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读写并高亮后的结果：
Listen to part of lecture in an astronomy class.
There's been a lot of talk recently about life on Mars, at the level of microorganisms anyway, mainly because of a few important discoveries and inventions.
For example, one major discovery was that at one point water was present on Mars. How do we know? Well, in 2004, an exploration robot discovered jarosite there.
Jarosite is a yellowish brown mineral with a crystalline structure that's also found on Earth. It contains iron, potassium, and hydroxide. The interesting thing is that on Earth at least it needs highly acidic water to form. So we've got water or had it at one point. And since most planetary scientists believe that water is essential to life, the presence of jarosite means that one prerequisite for life was once present on Mars.
But there's another thing about jarosite. One step in its formation on Earth involves microorganisms; they actually speed up the formation of jarosite dramatically. Now, theoretically it is possible for jarosite to form without the help of biological life forms. But we don't really know for sure if this happens 'cause... well, because every corner of Earth has some form of biological life.
But jarosite on Earth incorporates all kinds of of microorganisms into its crystalline structure. So it's possible that if the jarosite on Mars was also formed with the help of microorganisms, we might be able to detect remnants of them in the samples we find. And we have instruments now that will enable us to try to do this. For example, there's a new instrument called the microfabricated organic analyzer, or M.O.A.
The organic analyzer is an amazing tool. It will be able to collect soil samples and analyze them right there on Mars, pure, untouched samples. It will let us eliminate the risk we would take of contaminating the samples if they were brought back to Earth. And what they'll look for specifically in the soil is amino acids.
Amino acids, as you may know, are the building blocks of proteins. In fact, there are twenty standard amino acids involved in making proteins and lots more that aren't.
And here's the important thing. Amino acids are what we call handed. They can exist in two forms, which are mirror images of each other like hands, Right and left have the same number of fingers in the same order plus one thumb.
But right and left hand are not the same; they are mirror images. Well, like hands amino acids can be right or left-handed. And the twenty that make up the protein on Earth are all left-handed.
Now, one reason the M.O.A. , the organic analyzer is so impressive is that it tests not just for the presence of amino acids but also for the handedness of amino acids. If amino acids are found, it would be especially interesting if they show a prevalence of one type of handedness, either left, like amino acids on Earth, or right.
See, other physical processes in space, processes that don't involve living organisms, can create amino acids. But the ones synthesized through abiotic processes, which is to say not involving microorganisms, occur in equal numbers of right- and left-handed.
So, a prevalence of left-handed amino acids would indicate they were biological in orgin, which would be amazing! A prevalence of right-handed ones... well, that would be really amazing! Because the organisms that created them would be unlike anything we have on Earth, which produce only left-handed ones.
这堂天文学lecture由火星上是否存在生命的话题，延伸到了最近的一些重要发现和发明。比如发现火星上是有水的，原因是2004年一个探索机器人在那里发现了黄钾铁矾。黄钾铁矾，在地球上形成是需要强酸性的水，所以说它的存在意味着火星上生命存在的先决条件曾经存在过。
但是牵扯到黄钾铁矾，就进一步牵扯到微生物，它们大大加快了黄钾铁矾的形成。从理论上讲，黄钾铁矾是可能在没有任何生物体的帮助下形成的，但是我们不是很肯定是不是真的会发生，因为地球上的任意角落都包含了微生物的存在。
地球上的黄钾铁矾在它的晶体结构中包含了所有种类的微生物，那么，火星上的黄钾铁矾也是在微生物的帮助下形成的也是有可能的。我们也能在找到的Sample里面用MOA分析出来。
有一件很重要的事情，氨基酸是有手的，分左手和右手，地球上所有构成蛋白质的那20种氨基酸都是左手的。如果在火星上也能找到左手氨基酸的话，那预示着它们是起源生物的；如果右手氨基酸比较普遍，那也是重大发现，因为创造它们的生命体可能和我们地球上创造的左手氨基酸不一样。
不熟悉的单词：
- astronomy 天文学
- microorganisms 微生物
- jarosite 黄钾铁矾
- crystalline 结晶的
- iron 铁
- potassium 钾盐
- hydroxide 氢氧化物
- acidic 酸性的
- planetary 行星的
- essential 并不可少
- prerequisite 先决条件
- theoretically 理论上
- incorporate 包含
- remnants 残余物
- instruments 仪器
- microfabricated 超细加工
- organic 有机的
- microfabricated organic analyzer 微型有机分析仪
- soil 土壤
- eliminate 排除
- contaminating 污染
- amino 氨基
- amino acids 氨基酸
- blocks 块
- proteins 蛋白质
- involved 涉及
- impressive 令人印象深刻的
- presence 存在
- prevalence 流行;卓越
值得注意的表达方式：
- show a prevalence 盛行
- a prevalence of ...的流行