EXPLORATIONS - Cassini-Huygens at Saturn

EXPLORATIONS - Cassini-Huygens at Saturn¹
By Paul Thompson

Broadcast: Wednesday, July 14, 2004

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VOICE ONE:

This is Faith Lapidus

VOICE TWO:

 
A false color image of Saturn's rings.
And this is Steve Ember with EXPLORATIONS in VOA Special English. Today we tell about NASA's Cassini-Huygens spacecraft that is now in orbit² around Saturn. The spacecraft has already started sending back exciting information and photographs of Saturn's famous rings and its moon, Titan.

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VOICE ONE:

 
A picture of Saturn from Cassini Huygens. 
The Cassini-Huygens spacecraft arrived at the planet³ Saturn on July first. It flew into orbit from below the famous rings that circle the planet. Carefully, Cassini crossed through a large space between two of the huge rings at speeds close to eighty-seven-thousand kilometers an hour. Cassini flew to within one-hundred-fifty-eight-thousand kilometers of Saturn's center. That is the closest Cassini will come to Saturn.

After passing through the rings, Cassini fired its rocket engines. This slowed the spacecraft, permitting it to be captured⁴ by Saturn's gravity. In this way, the Cassini spacecraft entered an orbit around Saturn. It had taken Cassini almost seven years to reach Saturn after traveling more than three-thousand-million kilometers through space.

VOICE TWO:

It did not take long for Cassini to start making discoveries. Cassini took photographs of Saturn's giant moon Titan in its first few days of orbit. These photographs provided⁵ details of Titan's surface that had never been seen before.

Dennis Matson is a scientist for the International Cassini-Huygens project. He says the photographs sent back by Cassini are difficult to understand.

He says the photographs do provide the first clear images of Titan's surface, but will require a great amount of study. Titan has a thick atmosphere that usually looks almost white in photographs taken with telescopes. However Cassini has special cameras that can see through the giant moon's atmosphere to study the surface.

Elizabeth Turtle is a scientist with the University of Arizona. She says Cassini's first photographs of Titan's surface have shown unusual features. Mizz Turtle says they do not know what some of these features mean. She says it will take a great deal of work to understand the surface of Titan.

VOICE ONE:

Cassini-Huygens carries a total of eighteen scientific instruments. It used several of these to photograph and make maps of the surface of Titan. It also used several instruments to study minerals and chemicals on the surface of the huge moon.

Kevin Baines is a science team member of the Cassini-Huygens project. He says Cassini provided evidence of pure water ice in some areas of the surface.

He said it also showed areas of non-ice materials such as hydrocarbons⁶. Mister⁷ Baines said the evidence was much different from what scientists had expected. Mister Baines also said Cassini showed clouds of gas made of methane⁸ near the moon's south pole. He said the clouds showed good evidence that Titan has a very active atmosphere.

VOICE TWO:

The science team for Cassini says these first images of Titan are just the beginning. It is only the first information gathered in a four-year study of Saturn and its moons. In the future, the Cassini spacecraft will fly closer to Titan and be able to use radar⁹ to gather much better details of the moon's surface.

The study of Titan is one of the major goals of the Cassini-Huygens flight. Cassini's first trip near Titan was still more than three-hundred-thirty-nine thousand kilometers away. Future plans call for Cassini to make more than seventy orbits¹⁰ around Saturn. Forty-five of these will include passing close to Titan.

The closest flight will be only nine-hundred-fifty kilometers away from the giant moon. This very close flight will permit extremely detailed¹¹ mapping of the surface.

VOICE ONE:

 
Scientists prepare the Huygens probe¹².
The Huygens part of the spacecraft will cut its link to Cassini on December twenty-fourth. It will then fly down through the atmosphere of Titan to the surface. As it passes into the atmosphere, it will deploy¹³ a large parachute. The Huygens instrument will send information back to Cassini. Cassini will then transmit¹⁴ the information back to Earth.

