The flower-shaped starshade that might help us detect Earth-like planets
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0:01 - 0:04The universe is teeming with planets.
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0:04 - 0:06I want us, in the next decade,
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0:06 - 0:08to build a space telescope that'll be able to image
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0:08 - 0:10an Earth about another star
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0:10 - 0:13and figure out whether it can harbor life.
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0:13 - 0:15My colleagues at the NASA
Jet Propulsion Laboratory -
0:15 - 0:18at Princeton and I are working on technology
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0:18 - 0:22that will be able to do just that in the coming years.
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0:22 - 0:24Astronomers now believe that every star
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0:24 - 0:26in the galaxy has a planet,
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0:26 - 0:28and they speculate that up to one fifth of them
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0:28 - 0:29have an Earth-like planet
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0:29 - 0:31that might be able to harbor life,
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0:31 - 0:33but we haven't seen any of them.
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0:33 - 0:35We've only detected them indirectly.
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0:35 - 0:38This is NASA's famous picture of the pale blue dot.
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0:38 - 0:41It was taken by the Voyager spacecraft in 1990,
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0:41 - 0:44when they turned it around as
it was exiting the solar system -
0:44 - 0:46to take a picture of the Earth
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0:46 - 0:48from six billion kilometers away.
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0:48 - 0:50I want to take that
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0:50 - 0:52of an Earth-like planet about another star.
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0:52 - 0:55Why haven't we done that? Why is that hard?
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0:55 - 0:56Well to see, let's imagine we take
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0:56 - 0:58the Hubble Space Telescope
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0:58 - 1:00and we turn it around and we move it out
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1:00 - 1:01to the orbit of Mars.
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1:01 - 1:02We'll see something like that,
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1:02 - 1:05a slightly blurry picture of the Earth,
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1:05 - 1:07because we're a fairly small telescope
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1:07 - 1:08out at the orbit of Mars.
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1:08 - 1:10Now let's move ten times further away.
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1:10 - 1:12Here we are at the orbit of Uranus.
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1:12 - 1:15It's gotten smaller, it's got less detail, less resolve.
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1:15 - 1:17We can still see the little moon,
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1:17 - 1:19but let's go ten times further away again.
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1:19 - 1:20Here we are at the edge of the solar system,
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1:20 - 1:22out at the Kuiper Belt.
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1:22 - 1:23Now it's not resolved at all.
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1:23 - 1:26It's that pale blue dot of Carl Sagan's.
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1:26 - 1:28But let's move yet again ten times further away.
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1:28 - 1:30Here we are out at the Oort Cloud,
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1:30 - 1:31outside the solar system,
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1:31 - 1:33and we're starting to see the sun
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1:33 - 1:34move into the field of view
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1:34 - 1:36and get into where the planet is.
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1:36 - 1:38One more time, ten times further away.
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1:38 - 1:40Now we're at Alpha Centauri,
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1:40 - 1:41our nearest neighbor star,
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1:41 - 1:42and the planet is gone.
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1:42 - 1:45All we're seeing is the big beaming image of the star
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1:45 - 1:48that's ten billion times brighter than the planet,
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1:48 - 1:50which should be in that little red circle.
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1:50 - 1:52That's what we want to see. That's why it's hard.
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1:52 - 1:54The light from the star is diffracting.
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1:54 - 1:56It's scattering inside the telescope,
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1:56 - 1:57creating that very bright image
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1:57 - 1:59that washes out the planet.
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1:59 - 2:00So to see the planet,
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2:00 - 2:03we have to do something about all of that light.
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2:03 - 2:04We have to get rid of it.
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2:04 - 2:05I have a lot of colleagues working on
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2:05 - 2:07really amazing technologies to do that,
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2:07 - 2:09but I want to tell you about one today
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2:09 - 2:11that I think is the coolest,
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2:11 - 2:13and probably the most likely to get us an Earth
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2:13 - 2:14in the next decade.
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2:14 - 2:16It was first suggested by Lyman Spitzer,
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2:16 - 2:20the father of the space telescope, in 1962,
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2:20 - 2:22and he took his inspiration from an eclipse.
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2:22 - 2:24You've all seen that. That's a solar eclipse.
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2:24 - 2:26The moon has moved in front of the sun.
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2:26 - 2:28It blocks out most of the light
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2:28 - 2:30so we can see that dim corona around it.
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2:30 - 2:32It would be the same thing if I put my thumb up
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2:32 - 2:34and blocked that spotlight
that's getting right in my eye, -
2:34 - 2:36I can see you in the back row.
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2:36 - 2:38Well, what's going on?
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2:38 - 2:40Well the moon
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2:40 - 2:42is casting a shadow down on the Earth.
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2:42 - 2:45We put a telescope or a camera in that shadow,
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2:45 - 2:47we look back at the sun,
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2:47 - 2:48and most of the light's been removed
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2:48 - 2:50and we can see that dim, fine structure
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2:50 - 2:52in the corona.
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2:52 - 2:54Spitzer's suggestion was we do this in space.
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2:54 - 2:57We build a big screen, we fly it in space,
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2:57 - 2:59we put it up in front of the star,
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2:59 - 3:01we block out most of the light,
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3:01 - 3:04we fly a space telescope in
that shadow that's created, -
3:04 - 3:06and boom, we get to see planets.
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3:06 - 3:08Well that would look something like this.
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3:08 - 3:10So there's that big screen,
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3:10 - 3:11and there's no planets,
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3:11 - 3:13because unfortunately it doesn't
actually work very well, -
3:13 - 3:16because the light waves of the light and waves
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3:16 - 3:18diffracts around that screen
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3:18 - 3:20the same way it did in the telescope.
