PBS高端访谈:揭秘矮行星--谷神星的秘密

 　　JUDY WOODRUFF: Let's look at a space mission that's generating lots of interest and excitement. It's the mission to orbit the dwarf¹ planet Ceres by the NASA spacecraft named Dawn.

　　It arrived in March, and as the spacecraft has gotten closer in recent weeks, it's getting a better view of the planet, leading to some intriguing² questions.

　　MARC RAYMAN, Dawn Mission Director: Our team sat down with Dawn's mission director in California and put together this video.

　　We launched Dawn from Cape³ Canaveral in September 2007. In my view, Dawn is exploring two of the last uncharted worlds in the inner solar system. In more than 57 years of space exploration, it's the only spacecraft ever to orbit two extraterrestrial destinations.

　　I'm Marc Rayman, the chief engineer and mission director for the Dawn mission.

　　Vesta and Ceres are the two most massive objects in the main asteroid⁴ belt. There are millions of objects orbiting the sun there between Mars and Jupiter. But Ceres itself contains about a third of the mass of all of those objects.

　　Ceres is the largest object in the main asteroid belt. In fact, it's the largest object between the sun and Pluto⁵ that a spacecraft had not visited prior to Dawn, so it's almost 600 miles across. This is a big place. It's more than one million square miles. It's got 38 percent of the area of the continental⁶ United States.

　　Ceres and Vesta, they are remnants from the epic⁷ in our solar system of the formation of planets, the dawn of our solar system. And so scientists want to study these bodies because they may tell us more about the conditions and the processes that were acting⁸ at the times planets formed.

　　As Dawn got closer to Ceres, one of the first things we saw were those bright spots. And it's impossible not to be mesmerized⁹ by these glowing beacons¹⁰ shining out from the unfamiliar¹¹ lands ahead.

　　The reason these are so bright is that they reflect so much more light than the rest of Ceres does, maybe five times or more as much light as the rest of Ceres. And so the contrast is just stark¹².

　　There are many possibilities for what the bright spots might be. They might be ice in some form. They also might be the remnants from ice that was on the surface and sublimated¹³. That is, it's almost as if the ice evaporated into space and left behind the materials that had been dissolved in it, so essentially¹⁴ salts that could be very, very reflective.

　　And while we don't know yet what they are, as we continue to get in closer and get measurements, not only with the camera, but with the other sensors¹⁵ on the spacecraft, we will figure out what they are.

　　What it is about them, whether it's a difference in the chemical compositional nature of this material or something about its structure, its makeup¹⁶, why it reflects so much more light, we don't know. And it makes you want to send a spacecraft there to find out. And, by golly, that's what we're doing.

　　At Ceres, we fly the spacecraft in four different orbits in order to study this alien world. So, we started out in an orbit 8,400 miles high, and then eventually, we will fly it down to only about 230 miles, which is actually a little bit closer to the surface of Ceres than the International Space Station is to the surface of Earth.

　　Part of what is so exciting is, not only does each orbit answer questions for us, but it raises new questions. And then we can answer those questions by going lower and getting more detailed¹⁷ data. It's been a remarkable¹⁸, ambitious interplanetary adventure.

　　JUDY WOODRUFF: Our own Jenny Marder helped produce that piece. And visited NASA for the story. And she joins me now.

　　So, Jenny, thank you for being here.

　　Really interesting. And you just — you heard the mission director say, this is really about learning about the origins of our solar system.

　　JENNY MARDER: That's right.

　　Ceres is known as a protoplanet, and that means that scientists believe it was in the process of forming, like a full-pledged planet, and its formation was suddenly halted, likely by the tremendous gravity of Jupiter.

　　So what you're really seeing is a planet in the process of forming which is frozen in time, so that it's really a window into the beginning of the solar system.

　　JUDY WOODRUFF: And, as we just saw in that description in the pictures, the spacecraft Dawn is getting closer and closer. We heard him talk about the bright spots. What is the spacecraft seeing now?

　　JENNY MARDER: The spacecraft is maneuvering¹⁹ now from its third to its second orbit. Each orbit brings it closer and closer to the surface of Ceres.

　　So the images that we're seeing, we're seeing images of the craters²⁰, of valleys, a three-mile-high cone²¹ that sort of looks like a volcano on Earth. And we're seeing these bright spots which are very interesting. In August, we will start getting a new crop of photos. These are images coming from Dawn at the third orbit.

　　Those photos will be three times sharper than the images we're seeing now. And then, in early December, when it gets to its closest altitude, those will be 12 times sharper than what we're seeing now and actually 850 times sharper than what we were seeing back in January, when Dawn first started capturing these images.

　　JUDY WOODRUFF: So, still trying to figure out if there could have been life or could be life on this dwarf planet?

