【英语语言学习】火星上有生命的新证据

This is SCIENCE FRIDAY. I'm Ira Flatow. Last August, NASA's Curiosity Rover staked its claim in Gale¹ Crater² on the surface of Mars, and since then it's been cruising around, zapping rocks, sniffing⁴ the Martian air and snapping some self-portraits. But now Curiosity has begun to drill, and it looks like it just struck pay dirt, evidence that microbes would have been able to thrive on the red planet billions of years ago in a wet, freshwater habitat far different from the dusty red plains we see today.

 

How can we squeeze these clues from ancient stones? And if microbes really did live on Mars at some point, how did they make a living? What did they eat? And might there be similar microbes right here on Earth? David Blake is principal investigator⁵ for the CheMin instrument on the Curiosity Rover. He's also a research scientist at NASA Ames Research Center in Moffett Field. Welcome to SCIENCE FRIDAY, Dr. Blake.

 

DAVID BLAKE: Thanks, Ira, it's nice to be here.

 

FLATOW: Tell us about the area you're drilling in. It's an old lake bed, assumed lake bed?

 

BLAKE: Yeah, that's what we think. We've been kind of going downhill into this area that's a local, you know, depression, and the area looks very much like it's all - it's flat-lying. There are these flagstone-sized cracked cobbles, and so yeah, it looks very much like a really old lake bed.

 

FLATOW: And so Curiosity just drilled into one of the rocks on the lake bed?

 

BLAKE: We did, yeah, and the rocks are actually pretty soft compared to what you would expect from a three-billion-year-old rock. So we drilled a sample and analyzed⁷ it.

 

FLATOW: And you scooped⁹ it up, and what - and I saw it on the Web, and it has - it doesn't look like the red Martian soil.

 

BLAKE: Well, that's the - that was a really exciting thing for us. You know, we analyzed something like a sand dune¹⁰ a few months ago, and it's, you know, it's red like the red planet, and that's because the iron is oxidized like rust¹¹. So we drilled into this rock, and the rock on the outside is red because of the dust that's on it, but inside it's kind of a gray-green color, which was - the reason we were excited is this is the color of more of a reduced iron.

 

So if it was a habitable environment a really long time ago, then there was the opportunity for maybe if organics were there for them to have been preserved, not oxidized.

 

FLATOW: Did you find organics in the soil?

 

BLAKE: Well, that's still an ongoing¹² question because we took one drill sample, analyzed it, and starting this Monday we're going to start doing more organic analyses with the SAM instrument. There were organics found, very small quantities, but because they - we hadn't, you know, flushed out kind of the drill stream, the drill stem and dumped the powder to try and get rid of any possible contamination on the drill stem, we'll have to wait until the second drill to try it out.

 

FLATOW: Sort of clean the drill off while you're drilling.

 

BLAKE: That's right. Actually, you know, the first drill was supposed to be kind of like clean and dump, but we were excited about seeing what it was. So we analyzed it.

 

FLATOW: I can bet. If it does have, you know, bits of carbon, if it is organic, are you thinking that it's possible, not certain but possible, that organic was left by life forms that might have existed?

 

BLAKE: It's possible. There are abiotic organic materials that had formed on Mars, and there's also meteoritic¹³ input¹⁴ with carbon compounds. So there is carbon on Mars that's not either from Mars or that is not biological in origin. But, you know, it is possible we would see some organic material from biota¹⁵ if it existed.

 

FLATOW: Is it the kind of soil that bacteria or other kinds of life could have thrived in?

 

BLAKE: Yeah, you know, it easily could be. When we call something habitable, we mean that first of all - well first, we're very Earth-centric, and when we describe what's habitable, because it's all we really know about, but we look for presence of water, we look for the possibility of an energy source. And in this case we're not thinking photosynthesis¹⁶ or...

 

You know, there are three ways you can live, right. You can live like a plant and get energy from the sun; or you can eat other organisms; or you can kind of get your own energy from rocks, from chemical reactions that happen in rocks. And it happens that these rocks had some unrequited chemistry from the minerals that could used as an energy source.

 

FLATOW: How would that happen? How would that work?

 

BLAKE: Well, one way it could work, and I'm not saying this is a way it is working, but this is a basaltic rock, a basaltic sediment¹⁷, rather, and it has - or maphic sediment. It has a mineral called olivine. And olivine is stable deep down below the surface of the Earth, or Mars, maybe tens to hundreds of kilometers.

