Is there life beyond Earth in our solar system? Wow, what a powerful question.
在地球以外，太阳系里还有生命吗？哇，多么掷地有声的问题！
You know, as a scientist -- planetary scientist -- we really didn't take that very seriously until recently.
作为一名科学家--行星科学家--我们很久以来都没有认真的考虑过这个问题。
Carl Sagan always said, "It takes extraordinary evidence for extraordinary claims."
卡尔·萨根常说，“非凡的断言需要有非凡的证据”。
And the claims of having life beyond Earth need to be definitive,
地球之外有生命的断言必须是明确的，
they need to be loud and they need to be everywhere for us to be able to believe it.
必须是响亮的，还需要证据充分，这样我们才会相信。
So how do we make this journey? What we decided to do is first look for those ingredients for life.
那么，我们要如何开始这段旅行呢？我们决定首先去寻找生命的基本要素。
The ingredients of life are: liquid water -- we have to have a solvent, can't be ice, has to be liquid.
生命的基本要素是：液态水--我们需要溶剂，不能是冰，必须是液态的。
We also have to have energy. We also have to have organic material -- things that make us up, but also things that we need to consume.
我们还需要能量。有机物质也是必不可少的--这些都是组成我们的生命体，以及供我们消耗的东西。
So we have to have these elements in environments for long periods of time for us to be able to be confident that life,
环境中必须长期存在这些元素，才会让我们相信：
in that moment when it starts, can spark and then grow and evolve.
生命在诞生的那一刻，能够迸发出火花，并且能够成长和演变。
Well, I have to tell you that early in my career, when we looked at those three elements,
我必须坦白，在我职业生涯早期，当我们研究这三个要素时，
I didn't believe that they were beyond Earth in any length of time and for any real quantity.
我并不相信它们能在地球之外存在足够长的时间，或达到足够的规模。
Why? We look at the inner planets. Venus is way too hot -- it's got no water. Mars -- dry and arid. It's got no water.
为什么？让我们看看太阳系的行星：金星太热--所以没水。火星--干旱贫瘠，也不会有水。
And beyond Mars, the water in the solar system is all frozen.
在太阳系中比火星更远的地方，水全部冻成了固态的冰。
But recent observations have changed all that.
但是最近的观测改变了这一切。
It's now turning our attention to the right places for us to take a deeper look and really start to answer our life question.
现在它把我们的注意力带到了正确的地方，让我们去进一步观察，并且真正开始回答生命的问题。
So when we look out into the solar system, where are the possibilities?
那么，当我们探索太阳系时，生命可能存在于哪里呢？
We're concentrating our attention on four locations.
我们将注意力集中在以下四处：
The planet Mars and then three moons of the outer planets: Titan, Europa and small Enceladus.
火星和更远的三个卫星：泰坦（土卫六），欧罗巴（木卫二）和小小的恩赛拉多斯（土卫二）。
So what about Mars? Let's go through the evidence.
火星到底是什么情况呢？让我们看看证据。
Well, Mars we thought was initially moon-like: full of craters, arid and a dead world.
起初我们以为火星像月亮一样：布满陨石坑，荒凉，没有生命。
And so about 15 years ago, we started a series of missions to go to Mars and see if water existed on Mars in its past that changed its geology.
大约在15年前，我们开始了一系列登陆火星的任务，去查看那里过去是否有水存在过，还因此改变了它的地质。
We ought to be able to notice that. And indeed we started to be surprised right away.
我们应该可以观察得到。而实际上，我们一开始就很惊讶。
Our higher resolution images show deltas and river valleys and gulleys that were there in the past.
高清图片显示，那里有三角洲，河谷和沟渠，它们过去都曾存在过。
And in fact, Curiosity -- which has been roving on the surface now for about three years
事实上，好奇号探测车在火星表面上漫游已经有三年了
has really shown us that it's sitting in an ancient river bed, where water flowed rapidly.
我们看到它停在一条古老的河床上，那里曾有过湍急的水流。
And not for a little while, perhaps hundreds of millions of years.
时间还不短，可能曾持续过数亿年之久。
And if everything was there, including organics, perhaps life had started.
如果所有要素都存在，包括有机物在内，也许生命曾在那里诞生过。
Curiosity has also drilled in that red soil and brought up other material.
好奇号还在红土上打了洞，并且发现了其他物质。
And we were really excited when we saw that. Because it wasn't red Mars, it was gray material, it's gray Mars.
