is that the comets we know eventually stop outgassing. Is this because they have exhausted²² all the gas in the interior, or is it because the surface layer has developed some sort of a crust that prevents the ice inside from evaporating and escaping as gas?

 

Whatever Deep Impact gleans²³ from its encounter with comet Tempel 1, Mr. A'Hearn says the crash will not push it into a collision course with Earth.

 

A'Hearn: The impact will, of course, will make a change in the orbit of the comet, but the change will be so small as to be undetectable.

 

David McAlary, VOA news, Washington.

 

注释：

probe [prEub] n. 探测器

reveal [ri5vi:l] vt. 揭示

comet [5kCmit] n. 彗星

celestial [si5lestjEl] adj. 天上的

nucleus [5nju:kliEs] n. 核子

blast [blB:st] vt. 爆炸

emerge [i5mE:dV] vi. 显现

interior [in5tiEriE] adj. 内部的

intriguing [in5tri:^iN] adj. 引起兴趣的

organic compound 有机化合物

satellite [5sAtElait] n. 人造卫星

penetrate [5penitreit] vt. 穿透

deflect¹³ [di5flekt] v.（使）偏斜

maneuver [mE5nu:vE] n. 机动

demise [di5maiz] n. 消失，结束

spectacular [spek5tAkjulE] adj. 引人入胜的

eject [i5dVekt] vt. 喷射

fluffy [5flQfi] adj. 蓬松的

outgassing 除气作用

exhaust [i^5zC:st] vt. 用尽

evaporate [i5vApEreit] v.（使）蒸发

 

1 celestial   

adj.天体的；天上的

参考例句：

• The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
• Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。

2 nucleus   

n.核，核心，原子核

参考例句：

• These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
• These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

3 Neptune   

n.海王星

参考例句：

• Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
• Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。

4 intriguing   

adj.有趣的；迷人的v.搞阴谋诡计(intrigue的现在分词)；激起…的好奇心

参考例句：

• These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
• It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》

5 coma   

n.昏迷，昏迷状态

参考例句：

• The patient rallied from the coma.病人从昏迷中苏醒过来。
• She went into a coma after swallowing a whole bottle of sleeping pills.她吃了一整瓶安眠药后就昏迷过去了。

6 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

7 leftover   

n.剩货，残留物，剩饭；adj.残余的

参考例句：

• These narrow roads are a leftover from the days of horse-drawn carriages.这些小道是从马车时代沿用下来的。
• Wonder if that bakery lets us take leftover home.不知道那家糕饼店会不会让我们把卖剩的带回家。

8 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？

9 copper   

n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的

参考例句：

• The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
• Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。

10 penetrate   

v.透(渗)入；刺入，刺穿；洞察，了解

参考例句：

• Western ideas penetrate slowly through the East.西方观念逐渐传入东方。
• The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。

11 rendezvous   

n.约会，约会地点，汇合点；vi.汇合，集合；vt.使汇合，使在汇合地点相遇

参考例句：

• She made the rendezvous with only minutes to spare.她还差几分钟时才来赴约。
• I have a rendezvous with Peter at a restaurant on the harbour.我和彼得在海港的一个餐馆有个约会。

12 projectile   

n.投射物，发射体；adj.向前开进的；推进的；抛掷的

参考例句：

• The vertical and horizontal motions of a projectile can be treated independently.抛射体的竖直方向和水平方向的运动能够分开来处理。
• Have you altered the plans of the projectile as the telegram suggests?你已经按照电报的要求修改炮弹图样了吗?

13 deflect   

v.(使)偏斜，(使)偏离，(使)转向

参考例句：

• Never let a little problem deflect you.决不要因一点小问题就半途而废。
• They decided to deflect from the original plan.他们决定改变原计划。

14 deflecting   

（使）偏斜， （使）偏离， （使）转向( deflect的现在分词 )

参考例句：

• A variety of mechanical surfaces have been employed for deflecting the exhaust jets of solid-propellant rockets. 人们已经用过各种类型的机械控制面来偏转固体推进剂火箭的排气流。
• If she made a leading statement, he was expert deflecting her into more impersonal channels. 只要她一开口，他就会巧妙地把她的话题转到与个人无关的问题上去。

15 maneuver   

n.策略[pl.]演习；v.(巧妙)控制；用策略

参考例句：

• All the fighters landed safely on the airport after the military maneuver.在军事演习后，所有战斗机都安全降落在机场上。
• I did get her attention with this maneuver.我用这个策略确实引起了她的注意。

16 demise   

n.死亡；v.让渡，遗赠，转让

参考例句：

• He praised the union's aims but predicted its early demise.他赞扬协会的目标，但预期这一协会很快会消亡。
• The war brought about the industry's sudden demise.战争道致这个行业就这么突然垮了。

17 excavation   

n.挖掘，发掘；被挖掘之地

参考例句：

• The bad weather has hung up the work of excavation.天气不好耽误了挖掘工作。
• The excavation exposed some ancient ruins.这次挖掘暴露出一些古遗迹。

18 observatories   

n.天文台，气象台( observatory的名词复数 )

参考例句：

• John Heilbron, The Sun in the Church: Cathedrals as Solar Observatories, 3-23. 约翰．海耳布隆，《教会里的太阳：教堂即太阳观测台》，第3-23页。 来自互联网
• Meteorologists use satellites, land observatories and historical data to provide information about the weather. 气象学家使用卫星、上天文台和历史资料来提供有关天气的信息。 来自互联网

19 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

20 fluffy   

adj.有绒毛的，空洞的

参考例句：

• Newly hatched chicks are like fluffy balls.刚孵出的小鸡像绒毛球。
• The steamed bread is very fluffy.馒头很暄。

21 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

22 exhausted   

adj.极其疲惫的，精疲力尽的

参考例句：

• It was a long haul home and we arrived exhausted.搬运回家的这段路程特别长，到家时我们已筋疲力尽。
• Jenny was exhausted by the hustle of city life.珍妮被城市生活的忙乱弄得筋疲力尽。

23 gleans   

v.一点点地收集（资料、事实）( glean的第三人称单数 )；（收割后）拾穗

参考例句：

• Book II gleans about seventy tales of wit and humor. 第二册搜集了近七十个饱蘸机智和幽默的故事。 来自互联网
• It gleans information through infrared sensing units. It is controlled by PLC system. 它是通过光电传感器来采集信息再由PLC控制系统来实现控制的。 来自互联网