 

And when it comes to the surface in the presence of water, that olivine could be turned into a mineral called serpentine¹⁸ with reaction of water. And when that happens, then the iron in the olivine is oxidized to magnetite, and that delivers a little bit of hydrogen. And that hydrogen can be used as fuel.

 

FLATOW: By whatever it is living there.

 

BLAKE: That's right, that's right, by what we call methanogens on Earth.

 

FLATOW: And we know that happens here on Earth, and you assume it might happen on Mars.

 

BLAKE: Yes.

 

FLATOW: So what do you do next? Are you going to re-drill another hole, or have you done that already?

 

BLAKE: Well, we did drill the one hole, and the CHIMRA, which is the sample handling and analysis - sample handing system on the arm is holding a whole batch¹⁹ of powder still from the first drilling. And so we're still analyzing²⁰ that stuff. Now we're kind of fighting time because Mars is going to go behind the sun in another couple of weeks, and we can't really community with Curiosity for about a month. So we're trying to get as much as we can get done on this sample, and then we'll drill a second sample after Mars come out from behind the sun.

 

FLATOW: So it turns out that just your test drill has turned up something unexpected.

 

BLAKE: Absolutely, yeah, just the color of that powder made us think, you know, this is pay dirt, we hit the right rock.

 

FLATOW: What is the ultimate destination for Curiosity? It's on a long journey, is it not?

 

BLAKE: It is. We're - you know, we went to this area, we actually drove away from our primary destination, which is a place called Mount Sharp. It's a 5,000-meter, about a 14,000-foot-tall mountain in the middle of Gale Crater that has all these layered sediments²¹ from early Mars. So that's our ultimate destination. But it's about eight kilometers away.

 

We kind of drove in the opposite direction because there was this real interesting area that many people on the team thought actually could be a lake bed. And so we're going to do one additional drill here to kind of make sure what we have and understand what it is, and then we'll take the long march to Mount Sharp.

 

FLATOW: Do you think you can go up the whole mountain, top of the mountain?

 

BLAKE: That'd be nice.

 

(LAUGHTER)

 

FLATOW: Some view from up there, I would imagine.

 

BLAKE: That would be really nice. You know, there are Rover drivers and planners at Jet Propulsion Laboratory, and we have these really nice high-resolution images of Mount Sharp, and they've actually plotted ways to kind of go up the canyons²³ and look at the side walls of the canyon²². So we'll go as far as we can.

 

FLATOW: What - in this drill, right where you are here, what would be the best outcome that you could find, the most optimistic thing that you could find if you went through the dust you have or the next drill?

 

BLAKE: Oh man. Well, I think that the next drill would be the one because we want to make sure we've kind of flushed out any possible terrestrial contamination from the drill. But, you know, if we find what we think we've already found in the minerals, which tell us it's a habitable environment, and if the SAM instrument, which is a suite²⁴ of instruments that do organic analyses, can find some organic compounds that clearly aren't from Earth, well, that would be a home run.

 

And I'm not even suggesting it would be from organisms, just to know that there was carbon contained - organic carbon contained inside this rock for three billion years that we could come there and analyze⁶ today.

 

FLATOW: Could life have existed three billion years ago on Mars?

 

BLAKE: Absolutely, I'm - well, I'm not certain of it, but yeah, I believe it.

 

FLATOW: You almost said you were.

 

(LAUGHTER)

 

BLAKE: Well, I like "Star Trek," too. No, you know, I'm - the fact is that early Mars and early Earth were very similar, and, you know, Mars was wet and warm and had a denser²⁵ atmosphere back then. And we know it's about the time that on Earth life developed. So there's no reason to believe that it didn't develop. The conditions were similar.

 

FLATOW: Is Curiosity going to follow up on the results presented in 2009 about that methane²⁶ in the atmosphere of Mars? Because wouldn't the methane signal there was life at one point?

 

BLAKE: Well, that's one possibility. Methane is produced abiotically, as well. So in fact we are following up on it. The SAM instrument can sniff³ the atmosphere and look at not only the gases but the isotopic²⁷ composition of the gases. So they did that early on, and essentially²⁸ they found the answer to be zero plus or minus two part per billion.

 

So essentially they got a zero answer. It's not to say that at another time, another place, we wouldn't find methane, but that first measurement was zero.

 

FLATOW: So are you just in a hold mode now, sitting there with that scoop⁸ full of soil and waiting, you know, for that journey to be in a right position for you to do the second drill?

 

BLAKE: Yeah, right now the CHIMRA has the samples, and we already have a sample that we're going to start analyzing again with CheMin on Monday, and there are going to be more samples delivered from the same drill powder to SAM to do other measurements. And they have a variety of conditions they can use to tease out different answers from the sample.