我们看到后非常兴奋，因为那不是红色的物质，而是灰色的，火星地表下面是灰色的。
We brought it into the rover, we tasted it, and guess what?
我们把挖出来的东西带回探测车，仔细地分析了它，你们猜怎么着？
We tasted organics -- carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur -- they were all there.
我们分析出了有机物--碳，氢，氧，氮，磷，硫--统统都有。
So Mars in its past, with a lot of water, perhaps plenty of time, could have had life, could have had that spark, could have grown.
所以过去的火星曾有很多的水，也许存在过很长时间，可能有过生命，可能有过生命的火花，还可能繁衍过一段时间。
And is that life still there? We don't know that.
那时候的生命还在么？我们不知道。
But a few years ago we started to look at a number of craters.
但是几年前，我们开始观察一些陨石坑。
During the summer, dark lines would appear down the sides of these craters.
在夏季，陨石坑的边沿会出现深色的线条。
The more we looked, the more craters we saw, the more of these features. We now know more than a dozen of them.
随着我们观察得越多，看到的陨石坑越多，这样的特征也越多。现在已知的已经超过十二个了。
A few months ago the fairy tale came true.
几个月前，童话故事成真了！

We announced to the world that we know what these streaks are. It's liquid water.
我们向世界宣布，我们已经知道这些条纹是什么了。是液态水。
These craters are weeping during the summer. Liquid water is flowing down these craters.
这些陨石坑在夏天浸出水分。这些液态水顺着陨石坑向下流。
So what are we going to do now -- now that we see the water?
我们接下来要做什么--在发现了液态水之后？
Well, it tells us that Mars has all the ingredients necessary for life.
这说明火星拥有生命的所有必需成分。
In its past it had perhaps two-thirds of its northern hemisphere -- there was an ocean.
在过去，可能它的北半球有三分之二都曾是海洋。
It has weeping water right now. Liquid water on its surface. It has organics. It has all the right conditions.
现在它有冒出的水流。星球表面有液态水。它有有机物。它有一切合适（孕育生命）的条件。
So what are we going to do next? We're going to launch a series of missions to begin that search for life on Mars.
那么我们接下来要做什么呢？我们将开展一系列任务开始寻找火星上的生命。
And now it's more appealing than ever before.
现在行动要比以往任何时候都更有吸引力。
As we move out into the solar system, here's the tiny moon Enceladus.
在离地球更远的太阳系里，有一个小小的土卫二。
This is not in what we call the traditional habitable zone, this area around the sun.
它不在我们以往公认的宜居区域内，也就是靠近太阳的区域。
This is much further out. This object should be ice over a silicate core.
这里离太阳很远。这个星球应该像个被冰层覆盖的硅酸盐核心。
But what did we find? Cassini was there since 2006, and after a couple years looked back after it flew by Enceladus and surprised us all.
但我们找到了什么？自2006年起，卡西尼太空船就在那里，在飞过土卫二的几年后，再回过头看，我们都大吃一惊。
Enceladus is blasting sheets of water out into the solar system and sloshing back down onto the moon.
土卫二在向太阳系喷出一片片的水，再回落到它的表面。
What a fabulous environment. Cassini just a few months ago also flew through the plume, and it measured silicate particles.
多么美妙的环境啊。卡西尼太空船几个月前又从这些飞溅的水流中穿过，它检测到了硅酸盐颗粒。
Where does the silica come from? It must come from the ocean floor.
这些硅从哪来的？它肯定是从海底来的。
The tidal energy is generated by Saturn, pulling and squeezing this moon -- is melting that ice, creating an ocean.
土星产生的潮汐动能拉扯，挤压着这个星球--正融化那里的冰，形成着海洋。
But it's also doing that to the core.
这潮汐能同样拉扯挤压着硅酸盐核心。
Now, the only thing that we can think of that does that here on Earth as an analogy ... are hydrothermal vents.
我们唯一能想到地球上类似的现象是--深海热泉。
Hydrothermal vents deep in our ocean were discovered in 1977.
深海热泉在1977年的时候在海洋深处被发现。
Oceanographers were completely surprised. And now there are thousands of these below the ocean.
海洋学家们对此非常惊讶。如今在海洋之下有成千上万这样的深海热泉。
What do we find? The oceanographers, when they go and look at these hydrothermal vents,
我们找到了什么？当海洋学家们研究这些深海热泉时，
they're teeming with life, regardless of whether the water is acidic or alkaline -- doesn't matter.
