Nathalie Cabrol: How Mars might hold the secret to the origin of life

翻译人员: Yan Peng 校对人员: 杏儀 歐陽

Well, you know, sometimes

你们知道吗，

有时最重要的信息 会通过最细微的事物传达。

the most important things come in the smallest packages.

I am going to try to convince you, in the 15 minutes I have,

在接下来15分钟里， 我将很确定的告诉你们：

that microbes have a lot to say about questions such as,

微生物可以从很大程度上 解释这样的问题，比如，

"Are we alone?"

“我们是独一无二生命的吗？”

and they can tell us more about not only life in our solar system

微生物能告诉我们的还有很多， 不仅是关于我们太阳系以内的生物，

but also maybe beyond,

可能还包括以外的，

这就是为什么我正在地球上 最恶劣的环境中寻找它们的踪迹，

and this is why I am tracking them down in the most impossible places on Earth,

in extreme environments where conditions

那些极端的环境会

are really pushing them to the brink of survival.

把微生物推向生存危机的边缘。

Actually, sometimes me too, when I'm trying to follow them too close.

有时候试图追踪得太紧， 连我自己也会面临生命危险。

But here's the thing:

然而重点是：

We are the only advanced civilization in the solar system,

我们是太阳系里唯一的高级文明物种，

but that doesn't mean that there is no microbial life nearby.

但这并不意味着附近没有微生物生命。

In fact, the planets and moons you see here

事实上，大家看到的这些行星和卫星

could host life -- all of them -- and we know that,

我们确信，都可能孕育着生命，

and it's a strong possibility.

而且可能性还很高。

And if we were going to find life on those moons and planets,

如果我们能够在 那些行星和卫星上找到生命，

then we would answer questions such as,

那么我们就能回答这样的问题，比如，

are we alone in the solar system?

在太阳系里我们是唯一生物吗？

Where are we coming from?

我们是从哪里来的呢？

Do we have family in the neighborhood?

我们的邻居中有我们的同类吗？

Is there life beyond our solar system?

太阳系以外有没有生命呢？

And we can ask all those questions because there has been a revolution

我们之所以能够提出这些问题

in our understanding of what a habitable planet is,

是因为我们对于“可居住星球”的理解 有了革命性的发展，

and today, a habitable planet is a planet

“适居行星”如今的定义是

that has a zone where water can stay stable,

一个具有可储存稳定状态水地域的行星，

but to me this is a horizontal definition of habitability,

但是对我来说，这是 可居住性的横向定义，

because it involves a distance to a star,

因为这可以涉及到另一个星球，

but there is another dimension to habitability,

其实可居住性 还有另一个维度的定义，

and this is a vertical dimension.

一个纵向的维度。

Think of it as

把它想成

conditions in the subsurface of a planet where you are very far away from a sun,

某个行星次地表的环境， 在那里你离恒星很远，

but you still have water, energy, nutrients,

但你仍旧有水、能量、营养，

which for some of them means food,

对于其中一些生物来说，

and a protection.

这意味着食物和保护。

And when you look at the Earth,

当我们再观察地球，

very far away from any sunlight, deep in the ocean,

在远离阳光的深海里，

you have life thriving

你会找到欣欣向荣的生命，

and it uses only chemistry for life processes.

它们的生命过程只涉及到化学反应。

So when you think of it at that point, all walls collapse.

因此当你这样考虑， 所有的围墙都坍塌了。

You have no limitations, basically.

你基本上不受任何限制了。

And if you have been looking at the headlines lately,

如果你最近有看新闻头条，

then you will see that we have discovered a subsurface ocean

你就会了解到

我们在木卫二、木卫三、土卫二 和土卫六上发现了冰下海洋，

on Europa, on Ganymede, on Enceladus, on Titan,

and now we are finding a geyser and hot springs on Enceladus,

现在我们又在土卫二上 发现了间歇泉和温泉。

Our solar system is turning into a giant spa.

