Adventures of an asteroid hunter | Carrie Nugent

譯者: Cheng Zhang-Stoddard 審譯者: Melody Tang

I am holding something remarkably old.

我手中拿的是一個非常古老的東西。

It is older than any human artifact,

它比任何人造製品，

older than life on Earth,

比地球上任何生命，

older than the continents and the oceans between them.

比任何陸地和大洋都要古老。

This was formed over four billion years ago

它是四十多億年前形成的。

in the earliest days of the solar system

那時還是太陽系的最早期，

while the planets were still forming.

眾星球還在形成。

This rusty lump of nickel and iron may not appear special,

這一塊生鏽的鎳鐵， 看起來可能沒有什麼特別之處。

but when it is cut open ...

但如果把它切開，

you can see that it is different from earthly metals.

你會發現它與地球的金屬不同。

This pattern reveals metallic crystals that can only form out in space

它的紋路顯示它是只能在 太空中形成的金屬晶體。

where molten metal can cool extremely slowly,

在太空中，熔化了的金屬， 可以以極慢的速度冷卻。

a few degrees every million years.

每幾百萬年，只冷卻幾度。

This was once part of a much larger object,

這是一個比它 大很多的物體的一部分。

one of millions left over after the planets formed.

星球形成後，它是 數百萬被遺落的物體之一。

We call these objects asteroids.

我們把這些物體叫做小行星。

Asteroids are our oldest and most numerous cosmic neighbors.

小行星是我們宇宙鄰居裡 最古老和為數最多的。

This graphic shows near-Earth asteroids orbiting around the Sun,

這幅圖像展示了靠近地球的小行星 繞太陽運轉。

shown in yellow,

太陽是圖中黃色的那個。

and swinging close to the Earth's orbit,

它們活躍於地球繞行軌道附近，

shown in blue.

地球軌道是圖中藍色部分。

The sizes of the Earth, Sun and asteroids have been greatly exaggerated

為了讓大家看得清楚， 圖中的地球、太陽和小行星

都被放大了很多倍。

so you can see them clearly.

Teams of scientists across the globe are searching for these objects,

世界各地的科學家團隊 都在尋找這些物體。

discovering new ones every day,

他們每天發現新的小行星，

steadily mapping near-Earth space.

逐漸繪製著近地空間的地圖。

Much of this work is funded by NASA.

這項工作大部分是由 美國國家航空暨太空總署資助的。

I think of the search for these asteroids as a giant public works project,

我覺得，搜尋小行星的工作， 是極為浩大的公共工程項目，

but instead of building a highway, we're charting outer space,

我們為太空製圖， 而不是在建高速公路，

building an archive that will last for generations.

並建立著能夠世代延續的檔案。

These are the 1,556 near-Earth asteroids discovered just last year.

光是去年，科學家就發現了 1556 顆近地小行星。

And these are all of the known near-Earth asteroids,

圖上的這些，是我們已知的 全部近地小行星。

which at last count was 13,733.

根據最近的統計， 總數是 13,733 顆。

Each one has been imaged, cataloged

每一顆小行星， 都已經被繪圖和編入目錄，

and had its path around the Sun determined.

它繞太陽運行的軌跡， 也都已經被確定。

Although it varies from asteroid to asteroid,

雖然每一顆小行星都不同，

the paths of most asteroids can be predicted for dozens of years.

它們大多數在未來幾十年的 運行軌跡都可以被預測。

And the paths of some asteroids can be predicted with incredible precision.

有一些小行星的軌跡， 可以被無比精確地預測。

For example, scientists at the Jet Propulsion Laboratory

舉個例子來講， 噴氣推進實驗室的科學家們，

predicted where the asteroid Toutatis was going to be four years in advance

提前四年預測了 圖塔迪斯小行星的位置，

to within 30 kilometers.

誤差小於 30 公里。

In those four years,

在這四年裡，

Toutatis traveled 8.5 billion kilometers.

圖塔迪斯運行了 85 億公里 。

That's a fractional precision

小數精度為

of 0.000000004.

0.000000004。

(Laughter)

（笑聲）

Now, the reason I have this beautiful asteroid fragment

我之所以有手中 這塊美麗的小行星碎片，

is because, like all neighbors,

是因為，像所有的人類鄰居一樣，

asteroids sometimes drop by unexpectedly.

小行星有時候也會意外造訪。

(Laughter)

（笑聲）

Three years ago today,

三年前的今天，

a small asteroid exploded over the city of Chelyabinsk, Russia.

一顆小型的小行星在俄羅斯的 車里雅賓斯克市上方爆炸。

That object was about 19 meters across,

當時，這塊物體的 截面長度大約為 19 米，

or about as big as a convenience store.

和一個便利店的大小差不多。

Objects of this size hit the Earth every 50 years or so.

大約每五十年， 就會有這樣體積的物體撞擊地球。

66 million years ago,

六千六百萬年前，

a much larger object hit the Earth,

一個還要大很多的物體撞擊了地球，

causing a massive extinction.

導致了大規模的生物滅絕。

75 percent of plant and animal species were lost,

百分之 75 的動植物 物種都徹底消失，

including, sadly, the dinosaurs.

