国家地理:Is It Real? Life on Mars 火星生命

Believe it or not, astrobiologist Penny Boston is searching for life on Mars by dropping deep into this heart of darkness. This is a lava¹ tube, a subterranean² cave formed by underground lava flows during volcanic³ eruptions⁴ that occurred thousands of years ago. And Boston has someone she wants us to meet.

Sometimes they are in crevices⁵. Sometimes they are kinda hard to see.
Is this one, the scary monster reveals itself?
Ah! There is one.
Actually no. This is an extremophile.

We are looking for what we astrobiologyists call extremophiles in this environment. That means that they are organisms that are living in very difficult conditions. In this particular case, these organisms are living in a very cold cave right around freezing. They are making their living without benefit of sunlight and there is almost nothing to eat in this cave.

In recent years, scientists have discovered tenacious⁶ microorganisms living in all forms of extreme environments. So if on Earth, why not on Mars?

We think that Mars is covered with lava tubes. We believe that by looking at organisms that live in these extreme circumstances on Earth, we can learn a lot about what to look for on Mars; and that, similar Martian organisms may be able to persist on Mars in places very similar to this lava tube.

To find out, Dr. Boston has created her own little Mars environment biospheres, essentially⁷ exposing a range of microscopic⁸ Earth life forms to various elements to be expected on Mars.

They have been subjected to Mars-like levels of high ultraviolet radiation, and Mars-like temperature cycles. We have given them atmosphere compositions from very low levels of carbon dioxide with nothing else to, perhaps, 1/10 the density⁹ of Earth's atmosphere, and tested them under those conditions.

And so far, she's isolated¹⁰ 36 different strains of organism that thrive quite happily. So in theory at least, life could survive the harsh conditions of Mars except for one problem.

There is one thing for sure that we know, and that is that all forms of life on our planet require liquid water. We don't know if that's going to be true on other planets. But we think that where there is going to be life, there is going to have to be water.

astrobiologist: one who specializes in astrobiology, one who studies life on celestial

subterranean: existing, occurring, or done under the earth's surface

extremophile: microorganism that lives in extreme environmental conditions

tenacious: persisting in existence

1 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。

2 subterranean   

adj.地下的，地表下的

参考例句：

• London has 9 miles of such subterranean passages.伦敦像这样的地下通道有9英里长。
• We wandered through subterranean passages.我们漫游地下通道。

3 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。

4 eruptions   

n.喷发，爆发( eruption的名词复数 )

参考例句：

• There have been several volcanic eruptions this year. 今年火山爆发了好几次。 来自《简明英汉词典》
• Over 200 people have been killed by volcanic eruptions. 火山喷发已导致200多人丧生。 来自辞典例句

5 crevices   

n.（尤指岩石的）裂缝，缺口( crevice的名词复数 )

参考例句：

• It has bedded into the deepest crevices of the store. 它已钻进了店里最隐避的隙缝。 来自辞典例句
• The wind whistled through the crevices in the rock. 风呼啸着吹过岩石的缝隙。 来自辞典例句

6 tenacious   

adj.顽强的，固执的，记忆力强的，粘的

参考例句：

• We must learn from the tenacious fighting spirit of Lu Xun.我们要学习鲁迅先生韧性的战斗精神。
• We should be tenacious of our rights.我们应坚决维护我们的权利。

7 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。

8 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

9 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

10 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。