Phil Plait: How to defend Earth from asteroids

翻译人员: Lili Liang 校对人员: Ting Huang

I want to talk to you about something

我想和大家探讨一样东西

kind of big.

一个庞然大物

We'll start here.

我们先从这里讲起

Sixty-five million years ago --

6500万年前

(Laughter)

the dinosaurs had a bad day.

恐龙们倒了大霉了

(Laughter)

（众人笑）

A chunk of rock six miles across,

一块长达6英里的巨石

moving something like 50 times the speed of a rifle bullet,

以出膛子弹50倍的速度

向前运行

slammed into the Earth.

当头撞上了地球

It released its energy all at once,

一时间 它释放出了所有能量

and it was an explosion that was mind-numbing.

爆炸所产生的威力

令人无法想象

If you took every nuclear weapon ever built

如果将冷战最紧张时期

所有核武器

at the height of the Cold War,

lumped them together,

堆成一堆

and blew them up at the same time,

再同时引爆

that would be one one-millionth of the energy released at that moment.

所产生的威力

充其量还只是其百万分之一

The dinosaurs had a really bad day.

恐龙们真是倒了大霉了

OK?

对吧

Now, a six-mile-wide rock is very large.

一块6英里宽的巨石非常大

We all live here in Boulder.

我们都住在Boulder市

If you look out your window and see Longs Peak --

从窗外看去 你可以看见

you're probably familiar with it --

朗斯峰 你们对这山都不陌生吧

now, scoop up Longs Peak and put it out in space.

把朗斯峰连锅端起来

Take ... Meeker, Mt. Meeker.

把它放到外太空

把米克山也拔起来

Lump that in there, and put that in space as well.

放到外太空去

And Mt. Everest. And K2.

再加上珠穆朗玛峰 乔戈里峰

印第安山脉群峰

And the Indian peaks.

现在你们应该可以想象

Then you're starting to get an idea of how much rock we're talking about, OK?

这块巨石有多大了吧

We know it was that big

我们从爆炸释放的威力和之后留下的陨坑

because of the impact it had and the crater it left.

得知这块巨石的确有这么大

It hit in what we now know as Yucatan, the Gulf of Mexico.

它所撞击的地点

是现位于墨西哥湾的尤卡坦

You can see here, there's the Yucatan Peninsula,

你可以看这里

如果你认得东海岸的科祖梅尔岛

if you recognize Cozumel off the east coast there.

这里就是尤卡坦半岛

Here is how big of a crater was left.

留下的陨坑有这么大

It was huge.

To give you a sense of the scale ... there you go.

它非常大 你可以估计一下它的大小

你看

The scale here is 50 miles on top, a hundred kilometers on the bottom.

它上面宽50英里

下面宽100公里

This thing was 300 kilometers across -- 200 miles --

跨度为300公里 也就是200英里

an enormous crater that excavated out vast amounts of earth

这个巨大的陨坑

把大量泥土掘起 抛散开来 尘土弥漫

that splashed around the globe and set fires all over the planet,

整个地球四处起火

threw up enough dust to block out the sun.

烟尘遮盖了阳光

It wiped out 75 percent of all species on Earth.

地球上75%的物种

就此灭绝

Now, not all asteroids are that big.

并不是所有小行星都这么大

Some of them are smaller.

有些小行星或陨石体型较小

Here is one that came in

这是1992年10月

over the United States in October of 1992.

砸到美国的

一块陨石

It came in on a Friday night.

那是一个星期五的晚上

Why is that important?

这为什么值得一提

Because back then, video cameras were just starting to become popular,

当时摄影机

才刚开始普及

and parents would bring them to their kids' football games

人们都随身携带 家长们带着摄影机

去拍摄孩子的足球比赛

to film their kids playing football.

这颗陨石在一个周五从天而降

And since this came in on a Friday,

they were able to get this great footage of this thing breaking up

划过西弗吉尼亚州 马里兰州

宾夕法尼亚洲 新泽西州

as it came in over West Virginia, Maryland, Pennsylvania and New Jersey

一路解体

直到它砸在纽约州的一辆车上

until it did that

to a car in New York.