我们的太阳系正在变成 一个巨大的温泉浴场。

For anybody who has gone to a spa knows how much microbes like that, right?

去泡过温泉的人应该知道 里边能有多少微生物，对吧？

(Laughter)

（笑声）

So at that point, think also about Mars.

在这个前提下，再来想想火星。

There is no life possible at the surface of Mars today,

现在的火星表面不可能有生命，

but it might still be hiding underground.

但地下仍可能潜藏着生命。

So, we have been making progress in our understanding of habitability,

我们不仅在进一步理解宜居性，

but we also have been making progress in our understanding

我们也在进一步了解

of what the signatures of life are on Earth.

地球上有哪些生命的印记。

And you can have what we call organic molecules,

我们有所谓的"有机分子"，

and these are the bricks of life,

这些是生命大厦的建筑材料，

and you can have fossils,

我们有化石，

and you can minerals, biominerals,

还有矿物质、生物矿物质，

which is due to the reaction between bacteria and rocks,

生物矿物质是由细菌和 岩石发生反应所产生的，

and of course you can have gases in the atmosphere.

当然，我们还有大气中的气体。

And when you look at those tiny green algae

看看幻灯片右边

on the right of the slide here,

那些微小的绿藻，

they are the direct descendants of those who have been pumping oxygen

它们是十亿年前往地球大气中

a billion years ago in the atmosphere of the Earth.

输送氧气的生物的直系后裔。

When they did that, they poisoned 90 percent of the life

当时它们制造的氧气，

毒害了地球表面百分之九十的生命，

at the surface of the Earth,

but they are the reason why you are breathing this air today.

但却造就了现如今你们呼吸的这种空气。

But as much as our understanding grows of all of these things,

但是随着我们对所有这些事情的 认知不断增长，

there is one question we still cannot answer,

我们仍然有一个问题无法回答，

and this is, where are we coming from?

那就是：我们是从哪里来的？

And you know, it's getting worse,

事实上情况正在变糟，

because we won't be able to find the physical evidence

因为我们永远无法找到实物证据

of where we are coming from on this planet,

证明我们起源于这个星球上的何处，

and the reason being is that anything that is older than four billion years is gone.

原因是四十亿年前的所有事物都不在了。

All record is gone,

所有记录都消失了，

erased by plate tectonics and erosion.

被板块运动和侵蚀抹得一干二净。

This is what I call the Earth's biological horizon.

我把这个称为“地球的生物视野”。

Beyond this horizon we don't know where we are coming from.

超出了这个视界范围， 我们看不到我们的起源。

So is everything lost? Well, maybe not.

那么是否所有证据都丢失了呢？ 也许并没有。

And we might be able to find evidence of our own origin

我们也许会在最不可能的地方 找到我们的起源，

in the most unlikely place, and this place in Mars.

这个地方就是火星。

How is this possible?

这是如何做到的呢？

Well clearly at the beginning of the solar system,

我们知道，太阳系刚诞生的时候，

Mars and the Earth were bombarded by giant asteroids and comets,

火星和地球被巨大的 小行星和彗星撞击过，

and there were ejecta from these impacts all over the place.

这些强力撞击形成的 喷出物到处都是。

Earth and Mars kept throwing rocks at each other for a very long time.

地球和火星曾经很长一段时间 一直向对方丢岩石。

Pieces of rocks landed on the Earth.

一片片岩石落到地球上。

Pieces of the Earth landed on Mars.

一片片地球碎片落在火星上。

So clearly, those two planets may have been seeded by the same material.

很明显，这两个行星有可能 是由同种物质孕育形成的。

So yeah, maybe Granddady is sitting there on the surface and waiting for us.

所以是的，有可能老祖宗 正坐在火星表面等着我们呢。

But that also means that we can go to Mars and try to find traces of our own origin.

但这也意味着，我们可以在火星上 试试寻找人类起源的蛛丝马迹。

Mars may hold that secret for us.

火星有可能为我们保存了这个秘密。

This is why Mars is so special to us.

