Adventures of an asteroid hunter | Carrie Nugent

翻译人员: Thelma Li 校对人员: Conway Ye

I am holding something remarkably old.

我拿着的是一个十分古老的东西。

It is older than any human artifact,

它比任何一个人工制品都要古老，

older than life on Earth,

比地球上的生命古老，

older than the continents and the oceans between them.

也比大陆和它们之间的海洋古老。

This was formed over four billion years ago

它形成于四十亿年前，

in the earliest days of the solar system

在太阳系最初阶段

while the planets were still forming.

行星还在形成的过程中。

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

这一块粗糙的镍铁合金看起来并不特殊，

but when it is cut open ...

但它一旦被切开...

you can see that it is different from earthly metals.

你就会发现它与地球上的金属有很大不同。

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

这种花纹意味着只能 在外太空形成的金属晶体，

where molten metal can cool extremely slowly,

在那里融化的金属能以极慢的速度冷却，

a few degrees every million years.

每百万年下降几度。

This was once part of a much larger object,

它曾经是一个巨大物体的一部分，

one of millions left over after the planets formed.

是在星球形成后 存留下来的百万块中的一个。

We call these objects asteroids.

我们称这些物体为小行星。

Asteroids are our oldest and most numerous cosmic neighbors.

小行星是我们已知的 最古老数量最多的宇宙邻居。

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

这张图显示了近地 小行星绕太阳运行的轨道，

shown in yellow,

用黄色标出的部分，

and swinging close to the Earth's orbit,

同时在地球轨道附近转动的行星，

shown in blue.

用蓝色标出。

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

关于地球，太阳以及小行星的大小 被放大

so you can see them clearly.

所以大家能很清楚地看到。

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

全球许多科学家都在寻找这些东西，

discovering new ones every day,

并且每天都有新的发现，

steadily mapping near-Earth space.

稳定分布在近地空间。

Much of this work is funded by NASA.

NASA支持着绝大部分该方面的工作。

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

我把搜寻这些小行星 看作一项大型公众项目，

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

没有修建快速通道， 恰恰相反，我们在绘制外太空图，

building an archive that will last for generations.

建立一个能延传几代人的资料库。

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

这些是仅去年一年 被发现的1556个近地小行星。

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

这些则是已知的近地行星，

which at last count was 13,733.

它们的最新统计量为13733。

Each one has been imaged, cataloged

每一个都被拍照，分类

and had its path around the Sun determined.

并且确定了它绕太阳旋转的轨道。

Although it varies from asteroid to asteroid,

虽然行星之间差异很多，

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

但绝大多数行星在未来 几十余年的轨道是可被预测的。

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

而且一部分行星的轨道 能被极其精准地预测。

For example, scientists at the Jet Propulsion Laboratory

举个例子，喷气推进实验室的科学家

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

提前四年预测了 图塔蒂斯小行星的运行轨迹，

to within 30 kilometers.

误差在30公里内。

In those four years,

在那四年中，

Toutatis traveled 8.5 billion kilometers.

图塔蒂斯小行星 运行了85亿公里。

That's a fractional precision

它的分级精度

of 0.000000004.

达到了0.000000004。

(Laughter)

（笑声）

Now, the reason I have this beautiful asteroid fragment

现在，我能拿到这块美丽的行星碎片是因为

is because, like all neighbors,

就像所有的邻居一样，

asteroids sometimes drop by unexpectedly.

行星有时也会毫无预兆地拜访。

(Laughter)

（笑声）

Three years ago today,

三年前的今天，

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

一个小行星在 俄罗斯的车里雅宾斯克爆炸。

That object was about 19 meters across,

那个东西有19米宽，

or about as big as a convenience store.

或者说像一个便利店一样大。

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

像这样大的物体 每五十年左右撞击一次地球。

66 million years ago,

六百六十万年前，

a much larger object hit the Earth,

一个更大的物体撞击地球，

causing a massive extinction.

造成了物种大灭绝。

75 percent of plant and animal species were lost,

当时地球上百分之七十五的动植物消失，

including, sadly, the dinosaurs.