人们就把这一壮景拍了下来

(Laughter)

（众人笑）

Now, this is not a 200-mile-wide crater,

它没有形成一个200英里宽的陨坑

but then again, you can see the rock, which is sitting right here,

但是你看那块陨石

落在地上

about the size of a football,

大概有一个橄榄球大小

that hit that car and did that damage.

能把那车砸成那样

Now, this thing was probably about the size of a school bus

这块陨石在刚进入大气层时

when it first came in.

大概有一辆公共汽车那么大

It broke up through atmospheric pressure,

它在大气层中摩擦燃烧

it crumbled, and then the pieces fell apart

解体 碎片四散

and did some damage.

造成了一些破坏

Now, you wouldn't want that falling on your foot or your head,

你可不想被这些家伙砸到脚或头

因为一被砸到

because it would do that to it.

That would be bad.

就糟糕了

But it won't wipe out, you know, all life on Earth, so that's fine.

但至少它不会毁灭

地球上所有的生命 所以问题不大

But it turns out, you don't need something six miles across

然而 即使是体型小于6英里宽的小行星陨石

to do a lot of damage.

也能造成巨大的破坏

There is a median point between tiny rock and gigantic rock,

在小石块和巨石之间

存在一个中间点

and in fact, if any of you have ever been to near Winslow, Arizona,

你们可能有人去过亚利桑那州的温斯洛

there is a crater in the desert there that is so iconic

那里附近的沙漠里就有一个陨坑

这个著名的陨坑就叫做“陨石坑”

that it is actually called "Meteor Crater."

To give you a sense of scale, this is about a mile wide.

它大概有一英里宽

If you look up at the top, that's a parking lot,

往上看 那是一个停车场

and those are recreational vehicles right there.

那些房车就停放在那里

So it's about a mile across, 600 feet deep.

它大约1英里宽 600英尺深

The object that formed this was probably about 30 to 50 yards across,

陨石的大小大概为

30到50码宽

so roughly the size of Macky Auditorium here.

大概有这个礼堂这么大

It came in at speeds that were tremendous,

它的飞行速度极快

slammed into the ground, blew up,

撞入地表 爆炸

and exploded with the energy of roughly a 20-megaton nuclear bomb --

释放的能量

相当于一枚20兆吨的核弹

a very hefty bomb.

一枚相当给力的炸弹

This was 50,000 years ago,

这发生在5万年前

so it may have wiped out a few buffalo or antelope,

当时可能也就消灭了

or something like that out in the desert,

沙漠上的几头野牛或羚羊

but it probably would not have caused global devastation.

可能不会造成

全球性的灾难

It turns out that these things don't have to hit the ground

陨石即使没有砸到地面

也会造成巨大的破坏

to do a lot of damage.

Now, in 1908, over Siberia, near the Tunguska region --

1908年在西伯利亚

靠近通古斯卡河流域--大家可能有人

for those of you who are Dan Aykroyd fans and saw "Ghostbusters,"

是Dan Aykroyd的粉丝 看过“捉鬼敢死队”

他谈到过1909年西伯利亚大爆炸后出现的大裂谷

when he talked about the greatest cross-dimensional rift

他当时把时间说错了

since the Siberia blast of 1909,

where he got the date wrong, but that's OK.

不过没关系（众人笑）

(Laughter)

应该是1908年 没事儿 我可以忍受

It was 1908. That's fine. I can live with that.

（众人笑）

(Laughter)

Another rock came into the Earth's atmosphere

另一块陨石进入了大气层

and this one blew up above the ground,

在距地表几英里的地方

several miles up above the surface of the Earth.

爆炸

The heat from the explosion set fire to the forest below it,

爆炸产生的热

将下面的森林点燃

and then the shock wave came down and knocked down trees

冲击波将几百平方英里的森林

for hundreds of square miles.

夷为平地

This did a huge amount of damage.

这造成了巨大的破坏

And again, this was a rock probably roughly the size

这块陨石

of this auditorium that we're sitting in.