这就是为什么火星对我们如此重要。

But for that to happen,

但是寻找的前提是：

Mars needed to be habitable at the time when conditions were right.

火星在曾经条件适宜的时候 必须具备可居住性。

So was Mars habitable?

那么，火星曾经具有宜居性吗？

We have a number of missions telling us exactly the same thing today.

如今，一系列的研究行动 正告诉着我们同一个答案。

At the time when life appeared on the Earth,

当地球上出现生命的时候，

Mars did have an ocean, it had volcanoes, it had lakes,

火星确实有过海、火山、湖泊，

and it had deltas like the beautiful picture you see here.

还拥有过图中那样的美丽三角洲。

This picture was sent by the Curiosity rover only a few weeks ago.

这张照片是仅仅几周前 由好奇号发送回来的。

It shows the remnants of a delta, and this picture tells us something:

照片显示一个三角洲的残骸， 而且告诉我们：

water was abundant

水资源曾经很丰富，

and stayed founting at the surface for a very long time.

并且很长一段时间 在地表保持喷涌状态。

This is good news for life.

这对于生命是个好消息。

Life chemistry takes a long time to actually happen.

生命化学要用很长时间才能真正发生。

So this is extremely good news,

所以这是非常好的消息，

but does that mean that if we go there, life will be easy to find on Mars?

但是这是否表示如果我们去火星， 就能轻松找到生命呢？

Not necessarily.

并不见得。

Here's what happened:

事情是这样的：

At the time when life exploded at the surface of the Earth,

当生命在地球表面爆发时，

then everything went south for Mars,

火星上的一切是背道而驰的，

literally.

真的是完全相反。

The atmosphere was stripped away by solar winds,

大气被太阳风一揭而散，

Mars lost its magnetosphere,

火星失去了它的磁层，

and then cosmic rays and U.V. bombarded the surface

接着宇宙射线和紫外线冲击了地表

and water escaped to space and went underground.

然后水资源逃离到了空间中和地层下。

So if we want to be able to understand,

所以如果我们想要了解，

if we want to be able to find those traces of the signatures of life

如果我们想要在火星表面 找到那些生命印记的蛛丝马迹，

at the surface of Mars, if they are there,

如果它们在那里的话，

we need to understand what was the impact of each of these events

我们需要了解这每一个事件

on the preservation of its record.

对于火星保存的记录有过怎样的影响。

Only then will we be able to know where those signatures are hiding,

只有这样我们才能知道 那些生命的印记藏在哪里了，

and only then will we be able to send our rover to the right places

只有到那时我们才能 将火星车发送到正确的地点，

where we can sample those rocks that may be telling us something

在那里提取那些 可能蕴含重要信息的岩石，

really important about who we are,

并借此解开关于我们是谁的秘密，

or, if not, maybe telling us that somewhere, independently,

不然，或许它能告诉我们在某个地方

life has appeared on another planet.

生命曾在另一个星球上独立地出现过。

So to do that, it's easy.

那么为了做到这件事，其实很简单。

You only need to go back 3.5 billion years ago

你仅需要回到35亿年前

in the past of a planet.

回到一个行星的过去。

We just need a time machine.

我们只需要一个时光机。

Easy, right?

很简单，对吧？

Well, actually, it is.

事实上的确很简单。

Look around you -- that's planet Earth.

看看你的周围——答案是地球。

This is our time machine.

这就是我们的时光机。

Geologists are using it to go back in the past of our own planet.

地质学家正在利用这个时光机 返回我们星球的过去。

I am using it a little bit differently.

我所使用的方式稍有不同。

I use planet Earth to go in very extreme environments

我用地球去到非常极端的环境，

where conditions were similar to those of Mars

过去在气候变化的时候

at the time when the climate changed,

那里的环境条件和火星上的非常相似，

and there I'm trying to understand what happened.

在那里，我正试图理解 曾经发生过什么。

What are the signatures of life?

