Alien Neighbors 寻访外星人 4

...in Mars. Although it was completely wrong about Mars and everything he said about Mars practically was wrong. But, he built up interest in the planet which has carried over to this day. And, so, he was, he was quite useful to the Mars exploration program.'

Space exploration revealed Mars has little atmosphere and no liquid water on the surface. Yet, Its terrain¹ appears to have been sculpted by water.

NASA geologist³, Ken⁴ Herkenhoff, explains, 'It appears that there were great oceans on Mars sometime in the past and there is currently a debate raging as to exactly when these oceans occurred and how long they lasted and whether there were ice sheets that flowed on Mars.'

Today, the dry, cold Martian climate makes it inhospitable to life, but maybe not completely. An amazing survival story during the Apollo missions to our moon provided evidence that life can endure even harsher conditions.

Two and a half years after the SurveyorIII spacecraft was left on the moon, Apollo 12 astronauts returned, retrieved⁶ the lens of its TV-camera and with it a collection of what seemed to be alien bacteria. But they turned out to be stowaways, bacteria from earth, that had travelled on Surveyor to the moon and survived there for nearly three years, in an environment less hospitable⁵ than Mars. Here was the proof that life could endure, at least for a time, on a world other than our own.

What are the characteristics defining life as we know it? What else should seekers of life on other moons or planets be looking for? Living things move and grow. Life needs to take in nutrients⁸ and eliminate waste. And there is one other quality that is perhaps the most important indicator⁹ of all.

Oxford¹⁰ University biologist and author, Richard Dawkins: 'the most general characteristic's got to be reproduction, the property of heredity, everything else follows from that. Once you've got anywhere in the universe, heredity, the equivalent to DNA¹¹, doesn't have to be DNA, but the equivalent of something that makes copies of itself, genes¹² in other words. Then, Darwinian Natural Selection, evolution and life will follow. Now , in practice, on this planet, life has all sorts of other properties like respiration¹³ and feeding and things like that, but the fundamental one is reproduction. '

Today, our planet is a haven¹⁴ for life, a far cry from its violent beginning. The young earth was radioactive, hot, volcanic¹⁵ with no oxygen. The atmosphere was cloudy, full of noxious¹⁶ gases, carbon dioxide, ammonia, methane¹⁷. Red carpets of lava¹⁸ flowed over dark volcanic rock until water from planet's interior formed the vast oceans where life first appeared.

-----------------------------------------------------------------------------------------------
words in this passage

carry over:If something from one situation carries over or is carried over into another situation, it is allowed to exist in or affect the other situation: 延期至...

sculpt: to form into a particular shape雕刻, 造型

stowaway:a person who hides on a ship, aircraft or other vehicle偷渡者(here it means the bacteria from earth)

haven:a safe or peaceful place港口, 避难所,安全的地方

be a far cry from sth:to be completely different from something:大不相同的东西 (后接地点时也表示距离很远）

noxious gas: 有毒气体

1 terrain   

n.地面，地形，地图

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• He knows the terrain of this locality like the back of his hand.他对这一带的地形了如指掌。

2 sculpted   

adj.经雕塑的

参考例句：

• a display of animals sculpted in ice 冰雕动物展
• The ladies had their hair sculpted by the leading coiffeur of the day. 女士们的发型都是当代有名的理发师做的。

3 geologist   

n.地质学家

参考例句：

• The geologist found many uncovered fossils in the valley.在那山谷里，地质学家发现了许多裸露的化石。
• He was a geologist,rated by his cronies as the best in the business.他是一位地质学家，被他的老朋友们看做是这门行当中最好的一位。

4 ken   

n.视野，知识领域

参考例句：

• Such things are beyond my ken.我可不懂这些事。
• Abstract words are beyond the ken of children.抽象的言辞超出小孩所理解的范围.

5 hospitable   

adj.好客的；宽容的；有利的，适宜的

参考例句：

• The man is very hospitable.He keeps open house for his friends and fellow-workers.那人十分好客，无论是他的朋友还是同事，他都盛情接待。
• The locals are hospitable and welcoming.当地人热情好客。

6 retrieved   

v.取回( retrieve的过去式和过去分词 )；恢复；寻回；检索（储存的信息）

参考例句：

• Yesterday I retrieved the bag I left in the train. 昨天我取回了遗留在火车上的包。 来自《简明英汉词典》
• He reached over and retrieved his jacket from the back seat. 他伸手从后座上取回了自己的夹克。 来自辞典例句

7 stowaways   

n.偷乘船[飞机]者( stowaway的名词复数 )

参考例句：

• Smuggling guns, ammunition and drugs or assisting stowaways. 七私运枪械、弹药、品或协助偷渡人口者。 来自互联网
• Officious immigration and customs officers scrutinised documents and searched cabins for stowaways or illicit goods. 一本正经的边境和海关官员仔细检查文件，在车厢里搜索偷渡者和走私货物。 来自互联网

8 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

9 indicator   

n.指标；指示物，指示者；指示器

参考例句：

• Gold prices are often seen as an indicator of inflation.黃金价格常常被看作是通货膨胀的指标。
• His left-hand indicator is flashing.他左手边的转向灯正在闪亮。

10 Oxford   

n.牛津（英国城市）

参考例句：

• At present he has become a Professor of Chemistry at Oxford.他现在已是牛津大学的化学教授了。
• This is where the road to Oxford joins the road to London.这是去牛津的路与去伦敦的路的汇合处。

11 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

12 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

13 respiration   

n.呼吸作用；一次呼吸；植物光合作用

参考例句：

• They tried artificial respiration but it was of no avail.他们试做人工呼吸，可是无效。
• They made frequent checks on his respiration,pulse and blood.他们经常检查他的呼吸、脉搏和血液。

14 haven   

n.安全的地方，避难所，庇护所

参考例句：

• It's a real haven at the end of a busy working day.忙碌了一整天后，这真是一个安乐窝。
• The school library is a little haven of peace and quiet.学校的图书馆是一个和平且安静的小避风港。

15 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

16 noxious   

adj.有害的，有毒的；使道德败坏的，讨厌的

参考例句：

• Heavy industry pollutes our rivers with noxious chemicals.重工业产生的有毒化学品会污染我们的河流。
• Many household products give off noxious fumes.很多家用产品散发有害气体。

17 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。

18 lava   

n.熔岩，火山岩

参考例句：

• The lava flowed down the sides of the volcano.熔岩沿火山坡面涌流而下。
• His anger spilled out like lava.他的愤怒像火山爆发似的迸发出来。