大概有我们这个礼堂这么大

In Meteor Crater, it was made of metal,

形成陨石坑的陨石由金属组成

and metal is much tougher, so it made it to the ground.

金属较为坚固

因此最终到达了地面

The one over Tunguska was probably made of rock,

经过通古斯上空的那颗陨石

and that's much more crumbly, so it blew up in the air.

可能是由石头组成的 比较脆

Either way, these are tremendous explosions -- 20 megatons.

所以在空中爆炸了 而这两颗陨石

都造成了20兆吨的巨大爆炸

Now, when these things blow up,

这样的陨石爆炸

they're not going to do global ecological damage.

不会造成全球性的生态破坏

They're not going to do something like the dinosaur killer did.

它们不会像灭绝恐龙的那颗小行星那样

造成如此严重的破坏

They're just not big enough.

它们不够大

But they will do global economic damage,

但它们可以造成全球性的经济破坏

because they don't have to hit, necessarily,

因为它们即使不着地

to do this kind of damage.

也能造成这样的破坏

They don't have to do global devastation.

它们即使不造成全球性的灾难 也能达到破坏的效果

If one of these things were to hit pretty much anywhere,

任何一颗陨石要是即将撞上地球

不管撞在哪里 都会引起恐慌

it would cause a panic.

But if it came over a city, an important city --

如果它经过一个城市 一个重要的城市

我不是说一个城市比其它城市重要

not that any city is more important than others,

但是我们在全球经济层面上

but some of them we depend on more on the global economic basis --

更依赖某些城市

that could do a huge amount of damage to us as a civilization.

这会对我们的文明

造成巨大破坏

So, now that I've scared the crap out of you --

我把你们都吓趴下了吧

(Laughter)

（众人笑）

what can we do about this?

我们怎么办呢

This is a potential threat.

这是个潜在的威胁

Let me note that we have not had a giant impact like the dinosaur killer

我提醒你们一下

我们已经有6500万年没有遭遇

for 65 million years.

灭绝恐龙的小行星造成的那种破坏了 这非常罕见

They're very rare.

The smaller ones happen more often,

体积较小的小行星袭击地球的次数稍多一些

but probably on the order of a millennium,

但也就一千年

every few centuries or every few thousand years.

几百年或几千年发生一次

但这还是值得引起注意

But it's still something to be aware of.

Well, what do we do about them?

我们怎么对付它们

The first thing we have to do is find them.

我们首先要把它们找出来

This is an image of an asteroid that passed us in 2009.

这是2009年

经过地球的一颗小行星

It's right here.

就在这里

But you can see that it's extremely faint.

可以看到 它非常暗

I don't know if you can see that in the back row.

我都不确定坐在后排的观众能否看到

These are just stars.

这些只是星星

This is a rock that was about 30 yards across,

这是一颗直径约为30码的陨石

so roughly the size of the ones that blew up over Tunguska

它的大小和在通古斯上空爆炸的小行星

以及5万年前砸到亚利桑那州的小行星差不多

and hit Arizona 50,000 years ago.

These things are faint.

这些行星都很暗

They're hard to see, and the sky is really big.

很难看清楚 天空实在太大了

We have to find these things first.

我们必须先把它们找出来

Well, the good news is, we're looking for them.

好消息是 我们正在寻找这些小行星

NASA has devoted money to this;

美国国家航空航天局正在这上面投钱

the National Science Foundation and other countries

美国国家科学基金

还有其它国家都有意这么做

are interested in doing this.

We're building telescopes that are looking for the threat.

我们正在建造望远镜来寻找可能的威胁

这是意义非凡的第一步

That's a great first step. But what's the second step?

那么第二步呢

The second step is if we see one heading toward us, we have to stop it.

第二步就是 当发现有一颗小行星向我们飞来

我们必须阻止它 怎么阻止

What do we do?

You've probably heard about the asteroid Apophis.

你们可能听说过一颗名叫

阿波菲斯的小行星 如果没听过 现在你就知道了

If you haven't yet, you will.

If you've heard about the Mayan 2012 apocalypse,

如果你听说过玛雅人的2012末日说

you're going to hear about Apophis,

你就会听到阿波菲斯

because you're keyed in to all the doomsday networks, anyway.

