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The universe is teeming with planets.

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I want us, in the next decade,

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

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an Earth about another star

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and figure out whether it can harbor life.

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My colleagues at the NASA[br]Jet Propulsion Laboratory

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at Princeton and I are working on technology

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

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Astronomers now believe that every star

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in the galaxy has a planet,

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and they speculate that up to one fifth of them

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have an Earth-like planet

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that might be able to harbor life,

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but we haven't seen any of them.

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We've only detected them indirectly.

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

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It was taken by the Voyager spacecraft in 1990,

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when they turned it around as[br]it was exiting the solar system

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to take a picture of the Earth

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from six billion kilometers away.

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I want to take that

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of an Earth-like planet about another star.

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

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Well to see, let's imagine we take

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the Hubble Space Telescope

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and we turn it around and we move it out

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to the orbit of Mars.

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We'll see something like that,

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a slightly blurry picture of the Earth,

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because we're a fairly small telescope

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out at the orbit of Mars.

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Now let's move ten times further away.

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Here we are at the orbit of Uranus.

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

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We can still see the little moon,

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but let's go ten times further away again.

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Here we are at the edge of the solar system,

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out at the Kuiper Belt.

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Now it's not resolved at all.

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

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

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Here we are out at the Oort Cloud,

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outside the solar system,

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and we're starting to see the sun

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move into the field of view

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and get into where the planet is.

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One more time, ten times further away.

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Now we're at Alpha Centauri,

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our nearest neighbor star,

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and the planet is gone.

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

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that's ten billion times brighter than the planet,

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which should be in that little red circle.

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

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The light from the star is diffracting.

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It's scattering inside the telescope,

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creating that very bright image

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that washes out the planet.

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So to see the planet,

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we have to do something about all of that light.

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We have to get rid of it.

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I have a lot of colleagues working on

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really amazing technologies to do that,

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but I want to tell you about one today

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that I think is the coolest,

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and probably the most likely to get us an Earth

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in the next decade.

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It was first suggested by Lyman Spitzer,

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the father of the space telescope, in 1962,

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and he took his inspiration from an eclipse.

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

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The moon has moved in front of the sun.

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It blocks out most of the light

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so we can see that dim corona around it.

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

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

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I can see you in the back row.

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Well, what's going on?

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Well the moon

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is casting a shadow down on the Earth.

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We put a telescope or a camera in that shadow,

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we look back at the sun,

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and most of the light's been removed

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and we can see that dim, fine structure

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in the corona.

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Spitzer's suggestion was we do this in space.

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

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we put it up in front of the star,

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we block out most of the light,

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

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and boom, we get to see planets.

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Well that would look something like this.

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So there's that big screen,

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and there's no planets,

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because unfortunately it doesn't[br]actually work very well,

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because the light waves of the light and waves

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diffracts around that screen

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the same way it did in the telescope.

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

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and all that light just destroys the shadow.

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

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But Spitzer actually knew the answer.

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If we can feather the edges, soften those edges

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so we can control diffraction,

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well then we can see a planet,

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

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with optimal solutions for doing that.

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It looks something like that.

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We call that our flower petal starshade.

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If we make the edges of those petals exactly right,

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if we control their shape,

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we can control diffraction,

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and now we have a great shadow.

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

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

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

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That starshade is about

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the size of half a football field

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

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that has to be held right in its shadow,

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and then we can see those planets.

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This sounds formidable,

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but brilliant engineers, colleagues of mine at JPL,

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came up with a fabulous design for how to do that

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and it looks like this.

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It starts wrapped around a hub.

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It separates from the telescope.

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The petals unfurl, they open up,

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the telescope turns around.

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Then you'll see it flip and fly out

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that 50,000 kilometers away from the telescope.

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It's going to move in front of the star

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just like that, creates a wonderful shadow.

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Boom, we get planets orbiting about it.

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(Applause)

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Thank you.

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That's not science fiction.

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

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Last summer, we did a really cool test

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out in California at Northrop Grumman.

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So those are four petals.

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This is a sub-scale star shade.

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

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You'll see the petals unfurl.

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Those four petals were built by four undergraduates

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doing a summer internship at JPL.

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Now you're seeing it deploy.

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Those petals have to rotate into place.

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The base of those petals

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has to go to the same place every time

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to within a tenth of a millimeter.

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We ran this test 16 times,

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and 16 times it went into the exact same place

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to a tenth of a millimeter.

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This has to be done very precisely,

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

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if we can get it into space,

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you might see something like this.

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That's a picture of one our nearest neighbor stars

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taken with the Hubble Space Telescope.

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If we can take a similar space telescope,

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slightly larger,

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put it out there,

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fly an occulter in front of it,

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what we might see is something like that --

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

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

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as seen through an occulter,

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through a starshade like that.

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You can see Jupiter, you can see Saturn,

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Uranus, Neptune, and right there in the center,

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next to the residual light

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is that pale blue dot. That's Earth.

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

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oxygen, ozone,

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

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I think this is the coolest possible science.

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That's why I got into doing this,

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because I think that will change the world.

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That will change everything when we see that.

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Thank you.

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(Applause)