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3:20 - 3:23It's like water bending around a rock in a stream,
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3:23 - 3:25and all that light just destroys the shadow.
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3:25 - 3:27It's a terrible shadow. And we can't see planets.
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3:27 - 3:29But Spitzer actually knew the answer.
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3:29 - 3:32If we can feather the edges, soften those edges
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3:32 - 3:33so we can control diffraction,
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3:33 - 3:35well then we can see a planet,
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3:35 - 3:37and in the last 10 years or so we've come up
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3:37 - 3:39with optimal solutions for doing that.
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3:39 - 3:43It looks something like that.
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3:43 - 3:45We call that our flower petal starshade.
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3:45 - 3:48If we make the edges of those petals exactly right,
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3:48 - 3:49if we control their shape,
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3:49 - 3:51we can control diffraction,
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3:51 - 3:52and now we have a great shadow.
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3:52 - 3:55It's about 10 billion times dimmer than it was before,
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3:55 - 3:58and we can see the planets beam out just like that.
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3:58 - 4:00That, of course, has to be bigger than my thumb.
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4:00 - 4:02That starshade is about
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4:02 - 4:03the size of half a football field
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4:03 - 4:07and it has to fly 50,000 kilometers
away from the telescope -
4:07 - 4:09that has to be held right in its shadow,
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4:09 - 4:11and then we can see those planets.
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4:11 - 4:12This sounds formidable,
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4:12 - 4:15but brilliant engineers, colleagues of mine at JPL,
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4:15 - 4:18came up with a fabulous design for how to do that
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4:18 - 4:19and it looks like this.
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4:19 - 4:21It starts wrapped around a hub.
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4:21 - 4:23It separates from the telescope.
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4:23 - 4:25The petals unfurl, they open up,
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4:25 - 4:27the telescope turns around.
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4:27 - 4:29Then you'll see it flip and fly out
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4:29 - 4:32that 50,000 kilometers away from the telescope.
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4:32 - 4:35It's going to move in front of the star
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4:35 - 4:38just like that, creates a wonderful shadow.
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4:38 - 4:42Boom, we get planets orbiting about it.
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4:42 - 4:44(Applause)
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4:44 - 4:46Thank you.
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4:46 - 4:48That's not science fiction.
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4:48 - 4:51We've been working on this
for the last five or six years. -
4:51 - 4:53Last summer, we did a really cool test
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4:53 - 4:56out in California at Northrop Grumman.
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4:56 - 4:57So those are four petals.
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4:57 - 4:59This is a sub-scale star shade.
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4:59 - 5:01It's about half the size of the one you just saw.
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5:01 - 5:03You'll see the petals unfurl.
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5:03 - 5:05Those four petals were built by four undergraduates
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5:05 - 5:07doing a summer internship at JPL.
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5:07 - 5:09Now you're seeing it deploy.
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5:09 - 5:11Those petals have to rotate into place.
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5:11 - 5:12The base of those petals
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5:12 - 5:14has to go to the same place every time
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5:14 - 5:16to within a tenth of a millimeter.
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5:16 - 5:17We ran this test 16 times,
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5:17 - 5:20and 16 times it went into the exact same place
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5:20 - 5:22to a tenth of a millimeter.
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5:22 - 5:24This has to be done very precisely,
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5:24 - 5:26but if we can do this, if we can build this technology,
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5:26 - 5:28if we can get it into space,
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5:28 - 5:29you might see something like this.
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5:29 - 5:32That's a picture of one our nearest neighbor stars
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5:32 - 5:34taken with the Hubble Space Telescope.
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5:34 - 5:37If we can take a similar space telescope,
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5:37 - 5:38slightly larger,
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5:38 - 5:39put it out there,
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5:39 - 5:41fly an occulter in front of it,
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5:41 - 5:43what we might see is something like that --
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5:43 - 5:46that's a family portrait of our
solar system -- but not ours. -
5:46 - 5:48We're hoping it'll be someone else's solar system
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5:48 - 5:50as seen through an occulter,
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5:50 - 5:51through a starshade like that.
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5:51 - 5:53You can see Jupiter, you can see Saturn,
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5:53 - 5:56Uranus, Neptune, and right there in the center,
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5:56 - 5:57next to the residual light
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5:57 - 5:59is that pale blue dot. That's Earth.
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5:59 - 6:01We want to see that, see if there's water,
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6:01 - 6:03oxygen, ozone,
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6:03 - 6:05the things that might tell us that it could harbor life.
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6:05 - 6:08I think this is the coolest possible science.
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6:08 - 6:09That's why I got into doing this,
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6:09 - 6:11because I think that will change the world.
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6:11 - 6:14That will change everything when we see that.
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6:14 - 6:15Thank you.
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6:15 - 6:19(Applause)
- Title:
- The flower-shaped starshade that might help us detect Earth-like planets
- Speaker:
- Jeremy Kasdin
- Description:
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Astronomers believe that every star in the galaxy has a planet, one fifth of which might harbor life. Only we haven't seen any of them — yet. Jeremy Kasdin and his team are looking to change that with the design and engineering of an extraordinary piece of equipment: a flower petal-shaped "starshade" that allows a telescope 50,000 kilometers away to photograph planets. It is, he says, the "coolest possible science."
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 06:38
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast approved English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Morton Bast edited English subtitles for The flower-shaped starshade that might help us detect Earth-like planets | ||
Madeleine Aronson accepted English subtitles for The flower-shaped starshade that might help us detect Earth-like planets |