 

FLATOW: A few weeks ago Curiosity had a computer glitch²⁹ and had to run in safe mode. We all know what safe mode is on our PCs.

 

(LAUGHTER)

 

FLATOW: Does a little sign come up on, you know, on the screen on Curiosity?

 

BLAKE: That was scary.

 

FLATOW: Was it scary? Is it resolved?

 

BLAKE: It's resolved now. The engineers actually called it zombie mode.

 

(LAUGHTER)

 

FLATOW: Zombie mode?

 

BLAKE: Zombie mode, yeah.

 

FLATOW: What does that mean in - I mean, does it mean that everything is shut down, or it's just it's not alive but not dead?

 

BLAKE: You know, they switched over - there are two computers, and the A-side computer, which we've been using all along, apparently³⁰ had a glitch. So they switched to the B-side, which operates, it is operable. But then you have the question will the same thing happen to this computer as happened to the other one.

 

And so they went back and queried³¹ the A computer to see what exactly happened and how to work around it. And so I think they've figured out a work-around with the memory so that now we're running on the B-side and using the A-side as a backup.

 

FLATOW: Well, we don't want the rolling dead on Mars, so...

 

BLAKE: Oh, it was just plain scary for a while there.

 

FLATOW: All right, David Blake, thank you very much for taking time to be with us, and we'll check back with you.

 

BLAKE: Well thank you, pleasure to be here.

 

FLATOW: David Blake, research scientist at NASA Ames Research Center. We're going to take a break, and Kathy Reichs is here. Your crime novel readers know her name. So stay tuned³². We'll be right back. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

1 gale   

n.大风，强风，一阵闹声（尤指笑声等）

参考例句：

• We got our roof blown off in the gale last night.昨夜的大风把我们的房顶给掀掉了。
• According to the weather forecast,there will be a gale tomorrow.据气象台预报，明天有大风。

2 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

3 sniff   

vi.嗅…味道；抽鼻涕；对嗤之以鼻，蔑视

参考例句：

• The police used dogs to sniff out the criminals in their hiding - place.警察使用警犬查出了罪犯的藏身地点。
• When Munchie meets a dog on the beach, they sniff each other for a while.当麦奇在海滩上碰到另一条狗的时候，他们会彼此嗅一会儿。

4 sniffing   

n.探查法v.以鼻吸气，嗅，闻( sniff的现在分词 )；抽鼻子（尤指哭泣、患感冒等时出声地用鼻子吸气）；抱怨，不以为然地说

参考例句：

• We all had colds and couldn't stop sniffing and sneezing. 我们都感冒了，一个劲地抽鼻子，打喷嚏。
• They all had colds and were sniffing and sneezing. 他们都伤风了，呼呼喘气而且打喷嚏。 来自《现代英汉综合大词典》

5 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

6 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。

7 analyzed   

v.分析( analyze的过去式和过去分词 )；分解；解释；对…进行心理分析

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
• The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程，因为对他来说，爱是个不可分析的迷。 来自《简明英汉词典》

8 scoop   

n.铲子，舀取，独家新闻；v.汲取，舀取，抢先登出

参考例句：

• In the morning he must get his boy to scoop it out.早上一定得叫佣人把它剜出来。
• Uh,one scoop of coffee and one scoop of chocolate for me.我要一勺咖啡的和一勺巧克力的。

9 scooped   

v.抢先报道( scoop的过去式和过去分词 )；（敏捷地）抱起；抢先获得；用铲[勺]等挖（洞等）

参考例句：

• They scooped the other newspapers by revealing the matter. 他们抢先报道了这件事。 来自《简明英汉词典》
• The wheels scooped up stones which hammered ominously under the car. 车轮搅起的石块，在车身下发出不吉祥的锤击声。 来自《简明英汉词典》

10 dune   

n.(由风吹积而成的)沙丘

参考例句：

• The sand massed to form a dune.沙积集起来成了沙丘。
• Cute Jim sat on the dune eating a prune in June.可爱的吉姆在六月天坐在沙丘上吃着话梅。

11 rust   

n.锈；v.生锈；(脑子)衰退

参考例句：

• She scraped the rust off the kitchen knife.她擦掉了菜刀上的锈。
• The rain will rust the iron roof.雨水会使铁皮屋顶生锈。

12 ongoing   

adj.进行中的，前进的

参考例句：

• The problem is ongoing.这个问题尚未解决。
• The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。

