宇宙（2007）

The Universe S01E06

Part 3 April 22, 2021, 8:11 p.m.

向大气中喷发了大量水蒸气
When the Earth cooled,volcanic steam condensed into rain
在地球降温的过程中结成雨水
and thereby suppliedthe planet with water.
于是向地面注入了大量的水
But where did the steamy wateremitted from volcanoes come from?
但是,火山的水源来自何方?
Volcanoes basically recycle materialfrom melted rock
火山运动循环着许多物质
in the mantle of the Earth.
地表的任何覆盖物
Including water.
包括水
But that's not really new water
当然这不是凭空创造的水来自于早期海洋
in the sense that it wasthere before in the oceans
and is coming outagain for a second time.
已经循环了许多次了
NASA's seniorscientist, Michael Mumma,
NASA 科学家 Michael Mumma
says our planet's watercame from space.
认为地球上的水
来自太空
Comets, which are made upof frozen gases,
一些由冰组成的彗星
could have showered Earthwith water
给地球来了一场淋浴
during the relentless impactsof its infancy.
在地球形成之初就不断发生着
The deliver of water froman icy body
这些小冰体提供的水量
depends very critically onhow large the particle is.
取决于他们的大小
The smaller bodies that came in wouldbreak up high in the atmosphere.
较小的个体在大气层外部就蒸发了
The other bodies delivered theirmaterial to the surface of the Earth,
其他的才能把他们的物质留在地表
and they can actually vaporizethat material
他们自身蒸发后
that becomes the water on Earth.
成为地球上的水
Mumma is trying to determineif cometary water
Mumma 试图证实水是否是来自彗星
is made up of the same ingredientsas our planet's water.
彗星的水组成成分应该跟地球一样
We know the Earth's oceans containa mixture of normal water,
我们知道,海洋中拥有地球上水的混合物
H2O,
水(氧化氢)
and heavy water, HDO,
与重水(氧化氘)
which includes deuterium,
含有氘
a form of hydrogen that is twiceas heavy as normal hydrogen.
一种氢的同位素,为氢质量的两倍
But comets are difficultto study.
但是研究彗星十分困难
Few pass near our planet
它们极少靠近地球
because most orbit in theouter solar system.
绝大部分都在太阳系外部
But in 1986, Europe's Giotto spacecrafthad a close encounter with Comet Halley,
不过在1986年,欧洲空间局发射的探测器Giotto
非常近的访问了一个彗星
also known as Halley's Comet,
著名的哈雷彗星
which was 38 million miles from Earth.
距离地球3800万英里
One of the ways weanalyze samples
一个分♥析♥样本的方法
is to fly mass spectrometers
使用光谱分♥析♥仪
through cometary debris that's comingoff the comet when it's active.
分♥析♥透过彗星的光谱结构
And we can measure the gasesvery accurately in this way.
用这种方法精确地测量气体
This was donefor Comet Halley.
来自于哈雷彗星
Comet Halley's water issimilar to that on Earth.
哈雷彗星的水相似于地球
However, the other cometsanalyzed so far,
但是,目前分♥析♥的其他彗星的水
have twice the amount of HDO,or heavy water, that's in our oceans.
重水比例是地球水的两倍
We know now, by looking atother compounds in comets,
我们也开始观察彗星的其他化合物
that they're not all the same.
并不都相同
So we don't knowwhether Comet Halley
因此我们不知道哈雷彗星是否
was in fact representativeof all comets.
是最有代表的彗星
Most comets studiedthus far
我们目前研究的彗星
have come from the Kuiper Belt,located in the outer solar system.
多处于古比皮带位于太阳系外部
So, they probably didn'thelp form planet Earth.
这些彗星也许跟地球形成没有联♥系♥
But the Gemini NorthTelescope, in Hawaii,
但是通过在夏威夷的 Gemini 望远镜
recently discovered cometsin an unlikely place.
最近发现了某些彗星存在于一个不寻常之处
The Asteroid Beltlocated between Mars and Jupiter.
这就是火星和木星间的小行星带
These warmer ice-bearing bodiesmay have the same water as Earth,
这些相对温暖的彗星
也许拥有着与地球一样的水
because they were all formed in the innersolar system, which is closer to the Sun.
它们在太阳系内部运转
更靠近太阳
What's more, startlingnew evidence suggests
令人惊异的更多证据表明
that these unusual comets may notonly have delivered water to Earth,
这些不寻常的彗星不但可能给地球带来了水
they also may haveseeded our planet
甚至在地球上播种
with the building blocks of life.
带来那些基本生命单元
The origin of life.
生命的起源
It remains one of the most puzzling andcontroversial questions about our Planet.
始终是地球的一个迷
One thing is certain:3.9 billion years ago,
可以确定的是:39亿年前
humans would have lastedfor only a brief moment.
相比之下人类历史只是非常短的一段时间
The Earth's atmosphere consisted ofcarbon dioxide, water vapour,
大气含有大量二氧化碳,水蒸气
a little nitrogen,but no oxygen.
以及少量氮气,却没有氧
