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

翻译人员: Chien Yet Chong 校对人员: Zibo Huang

“探索其它世界，才能保卫我们的世界。” ——卡尔·萨根

Somewhere between the orbits of Mars and Jupiter,

在火星和木星的轨道之间， 距离地球 5 亿公里远的地方，

about 500 million kilometers away from Earth,

floats a metallic orb the size of Massachusetts.

漂浮着一个大小如 马萨诸塞州般的金属天体。

That’s no moon...it’s 16 Psyche,

那不是月球……是 16 号 小行星，灵神星（Psyche），

one of the most massive asteroids in the solar system.

太阳系中最大的小行星之一。

And it is the asteroid our droids are looking for.

那就是我们的机器人正要 寻找的小行星。

We humans have managed to send robotic spacecraft

我们人类已经成功发射了航天器

to all sorts of environments in space –

到太空的各种不同的环境中——

the gas clouds of Saturn and Jupiter,

土星和木星的气体云、

the icy wastes of Europa,

木卫二的冰封荒野、

and the rocky dunes of Mars.

还有火星的岩石沙丘。

But Psyche’s surface isn’t just hard rock –

但是灵神星的表面 并不是坚硬的岩石——

it’s heavy metal.

而是重金属。

The asteroid mostly consists of nickel and iron,

这颗小行星主要由镍和铁组成，

by far the largest known body with such a composition.

是所知天体中具有 该金属组合体积最大的一个。

But we don’t yet know what it looks like;

但是我们还不知道它长什么样子；

our best current radar images show a pixelated smudge.

我们目前最佳的雷达 图像分辨率还不够。

That’ll change in 2026,

2026 年，这种情况将会有所改善。

when an unmanned spacecraft sent as part of NASA’s Discovery Program

那时美国国家航空航天局 （NASA）“发现号计划”中所发射的

is scheduled to arrive.

无人航天器将会预期抵达。

So why is NASA so interested in Psyche?

为什么 NASA 对灵神星 那么感兴趣？

Are we going to mine all that metal, or build a giant space magnet?

我们将会开采那里的金属， 还是制作一个巨型太空磁铁？

Actually, the real reason is right under our feet.

其实，真正原因就在我们脚下。

The core of the Earth is thought to consist of a solid nickel-iron center

地核被认为是由固体的 镍和铁为核心，

with a molten outer layer.

包裹着液态的外层。

But we’re prevented from studying it up close by 2,800 kilometers of solid rock.

但是我们脚下 2800 公里厚的坚硬土层 阻碍了我们对地核的进一步研究。

The deepest we’ve been able to drill is 12 kilometers.

我们最深只能挖到 12 公里。

Even if we could go further,

就算我们可以挖得更深，

the pressure at the core is three million times higher than at the surface,

地核的压强将比地面高三百万倍，

with a temperature of 5,000 degrees Celsius.

而且温度高达 5000 摄氏度。

Simply put, a journey to the center of the Earth is out of the question for now.

简而言之，通往地心 的旅程现在是无法进行的。

So scientists have had to resort to indirect ways of studying the core,

所以科学家需要通过间接 的方式来研究地核，

like measuring earthquake waves that pass through it,

如测量穿透地核的地震波，

or studying minerals thought to have formed there.

或研究被认为是在 地核内形成的矿物。

But what if the best way to study Earth’s inner space

然而，如果研究地球内部的最好方法

is by visiting outer space?

其实是探访外太空呢？

After all, we have a pretty good idea of how our planets formed.

毕竟，我们已经知道 地球是怎么形成的了。

Dust and gas orbiting our young Sun cooled and collided

灰尘和气体围绕着新形成的太阳, 不断的冷却和碰撞

to form a few thousand miniature bodies we call planetesimals.

形成了数以千计的小型天体， 称之为小行星体。

As these continued to orbit, some combined to grow larger,

这些小行星体继续围绕太阳转动， 其中一些结合并逐渐变大，

eventually forming our planets.

最后形成了行星。

Others experienced impacts that broke them apart into smaller chunks–

另一些则经历撞击 而分裂成小块的碎片 ——

the asteroids we see today in the belt between Mars and Jupiter.

即如今位于火星和木星 之间的小行星带。

What makes Psyche so special

灵神星如此特别的原因是，

is that it appears to have been a planetesimal

该小行星曾经处于从小行星

well on its way to becoming a planet,

演变成为行星的过程中，

with a rocky exterior surrounding a metal core.

拥有岩石包围的金属核心。

But its progress was cut short by a series of hit-and-run collisions

但与其他小行星一系列的相撞

with other planetesimals

打断了这次演变，

that knocked off the rocky crust until only the core remained.

使它的岩石外壳剥离 直到只留下核心。

Experiencing that many destructive collisions

经历了许多破坏性的撞击，

with no additive ones in between is statistically very unlikely,

其间又不增加任何物质， 这样的情况十分罕见，

making Psyche an amazingly rare opportunity

因此，灵神星为我们提供了极为难得

to study an exposed metallic core.

的研究裸露核心的机会。

To do that, NASA’s robotic orbiter will be equipped

为了进行研究，NASA 的机器轨道飞行器将搭载

with an array of advanced instruments.

许多不同的高科技仪器。

A spectrometer will analyze the gamma rays and neutrons

光谱仪将会分析灵神星在 宇宙射线照射下

produced when Psyche is struck by cosmic rays.

所产生的伽玛射线和中子。

Each element in the periodic table

元素周期表内的每个元素

releases gamma rays of specific wavelengths,

都会释放特定波长的伽玛射线，

so these measurements will tell us what elements are found on the surface.

所以测量结果将告诉我们 行星表面含有什么元素。

A magnetometer will measure Psyche’s magnetic field,

磁力计将测量灵神星的磁场，

allowing us to learn more

帮助我们进一步了解

about how Earth’s magnetic field is generated at its core.

地球的磁场是 如何在地核生成。

And of course, an imager will give us a closer look at the surface

另外还有成像器，能够帮助我们

than ever before.

近距离的观察其表面。

Visiting a whole new kind of world is exciting enough on its own.

探访一个全新的世界本身 已经是非常令人振奋的了。

But the mission to Psyche gives us a unique chance

而灵神星探访之旅 更是给了我们一个独特的机会，

to discover our own planet’s innermost secrets in an orbit far, far away.

从遥远的外太空探寻 我们星球最深处的秘密。