美国国家公共电台 NPR--Scientists believe they have found a crucial building block of life on an asteroid

Scientists believe they have found a crucial building block of life on an asteroid¹

Transcript²

It's an intriguing³ finding that suggests life as we know it may have been seeded by asteroids⁴ and meteors.

STEVE INSKEEP, HOST:

Scientists think they've found a building block of life, and they found it on an asteroid. A robotic spacecraft returned samples that could provide clues about the beginnings of life on Earth. NPR's Geoff Brumfiel reports.

GEOFF BRUMFIEL, BYLINE⁵: A few years ago, a Japanese spacecraft called Hayabusa2 paid a visit to an asteroid named Ryugu. It's a diamond-shaped chunk⁶ of rock about half a mile across. The little Hayabusa spacecraft popped down onto the asteroid surface, snatched a sample and flew back to Earth. Amy Williams is an astrobiologist at the University of Florida. She says that asteroids like this have a lot of organic molecules⁸ - not life, but chemical building blocks for life.

AMY WILLIAMS: It's always exciting to have sample return missions because when we can collect samples from where they're made, it actually removes all of the bias⁹ of a potential terrestrial contamination.

BRUMFIEL: When she says terrestrial contamination, she's talking about us - life on Earth, smearing¹⁰ our DNA¹¹ all over the place. One of the big goals is to figure out whether organic molecules from space started life on Earth. Maybe some asteroid impacts brought critical chemicals. Writing in the journal Nature Communications, a team of Japanese scientists now report that the asteroid Ryugu had something on it called uracil. Uracil is a nucleobase like the G's, A's, T's and C's that make up DNA, except uracil is found in RNA. And that's particularly interesting because some scientists suspect life started with RNA.

WILLIAMS: In some models for the evolution of life, there's the idea that RNA was the major genetic¹² information molecule⁷ before DNA.

BRUMFIEL: So did uracil arrive on an asteroid? And if it did, did it spark life?

WILLIAMS: If I knew that, then I would be accepting some kind of award.

BRUMFIEL: Researchers are hoping for more answers soon. NASA has its own asteroid sample return mission scheduled to land later this year.

Geoff Brumfiel, NPR News.

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

3 intriguing   

adj.有趣的；迷人的v.搞阴谋诡计(intrigue的现在分词)；激起…的好奇心

参考例句：

• These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
• It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》

4 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

5 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

6 chunk   

n.厚片，大块，相当大的部分（数量）

参考例句：

• They had to be careful of floating chunks of ice.他们必须当心大块浮冰。
• The company owns a chunk of farmland near Gatwick Airport.该公司拥有盖特威克机场周边的大片农田。

7 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

8 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

9 bias   

n.偏见，偏心，偏袒；vt.使有偏见

参考例句：

• They are accusing the teacher of political bias in his marking.他们在指控那名教师打分数有政治偏见。
• He had a bias toward the plan.他对这项计划有偏见。

10 smearing   

污点，拖尾效应

参考例句：

• The small boy spoilt the picture by smearing it with ink. 那孩子往画上抹墨水把画给毁了。
• Remove the screen carefully so as to avoid smearing the paste print. 小心的移开丝网，以避免它弄脏膏印。

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 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。