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

翻译人员: Yuanqing Edberg 校对人员: Xin Cui

The universe is teeming with planets.

宇宙富含了星球。

I want us, in the next decade,

我想要我们，在下一个十年

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

建造一个宇宙望远镜，那样就可以看见

an Earth about another star

围绕另外星球的一个地球

and figure out whether it can harbor life.

并且弄清楚它是否能存活生命。

My colleagues at the NASA Jet Propulsion Laboratory

我在NASA普林斯顿喷射动力实验室

at Princeton and I are working on technology

的同事们和我正在致力于一项技术

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

在即将来到的年月里，将能够达到那个目的。

Astronomers now believe that every star

宇航员现在相信银河系的每个星球

in the galaxy has a planet,

都有一个行星，

and they speculate that up to one fifth of them

并且他们推测他们中间的五分之一

have an Earth-like planet

有着一个类似地球的行星

that might be able to harbor life,

可能会存在生命，

but we haven't seen any of them.

但是我们还没有看见他们中的任何一个

We've only detected them indirectly.

我们只是间接地测试到了它们。

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

这是NASA 著名的淡蓝色点的图像。

It was taken by the Voyager spacecraft in 1990,

是1990年由航天宇宙飞船摄制的，

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

当它们飞出地球作为太阳系的一个存在

to take a picture of the Earth

给地球照照片

from six billion kilometers away.

从六千万千米以外

I want to take that

我想要

of an Earth-like planet about another star.

给围绕另外一个星球的像地球模样的行星照相

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

我们为什么还没有那样做呢？那为什么很难呢？

Well to see, let's imagine we take

好吧，来看看，让我们想像我们带着

the Hubble Space Telescope

哈勃宇宙望远镜

and we turn it around and we move it out

我们掉转方向，并且把它从

to the orbit of Mars.

火星的轨道中挪出来

We'll see something like that,

我们会看到有些东西像那样，

a slightly blurry picture of the Earth,

一个很轻微的模糊的地球的照片，

because we're a fairly small telescope

因为我们是相对很小的望远镜

out at the orbit of Mars.

在火星的轨道上。

Now let's move ten times further away.

现在让我们把它移到十倍遥远的地方。

Here we are at the orbit of Uranus.

现在我们在天王星的轨道上。

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

它变小了，细节更少，分辨率更低。

We can still see the little moon,

我们还是能看到小小的月亮，

but let's go ten times further away again.

但现在让我们再次行进到十倍遥远

Here we are at the edge of the solar system,

这儿是我们在银河系的边界，

out at the Kuiper Belt.

在柯伊伯带之外。

Now it's not resolved at all.

现在完全不能分辨了。

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

它是那个是凯尔.赛甘的淡蓝点

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

但是，让我们再移到又一个十倍遥远的距离

Here we are out at the Oort Cloud,

这时我们在奥尔特云以外，

outside the solar system,

在银河系以外了，

and we're starting to see the sun

我们开始见到太阳

move into the field of view

移动到可见的地方

and get into where the planet is.

照进行星所在处

One more time, ten times further away.

再一次，十倍更远的距离

Now we're at Alpha Centauri,

现在我们在阿尔法半人马座，

our nearest neighbor star,

靠我们最近的星球，

and the planet is gone.

行星不见了，

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

我们所看见的是一个星球的巨大光柱。

that's ten billion times brighter than the planet,

那比行星耀眼一百亿倍，

which should be in that little red circle.

应该是在那个小小的红色圈子里。

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

那就是我们想看见的。那就是它为什么这么艰难的缘故。

从星球而来的光是衍射的。

The light from the star is diffracting.

在望远镜内分散，

It's scattering inside the telescope,

creating that very bright image

造成了很明亮的图像

that washes out the planet.

冲淡了行星的光亮

So to see the planet,

那样的话，要看到行星，

we have to do something about all of that light.

我们不得不对那些光做些事情。

We have to get rid of it.

我们必须消除它。

I have a lot of colleagues working on

我有很多同事们正在致力于

really amazing technologies to do that,

用真正的神奇的技术处理那个，

但今天我想要告诉你们的

but I want to tell you about one today

我认为是最酷的，

that I think is the coolest,

and probably the most likely to get us an Earth

最可能的给我们一个地球

in the next decade.

可能在下一个十年。

It was first suggested by Lyman Spitzer,

它最先由莱曼.思庇哲提议

the father of the space telescope, in 1962,

他是天文望远镜之父，在1962年

and he took his inspiration from an eclipse.

他带着他从一次日食而来的灵感

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

你们已经看到，那是太阳系的日食。

The moon has moved in front of the sun.

月亮已经移到太阳的前面。

It blocks out most of the light

它挡住了大部分的光

so we can see that dim corona around it.

所以我们能看到的是那种微弱的围绕它的光晕

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

如果我把我的大拇指竖起来也会是同样的

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

而且封锁了将要射进我眼里的光点

我能看见你在最后一排。

I can see you in the back row.

好了，怎么一回事呢？

Well, what's going on?

Well the moon

好吧，是月亮

在地球上投下了一个阴影

is casting a shadow down on the Earth.

We put a telescope or a camera in that shadow,

我们在那个阴影里放了一座望远镜或者一架照相机

we look back at the sun,

我们回看着太阳，

and most of the light's been removed

大部分的光被挡住了

and we can see that dim, fine structure

而且我们能看到那个微弱的，细致的结构

in the corona.

在光晕里的。

Spitzer's suggestion was we do this in space.

思庇哲建议的是我们在宇宙里这样做

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

我们要飞进宇宙，我们要建立一个大屏幕，

we put it up in front of the star,

我们把它放在星球之前，

we block out most of the light,

我们把大部分光都挡住

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

我们带着一架望远镜在人为的阴影中飞翔在宇宙，

and boom, we get to see planets.

