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为什么NASA要发射一艘飞行器到这颗金属星球上? – 译学馆
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为什么NASA要发射一艘飞行器到这颗金属星球上?

Why is NASA sending a spacecraft to a metal world? - Linda T. Elkins-Tanton

探索大千世界 皆为保护我们的家园——卡尔•萨根
在距离地球五亿公里的
Somewhere between the orbitsof Mars and Jupiter,
火星轨道与木星轨道之间
about 500 million kilometersaway from Earth,
漂浮着一个与马萨诸塞州同样大小的金属天体
floats a metallic orbthe size of Massachusetts.
它并不是卫星 它就是灵神星
That’s no moon…it’s 16 Psyche,
太阳系里最大的小行星之一
one of the most massiveasteroids in the solar system.
也是人类的机器努力找寻的小行星
And it is the asteroidour droids are looking for.
人类想方设法将航天器
We humans have managedto send robotic spacecraft
发射到宇宙各种环境之中
to all sorts of environments in space –
土星与木星的气体云
the gas clouds of Saturn and Jupiter,
木卫二的冰漠气候
the icy wastes of Europa,
火星上岩石遍布的山丘
and the rocky dunes of Mars.
但灵神星的表面却不是坚硬的岩石
But Psyche’s surfaceisn’t just hard rock –
而是重金属
it’s heavy metal.
这颗小行星主要由镍与铁组成
The asteroid mostly consistsof nickel and iron,
是目前已知最大的由此种成分构成的物体
by far the largest known bodywith such a composition.
但我们还不知道它长什么样子
But we don’t yet know what it looks like;
目前最好的雷达图像上仍然呈现出像素点
our best current radar imagesshow a pixelated smudge.
但这种情况将会在2026年改变
That’ll change in 2026,
作为美国宇航局发现计划的一部分
when an unmanned spacecraft sent aspart of NASA’s Discovery Program
美国发射的无人航天器将会于同年到达灵神星
is scheduled to arrive.
那么为什么美国航天局会对灵神星感兴趣呢?
So why is NASA so interested in Psyche?
我们要开采上面所有的金属
Are we going to mine all that metal,
还是要建造一个巨大的太空磁铁呢?
or build a giant space magnet? Actually,
事实上 答案就在我们的脚下
the real reasonis right under our feet.
地球的核心
The core of the Earth is
被认为是由固态的镍铁中心
thought to consist of a solid nickel-iron center
和它的液态外层组成的
with a molten outer layer.
但我们进一步的研究
But we ’ re prevented from studying it up close
却被2800千米深的岩石层拒之门外
by 2,800 kilometers of solid rock.
我们所能达到的最大钻孔深度为12千米
The deepest we’ve been ableto drill is 12 kilometers.
即便我们能够到达更深的地方
Even if we could go further,
核心的压力
the pressure at the core is
是表面压力的三百万倍
three million times higher than at the surface,
并且还伴随着5000摄氏度的高温
with a temperatureof 5,000 degrees Celsius.
简单来说 前往地球中心的旅程
Simply put, a journey to the center
目前还是不可能的
of the Earth is out of the question for now.
所以科学家们必须用间接的途径
So scientists have had to resort
来研究核心
to indirect ways of studying the core,
比如测量经过核心的地震波
like measuring earthquake wavesthat pass through it,
或者研究产生于其中的矿物质
or studying minerals thoughtto have formed there.
但如果研究地球内部空间的最好方法
But what if the best way to studyEarth’s inner space
是前往外太空呢?
is by visiting outer space?
毕竟我们对我们星球的成型过程比较了解
After all, we have a pretty good idea of how our planets formed.
围绕年轻太阳转动的尘埃与气体不断冷却碰撞
Dust and gas orbiting our young Suncooled and collided
形成了数千个微缩的天体 我们称之为星子
to form a few thousand miniature bodieswe call planetesimals.
它们不断转动 其中一些结合成为更大的星子
As these continued to orbit,some combined to grow larger,
最后就形成了我们的星球
eventually forming our planets.
而其它星子在碰撞之后分裂成小块
Others experienced impactsthat broke them apart into smaller chunks–
就有了今天我们看到的位于火星与木星之间的小行星带
the asteroids we see today in the belt between Mars and Jupiter.
灵神星之所以很特别
What makes Psyche so special
是因为它在演变成为星球的进程中
is that it appearsto have been a planetesimal
慢慢转变成了一个
well on its way to becoming a planet,
由石质外壳包裹着内部金属核心的小行星
with a rocky exteriorsurrounding a metal core.
但它的进程由于
But its progress was cut short
一系列的撞击而缩短
by a series of hit-and-run collisions
其他星子击碎了它的石质外壳最后只留下了核心
with other planetesimals that knocked off the rocky crust until only the core remained.
经历了如此之多的毁灭性撞击
Experiencing that manydestructive collisions
灵神星内却没有添加进任何外物这在统计学上来讲几乎是不可能的
with no additive ones in betweenis statistically very unlikely,
这也使得灵神星成为了一个极其珍贵的
making Psyche an amazinglyrare opportunity
研究裸露金属核心的契机
to study an exposed metallic core.
为此 美国航天局的航天器将会装备
To do that, NASA’s robotic orbiterwill be equipped
一系列先进的仪器设备
with an array of advanced instruments.
分光仪将会分析灵神星在高能宇宙射线的冲击下
A spectrometer will analyzethe gamma rays and neutrons
产生的伽马射线与中子
produced when Psycheis struck by cosmic rays.
元素周期表中的每个元素
Each element in the periodic table
所释放的伽马射线的波长都不同
releases gamma raysof specific wavelengths,
所以这些测量值将会告诉我们灵神星的表面都有哪些元素
so these measurements will tell us what elements are found on the surface.
磁力计能够测量灵神星的磁场
A magnetometer will measurePsyche’s magnetic field,
让我们能够进一步了解
allowing us to learn more
地球的核心是如何产生出磁场的
about how Earth ’ s magnetic field is generated at its core.
当然
And of course,
成像器将会传回比以往任何一张图片
an imager will give us a closer look at the surface
都更加接近灵神星表面的图像
than ever before.
就其本身而言拜访一个崭新的世界足够刺激
Visiting a whole new kind of world is exciting enough on its own.
但前往灵神星的旅程给了我们这样一个独一无二的机会
But the mission to Psyche gives usa unique chance
在遥远的轨道上
to discover our own planet ’ s innermost secrets
探寻我们自己星球最深处的秘密
in an orbit far, far away.

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视频概述

拜访外太空的金属天体,找寻地球中心的秘密

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翻译译者

jameschan

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审核员 EM

视频来源

https://www.youtube.com/watch?v=1JXq9779zwU

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