"Life Form Found" on Saturn"s Titan

Scientists say they have discovered hints of alien life1 on the Saturn"s moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spacecraft Cassini4,which pointed to,the existence of methane-based form of life on Saturn"s biggest moon.

Scientists have reportedly discovered clues showing primitive alien beings are"breathing" in

Titan"s dense atmosphere filled with hydrogen.

They argue that hydrogen gets absorbed before hitting Titan"s planet-like surface covered with methane lakes and rivers. This,they say,points to the existence of some"bugs"5 consuming the hydrogen at the surface of the moon less than half the size of the Earth.

"We suggested hydrogen consumption because it"s the obvious gas for life to consume on Titan,similar to the way we consume oxygen on Earth,"says NASA scientist Chris McKay."If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth."

To date,scientists have not yet detected this form of life anywhere,though there are liquid-

water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin6(minus 290 degrees Farenheit),a methanebased organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan"s surface and much too cold to support life as we know it.

Scientists had expected the Sun"s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan"s surface. But Cassini detected no acetylene on the surface.

The absence of detectable acetylene on the Titan"s surface can very well have a non-biological explanation,said Mark Allen,a principal investigator7 of the NASA Titan team.

"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,"Allen said. "We have a lot of work to do to rule out8 possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results."

 

词汇：

Saturn /"sætən/ n．土星        

methane/"mi:θein/ n．甲烷，沼气

Titan/"taitən/ n．土卫六       

acetylene/ə"setili:n/ n．乙炔

alien/"eiljən/ n．外星人；adj．外星球的；相异的 

conservatism/kən"sʒ:vətizəm/ n．保守主义,守旧

 

注释：

1.hints of alien life：外星生命迹象。

2.the Saturn"s moon：指土卫六（Titan) 。土卫六又称泰坦星，是土星卫星中最大的一颗。

3.NASA：美国国家航空航天局的缩写，全称是： National Aeronautics and Space

Administration。

4.spacecraft Cassini：卡西尼号探测器，以出生于意大利的法国天文学家卡西尼的名字命名，其任务是环绕土星飞行，对土星及其大气、光环、卫星和磁场进行深人考察。1997 年10 月15日，重六吨的“卡西尼”号星际探测器被发射飞往土星的轨道。这是上世纪发射的最后一艘行星际探测的大飞船。“卡西尼”号用了将近七年时间，在2004 年7月1日飞达土星轨道。

5.bugs：微生物。非正式口语表达，所以使用了引号。

6.Kelvin：可翻译成“绝对温度”。Kelvin Scale ，绝对温标，开氏温标，是由Kelvin 勋爵于19世纪中叶发明的温度计量方法，其零度相当于摄氏一273. 15" C ，被认为是宇宙中最低温度。这种温度计量方法多为科学家使用。

7.principal investigator：研究项目负责人

8.rule out：排除……的可能性

What have scientists found about Saturn?

A:They have found a new moon orbiting Saturn. B:They have found methane-based life on Saturn. C:They have found methane-based life on Titan. D:They have found earthlike life on a Saturn"s moon.

"Life Form Found" on Saturn"s Titan

Scientists say they have discovered hints of alien life1 on the Saturn"s moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spacecraft Cassini4,which pointed to,the existence of methane-based form of life on Saturn"s biggest moon.

Scientists have reportedly discovered clues showing primitive alien beings are"breathing" in

Titan"s dense atmosphere filled with hydrogen.

They argue that hydrogen gets absorbed before hitting Titan"s planet-like surface covered with methane lakes and rivers. This,they say,points to the existence of some"bugs"5 consuming the hydrogen at the surface of the moon less than half the size of the Earth.

"We suggested hydrogen consumption because it"s the obvious gas for life to consume on Titan,similar to the way we consume oxygen on Earth,"says NASA scientist Chris McKay."If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth."

To date,scientists have not yet detected this form of life anywhere,though there are liquid-

water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin6(minus 290 degrees Farenheit),a methanebased organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan"s surface and much too cold to support life as we know it.

Scientists had expected the Sun"s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan"s surface. But Cassini detected no acetylene on the surface.

The absence of detectable acetylene on the Titan"s surface can very well have a non-biological explanation,said Mark Allen,a principal investigator7 of the NASA Titan team.

