The flower-shaped starshade that might help us detect Earth-like planets | Jeremy Kasdin

譯者: Hanling Chen 審譯者: Qingqing Mao

The universe is teeming with planets.

宇宙裡到處都有行星

I want us, in the next decade,

我想要我們在下個十年里

to build a space telescope that'll be able to image

建一台太空望遠鏡

an Earth about another star

可以拍攝到繞著另一顆恆星的另一個地球

and figure out whether it can harbor life.

並弄清它是否可以孕育生命

My colleagues at the NASA Jet Propulsion Laboratory

我和美國太空總署噴氣推進實驗室的同事

at Princeton and I are working on technology

在普林斯頓正在研發

that will be able to do just that in the coming years.

可以在未來實現這技術

Astronomers now believe that every star

天文學家現在相信銀河系裡的

in the galaxy has a planet,

每顆恆星都有一個行星

and they speculate that up to one fifth of them

並且他們推測其中多達五分之一

have an Earth-like planet

是像地球一樣的行星

that might be able to harbor life,

也許能夠孕育生命

but we haven't seen any of them.

但是我們到現在一個也沒有看見

We've only detected them indirectly.

我們只是間接地探測

This is NASA's famous picture of the pale blue dot.

這是美國太空總署著名的暗淡藍點照片

It was taken by the Voyager spacecraft in 1990,

照片由旅行者號探測器拍攝於1990年

when they turned it around as it was exiting the solar system

當它準備離開太陽系的時候轉了個頭

to take a picture of the Earth

從六十億公里遠外

from six billion kilometers away.

拍攝了地球的照片

I want to take that

我想要拍張

of an Earth-like planet about another star.

環繞其它恆星的另一個地球的照片

Why haven't we done that? Why is that hard?

為什麼我們還沒有這麼做？為什麼這麼難？

Well to see, let's imagine we take

好吧，我們來想像

the Hubble Space Telescope

把哈勃太空望遠鏡

and we turn it around and we move it out

轉過頭來

to the orbit of Mars.

並移到火星軌道

We'll see something like that,

我們會看到類似這樣的東西

a slightly blurry picture of the Earth,

一張略為模糊的地球照片

because we're a fairly small telescope

因為我們是位於火星軌道的

out at the orbit of Mars.

一台相當小的望遠鏡

Now let's move ten times further away.

現在我們移到十倍遠外

Here we are at the orbit of Uranus.

我們現在在天王星軌道

It's gotten smaller, it's got less detail, less resolve.

它變得更小，細節更少，分辨率更低

We can still see the little moon,

我們仍能看到小小的月亮

but let's go ten times further away again.

但是讓我們再遠離十倍

Here we are at the edge of the solar system,

現在我們到了太陽系的邊緣

out at the Kuiper Belt.

在柯伊伯帶

Now it's not resolved at all.

現在就無法解析了

It's that pale blue dot of Carl Sagan's.

它是卡爾·薩根的暗淡藍點

But let's move yet again ten times further away.

但是讓我們再遠離十倍

Here we are out at the Oort Cloud,

我們到了奧爾特雲

outside the solar system,

太陽系外

and we're starting to see the sun

我們開始看到太陽

move into the field of view

進入了視野

and get into where the planet is.

取代了地球的位置

One more time, ten times further away.

再一次的，十倍遠外

Now we're at Alpha Centauri,

我們現在到了半人馬座阿爾法星

our nearest neighbor star,

我們最近的鄰居恆星

and the planet is gone.

現在完全看不見地球

All we're seeing is the big beaming image of the star

我們僅能看到大的發光的恆星

that's ten billion times brighter than the planet,

比地球亮一百億倍

which should be in that little red circle.

地球應該在那個小紅圈內

That's what we want to see. That's why it's hard.

那是我們想要看到的。這就是為什麼這麼難。

The light from the star is diffracting.

恆星發的光會衍射

It's scattering inside the telescope,

會在望遠鏡裡散射

creating that very bright image

製造很亮的圖像

that washes out the planet.