发现那里有富饶的生命，不管水是酸性的还是碱性的--这不重要。
So hydrothermal vents are a fabulous abode for life here on Earth.
地球上的深海热泉是生命的绝佳住所。
So what about Enceladus? Well, we believe because it has water and has had it for a significant period of time,
那么土卫二呢？我们相信因为它有水，并且在相当长的一段时间里拥有水，
and we believe it has hydrothermal vents with perhaps the right organic material, it is a place where life could exist.
加上我们认为它有深海热泉，以及适合的有机物质。那是一个生命可能存在的地方。
And not just microbial -- maybe more complex because it's had time to evolve.
并且不仅仅是微生物--可能存在更复杂的生命，因为它有足够的时间去进化。
Another moon, very similar, is Europa. Galileo visited Jupiter's system in 1996 and made fabulous observations of Europa.
另一个非常相似的卫星，木卫二。伽利略号在1996年时探访了木星系统，对木卫二进行了详细的观察。
Europa, we also know, has an under-the-ice crust ocean.
我们知道木卫二拥有存在于冰层下的海洋。
Galileo mission told us that, but we never saw any plumes. But we didn't look for them.
伽利略号告诉了我们这些，但我们从未看到过任何的片状水。因为我们从未找寻过它们。
Hubble, just a couple years ago, observing Europa, saw plumes of water spraying from the cracks in the southern hemisphere, just exactly like Enceladus.
哈勃望远镜，就在几年前观察木卫二时，看到了片状水，它们从南半球的裂缝中喷洒出来，就跟土卫二一模一样。
These moons, which are not in what we call a traditional habitable zone, that are out in the solar system, have liquid water.
这些卫星，不在我们称作传统宜居地的区域，而在太阳系更远的地方，却拥有着液态水。
And if there are organics there, there may be life.
如果那里有有机物的话，那里就可能有生命。
This is a fabulous set of discoveries because these moons have been in this environment like that for billions of years.
这是一系列绝佳的发现，因为这些卫星已经在这样的环境中存在了数十亿年。
Life started here on Earth, we believe, after about the first 500 million, and look where we are. These moons are fabulous moons.
我们相信地球上的生命开始于地球形成5亿年之后，看看现在的我们（进化的程度）。这些卫星让人难以置信。
Another moon that we're looking at is Titan. Titan is a huge moon of Saturn.
我们在研究的另一个卫星是土卫六。土卫六是土星的一个非常大的卫星。
It perhaps is much larger than the planet Mercury. It has an extensive atmosphere.
它可能比水星还要大很多。它有着广阔的大气层。
It's so extensive -- and it's mostly nitrogen with a little methane and ethane -- that you have to peer through it with radar.
非常的广阔--主要成分是氮气，还有一点点甲烷和乙烷--所以你需要用雷达来观测它。
And on the surface, Cassini has found liquid.
在它的表面，卡西尼号发现了液态水。
We see lakes ... actually almost the size of our Black Sea in some places.
我们看到了湖泊--实际上，某些地方的湖几乎跟我们的黑海一样大。
And this area is not liquid water; it's methane.
然而这块地方并不是液态水；它实际上是甲烷。
If there's any place in the solar system where life is not like us,
如果在太阳系里存在这样一个地方，那里的生命与我们不同，
where the substitute of water is another solvent -- and it could be methane -- it could be Titan.
那里水的代替物是另一种溶剂--可以是甲烷--那个地方就可以是土卫六。
Well, is there life beyond Earth in the solar system? We don't know yet, but we're hot on the pursuit.
回到这个问题：在地球以外，在太阳系中有生命么？我们还不知道，但我们正在努力寻求答案。
The data that we're receiving is really exciting and telling us -- forcing us to think about this in new and exciting ways.
我们现在接收到的信息非常让人激动，它告诉我们--并迫使我们以新的、令人激动的方式去思考这个问题。
I believe we're on the right track. That in the next 10 years, we will answer that question.
我相信我们正朝着正确的方向努力。在接下来的10年内，我们将能够回答这个问题。
And if we answer it, and it's positive, then life is everywhere in the solar system.
如果我们做出了解答，并且结果是积极的，那么太阳系中的生命将会无所不在。
Just think about that. We may not be alone. Thank you.
想想看吧。我们也许并不孤单。谢谢。