The Huygens instrument will land on the surface of Titan on January fourteenth, two-thousand-five. It will be the first scientific instrument to land on the surface of a moon of another planet.

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VOICE TWO:

 
A real color image of Titan.
Saturn's moon, Titan, is very large. In fact, it is larger than the planets¹⁵ Mercury¹⁶ and Pluto¹⁷. Scientists are very interested in Titan because it is the only known moon in our solar system to have an atmosphere. It also has large amounts of nitrogen¹⁸ similar to Earth. And scientists believe it has large amounts of carbon material.

This is the same material needed to form life as we know it on Earth. However, scientists are quick to say this does not mean there is life on Titan.

VOICE ONE:

The exploration of Titan is exciting for many scientists. Scientists believe evidence found on Titan may help to answer the question of how life began on Earth. Most experts agree this question is hard to answer because not enough is known about the atmosphere when Earth was a young planet.

Scientists say they need to know what materials were present at the beginning of life on Earth. They say some of these answers may be present on Titan. The carbon material methane on Titan may have been easily found on Earth when it was young.

VOICE TWO:

Cassini carries more scientific instruments and can do more science work than any spacecraft ever sent to explore a planet. It carries twelve science instruments on the Cassini spacecraft and six more on the Huygens exploration device¹⁹.

Cassini is six-point-seven meters high, four meters wide and weighs almost six-thousand kilograms. Electric power for the spacecraft is supplied by thirty-three kilograms of the nuclear fuel, plutonium.

The flight to Saturn represents the work of two-hundred-sixty scientists from the United States and seventeen European nations. The flight of the Cassini-Huygens spacecraft cost more than three-thousand-million dollars.

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VOICE ONE:

The Cassini-Huygens spacecraft is expected to carry out many tasks. There is much to learn about Saturn. First, there are the seven huge rings that circle the planet. They are made of water ice, rock and dust.

Only minutes after it arrived in orbit, Cassini made sixty-one photographs of the beautiful rings. Cassini's radio sent the pictures to Earth. Radio signals travel at almost the speed of light. But even at that great speed, it took almost eighty-five minutes for the information to arrive on Earth. What scientists saw excited them.

They saw unusual designs and structures in the rings they had never seen before. Cassini's photographs provided evidence that the rings are not a solid mass of objects, but many individual lines that circle the planet. These thin lines are held together and kept in orbit by gravity. Scientists now believe there may be more than one-thousand different lines or rings that make up the seven great rings.

VOICE TWO:

The huge moon Titan is not alone in its orbit around Saturn. Saturn has thirty-one known moons. Thirteen of these moons were discovered after Cassini was launched²⁰ on October fifteenth, nineteen-ninety-seven. Scientists want to learn more about how these moons affect the rings. New photographs already show that the gravity of the moons has a great effect on the rings. Scientists hope Cassini will provide more information about this in the future.

The Cassini spacecraft is named for astronomer²¹ Jean Dominique Cassini. He was born in Italy in the sixteen-hundreds. He later became a French citizen. He made important observations of Saturn and discovered four of its moons. The Huygens exploration device is named for Dutch astronomer Christiaan Huygens who also lived during the seventeenth century. He discovered the moon Titan.

VOICE ONE:

If you have a computer that can link to the Internet, you too can see the photographs of Saturn. You can see the moon Titan and the rings that make Saturn such a beautiful planet. Have your computer link with www.nasa.gov. Then follow the links to Cassini-Huygens.

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VOICE TWO:

This program was written by Paul Thompson. It was produced by Mario Ritter. This is Steve Ember.

VOICE ONE:

And this is Faith Lapidus. Join us again next week for another EXPLORATIONS program in VOA Special English.