包括不幸的恐龙。

That object was about 10 kilometers across,

那个物体有十千米宽，

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

而十千米是波音747的巡航高度。

So the next time you're in an airplane,

所以下次当你坐飞机时，

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

抢一个靠窗的座位， 看着窗外想象一个如此巨大的石块

that resting on the ground,

躺在地上，

it just grazes your wingtip.

它恰好擦过机翼。

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

它大到飞机需要整整一分钟 才能飞过它。

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

这是曾经撞击地球的小行星的大小。

It has only been within my lifetime

这是小行星在我有生以来唯一一次

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

被视作我们星球的威胁。

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

从那以后，人们集中努力

to discover and catalog these objects.

发现并分类这些物体。

I am lucky enough to be part of this effort.

我很幸运成为这项工作的一员。

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

我是使用NASA的NEOWISE 望远镜科学家小组的成员。

Now, NEOWISE was not designed to find asteroids.

现在，NEOWISE并不是 为了寻找小行星而设计的。

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

而是环绕地球运动 并观测太阳系外的情形，

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

寻找最冷的星球以及最亮的星系。

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

而且它在其七个月的预期寿命中 非常好的完成了工作。

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

但是现在，六年过去了， 它仍然在工作。

We've repurposed it to discover and study asteroids.

我们重新改造让它开始寻找并研究小行星。

And although it's a wonderful little space robot,

虽然它是一个完美的太空机器人，

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

但是现在它更像一辆用过的汽车。

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

对其传感器进行降温 的制冷剂长时间供应不足，

so we joke that its air-conditioning is broken.

所以我们开玩笑说 它的制冷系统已经损坏。

It's got 920 million miles on the odometer,

它的里程表上显示已经 运行了九亿两千万英里，

but it still runs great

但它的状态依旧良好

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

并且稳定的在每十一秒 拍摄一张天空的照片。

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

从我开始和大家讲话到现在， 它已经拍了23张照片了。

One of the reasons NEOWISE is so valuable

NEOWISE有这样高价值的原因之一便是

is that it sees the sky in the thermal infrared.

它使用红外感应观测天空。

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

这意味着NEOWISE看到的 是小行星辐射的热量

NEOWISE sees the heat that they emit.

而不是它们反射的太阳光。

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

这是一项很重要的能力， 因为一些小行星像黑碳一样暗，

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

其他的探测器很难或 不可能发现这类行星。

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

但所有亮或暗的行星 对NEOWISE来说，都是发光的。

Astronomers are using every technique at their disposal

宇航员在使用一切可能的手段和技术

to discover and study asteroids.

去寻找并研究小行星。

In 2010, a historic milestone was reached.

2010年，我们达到了一个里程碑。

The community, together, discovered over 90 percent of asteroids

参与的组织共同发现直径大于一公里的

bigger than one kilometer across --

百分之九十以上的小行星。

objects capable of massive destruction to Earth.

这些物体能对地球造成巨大破坏。

But the job's not done yet.

但是工作并没有结束。

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

一个140米宽或更大的物体 能够摧毁一座中型城市。

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

迄今为止，我们只找到了 它们中的四分之一。

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

我们必须继续搜索天空， 寻找近地小行星。

We are the only species able to understand calculus

我们是唯一能理解微积分

or build telescopes.

或制造望远镜的物种。

We know how to find these objects.

我们知道如何找到这些物体。

This is our responsibility.

这是我们的责任。

If we found a hazardous asteroid with significant early warning,

如果我们发现一个极具危险性 的小行星并提前发出有效警告，

we could nudge it out of the way.

我们便可以把它推走。

Unlike earthquakes, hurricanes or volcanic eruptions,

不像地震，飓风或火山爆发，

an asteroid impact can be precisely predicted

行星所产生的影响是可以被准确预测

and prevented.

并预防的。

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

我们现在所需的是将 地球附近的太空准确标记。

We must keep searching the sky.

所以，我们必须继续对天空的搜索。

Thank you.

谢谢。

(Applause)

（掌声）