有什么生命的印记？

What is left? How are we going to find it?

留下了什么？我们要如何找到它？

So for one moment now I'm going to take you with me

那么现在暂且由我带领你们和我一起

on a trip into that time machine.

进行一次时光机旅行。

And now, what you see here, we are at 4,500 meters in the Andes,

现在大家看到的是， 我们在4500米的安第斯山脉上，

but in fact we are less than a billion years after the Earth and Mars formed.

但事实上我们处在地球和火星 形成后不到十亿年的时间。

The Earth and Mars will have looked pretty much exactly like that --

地球和火星应该看起来 差不多就是这个样子：

volcanoes everywhere, evaporating lakes everywhere,

到处都是火山， 到处都是热气腾腾的湖泊，

minerals, hot springs,

矿物质，温泉，

and then you see those mounds on the shore of those lakes?

你们看到那些湖边的土丘了吗？

Those are built by the descendants of the first organisms

那些是由首个微生物的后代建造的，

that gave us the first fossil on Earth.

它们给了我们地球上的第一枚化石。

But if we want to understand what's going on, we need to go a little further.

但是如果我们要了解正在发生什么， 我们需要前进得更远一些。

And the other thing about those sites

和火星三十五亿年前很像的一点是，

is that exactly like on Mars three and a half billion years ago,

the climate is changing very fast, and water and ice are disappearing.

那些地方的气候正迅速变化，

水和冰正在消融。

But we need to go back to that time when everything changed on Mars,

但是我们需要回到 火星上一切都已变迁的时候，

and to do that, we need to go higher.

为此，我们需要向更高处前进。

Why is that?

为什么呢？

Because when you go higher,

因为当你到了更高处，

the atmosphere is getting thinner, it's getting more unstable,

大气会变得更稀薄，更不稳定，

the temperature is getting cooler, and you have a lot more U.V. radiation.

温度会降得更低， 你会得到更多的紫外线辐射。

Basically,

基本上，

you are getting to those conditions on Mars when everything changed.

你会更接近火星上 一切都改变时的环境条件。

So I was not promising anything about a leisurely trip on the time machine.

我没有保证这次时光旅行 会是一个安逸的旅行。

You are not going to be sitting in that time machine.

在这个时光机里，你不会光坐着。

You have to haul 1,000 pounds of equipment to the summit

你要把1000磅的设备 拖到安第斯山脉上

of this 20,000-foot volcano in the Andes here.

20000英尺高的火山山顶。

That's about 6,000 meters.

差不多有6000米。

And you also have to sleep on 42-degree slopes

而且你要在42度的斜坡上睡觉，

and really hope that there won't be any earthquake that night.

并且希望那晚不要发生任何地震。

But when we get to the summit, we actually find the lake we came for.

但是当我们到达峰顶， 我们找到了我们此行想要寻找的湖泊。

At this altitude, this lake is experiencing exactly the same conditions

在这个高度上，这一湖泊正经历着

跟三十五亿年前火星上 一模一样的环境条件。

as those on Mars three and a half billion years ago.

And now we have to change our voyage

现在我们要改变路线，

into an inner voyage inside that lake,

开始一段湖内的旅程，

and to do that, we have to remove our mountain gear

为此，我们要脱掉登山用具，

and actually don suits and go for it.

穿上潜水服，然后就下水吧。

But at the time we enter that lake, at the very moment we enter that lake,

但是，当我们进入湖中的时候， 就在我们踏入湖里的那一刻，

we are stepping back

我们正在返回到

three and a half billion years in the past of another planet,

三十五亿年前的另一个星球上，

and then we are going to get the answer came for.

接着我们就要找到 我们此行要找的答案。

Life is everywhere, absolutely everywhere.

到处都是生命，完完全全到处都是。

Everything you see in this picture is a living organism.

你们在这个照片里看到的一切 都是活生生的微生物。

Maybe not so the diver, but everything else.

也许这个潜水员并不是， 但所有其他都是。

But this picture is very deceiving.