掩蓋了地球

So to see the planet,

所以為了看到地球

we have to do something about all of that light.

我們必須對這些光做點什麼

We have to get rid of it.

我們必須除掉它

I have a lot of colleagues working on

我有很多同事正在研發

really amazing technologies to do that,

很多可以做到這點的驚人的科技

but I want to tell you about one today

但是今天我想告訴你其中一個

that I think is the coolest,

我認為是最酷的

and probably the most likely to get us an Earth

而且是最可能幫我們

in the next decade.

在下個十年看到另一個地球

It was first suggested by Lyman Spitzer,

它首先被太空望遠鏡之父

the father of the space telescope, in 1962,

萊曼·史匹哲在1962年提出

and he took his inspiration from an eclipse.

他從日蝕中得到靈感

You've all seen that. That's a solar eclipse.

你們都看過日蝕

The moon has moved in front of the sun.

月亮移到太陽前面

It blocks out most of the light

阻擋了大部分光

so we can see that dim corona around it.

所以我們能看到太陽外層黯淡的日冕

It would be the same thing if I put my thumb up

這個效果就如同

and blocked that spotlight that's getting right in my eye,

如果我把大拇指放到眼前擋住那個聚光燈

I can see you in the back row.

我可以看見後面幾排的人們

Well, what's going on?

那麼，這是什麼情況？

Well the moon

事實上月亮

is casting a shadow down on the Earth.

在地球表面印出了一個影子

We put a telescope or a camera in that shadow,

我們把望遠鏡或者相機放在影子裡

we look back at the sun,

我們再去看太陽

and most of the light's been removed

大部分光線就被擋住了

and we can see that dim, fine structure

我們可以看見日冕裡

in the corona.

暗淡的細節結構

Spitzer's suggestion was we do this in space.

史匹哲的建議我們在太空裡這麼做

We build a big screen, we fly it in space,

我們建一個巨大的擋板發射到太空

we put it up in front of the star,

我們把它放在恆星前面

we block out most of the light,

擋住大部分光線

we fly a space telescope in that shadow that's created,

再發射一個天文望遠鏡到製造的影子裡

and boom, we get to see planets.

從而，我們可以看見行星

Well that would look something like this.

這個想法看起來就像這樣

So there's that big screen,

這就是那個大螢幕，

and there's no planets,

because unfortunately it doesn't actually work very well,

但是並沒有行星

因為很不幸的是那並不能很好的工作

because the light waves of the light and waves

因為光波

在螢幕周圍衍射

diffracts around that screen

the same way it did in the telescope.

和在望遠鏡中一樣

It's like water bending around a rock in a stream,

就像是溪流中的水繞過石頭

and all that light just destroys the shadow.

所以這些光就把影子破壞了，變成糟糕的影子

It's a terrible shadow. And we can't see planets.

這樣我們看不見行星

But Spitzer actually knew the answer.

但是史匹哲實際上知道答案

If we can feather the edges, soften those edges

如果我們可以羽化邊緣，使邊緣變得柔和

so we can control diffraction,

我們就可以控制衍射

well then we can see a planet,

那樣我們就可以看見行星

and in the last 10 years or so we've come up

在最近十年我們想出了

with optimal solutions for doing that.

最好的解決辦法

It looks something like that.

看起來像那樣的東西

We call that our flower petal starshade.

我們稱之為花瓣形遮星板

If we make the edges of those petals exactly right,

如果我們把花瓣的邊緣設計得剛剛好

if we control their shape,

如果我們可以控制它們的形狀

we can control diffraction,

我們就可以控制衍射

and now we have a great shadow.

這樣我們就可以有一個非常好的影子

It's about 10 billion times dimmer than it was before,

比以前的要暗約一百億倍

and we can see the planets beam out just like that.

我們就可以像這樣看見行星

That, of course, has to be bigger than my thumb.

那個，當然要比我的大拇指要大

That starshade is about

那個遮星板大概

the size of half a football field

和半個足球場差不多大

and it has to fly 50,000 kilometers away from the telescope

而且它必須飛離望遠鏡五萬公里

that has to be held right in its shadow,

望遠鏡必須在影子裡放對位置

and then we can see those planets.