"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,"Allen said. "We have a lot of work to do to rule out8 possible non-biological explanations. It is more likely that a chemical process,without biology,can explain these results."

 

词汇：

Saturn /"sætən/ n．土星        

methane/"mi:θein/ n．甲烷，沼气

Titan/"taitən/ n．土卫六       

acetylene/ə"setili:n/ n．乙炔

alien/"eiljən/ n．外星人；adj．外星球的；相异的 

conservatism/kən"sʒ:vətizəm/ n．保守主义,守旧

 

注释：

1.hints of alien life：外星生命迹象。

2.the Saturn"s moon：指土卫六（Titan) 。土卫六又称泰坦星，是土星卫星中最大的一颗。

3.NASA：美国国家航空航天局的缩写，全称是： National Aeronautics and Space

Administration。

4.spacecraft Cassini：卡西尼号探测器，以出生于意大利的法国天文学家卡西尼的名字命名，其任务是环绕土星飞行，对土星及其大气、光环、卫星和磁场进行深人考察。1997 年10 月15日，重六吨的“卡西尼”号星际探测器被发射飞往土星的轨道。这是上世纪发射的最后一艘行星际探测的大飞船。“卡西尼”号用了将近七年时间，在2004 年7月1日飞达土星轨道。

5.bugs：微生物。非正式口语表达，所以使用了引号。

6.Kelvin：可翻译成“绝对温度”。Kelvin Scale ，绝对温标，开氏温标，是由Kelvin 勋爵于19世纪中叶发明的温度计量方法，其零度相当于摄氏一273. 15" C ，被认为是宇宙中最低温度。这种温度计量方法多为科学家使用。

7.principal investigator：研究项目负责人

8.rule out：排除……的可能性

To date,scientists have not yet detected this form of life...(paragraph 5)What does"this form of life" refer to?

A:Water-based life. B:Methane-based life. C:Liquid-water-based microorganisms. D:Gas-based life.

? ?Scientists say they have discovered hints of alien life on the Saturn’s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn’s biggest moon.
? ?Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan’s dense atmosphere filled with hydrogen.
? ?They argue that hydrogen gets absorbed before hitting Titan’s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth.
? ?"We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth. "
? ?To date, scientists have not yet detected this form of life anywhere, though there are liq-uid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Farenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it.
? ?Scientists had expected the Sun’s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan’s surface. But Cassini detected no acetylene on the surface.
? ?The absence of detectable acetylene on the Titan’s surface can very well have a non-bio-logical explanation, said Mark Allen, a principal investigator of the NASA Titan team.
? ?"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed," Alien said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results. /

What have scientists found about Saturn?

A:They have found methane-based life on Saturn. B:They have found a new moon orbiting Saturn. C:They have found methane-based life on Titan. D:They have found earthlike life on a Saturn’s moon.

? ?Scientists say they have discovered hints of alien life on the Saturn’s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn’s biggest moon.
? ?Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan’s dense atmosphere filled with hydrogen.
? ?They argue that hydrogen gets absorbed before hitting Titan’s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth.
? ?"We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth. "
? ?To date, scientists have not yet detected this form of life anywhere, though there are liq-uid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Farenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it.
? ?Scientists had expected the Sun’s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan’s surface. But Cassini detected no acetylene on the surface.
? ?The absence of detectable acetylene on the Titan’s surface can very well have a non-bio-logical explanation, said Mark Allen, a principal investigator of the NASA Titan team.
? ?"Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed," Alien said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results. /

Which of the following can replace the title of this passage?

A:Finding of One More Moon of Saturn. B:Titan, a New Satellite Found. C:A different Life Form, a Possibility. D:Earthlike Living Beings Found on Titan.

第三篇"Life Form Found" on Saturn’s Titan Scientists say they have discovered hints of alien life on the Saturn’s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn’s biggest moon. Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan’s dense atmosphere filled with hydrogen. They argue that hydrogen gets absorbed before hitting Titan’s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth. "We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth." To date, scientists have not yet detected this form of life anywhere, though there are liquid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Fahrenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it. Scientists had expected the Sun’s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan’s surface. But Cassini detected no acetylene on the surface. The absence of detectable acetylene on the Titan’s surface can very well have a non-biological explanation, said Mark Allen, a principal investigator of the NASA Titan team. "Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed." Allen said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results." What do scientists claim to have found about Saturn?