13 meteoritic   

adj.陨石的

参考例句：

• The momentum of the particles was deduced from meteoritic velocities. 粒子的冲量可以从陨石速度推导出来。 来自互联网

14 input   

n.输入(物)；投入；vt.把(数据等)输入计算机

参考例句：

• I will forever be grateful for his considerable input.我将永远感激他的大量投入。
• All this information had to be input onto the computer.所有这些信息都必须输入计算机。

15 biota   

n.生物区

参考例句：

• They have had serious effects upon the biota of stream.它们对河流中的生物群体产生严重影响。
• Historical biogeography attempts to reconstruct the biota history of the earth.历史生物地理学重建生物区系历史。

16 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

17 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

18 serpentine   

adj.蜿蜒的，弯曲的

参考例句：

• One part of the Serpentine is kept for swimmers.蜿蜒河的一段划为游泳区。
• Tremolite laths and serpentine minerals are present in places.有的地方出现透闪石板条及蛇纹石。

19 batch   

n.一批(组，群)；一批生产量

参考例句：

• The first batch of cakes was burnt.第一炉蛋糕烤焦了。
• I have a batch of letters to answer.我有一批信要回复。

20 analyzing   

v.分析；分析( analyze的现在分词 )；分解；解释；对…进行心理分析n.分析

参考例句：

• Analyzing the date of some socialist countries presents even greater problem s. 分析某些社会主义国家的统计数据，暴露出的问题甚至更大。 来自辞典例句
• He undoubtedly was not far off the mark in analyzing its predictions. 当然，他对其预测所作的分析倒也八九不离十。 来自辞典例句

21 sediments   

沉淀物( sediment的名词复数 )； 沉积物

参考例句：

• When deposited, 70-80% of the volume of muddy sediments may be water. 泥质沉积物沉积后，体积的70-80％是水。
• Oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。

22 canyon   

n.峡谷，溪谷

参考例句：

• The Grand Canyon in the USA is 1900 metres deep.美国的大峡谷1900米深。
• The canyon is famous for producing echoes.这个峡谷以回声而闻名。

23 canyons   

n.峡谷( canyon的名词复数 )

参考例句：

• This mountain range has many high peaks and deep canyons. 这条山脉有许多高峰和深谷。 来自辞典例句
• Do you use canyons or do we preserve them all? 是使用峡谷呢还是全封闭保存？ 来自互联网

24 suite   

n.一套(家具)；套房；随从人员

参考例句：

• She has a suite of rooms in the hotel.她在那家旅馆有一套房间。
• That is a nice suite of furniture.那套家具很不错。

25 denser   

adj. 不易看透的, 密集的, 浓厚的, 愚钝的

参考例句：

• The denser population necessitates closer consolidation both for internal and external action. 住得日益稠密的居民，对内和对外都不得不更紧密地团结起来。 来自英汉非文学 - 家庭、私有制和国家的起源
• As Tito entered the neighbourhood of San Martino, he found the throng rather denser. 蒂托走近圣马丁教堂附近一带时，发现人群相当密集。

26 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。

27 isotopic   

adj.同位素的，合痕的

参考例句：

• The isotopic signatures of most ancient limestones indicated the same process. 大多数古代石灰岩的同位素特征说明了同样的过程。 来自辞典例句
• Isotopic discrimination is not likely. 同位素甄别是不可能的。 来自辞典例句

28 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。

29 glitch   

n.干扰；误操作，小故障

参考例句：

• There is a glitch in the computer program somewhere.这个计算机程序中的某个部分有点小问题。
• It could just be a random glitch that can be solved by restarting the machine.可能只是一个小故障，重新启动主机就能解决了。

30 apparently   

adv.显然地；表面上，似乎

参考例句：

• An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。
• He was apparently much surprised at the news.他对那个消息显然感到十分惊异。

31 queried   

v.质疑，对…表示疑问( query的过去式和过去分词 )；询问

参考例句：

• She queried what he said. 她对他说的话表示怀疑。 来自《简明英汉词典》
• \"What does he have to do?\" queried Chin dubiously. “他有什么心事？”琴向觉民问道，她的脸上现出疑惑不解的神情。 来自汉英文学 - 家（1-26） - 家（1-26）

32 tuned   

adj.调谐的，已调谐的v.调音( tune的过去式和过去分词 )；调整；（给收音机、电视等）调谐；使协调

参考例句：

• The resort is tuned in to the tastes of young and old alike. 这个度假胜地适合各种口味，老少皆宜。
• The instruments should be tuned up before each performance. 每次演出开始前都应将乐器调好音。 来自《简明英汉词典》