1 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

2 orbit   

n.轨道；vt.使沿轨道运行；使进入轨道运行；vi.沿轨道运行，环行

参考例句：

• The space rocket was launched and went into orbit.宇宙火箭发射后进入轨道。
• We can draw the earth's orbit round the sun.我们可以画出地球绕太阳运行的轨迹。

3 planet   

n.行星

参考例句：

• Neptune is the furthest planet from the sun. 海王星是离太阳最远的行星。
• Rubbish, however, is only part of the problem of polluting our planet. 然而, 垃圾只是我们这个星球的污染问题的一个方面。

4 captured   

俘获( capture的过去式和过去分词 )； 夺取； 夺得； 引起（注意、想像、兴趣）

参考例句：

• Allied troops captured over 300 enemy soldiers. 盟军俘虏了300多名敌方士兵。
• Most of the rebels were captured and disarmed. 大部分叛乱分子被俘获并解除了武装。

5 provided   

conj.假如，若是；adj.预备好的，由...供给的

参考例句：

• Provided it's fine we will have a pleasant holiday.如果天气良好，我们的假日将过得非常愉快。
• I will come provided that it's not raining tomorrow.如果明天不下雨，我就来。

6 hydrocarbons   

n.碳氢化合物，烃( hydrocarbon的名词复数 )

参考例句：

• Hydrocarbons (HC), like carbon monoxide, represent unburned and wasted fuel. 碳氢化合物(HC)像一氧化碳一样，为未燃尽的和被浪费掉的燃料。 来自英汉非文学 - 环境法 - 环境法
• With this restricted frequency range it is not applicable to hydrocarbons. 这个较紧缩的频率范围不适用于烃类。 来自辞典例句

7 mister   

n.(略作Mr.全称很少用于书面)先生

参考例句：

• Mister Smith is my good friend.史密斯先生是我的好朋友。
• He styled himself " Mister Clean ".他自称是“清廉先生”。

8 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

9 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

10 orbits   

轨道( orbit的名词复数 )； 势力范围

参考例句：

• The man-made satellite orbits the earth every 48 hours. 那颗人造卫星每48小时绕地球轨道运行一周。
• The earth orbits the sun once every 365.25 days. 地球每365.25天绕太阳轨道一圈。

11 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。

12 probe   

n.探针，调查，查究；v.探索，查究

参考例句：

• A doctor used a probe to remove metal fragments from a wound.医生用探针将伤口中的金属碎片取出。
• They will probe deeply into the matter.他们将深入调查这件事。

13 deploy   

v.（军）散开成战斗队形，布置，展开

参考例句：

• The infantry began to deploy at dawn.步兵黎明时开始进入战斗位置。
• The president said he had no intention of deploying ground troops.总统称并不打算部署地面部队。

14 transmit   

vt.播送，发射；传送，传递，传染

参考例句：

• A telegram will be the quickest way to transmit the message.打电报将是传递这个信息的最快途径。
• These symbols transmit a message in a simple and direct manner.这些标志用最简单直接的方式传达出一个信息。

15 planets   

行星( planet的名词复数 )； 地球（尤指环境）

参考例句：

• Does life exist on other planets? 其他行星上有生命吗？
• the planets of our solar system 太阳系的行星

16 mercury   

n.汞，水银，水银柱

参考例句：

• The liquid we can see in thermometers is mercury.我们看到的温度计里的液体是水银。
• Mercury has a much greater density than water.水银的密度比水大得多。

17 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。

18 nitrogen   

n.[化]氮

参考例句：

• The atmosphere consist of more than 70% of nitrogen.大气中含有70%以上的氮气。
• What is the percentage of nitrogen in air?空气中所含的氮的比例是多少？

19 device   

n.器械，装置；计划，策略，诡计

参考例句：

• The device will be in production by the end of the year.该装置将于年底投入生产。
• The device will save much time and effort for us.这种装置会使我们节省大量时间和气力。

20 launched   

v.发射( launch的过去式和过去分词 )；[计算机]开始（应用程序）；发动；开展（活动、计划等）

参考例句：

• He launched a bitter diatribe against the younger generation. 他对年轻一代发起了猛烈的抨击。
• The product was launched amid much fanfare worldwide. 这个产品在世界各地隆重推出。

21 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。