這樣我們就可以看見行星

This sounds formidable,

這聽起來很艱巨

but brilliant engineers, colleagues of mine at JPL,

但是聰明的工程師 -- 我在噴氣推進實驗室的同事們

came up with a fabulous design for how to do that

想出了極好的設計

and it looks like this.

看起來像這個

It starts wrapped around a hub.

它先是包裹著中心軸

It separates from the telescope.

它和望遠鏡分離

The petals unfurl, they open up,

花瓣張開，打開

the telescope turns around.

望遠鏡掉頭

Then you'll see it flip and fly out

接著它就翻轉飛離

that 50,000 kilometers away from the telescope.

離開望遠鏡五萬公里

It's going to move in front of the star

它會停在恆星前面

just like that, creates a wonderful shadow.

就像那樣，製造一個完美的影子

Boom, we get planets orbiting about it.

我們就得到了環繞的行星

(Applause)

（鼓掌）

Thank you.

謝謝

That's not science fiction.

這不是科幻

We've been working on this for the last five or six years.

我們最近五六年致力於此

Last summer, we did a really cool test

去年夏天，在加利福尼亞的 諾斯洛普·格魯門

out in California at Northrop Grumman.

我們進行了一個有意思的測試

So those are four petals.

這就是四片花瓣

This is a sub-scale star shade.

這是一個縮小的遮星板

It's about half the size of the one you just saw.

大概是剛才你看到的那個的一半大

You'll see the petals unfurl.

你會看到花瓣展開

Those four petals were built by four undergraduates

這四片花瓣是四個大學生

doing a summer internship at JPL.

在我們實驗室做暑假實習生的時候做的

Now you're seeing it deploy.

現在你看到的是它的部署

Those petals have to rotate into place.

這些花瓣必須必須旋轉到位

The base of those petals

花瓣的底部

has to go to the same place every time

每次必須到達相同的位置

to within a tenth of a millimeter.

誤差在十分之一毫米以內

We ran this test 16 times,

我們測試了16次

and 16 times it went into the exact same place

16次全部到達了相同位置

to a tenth of a millimeter.

在十分之一毫米以內

This has to be done very precisely,

這個必須非常精準

but if we can do this, if we can build this technology,

如果我們可以這麼做 如果我們可以實現這個技術

if we can get it into space,

如果我們可以把它發射到太空，

you might see something like this.

你將會看到這樣的東西

That's a picture of one our nearest neighbor stars

這是離我們最近的恆星

taken with the Hubble Space Telescope.

由哈勃太空望遠鏡拍攝

If we can take a similar space telescope,

如果我們可以用一個相似的望遠鏡

slightly larger,

稍微大一些的

put it out there,

放在那裡

fly an occulter in front of it,

放飛一個遮光體在它前面，

what we might see is something like that --

我們可能會看到類似這樣的東西

that's a family portrait of our solar system -- but not ours.

這是我們太陽系的全家福

We're hoping it'll be someone else's solar system

但是我們希望看到的是其他人的太陽系

as seen through an occulter,

通過遮光體

通過這樣的遮星板

through a starshade like that.

You can see Jupiter, you can see Saturn,

你可以看見木星，土星

Uranus, Neptune, and right there in the center,

天王星，海王星

就在中間緊靠著殘餘的光

next to the residual light

is that pale blue dot. That's Earth.

是那個暗淡的藍點。那就是地球。

We want to see that, see if there's water,

我們想要看見那個，想要看那裡有沒有水

oxygen, ozone,

氧氣，臭氧層

the things that might tell us that it could harbor life.

這些可以告訴我們 那裡是否可以孕育生命

I think this is the coolest possible science.

我認為這是最酷的可行的科學

That's why I got into doing this,

這就是我為什麼做這個的原因

because I think that will change the world.

因為我認為這將改變世界

That will change everything when we see that.

這將要改變我們看到的一切

Thank you.

謝謝

(Applause)

（鼓掌）