妙极了，我们就看见了行星。

Well that would look something like this.

好吧，那就像看见了这样的东西。

So there's that big screen,

这儿是那个大荧幕，

也没有什么行星，

and there's no planets,

because unfortunately it doesn't actually work very well,

因为很不幸地它并不怎么起作用，

because the light waves of the light and waves

因为光波的光和波

diffracts around that screen

在荧幕周围衍射

the same way it did in the telescope.

跟在望远镜里是一样的。

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

就像水绕着石头形成的溪流

and all that light just destroys the shadow.

所有的光只是毁掉了阴影。

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

它是一个可怕的阴霾，我们看不见行星。

But Spitzer actually knew the answer.

但思庇哲实际上知道这个答案。

If we can feather the edges, soften those edges

如果我们能把边缘弄成羽毛状，把边缘变成柔软的

so we can control diffraction,

那么我们就能控制衍射，

well then we can see a planet,

那么我们就能看到行星，

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

于是在过去十年，我们就有了

with optimal solutions for doing that.

那样做的光学解决办法。

It looks something like that.

它看起来就像那个样子。

We call that our flower petal starshade.

我们叫它做我们的花瓣星翳。

If we make the edges of those petals exactly right,

如果我们把这些花瓣的边缘做得正好正确，

if we control their shape,

如果我们控制它们的形状，

we can control diffraction,

我们就可以控制衍射，

and now we have a great shadow.

现在我们有了巨大的阴影。

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

大约比以前的暗淡了100亿倍，

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

接下来，我们能看见行星的光柱就像那个样子。

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

那，当然，一定要比我的拇指大。

That starshade is about

那个星翳的尺寸大约

the size of half a football field

半个足球场那么大

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

并且它必须飞到望远镜以外的5万千米

that has to be held right in its shadow,

在那儿它必须停在它的阴影中间，

and then we can see those planets.

然后我们就能看到那些行星。

This sounds formidable,

这个听起来艰巨

but brilliant engineers, colleagues of mine at JPL,

但卓越的工程师们，我的JPL的同事们

came up with a fabulous design for how to do that

想出了制作那个的极好的设计

and it looks like this.

它看起来就像这个样子。

It starts wrapped around a hub.

It separates from the telescope.

它开始围绕着一个枢纽。

它可以从望远镜分离。

The petals unfurl, they open up,

花瓣撑着，全部打开，

the telescope turns around.

望远镜旋转过来，

Then you'll see it flip and fly out

然后你会看到它翻转并且飞出

that 50,000 kilometers away from the telescope.

到离开望远镜5万千米以外

It's going to move in front of the star

它会移动到星球前面

just like that, creates a wonderful shadow.

就像那样，营造一个神奇的阴影。

Boom, we get planets orbiting about it.

妙极了，我们得到它的行星轨道。

(Applause)

鼓掌

Thank you.

谢谢你们。

That's not science fiction.

那不是科幻小说。

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

我们已经工作了五六年

Last summer, we did a really cool test

去年夏天，我们做了一个很酷的试验

out in California at Northrop Grumman.

在加州的诺斯洛浦.格鲁门公司。

So those are four petals.

那是四个花瓣，

This is a sub-scale star shade.

这是一个亚尺寸的星翳

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

是你才看到的一半大小。

You'll see the petals unfurl.

你会看见撑开的花瓣。

Those four petals were built by four undergraduates

这四个花瓣由四个大学生组建

doing a summer internship at JPL.

他们在JPL做夏天的实习。

Now you're seeing it deploy.

现在你看到它的配置。

Those petals have to rotate into place.

这些花瓣必须旋转到位。

The base of those petals

这些花瓣的底部

has to go to the same place every time

每次必须走到同一个地方

to within a tenth of a millimeter.

在十分之一毫米之间

We ran this test 16 times,

我们试验了十六次，

and 16 times it went into the exact same place

十六次它都进入了的的确确的同一个地方

to a tenth of a millimeter.

在十分之一毫米处。

This has to be done very precisely,

这必须做得非常精确，

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

但如果我们能做到这个，如果我们能建造这个技术，

if we can get it into space,

如果我们能把它带入宇宙，

you might see something like this.

你也许可以看见像这样的一些东西。

That's a picture of one our nearest neighbor stars

那是最靠近我们的邻居星球的图片

taken with the Hubble Space Telescope.

是用哈勃望远镜摄制的。

If we can take a similar space telescope,

如果我们能带着类似的望远镜，

slightly larger,

稍微大一些的

put it out there,

把它发放到那里，

fly an occulter in front of it,

在它前面飞起一个遮光体，

what we might see is something like that --

我们有可能看到像那样的东西－

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

那是我们太阳系的家庭合照－但不是我们的，

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

我们希望它会是其他人的太阳系

as seen through an occulter,

通过遮光体看到的，

through a starshade like that.

通过那样一个星翳。

You can see Jupiter, you can see Saturn,

你能看到木星，你能看到土星，

Uranus, Neptune, and right there in the center,

天王星，海王星，并且在正中间这儿

next to the residual light

挨着这点儿余光

is that pale blue dot. That's Earth.

是那个淡蓝的圆点。那就是地球。

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

我们想看到那个，看看那里是否有水，

oxygen, ozone,

氧气，大气层，

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

这些东西可以告诉我们它是否能让生命存活。

I think this is the coolest possible science.

我以为这是最酷的有可能实现的科学

That's why I got into doing this,

那就是我为什么专注于此，

because I think that will change the world.

因为我认为那会改变世界。

That will change everything when we see that.

那会改变每一件事，当我们看见那个行星的时候

Thank you.

感谢你们

(Applause)

鼓掌