可悲的是，其中包括恐龍。

That object was about 10 kilometers across,

當時的物體截面長度 長達 10 公里。

and 10 kilometers is roughly the cruising altitude of a 747 jet.

10 公里差不多是一架 波音 747 的飛行高度。

So the next time you're in an airplane,

你下次坐飛機的時候，

snag a window seat, look out and imagine a rock so enormous

選一個臨窗的座位，然後想像一下

一顆巨石拔地而立，

that resting on the ground,

it just grazes your wingtip.

和你的機翼擦身而過。

It's so wide that it takes your plane one full minute to fly past it.

你的飛機需要飛整整一分鐘 才能越過它的寬度。

That's the size of the asteroid that hit the Earth.

這就是撞擊地球的 那顆小行星的尺寸。

It has only been within my lifetime

在我們這個世代，

that asteroids have been considered a credible threat to our planet.

小行星才被認為 是我們星球的一個威脅。

And since then, there's been a focused effort underway

那以後，我們才開始致力於

to discover and catalog these objects.

對這些物體進行搜尋和紀錄。

I am lucky enough to be part of this effort.

我非常幸運能夠參與這一個工作。

I'm part of a team of scientists that use NASA's NEOWISE telescope.

我是使用 NASA NEOWISE 望遠鏡的科學家團隊一員。

Now, NEOWISE was not designed to find asteroids.

要知道，NEOWISE 並不是為搜尋小行星設計的。

It was designed to orbit the earth and look far beyond our solar system

它是為了能夠繞行地球 以遙望太陽系之外，

to seek out the coldest stars and the most luminous galaxies.

為了尋找最寒冷的星球和 最明亮的星系而設計的。

And it did that very well for its designed lifetime of seven months.

在七個月的既定壽命中， 它很出色地完成了任務。

But today, six years later, it's still going.

但六年後的今天，它還在運轉。

We've repurposed it to discover and study asteroids.

我們將它的用途變成了 搜尋和研究小行星。

And although it's a wonderful little space robot,

雖然它是個非常出色的 太空小機器人，

these days it's kind of like a used car.

但現在它有些像二手車。

The cryogen that used to refrigerate its sensors is long gone,

用於傳感器的製冷劑 很早以前就消耗殆盡了，

so we joke that its air-conditioning is broken.

我們開玩笑說，空調壞了。

It's got 920 million miles on the odometer,

它的里程表上， 已經有了 9.2 億英里，

but it still runs great

但它依然運行良好。

and reliably takes a photograph of the sky every 11 seconds.

它每 11 秒就會拍一張天空的照片。

It's taken 23 photos since I began speaking to you.

從我開始演講到現在， 它已經拍了 23 張照片了。

One of the reasons NEOWISE is so valuable

NEOWISE 如此寶貴的原因之一是，

is that it sees the sky in the thermal infrared.

它是通過熱紅外線觀測天空的。

That means that instead of seeing the sunlight that asteroids reflect,

這意味著，NEOWISE 看到的 不是小行星折射的陽光，

NEOWISE sees the heat that they emit.

而是它們放散發的熱量。

This is a vital capability since some asteroids are as dark as coal

這種能力至關重要， 因為有些小行星暗如黑炭，

and can be difficult or impossible to spot with other telescopes.

幾乎不可能被其他的望遠鏡觀測到。

But all asteroids, light or dark, shine brightly for NEOWISE.

但所有的小行星，無論明暗，

在 NEOWISE 的眼中， 都一樣熠熠閃耀。

Astronomers are using every technique at their disposal

天文學家們正在利用他們所有的技術

to discover and study asteroids.

來發現和研究小行星。

In 2010, a historic milestone was reached.

2010 年，一項歷史性的 里程碑得以樹立。

The community, together, discovered over 90 percent of asteroids

通過研究者的共同努力， 我們已經發現了超過 90%

截面長度大於一公里的小行星——

bigger than one kilometer across --

objects capable of massive destruction to Earth.

這些物體足以給地球 帶來巨大的破壞。

But the job's not done yet.

但我們的工作還沒有結束，

An object 140 meters or bigger could decimate a medium-sized country.

一個横截長度大於 140 米的物體， 就足以摧毁一個中型國家。

So far, we've only found 25 percent of those.

至今，我們只發現了 25% 這種大小的。

We must keep searching the sky for near-Earth asteroids.

我們必須不停地 探索天空中的近地小行星。

We are the only species able to understand calculus

我們是唯一能夠理解微積分

or build telescopes.

或者製造望遠鏡的物種。

We know how to find these objects.

我們知道如何找到這些物體。

This is our responsibility.

這是我們的責任。

If we found a hazardous asteroid with significant early warning,

如果我們能夠在危險的 小行星出現早期就發現它們，

we could nudge it out of the way.

我們就可以把它 從原來的軌跡上推開。

Unlike earthquakes, hurricanes or volcanic eruptions,

不同於地震、颶風和火山爆發，

an asteroid impact can be precisely predicted

我們可以準確地預測和預防

and prevented.

小行星的衝擊。

What we need to do now is map near-Earth space.

我們現在需要做的是 繪製出近地的空間地圖。

We must keep searching the sky.

我們必須繼續不停地探索天空。

Thank you.

謝謝各位。

(Applause)

（鼓掌）