了解宇宙是如何运行的（2010）

How the Universe Works S11E02

Part 4 April 10, 2023, 10:20 a.m.

But a question remains.
拉德博:我们知道火星的大气层在过去要厚得多
RADEBAUGH: We know that Mars's
atmosphere was much thicker
非常类似于地球
in the past,
really similar to Earth's.
那么，为什么地球的大气层
So why is it
that Earth's atmosphere
大部分还在
is still mostly there,
而火星的大气层已经被剥离了呢？
whereas Mars's has been
stripped away?
地球有一个保护人
ROWE:
Earth has a protector,
有一个磁场保护着我们的大气层
a magnetic field
that shields our atmosphere
免受太阳风的破坏
from the ravages
of the solar wind.
拉德博:地球磁场是在地核深处
RADEBAUGH: The Earth's
magnetic field is generated
拉德博:地球磁场是在地核深处
RADEBAUGH: The Earth's
magnetic field is generated
产生的
deep in the core.
实际上有两个核心
There are actually two cores.
有一个固体内核和一个液体外核
There's a solid inner core
and a liquid outer core,
固体内核向外核传递热量
and that solid inner core
is delivering
在这个过程中
heat to the outer core,
and as it does this,
就产生了对流
it causes convection currents.
对流将电荷拉向周围
The convection currents
pull electric charges around
导致磁场向内折叠
and cause magnetic fields
to fold in on themselves.
我们称之为发电机
We call this a dynamo,
and this is what's capable
它就能产生强大的磁场
of generating powerful
magnetic fields.
磁场在地球周围形成一个保护气泡
ROWE: The magnetic field forms
a protective bubble around Earth
使太阳风偏离我们的星球
that deflects the solar wind
away from our planet.
火星曾经有自己的力场吗？
Did Mars once have
its own force field?
为了找到答案
To find out,
MAVEN仔细研究了火星表面的
MAVEN hones in on some
ancient volcanic rocks
一些古老火山岩
on the Martian surface.
它能探测到微弱的磁迹
It detects faint
magnetic traces.
拉德博:火星岩石，通常以熔岩的形式存在
RADEBAUGH: Martian rocks,
typically in the form of lava,
拉德博:火星岩石，通常以熔岩的形式存在
RADEBAUGH: Martian rocks,
typically in the form of lava,
当岩石中的铁粒子
become magnetic
when the iron particles
与当时活跃的磁场排成一列时
in the rocks become aligned
with the magnetic field
这些物质就会具有磁性，然后随着岩石冷却
that's active at the time,
and then as the rock cools,
这些物质就会冻结在原地
those things
get frozen in place.
这样就把磁场冻结在了合适的位置
That sort of freezes
a magnetic field into place.
这告诉我们，这些火山物质
What that tells us,
that these volcanic materials
爆发的时候
were erupted at a time
火星上是有磁场的
where there was a magnetic
field present on Mars.
测定磁化岩石的年代表明
ROWE: Dating the magnetized
rocks reveals that Mars had
火星的活跃磁场持续了近10亿年
an active magnetic field for
almost a billion years.
一个活跃的磁场持续了近10亿年
an active magnetic field for
almost a billion years.
萨特:这意味着火星的大气层
SUTTER: This means
that the atmosphere of
在那十亿年里受到了保护
Mars was protected
for those billion years,
如果大气层受到保护
and if the atmosphere
was protected,
液态水也就受到了保护
the liquid water
was protected.
如果液态水是生命的家园
And if that liquid water was
a home for life,
那么生命就受到了保护
then that life was protected.
但是发生了一些事情使火星的磁场下降了
ROWE: But something happened to
bring Mars's force field down.
为了找到答案，我们的地震专家，“洞察号♥”
To discover what, our quake
specialist, Insight, is ready to
为了找到答案，我们的地震专家，“洞察号♥”
To discover what, our quake
specialist, Insight, is ready to
准备好了揭开星球失去保护层的
burst open the mystery of
the planet's lost
神秘面纱
protective shield.
机器人正在改写火星的历史
ROWE: Robots are rewriting
the history of Mars.
他们发现火星曾经
They found
that Mars once had
有一个磁场保护它的大气层
a magnetic field that
protected its atmosphere.
现在，另一名队员“洞察号♥”
Now, another team member,
Insight,
正在探测这颗行星的内部
probes the planet's interior.
它的任务就是去发现
Its mission --
to discover if the secret of
星球磁场消失的秘密是否就在
the planet's lost magnetic
field lies
星球磁场消失的秘密是否就在
the planet's lost magnetic
field lies
火星的表面之下
beneath the Martian surface.
洞察号♥是用世界上最好的地震仪开♥发♥的
Insight was developed with
the world's best seismometer.
这是一个非常非常精细
This is a really precise,
really delicate,
非常非常灵敏的仪器，它被放在表面上
really sensitive instrument,
and it just was placed on
然后开始监听
the surface
and started listening.
2021年
ROWE: 2021.
洞察号♥监听地震振动，即火星地震
Insight listens for seismic
vibrations, called Mars quakes,
当它们穿过火星内部时
as they travel through
the planet's interior.
普莱特:它探测到不少火星地震
PLAIT: It's detected
quite a few Mars quakes,
但这些都非常小
but these were very small,
但这些都非常小
but these were very small,
不过后来它探测到两次更大的地震
but then it detected
two much larger ones.
这真的很有趣
And these were interesting.
它们不仅威力更大，而且来自
Not only were they more
powerful, but they were coming
科柏洛斯槽沟的方向
from the direction of
Cerberus Fossae,
这是火星上一个非常有趣的地区
which is a very interesting
region on Mars.
3.1级和3.3级的地震
ROWE: The magnitude 3.1
and 3.3 quakes
来自科柏洛斯槽沟
came from Cerberus Fossae,
这是数条在火星表面延伸750英里的
a series of trenches that
stretched for 750 miles across
裂隙
the Martian surface.
裂隙
the Martian surface.
一些裂缝穿过
Some fissures cut through
impact craters that
只有几百万年历史的撞击坑
are only a few million
years old.
这意味着科柏洛斯槽沟
This means Cerberus Fossae
一定更年轻
must be younger.
洞察号♥与火星勘测轨道飞行器合作
Insight teams up with
the Mars Reconnaissance Orbiter,
在火星上空飞行数百英里
flying hundreds of miles above.
天空中的这只眼睛
This eye in the sky
发现了一条古老的熔岩流
spots an ancient lava flow,
蔓延了三英里的范围
spreading out
over a three mile area.
对熔岩流的年代测定表明它是最近发生的
Dating of the flow
reveals that it's recent.
对熔岩流的年代测定表明它是最近发生的
Dating of the flow
reveals that it's recent.
火星勘测轨道飞行器在科柏洛斯槽沟地区
The Mars Reconnaissance Orbiter
spotted,
发现了一些
in the Cerberus Fossae region,
大约有5万年历史的熔岩
some lavas that appear to be
about 50,000 years old.
这对火星来说太年轻了