an asteroid was on a collision course for earth?

一個小行星進入了撞擊地球的軌道時會發生什麼事?

Could we detect it ahead of time? And more importantly could we stop it? I believe

我們能不能提前偵測到它? 而更重要的是，我們能否阻止它? 我相信

I have an answer, now you see, asteroid impacts

我有一個答案，你知道，小行星撞撃地球

are serious business, when I was in second grade Ms. McGonigal told us

是一件非常嚴重的事情，當我在二年級時McGonigal女士告訴我們

that the dinosaurs the ancient dinosaurs died out because they had small brains

古老的恐龍消失，是因為牠們的腦細小

may be like

可能像...

my old boss. But even she knew that was kinda lamethat theory was

我的老上司。但即使她知道這是挺無說服力的理論

nothing.

結果事實證明，在我有生之年，人們發現了隕石坑

It turns out in my lifetime people found this crater,

於墨西哥希克蘇鲁伯。這個隕石坑非常之大，有多大? 它就是

off Chicxulub mexico. This crator was so big, how big was it, it was so big

一個小行星撞擊地球那麼大（或是一些撞擊物撞擊地球的大小）

that an asteroid hit the earth (or impactors hit the earth).

撞擊地球時將一大堆的東西放進地球的天空，它本來的直徑

Threw so much stuff into the Earth's sky it was bigger in diameter

比地球本身的還要大，所以地球就被熾熱的岩石包圍著一段時間

than the earth itself so the earth was surrounded by red hot rock for weeks at

它煮熟了一切，只是除了一些住在洞穴的動物

a time,

即我們的祖先，最後演化為我們。一些嚴重的事故你可能會記起情人節

it cooked everything. And just the animals that lived in burrows and caves,

2013年

our ancestors lead to us so serious business you may recall Valentine's Day

俄羅斯車里雅賓斯克空爆。

2013?

如果你是一個小行星，你正以10公里/秒或20公里/秒的速度前進

Chelyabinsk Russia (boom) air burst.

而你擊中地球的大氣層，大氣層就像混凝土一樣硬

See if you are an asteroid, and you are going 10 km /s or 20 km /s

你不能有其他方法，只能在空氣中爆炸。

And you hit the Earth's atmosphere, the atmosphere is like concrete.

因此，這些小行星是嚴重的，其中大多數

you can't get out of the way so the asteroid just explodes in air burst.

都是非常小的。如果你直徑少於10米，你擊中地球的大氣層時會燒掉，成為了

So these asteroids are serious, most of them

藍色的條紋﹑綠色的條紋

are very small. If you're under 10 meters in diameter you hit the Earth's atmosphere you burn up all Big

和白色的條紋，然後人類就會對你許下願望

Blue streak, green streak

（我不知道這些願望有多靈驗，但人們就是這樣做）

white streak and then humans make wishes upon you.

無論如何，

(I don't know house efficacious those wishes are but people do that), alright

如果小行星的體積開始是大一些的，直徑到25米至

so,

45米，那麼你就會有亞利桑那州的流星隕石坑，

if ther asteroid starts to get bigger, starts to get into the twenty-five meters and the

巨大的事情

45 meters in diameter then you get Meteor Crater Arizona (wham) huge

這就好比一個城市的殺手，或是一個縣的殺手

thing.

然後，當它們直徑到達100米至140米，你就會遇到一個國家殺手

That would be like a city killer, or a county killer.

，當它們再大一些就會是一整個大陸的殺手；再變得更大的時候

And then when they get to be a 100 meters / 140 meters now you're into a country killer,

你就會

and then they get bigger than that and it's a continent killer, much bigger than that

有整個不同古老物種的滅亡。

and you're taking out

所以，如果我們發現了一個小行星正向我們前來，我們是怎樣發現它的呢？

whole races of ancient species.

「我們是如何找到向著我們前進的小行星？」這是一個很好的問題

So, what if we found an asteroid that was headed our way, how would we find it?

你可以使用望遠鏡，一些熟練的人可以用相機對準天空並

How would we find an asteroid headed our way? That's a good question, well

尋找快速移動的物體

you can use telescopes. Skilled people can point the cameras at the sky and

一些穿越地球軌道的物體。但我們也許未能發現

look for fast-moving objects.

十萬個這些東西：

Objects that are crossing the Earth's orbit, but we're missing perhaps a

這些縣的殺手，城市的殺手和國家的殺手。

hundred thousand

所以，我們想要做的是去建立一個被稱作"哨兵"的飛船

of these things, of these county killers, city killers and country killers.

就如我們說：「這就像在漆黑中找尋(深黑色的)木炭蜂窩煤」

So, what we want to do is build a spacecraft called The Sentinel,

這些東西是很難找到的。它們與浩瀚的空間相比是微不足道的

and as we say "it's like looking for a charcoal briquette

但红外光和熱會從它們身上反彈，所以你會做什麼 -

in the dark", these things are hard to find. They are tiny compared to the vastness

當你是一顆衛星，你是一個測量飛船

of space.

你會將你的背向著太陽，然後

But infrared light / heat bounces off them so what you will do -

從大約金星的軌道向外看，嘗試找到

you are a satellite, you are a surveying spacecraft,

所有這些小行星。然後當你發現了一個，你會怎樣做？你會跑圈圈尖叫？

you get your back to the Sun and look out

不！不！不！我們應該要將它從軌道中偏離，只是

from about the orbit of Venus. And try to find

一點點，只是一點點就足夠。小行星可能會以10公里/秒前進

all these asteroids. And then you find one, what do you do? Do you run in circles

我們希望改變它的速度

screaming?