A:Water-based life on it. B:Methane—based life on its biggest moon. C:A new moon moving around it. D:Earthlike life on its biggest moon.

第三篇"Life Form Found" on Saturn’s Titan Scientists say they have discovered hints of alien life on the Saturn’s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn’s biggest moon. Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan’s dense atmosphere filled with hydrogen. They argue that hydrogen gets absorbed before hitting Titan’s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth. "We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth." To date, scientists have not yet detected this form of life anywhere, though there are liquid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Fahrenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it. Scientists had expected the Sun’s interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan’s surface. But Cassini detected no acetylene on the surface. The absence of detectable acetylene on the Titan’s surface can very well have a non-biological explanation, said Mark Allen, a principal investigator of the NASA Titan team. "Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed." Allen said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results." Which of the following can replace the title of this passage?

A:A different Life Form, a Possibility. B:Earthlike Living Beings Found on Titan. C:Finding of One More Moon of Saturn. D:Titan, a New Satellite Found.

Many scientists today are convinced that life exists elsewhere in the universe-life probably much like that on our own planet. They reason in the following way.
As far as astronomers can determine, the entire universe is built of the same matter. They have no reason to doubt that matter obeys the same laws in every part of the universe. Therefore, it is reasonable to guess that other stars, with their own planets, were born in the same way as our own solar system. What we know of life on earth suggests that life will arise wherever the proper conditions exist.
Life requires the right amount and kind of atmosphere. This eliminates all those planets in the universe that are not about the same size and weight as the earth. A smaller planet would lose its atmosphere; a larger one would hold too much of it.
Life also requires a steady supply of heat and light. This eliminates double stars, or stars that flare up suddenly. Only single stars that are steady sources of heat and light like our sun would qualify.
Finally, life could evolve only if the planet is just the right distance from its sun. With a weaker sun than our own, the planet would have to be closer to it. With a stronger sun, it would have to be farther away.
If we suppose that every star in the universe has a family of planets, then how many planets might support life First, eliminate those stars that are not like our sun. Next eliminate most of their planets; they are either too far from or too close to their suns. Then eliminate all those planets which are not the same size and weight as the earth. Finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. It may not have begun yet, or it may have already died out.
This process of elimination seems to leave very few planets on which earthlike life might be found. However, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist.
Which of the following statements is INCORRECT

A:The planet must be as big and heavy as the earth. B:Proper conditions are essential to the existence of life. C:Double stars can provide steady light and heat. D:The distance between a planet and its sun should be right.

Many scientists today are convinced that life exists elsewhere in the universe-life probably much like that on our own planet. They reason in the following way.
As far as astronomers can determine, the entire universe is built of the same matter. They have no reason to doubt that matter obeys the same laws in every part of the universe. Therefore, it is reasonable to guess that other stars, with their own planets, were born in the same way as our own solar system. What we know of life on earth suggests that life will arise wherever the proper conditions exist.
Life requires the right amount and kind of atmosphere. This eliminates all those planets in the universe that are not about the same size and weight as the earth. A smaller planet would lose its atmosphere; a larger one would hold too much of it.
Life also requires a steady supply of heat and light. This eliminates double stars, or stars that flare up suddenly. Only single stars that are steady sources of heat and light like our sun would qualify.
Finally, life could evolve only if the planet is just the right distance from its sun. With a weaker sun than our own, the planet would have to be closer to it. With a stronger sun, it would have to be farther away.
If we suppose that every star in the universe has a family of planets, then how many planets might support life First, eliminate those stars that are not like our sun. Next eliminate most of their planets; they are either too far from or too close to their suns. Then eliminate all those planets which are not the same size and weight as the earth. Finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. It may not have begun yet, or it may have already died out.
This process of elimination seems to leave very few planets on which earthlike life might be found. However, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist.
At the end of the passage the author suggests that ______.

A:it is impossible for life to exist on planets B:earthlike life could only exist on a few planets C:life could exist on only one planet in a million D:life could exist on a great number of planets