但这个照片很有欺骗性。

Life is abundant in those lakes,

生命在那些湖泊里十分丰富，

but like in many places on Earth right now and due to climate change,

但是正如现在地球上很多地方， 由于气候变化

there is a huge loss in biodiversity.

生物多样性遭受了巨大损失。

In the samples that we took back home,

在我们带回去的那些样本里，

36 percent of the bacteria in those lakes were composed of three species,

那些湖里36%的细菌 都是由三种物种组成的，

and those three species are the ones that have survived so far.

并且它们是迄今为止 存活下来的仅有的物种。

Here's another lake, right next to the first one.

这是另一个湖，就在第一个的旁边。

The red color you see here is not due to minerals.

大家所看到的这个红色 并不是由矿物质产生的，

It's actually due to the presence of a tiny algae.

而是由里面的某种微小藻类而产生。

In this region, the U.V. radiation is really nasty.

在这个区域，紫外线放射非常严重。

Anywhere on Earth, 11 is considered to be extreme.

地球上的任何地方， 紫外线指数达到11都意味着极端数值。

During U.V. storms there, the U.V. Index reaches 43.

在那里的紫外线风暴中， 紫外线指数达到了43。

SPF 30 is not going to do anything to you over there,

防晒指数30在那里 起不到任何作用，

and the water is so transparent in those lakes

并且那些湖泊里的水清澈到

that the algae has nowhere to hide, really,

水藻完全没有地方藏身，

and so they are developing their own sunscreen,

所以它们形成了自己的防晒层，

and this is the red color you see.

也就是你所看到的这个红色。

But they can adapt only so far,

但它们只能适应到这个程度，

and then when all the water is gone from the surface,

当所有的水都从地表消失了之后，

microbes have only one solution left:

微生物就只能通过一种 途径继续生存下去：

They go underground.

到地下去。

And those microbes, the rocks you see in that slide here,

你们在图上里看到的这些岩石，

well, they are actually living inside rocks

其实那些微生物正生活在岩石里，

and they are using the protection of the translucence of the rocks

而且它们正利用着 岩石的半透明性对它们的保护

to get the good part of the U.V.

来合理的利用紫外线，

and discard the part that could actually damage their DNA.

并摒弃紫外线可能会 破坏它们DNA的部分。

And this is why we are taking our rover

这就是为什么我们训练火星车

to train them to search for life on Mars in these areas,

在这些地方探索火星生命，

because if there was life on Mars three and a half billion years ago,

因为如果三十五亿年前 火星上曾经有生命，

it had to use the same strategy to actually protect itself.

它们必然要用同样的方法来保护自己。

Now, it is pretty obvious

现在，非常明显地，

that going to extreme environments is helping us very much

去极端环境可以很大程度上帮助我们

for the exploration of Mars and to prepare missions.

进行火星的探测和任务准备。

So far, it has helped us to understand the geology of Mars.

到目前为止，这帮助我们 了解了火星的地质情况。

It has helped to understand the past climate of Mars and its evolution,

帮助我们了解到 火星过去的气候和气候变迁，

but also its habitability potential.

也帮助我们了解了 火星的宜居性潜能。

Our most recent rover on Mars has discovered traces of organics.

我们最近的一个火星探测车 发现了有机物的痕迹。

Yeah, there are organics at the surface of Mars.

是的，火星地表有有机物。

And it also discovered traces of methane.

它还发现了甲烷的印记。

And we don't know yet if the methane in question

我们还不知道那里的甲烷

is really from geology or biology.

是在地质过程中生成的 还是通过生物过程产生的。

Regardless, what we know is that because of the discovery,

不论如何，我们知道因为这个发现，

the hypothesis that there is still life present on Mars today

现如今火星上还有生命存在的假设

remains a viable one.