因为你横竖都已经被

关于世界末日的网罗给套牢了

(Laughter)

Apophis is an asteroid that was discovered in 2004.

阿波菲斯是2004年被发现的一颗小行星

It's roughly 250 [meters] across, so it's pretty big --

它的直径约为250码

可见它的个头可不小

bigger than a football stadium.

它比一个足球场还大

And it's going to pass by the Earth in April of 2029.

它将于2029年4月飞过地球上空

And it's going to pass us so close

它将非常接近地球

that it's actually going to come underneath our weather satellites.

会从我们的气象卫星下面

飞过去

The Earth's gravity is going to bend the orbit of this thing so much

而地心引力会使它的运行轨道发生弯曲

如果这正好使它

that if it's just right,

if it passes through this region of space,

穿过这个区域

this kidney-bean-shaped region called the keyhole,

这个蚕豆形状的区域

the Earth's gravity will bend it just enough that seven years later,

我们称钥匙眼 地心引力会使其轨道弯曲

这样它在七年之后

on April 13 -- which is a Friday, I'll note -- in the year 2036 --

也就是2036年4月13日星期五这一天

（众人笑）

(Laughter)

you can't plan that kind of stuff --

这种事情可没法作安排

(Laughter)

Apophis is going to hit us.

阿波菲斯会在这天撞上地球

And it's 250 meters across, so it would do unbelievable damage.

它的直径为250码

后果将不堪设想

The good news is that the odds of it actually passing through this keyhole

值得庆幸的是

它穿过这个钥匙眼

and hitting us next go-around are one in a million, roughly --

撞上地球的几率为百万分之一

very, very low odds.

几率非常非常低

So I personally am not lying awake at night worrying about this at all.

反正我可不会为了它而辗转反侧睡不着

我们不需要太担心阿波菲斯

I don't think Apophis is a problem.

阿波菲斯其实是件好事

In fact, Apophis is a blessing in disguise,

因为 它提醒了我们要注意

because it woke us up to the dangers of these things.

这些小行星的威胁

This thing was discovered just a few years ago

我们几年前发现了这颗小行星

and could hit us a few years from now.

它有可能在几年后与地球相撞

It won't, but it gives us a chance to study these kinds of asteroids.

它不会撞上地球 但它让我们有机会

研究这些小行星

We didn't really necessarily understand these keyholes, and now we do,

我们之前对这些钥匙眼并不了解

现在我们有所了解了

and it turns out that's really important,

并知道其中的重大意义

because how do you stop an asteroid like this?

要不我们如何阻止这样一颗小行星呢

Well, let me ask you:

我问你们 如果你站在路中间

What happens if you're standing in the road and a car's headed for you?

一辆车朝你驶来 会有什么情况发生

你会怎么做 你会这么做

What do you do?

You do this. Right? Move, and the car goes past you.

挪开 对吧 让车过去

But we can't move the Earth, at least not easily,

但是 我们不能挪动地球

就算要挪也没那么容易 但我们挪开那颗小行星

but we can move a small asteroid.

And it turns out, we've even done it.

其实 我们已经这么做过了

2005年 NASA发射了一个名为

In the year 2005, NASA launched a probe called Deep Impact,

"天地大冲撞"的探测器

which slammed a piece of itself into the nucleus of a comet.

探测器的一部分嵌入了一颗彗星的内核

Comets are very much like asteroids.

彗星跟小行星十分相似

The purpose wasn't to push it out of the way;

这么做目的不是为了把它推出轨道

the purpose was to make a crater to excavate the material

而是为了制造一个陨坑

从彗星表面刨出一些物质

and see what was underneath the surface of this comet,

接着对物质

which we learned quite a bit about.

进行深入研究

We did move the comet a little tiny bit --

我们的确将那颗彗星挪动了一点点

not very much, but that wasn't the point.

但这不是重点

However, think about this:

但是 我们这样想

This thing is orbiting the Sun at 10, 20 miles per second.