Yet, could primitive life have enduredin such an environment?
但是原始生命如何才能在这样环境下生存?
We have no firm evidence that therewas life 4.3 billion years ago,
我们没有确切的证明
约40亿年前的环境能产生生命
but we think now thatthe conditions were possible.
现在,我们相信这些都是可能的
The oldest fossils on Earth
一些地球上最古老的化石
only date back 3.7 to 3.9billion years ago.
形成于大约37到39亿年前
Some believe that theseremains once evolved
一些人认为这些最原始的生命
in ancient ponds or lakes.
在那些古老的湖泊中进化出来的
There, atmosphericchemicals and energy
这里大气中的化合物在能量作用下
formed a primordial soupof amino acids,
形成了含有一些基本氨基酸的汤
the essential elements of life.
生命的基本材料
But, could the buildingblocks of life
但是,万一这些原始生命
have come from somewhere else?
来自于别处?
Perhaps from anextraterrestrial object?
也许是天外来物?
Meteorites contain organic materials,including amino acids.
包括各种氨基酸的有机物
They were formed somehow in theearlier solar system.
因某些原因形成于太阳系某处
So there is this delivery of organicmaterial from space.
然后,这些有机物从太空中来到地球
But, if asteroids and cometsgave the building blocks of life
但是,如果小行星和彗星
携带基本生命物质
a space shuttle rideto Earth,
空间旅行,来到地球
how did they survive the highvelocity impact?
如何在高速撞击中存活
Back at NASA's Amesresearch facility,
回到 NASA 埃姆斯研究中心
Pete Schultz and Seiji Sugitaare conducting another
Pete Schultz 和 Seiji Sugita正进行着一项
cutting-edge experimentusing the VGR.
先进的实验依然使用VGR
They hope to one day confirmthat meteorites and comets
他们希望用1天的时间确认那些流行和彗星
could have delivered life's essentialingredients to Earth.
能够把基本生命物质带到地球上来
One of the things we are trying tolook at, what is the survival*
其中一点,我们观测其如何生存
of some of these building blocks?Can they be delivered to the earth
这些来到地球的物质,
so they would help seed a planet
播种地球
so the conditions for lifecould begin to exist?
创造了生命起源的条件
Comets and asteroidsprobably brought
彗星和小行星可能带来
essential ingredients for originof life to the surface of the Earth.
原始生命的基本物质
来到地球表面
Their impact probably madethe surface environment
撞击创造的环境
much more favourable for life.
更有利于生命
Their experimentsshow that meteorites
他们的实验显示这些流星
delivered primitive carboncompounds to early Earth.
给早期地球带来了这些基本的碳化合物
Some of these compoundsmay have produced
其中一些
the building blocks necessary for life.
是生命形成的基本元素
But more research is needed.
但是还需要更多的研究
So this is coming through the atmosphere,burning up as we go.
这些,穿过大气时,产生了燃烧
Still, many scientists agreethe first life forms
目前,多数科学家一致认为生命的最初形式
were single-cell organismsthat lived in the oceans.
单细胞生命体都诞生于早期海洋中
And today, biologistsare digging up
今天,生物学家们找到了
the descendants of ourearliest known ancestors
我们这些最初的祖先的后代
in some of the mostuninhabitable places on Earth.
存在于地球上一些最不适宜生存的地方
If you have a big Cadillac todayas modern life,
把一辆凯迪拉克比作现代生命
ancient lifewas more like a bicycle.
远古生命就像一辆自行车
There are no remains of theseorganisms other than their chemistry,
除了一些化合物,它们没有留下其他任何遗迹
and I think it's importantto keep in mind
在我看来非常重要的是
that for the first 2 billion yearsof this planet's living history,
地球生命的最初20亿年
it was all microbial.
都是微生物时期
Professor Ken Nealson isa bona fide microbe hunter.
Ken Nealson 教授是一个微生物收集者
He scours the planet forthe tiniest forms of primitive life
在世界各处寻找那些最小的
that still exist today.
依然存在的低等生物
The earliest Earth was fullof hydrogen, of hydrogen sulphate,
最初,地球上充满了氢,硫化氢
had a lot of methane,some carbon dioxide.
甲烷以及一些二氧化碳
It was a place full of energy.
这是一个充满能量的地方
The microbes exploited virtually
微生物充斥着
every niche on this planetfor energy.
地球的几乎每个角落
Some have dubbed theseearly life forms
有人称这些低等生物为
extremophiles or thermophiles,
嗜温生物或嗜极生物
organisms that can live inextreme environments.
就是能在极端环境下生存的微生物
Let's say there was a massivemeteorite that hit the Earth
想象一下有大量流行撞击地球
and the temperatureof the Earth went up 40 degrees.
温度升到40多度
Well, that would be just perfectfor these extremophiles.
很好,很适合这些嗜温生物
One of the things we know,for instance, is that