仍然是有望能被证实。

So by now, I think I have convinced you that Mars is very special to us,

所以现在，我想我已经让你们相信了 火星对我们有很特殊的意义，

but it would be a mistake to think that Mars is the only place

但是把火星看成太阳系中

唯一可能找到潜在微生物生命的地方 是一个错误的想法。

in the solar system that is interesting to find potential microbial life.

And the reason is because Mars and the Earth

原因是虽然火星和地球

could have a common root to their tree of life,

在生命树上可能拥有相同的根基，

but when you go beyond Mars, it's not that easy.

但是谈到火星以外的星球， 就并不是那么简单了。

Celestial mechanics is not making it so easy

天体力学上星球间物质的交换

for an exchange of material between planets,

并非那样容易，

and so if we were to discover life on those planets,

所以如果我们能 在那些星球上找到生命，

it would be different from us.

那里的生命将和我们不同。

It would be a different type of life.

它们会是不同种类的生命。

But in the end, it might be just us,

但是到最后，也有可能就只有我们，

it might be us and Mars,

或者只有我们和火星，

or it can be many trees of life in the solar system.

或者也可能太阳系里有很多生命树。

I don't know the answer yet, but I can tell you something:

我还不知道答案， 但是我能告诉大家的是：

No matter what the result is, no matter what that magic number is,

不论答案如何， 不论那个神奇的数字是几，

it is going to give us a standard

这将会给我们带来一个标准，

by which we are going to be able to measure the life potential,

我们将可以利用这个标准 衡量我们太阳系以外的

abundance and diversity beyond our own solar system.

生命的潜能、丰富性和多样性。

And this can be achieved by our generation.

这是可以在我们这一代实现的。

This can be our legacy, but only if we dare to explore.

这可以成为我们的遗赠， 但前提是我们敢于探索。

Now, finally,

现在，最后，

if somebody tells you that looking for alien microbes is not cool

如果有人告诉你 寻找外星微生物不是那么酷，

because you cannot have a philosophical conversation with them,

因为你不能和它们 进行一场有意义的对话，

let me show you why and how you can tell them they're wrong.

我来告诉你，为什么你能 以及如何能告诉他们，这是错的。

Well, organic material is going to tell you

有机物质会告诉你

about environment, about complexity and about diversity.

有关环境，复杂度 以及多样性的信息。

DNA, or any information carrier, is going to tell you about adaptation,

DNA，或者任何其他信息载体， 会告诉你有关适应性，

about evolution, about survival, about planetary changes

进化，生存，行星变迁，

and about the transfer of information.

以及信息传递的内容。

All together, they are telling us

所有的加在一起，它们能告诉我们

what started as a microbial pathway,

什么是微生物途径的开端，

and why what started as a microbial pathway

以及为什么有时候一些 微生物途径的开端

sometimes ends up as a civilization

会最终形成一个文明，

or sometimes ends up as a dead end.

另一些时候则会最终走到尽头。

Look at the solar system, and look at the Earth.

看看太阳系，再看看地球。

On Earth, there are many intelligent species,

地球上有很多智慧的物种，

but only one has achieved technology.

但只有一个物种实现了科技发展。

Right here in the journey of our own solar system,

就在我们自己太阳系的旅程里，

there is a very, very powerful message

有一个非常、非常强有力的信息：

that says here's how we should look for alien life, small and big.

这就是我们应当如何 寻找外星生命，无论生命大小。

So yeah, microbes are talking and we are listening,

微生物在叙述，我们在聆听，

and they are taking us,

并且它们正把我们带领到

one planet at a time and one moon at a time,

一个个行星，一个个卫星，

towards their big brothers out there.

带到它们外面的那些大哥哥那里。

And they are telling us about diversity,

它们在告诉我们多样性的信息，

they are telling us about abundance of life,

它们在告诉我们生命的丰富性，

and they are telling us how this life has survived thus far

它们在告诉我们 生命是如何存活至今

to reach civilization,

来取得文明、

intelligence, technology and, indeed, philosophy.

智能、科技，甚至是，哲学。

Thank you.

谢谢大家。

(Applause)

（鼓掌）