这个天体围绕着太阳

以每秒10英里 20英里的速度运行

We shot a space probe at it and hit it, OK?

我们把一个太空探测器发射过去并击中了它

想象一下 这有多困难 但我们做到了

Imagine how hard that must be, and we did it.

That means we can do it again.

这意味着 我们还能这么做

If we see an asteroid that's coming toward us, headed right for us,

如果有必要 如果看到一颗小行星飞来

正朝着我们飞过来

and we have two years to go?

我们还有两年的时间 砰！击中它

Boom! We hit it.

You know, if you watch the movies --

我们可以试试看 如果你看电影

(Laughter)

你可能会想

you might think:

Why don't we use a nuclear weapon?

为什么我们不用核武器呢

Well, you can try that, but the problem is timing.

你可以尝试用核武器 但是发射时间很成问题

Shoot a nuclear weapon at this thing,

对这样的天体发射核弹

you have to blow it up within a few milliseconds of tolerance,

你必须在几毫秒之内锁定目标

否则你就会脱靶

or else you'll miss it.

And there are a lot of other problems with that; it's very hard to do.

这里面有很多问题

操作相当困难

But just hitting something? That's pretty easy.

但想要打中一个物体 是轻而易举的

I think even NASA can do that, and proved that they can.

连NASA都办得到

他们以实力证明了这一点 （众人笑）

(Laughter)

The problem is, if you hit this asteroid, you've changed the orbit,

问题是 如果击中了这颗小行星

它的轨道改变了 会发生什么情况

you measure the orbit,

then you find out, oh yeah, we just pushed it into a keyhole,

你测量了它的轨道 结果发现

呀 正好 我们把它推到钥匙眼里了

and now it's going to hit us in three years.

它三年后就要撞地球了

Well, my opinion is: fine!

我以为 这也无妨

It's not hitting us in six months --

反正它不会在半年内撞上我们 这就行了

that's good.

Now we have three years to do something else.

我们有三年的时间来应对

And you can hit it again.

你可以再打它一次

That's kind of ham-fisted;

真是重拳出击啊 结果可能把它推进另一个钥匙眼

you might just push it into a third keyhole or whatever,

不太明智

so you don't do that.

这是我最喜欢的部分

And this is the part --

it's the part I just love.

(Laughter)

（众人笑）

After the big macho "Grr ... bam! We're gonna hit this thing in the face,"

我们先来硬的：“啊呀呀！砰！

我们给这个家伙当头一棒。"

接着再来软的

then we bring in the velvet gloves.

（众人笑）

(Laughter)

There's a group of scientists and engineers and astronauts,

有这样一群科学家 工程师

和宇航员 他们称自己为

and they call themselves The B612 Foundation.

B612 Foundation组织

For those of you who've read "The Little Prince,"

你们要是读过《小王子》这本书

you understand that reference, I hope --

就该明白这个名称的出处

the little prince lived on an asteroid called B612.

小王子住在一颗小行星上 这颗行星就叫B612

These are smart guys -- men and women -- astronauts, like I said, engineers.

这是一群聪明人 有男有女

宇航员 工程师

Rusty Schweickart, who was an Apollo 9 astronaut, is on this.

Rusty Schweickart 曾是阿波罗9号的宇航员

我的朋友Dan Durda

Dan Durda, my friend who made this image,

拍摄这张图片的人

works here at Southwest Research Institute in Boulder, on Walnut Street.

现在在Walnut街的博尔德西南研究院工作

他拍摄了这张图片

He created this image for this.

他实际上是在这里工作的

He's actually one of the astronomers who works for them.

天文学家之一 如果我们发现一颗小行星

If we see an asteroid that's going to hit the Earth

即将撞击地球

and we have enough time,

我们有足够的时间 对它进行打击

we can hit it to move it into a better orbit.

把它推入一个更利于我们的轨道

But then what we do is launch a probe that has to weigh a ton or two.

我们要做的是将一个重一两吨的探测器发射出去

探测器体积不需太大 几吨重就行了

It doesn't have to be huge -- a couple of tons, not that big --

个头不大 你可以把它停在小行星旁边

and you park it near the asteroid.