　　JENNY MARDER: Yes, that's a really interesting question.

　　It's a question that this mission likely won't answer, because they're not collecting anything from the surface of the planet. They will just — they're just orbiting it. However, Ceres does seem to possibly, very possibly have the ingredients for life.

　　JUDY WOODRUFF: Because of those bright spots?

　　JENNY MARDER: At least as we know it on Earth, life requires three ingredients, food, water, and energy.

　　And the energy could come from radioactive nuclear decay from the planet's interior. The planet is very dark, which they think indicates carbon-rich compounds on the surface. And then the third ingredient is water. And it looks like it's likely that these bright spots are evidence of water, of a liquid water mantle²² underneath²³ the surface.

　　JUDY WOODRUFF: Well, it sounds like the scientists are very excited about this.

　　JENNY MARDER: Yes.

　　What's so cool about this is, is it's incredible detective story that we're just seeing unfolding in real time. And as we get closer and closer to the surface of Ceres, this planet just comes increasingly into focus.

　　JUDY WOODRUFF: Jenny Marder, thank you very much.

　　JENNY MARDER: Thank you.

　　JUDY WOODRUFF: And you can learn more about the Dawn mission to Ceres by going to our Web site, PBS.org/NewsHour.

1 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

2 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》

3 cape   

n.海角，岬；披肩，短披风

参考例句：

• I long for a trip to the Cape of Good Hope.我渴望到好望角去旅行。
• She was wearing a cape over her dress.她在外套上披着一件披肩。

4 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

5 Pluto   

n.冥王星

参考例句：

• Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
• Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。

6 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

7 epic   

n.史诗，叙事诗；adj.史诗般的，壮丽的

参考例句：

• I gave up my epic and wrote this little tale instead.我放弃了写叙事诗，而写了这个小故事。
• They held a banquet of epic proportions.他们举行了盛大的宴会。

8 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

9 mesmerized   

v.使入迷( mesmerize的过去式和过去分词 )

参考例句：

• The country girl stood by the road, mesmerized at the speed of cars racing past. 村姑站在路旁被疾驶而过的一辆辆车迷住了。 来自《现代英汉综合大词典》
• My 14-year-old daughter was mesmerized by the movie Titanic. 我14岁的女儿完全被电影《泰坦尼克号》迷住了。 来自互联网

10 beacons   

灯塔( beacon的名词复数 )； 烽火； 指路明灯； 无线电台或发射台

参考例句：

• A chain of beacons was lit across the region. 整个地区点起了一系列灯塔。
• Lighthouse and beacons flash at night. 晚上灯塔与信号台闪着光。

11 unfamiliar   

adj.陌生的，不熟悉的

参考例句：

• I am unfamiliar with the place and the people here.我在这儿人地生疏。
• The man seemed unfamiliar to me.这人很面生。

12 stark   

adj.荒凉的；严酷的；完全的；adv.完全地

参考例句：

• The young man is faced with a stark choice.这位年轻人面临严峻的抉择。
• He gave a stark denial to the rumor.他对谣言加以完全的否认。

13 sublimated   

v.（使某物质）升华( sublimate的过去式和过去分词 )；使净化；纯化

参考例句：

• Their affection to each other was sublimated into a lasting friendship. 他俩之间的感情被升华成一种永久的友谊。 来自互联网
• Finally migrates the utilization, sublimated to the text the understanding. 最后是迁移运用，升华对文本的理解。 来自互联网

14 essentially   

adv.本质上，实质上，基本上

参考例句：

• Really great men are essentially modest.真正的伟人大都很谦虚。
• She is an essentially selfish person.她本质上是个自私自利的人。

15 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

16 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？

17 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

18 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

19 maneuvering   

v.移动，用策略( maneuver的现在分词 )；操纵

参考例句：

• This Manstein did, with some brilliant maneuvering under the worse winter conditions. 曼施坦因在最恶劣的严冬条件下，出色地施展了灵活机动的战术，终于完成了任务。 来自辞典例句
• In short, large goals required farsighted policies, not tactical maneuvering. 一句话，大的目标需要有高瞻远瞩的政策，玩弄策略是不行的。 来自辞典例句

20 craters   

n.火山口( crater的名词复数 )；弹坑等

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》

21 cone   

n.圆锥体，圆锥形东西，球果

参考例句：

• Saw-dust piled up in a great cone.锯屑堆积如山。
• The police have sectioned off part of the road with traffic cone.警察用锥形路标把部分路面分隔开来。

22 mantle   

n.斗篷，覆罩之物，罩子；v.罩住，覆盖，脸红

参考例句：

• The earth had donned her mantle of brightest green.大地披上了苍翠欲滴的绿色斗篷。
• The mountain was covered with a mantle of snow.山上覆盖着一层雪。

23 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。