約2毫米/秒。

"AH" No, No No, we've got to deflect it, just

所以10公里，即是10乘1000米，即是10000米，

a little, just a tiny amount. Asteroid might be going 10 km/s

一個毫米，即是千分之一米，

we want to change its speed

所以如果你拿千分之一，即會一千乘一萬

about 2 mm/s.

即是10萬。你想改變其速度的千萬分之一

So ten kilometers, that's ten times a thousand meters, that's 10,000 meters.

這其實不是非常多

A millimeter that's a thousandth of

但如果你是一個正衝向地球的小行星

a meter so that you take the one over the thousand its a thousand times ten

並有10,000吨至100,000吨

thousand,

這的確需要蠻多的力去改變它千萬分之一的速度。

that's 10 million. You want to change its speed a 10 millionth

好，那麼

of its total. That's not very much,

我們是怎樣做的呢? 最簡單的方法

but if you're an asteroid that comes in at

是用一支火箭，一支大的火箭，發射到那裡

10,000 tons / 100,000 tonnes,

並撞擊它。除了因為是在太空，它只是（沉默）的像這樣發生

it does take quite a bit force to change it a 10 millionth of its speed.

好吧，這會改變它的速度一點點。現在通知大家，

Okay,

萬一它不只是一塊石頭？如果它是一堆亂石

how do we do that? Well, the easiest way

鬆散地由原始的重力組合在一起？

is to get a rocket, just a big rocket, just go out there and

因此，如果你撞擊它們，他们只會散開，而你只得到一場岩石組成的雨

smack into it. Except as an outer space so it just goes (silence)

這個結果不好。那麼，這個又如何？

like that. Okay, that would change its speed a little, now notice everybody,

我們將會用一個巨大的飛船，這個巨大的飛船將會去那裡

what if it's not just a rock? What if its a pile of rocks just

接近小行星的地方

loosely held together by primordial gravity?

因為接近到它附近，之後就因為相互之間的引力

And so if you hit them they will just spread out and you will have a shower of

你 - 小行星 和 我 - 飛船 之間的引力

rocks.

會拉開小行星一點

That would be bad. So, how about this?

只是一個非常小的距離，或是可能從另一邊也是這樣拉開

We will get a big space craft that is massive, a massive spacecraft will go out there

這可能會奏效，但仍有問題

and just get nearer to the asteroid.

我們需要大量的燃料，以供應數天﹑

Just get near it, and then the mutual gravity

數周，數月以及數年。

of the you the asteroid and me the spacecraft

如果它停止運行，你也不能出去修復它的

will tug the asteroids just a little bit

那麼這又如何 -- 激光？

just a tiny amounth or maybe get on the other side and tug

一組

this way. That might work but here's the problem.

由太陽光為動力的激光器

We need a huge amount of fuel, for days

轟擊小行星的表面

and weeks and months and years.

年年月月如此

And what if it stops working, you can't go out there and fix it. Okay,

ZAP ZAP ZAP，會令到一些小行星，一些岩石被蒸發

how about this? The Laser Bees?

就會產生噴出物，或是將一些東西噴出時產生了動量

A swarm

就像火箭燃料，就像站在滑板上並嘗試

of sunlight powered lasers,

接著一個保齡球...

that are zapping the surface of the asteroid,

這樣做會令

for days, and weeks, and months,and years

小行星改變其速度。而你可以將一些能發射激光的

ZAP ZAP ZAP, so some asteroids, some rock is vaporized

航天器送上天上

so the ejecta, or the stuff ejected has momentum

如果其中一個航天器失效，你亦可以使用另外一個。而且，你可以

just like rocket fuel, just like just like standing on a skateboard and playing

將他們放置於不同角度，如果小行星

catch with a bowling ball...

的形狀是不規則的（像這樣）

the way you do. And so it would then

你可以射它平滑的表面

cause the asteroid to change its speed. And so you send a swarm of these laser

然後當有一个坑或凹陷的地方，你就關掉

spacecraft, so that

等到小行星轉到適合的面，就重新開啟。你看，

if one of them stops working you can use the other one. And you can

只是因為它是不太可能的，並不意味它是不重要的

have them come in from all different angles. And what if the asteroid is

你知道，這可能每幾千年才發生一次，但如果它發生在

irregularly shaped (like this)

我的手錶 (代表: 我生存的時侯)

you could beam it when the thing is smooth

它會像孩子們那樣說：「糟了」。嗯，我們都不希望這種事情發生，我們要

and then when there's a pit or an inefficient place to be beaming you turn

避免這情况。

off,

小行星是嚴重的問題，但它們同時是令人興奮的

you wait for the asteroid to turn, then you turn it back on. You see everybody,

（宇宙飛船噪音）除了我們是在太空中，所以它是（沉默的）。

just because it's unlikely, doesn't mean it's not a big deal.

你有一個極待解决的問題？那麼記緊要訂閱asapscience

You know if it only happens once every few thousand years, well if it happens

在Twitter和Facebook上跟隨我們，這是所有的孩子都在做的事

on my watch

如果它是一个小行星，它可能不是一个燃燒中(極待解决)的問題，而是

it would as the kids say "suck". Okay, so we don't want that to happen, we want to

一個富衝擊性的問題，甚至

avoid that.

是個燒蝕的問題

Asteroids are serious business, but they're exciting.

(Spaceship noise) Except we are in space so its (silence).

Got a burning question? Well be sure to subscribe asapscience, follow us

on Twitter and Facebook, that's what all the kids are doing.

And if it's an asteroid it may not be a burning question, it might be

an impacting question, or even

and ablating question.