You don't land on it, because these things are tumbling end over end.

不要把它降落在上面

因为这些天体不稳 很难在上面降落

It's very hard to land on them.

Instead you get near it.

因而要停在它近旁

The gravity of the asteroid pulls on the probe,

小行星的引力会把探测器拉近

and the probe has a couple of tons of mass.

探测器有几吨的质量

It has a little tiny bit of gravity,

探测器只有一点引力 但这足够

but it's enough that it can pull the asteroid,

让它与小行星拉近

and you have your rocket set up --

探测器上装有火箭 噢 你可能看不清楚

you can barely see it here, but there's rocket plumes --

但上面确有火箭发射器

这些家伙都由引力连接在一起

and these guys are connected by their own gravity,

如果你慢慢地 轻轻地移动探测器

and if you move the probe very slowly -- very, very gently,

你可以轻易地

you can very easily finesse that rock into a safe orbit.

把那颗小行星移入一个安全轨道

你甚至可以把它移到围绕地球的

You can even put in orbit around the Earth where we could mine it,

一个轨道上以便把它炸掉

although that's a whole other thing; I won't go into that.

但这是另一回事了 我就不奔那儿去了

（众人笑）

(Laughter)

But we'd be rich!

但是 我们到时候就发财了

(Laughter)

（众人笑）

So think about this, right?

设想一下

这些巨石在太空中飞来飞去

There are these giant rocks flying out there, and they're hitting us,

准备撞上地球

and they're doing damage to us.

造成破坏 而我们已经找到办法

But we've figured out how to do this,

所有防御工作都落实到位了

and all the pieces are in place to do this.

We have astronomers with telescopes, looking for them.

我们有天文学家 各就各位 使用望远镜

寻找这些天体 我们有一群聪明人

We have very, very smart people,

非常非常聪明的人 他们关心这个问题

who are concerned about this and figuring out how to fix the problem,

并想办法解决问题

我们还具备了相应的科技

and we have the technology to do this.

This probe actually can't use chemical rockets.

这个探测器实际上不能使用化学火箭

Chemical rockets provide too much thrust, too much push.

化学火箭的助推力太强

会把探测器打飞

The probe would just shoot away.

我们发明了离子助推器

We invented something called an ion drive,

这是个助推力非常低的引擎

which is a very, very, very low-thrust engine.

It generates the force a piece of paper would have on your hand --

它制造出的力

如同放在手上的一张纸 出奇地轻

incredibly light, but it can run for months and years,

但它能够经年累月地工作

制造这样一种轻柔的力

providing that very gentle push.

If anybody here is a fan of the original "Star Trek,"

喜欢原版“星际迷航”（电影）的人应该知道

当他们碰到一架装有

they ran across an alien ship that had an ion drive,

离子助推器的外星飞船时Spock说：

and Spock said, "They're very technically sophisticated.

“这些仪器的技术含量太高了。

They're a hundred years ahead of us with this drive."

他们的助推器领先我们一百年。”

我们现在也有离子助推器啦 （众人笑）

Yeah, we have an ion drive now.

We don't have the Enterprise, but we've got an ion drive now.

我们还没有“进取号”飞船

但我们有离子助推器

(Laughter)

（众人鼓掌）

(Applause)

Spock.

Spock（电影人物名）

(Laughter)

（众人笑）

So ...

因此

That's the difference --

这就是我们和恐龙之间的

that's the difference between us and the dinosaurs.

不同之处

This happened to them.

这是它们的结局

It doesn't have to happen to us.

这样的结局不会发生在我们身上

The difference between the dinosaurs and us

我们和恐龙之间的不同

is that we have a space program

在于我们有太空项目

我们可以投选票

and we can vote,

and so we can change our future.

因此我们能够改变未来

(Laughter)

（众人笑）

We have the ability to change our future.

我们有能力改变未来

Sixty-five million years from now,

6500万年之后

we don't have to have our bones collecting dust in a museum.

我们的骨头

不会被放在博物馆里接灰尘

Thank you very much.

非常感谢大家

(Applause)

（众人鼓掌）