WEBVTT 00:00:00.515 --> 00:00:04.118 The universe is teeming with planets. 00:00:04.118 --> 00:00:05.994 I want us, in the next decade, 00:00:05.994 --> 00:00:08.387 to build a space telescope that'll be able to image 00:00:08.387 --> 00:00:10.488 an Earth about another star 00:00:10.488 --> 00:00:13.232 and figure out whether it can harbor life. 00:00:13.232 --> 00:00:15.392 My colleagues at the NASA Jet Propulsion Laboratory 00:00:15.392 --> 00:00:18.253 at Princeton and I are working on technology 00:00:18.253 --> 00:00:21.791 that will be able to do just that in the coming years. 00:00:21.791 --> 00:00:23.776 Astronomers now believe that every star 00:00:23.776 --> 00:00:25.716 in the galaxy has a planet, 00:00:25.716 --> 00:00:27.992 and they speculate that up to one fifth of them 00:00:27.992 --> 00:00:29.068 have an Earth-like planet 00:00:29.068 --> 00:00:30.760 that might be able to harbor life, 00:00:30.760 --> 00:00:32.522 but we haven't seen any of them. 00:00:32.522 --> 00:00:35.260 We've only detected them indirectly. NOTE Paragraph 00:00:35.260 --> 00:00:38.493 This is NASA's famous picture of the pale blue dot. 00:00:38.493 --> 00:00:41.290 It was taken by the Voyager spacecraft in 1990, 00:00:41.290 --> 00:00:44.048 when they turned it around as it was exiting the solar system 00:00:44.048 --> 00:00:45.760 to take a picture of the Earth 00:00:45.760 --> 00:00:48.082 from six billion kilometers away. 00:00:48.082 --> 00:00:49.650 I want to take that 00:00:49.650 --> 00:00:52.232 of an Earth-like planet about another star. NOTE Paragraph 00:00:52.232 --> 00:00:54.632 Why haven't we done that? Why is that hard? 00:00:54.632 --> 00:00:56.054 Well to see, let's imagine we take 00:00:56.054 --> 00:00:58.000 the Hubble Space Telescope 00:00:58.000 --> 00:00:59.698 and we turn it around and we move it out 00:00:59.698 --> 00:01:01.232 to the orbit of Mars. 00:01:01.232 --> 00:01:02.440 We'll see something like that, 00:01:02.440 --> 00:01:04.508 a slightly blurry picture of the Earth, 00:01:04.508 --> 00:01:06.829 because we're a fairly small telescope 00:01:06.829 --> 00:01:08.368 out at the orbit of Mars. 00:01:08.368 --> 00:01:10.384 Now let's move ten times further away. 00:01:10.384 --> 00:01:12.320 Here we are at the orbit of Uranus. 00:01:12.320 --> 00:01:14.806 It's gotten smaller, it's got less detail, less resolve. 00:01:14.806 --> 00:01:16.591 We can still see the little moon, 00:01:16.591 --> 00:01:18.704 but let's go ten times further away again. 00:01:18.704 --> 00:01:20.435 Here we are at the edge of the solar system, 00:01:20.435 --> 00:01:21.733 out at the Kuiper Belt. 00:01:21.733 --> 00:01:23.439 Now it's not resolved at all. 00:01:23.439 --> 00:01:26.103 It's that pale blue dot of Carl Sagan's. 00:01:26.103 --> 00:01:28.303 But let's move yet again ten times further away. 00:01:28.303 --> 00:01:29.927 Here we are out at the Oort Cloud, 00:01:29.927 --> 00:01:31.487 outside the solar system, 00:01:31.487 --> 00:01:33.103 and we're starting to see the sun 00:01:33.103 --> 00:01:34.415 move into the field of view 00:01:34.415 --> 00:01:35.879 and get into where the planet is. 00:01:35.879 --> 00:01:38.010 One more time, ten times further away. 00:01:38.010 --> 00:01:39.663 Now we're at Alpha Centauri, 00:01:39.663 --> 00:01:40.903 our nearest neighbor star, 00:01:40.903 --> 00:01:42.252 and the planet is gone. 00:01:42.252 --> 00:01:44.860 All we're seeing is the big beaming image of the star 00:01:44.860 --> 00:01:47.817 that's ten billion times brighter than the planet, 00:01:47.817 --> 00:01:49.623 which should be in that little red circle. 00:01:49.623 --> 00:01:51.823 That's what we want to see. That's why it's hard. 00:01:51.823 --> 00:01:54.143 The light from the star is diffracting. 00:01:54.143 --> 00:01:55.884 It's scattering inside the telescope, 00:01:55.884 --> 00:01:57.388 creating that very bright image 00:01:57.388 --> 00:01:59.140 that washes out the planet. NOTE Paragraph 00:01:59.140 --> 00:02:00.411 So to see the planet, 00:02:00.411 --> 00:02:02.671 we have to do something about all of that light. 00:02:02.671 --> 00:02:03.902 We have to get rid of it. 00:02:03.902 --> 00:02:05.347 I have a lot of colleagues working on 00:02:05.347 --> 00:02:07.362 really amazing technologies to do that, 00:02:07.362 --> 00:02:09.177 but I want to tell you about one today 00:02:09.177 --> 00:02:10.674 that I think is the coolest, 00:02:10.674 --> 00:02:12.874 and probably the most likely to get us an Earth 00:02:12.874 --> 00:02:14.410 in the next decade. NOTE Paragraph 00:02:14.410 --> 00:02:16.482 It was first suggested by Lyman Spitzer, 00:02:16.482 --> 00:02:19.642 the father of the space telescope, in 1962, 00:02:19.642 --> 00:02:21.758 and he took his inspiration from an eclipse. 00:02:21.758 --> 00:02:23.941 You've all seen that. That's a solar eclipse. 00:02:23.941 --> 00:02:25.981 The moon has moved in front of the sun. 00:02:25.981 --> 00:02:27.741 It blocks out most of the light 00:02:27.741 --> 00:02:30.117 so we can see that dim corona around it. 00:02:30.117 --> 00:02:31.780 It would be the same thing if I put my thumb up 00:02:31.780 --> 00:02:34.365 and blocked that spotlight that's getting right in my eye, 00:02:34.365 --> 00:02:36.277 I can see you in the back row. 00:02:36.277 --> 00:02:37.579 Well, what's going on? 00:02:37.579 --> 00:02:39.524 Well the moon 00:02:39.524 --> 00:02:41.939 is casting a shadow down on the Earth. 00:02:41.939 --> 00:02:45.174 We put a telescope or a camera in that shadow, 00:02:45.174 --> 00:02:46.685 we look back at the sun, 00:02:46.685 --> 00:02:48.325 and most of the light's been removed 00:02:48.325 --> 00:02:50.415 and we can see that dim, fine structure 00:02:50.415 --> 00:02:51.690 in the corona. 00:02:51.690 --> 00:02:54.357 Spitzer's suggestion was we do this in space. 00:02:54.357 --> 00:02:57.134 We build a big screen, we fly it in space, 00:02:57.134 --> 00:02:59.181 we put it up in front of the star, 00:02:59.181 --> 00:03:00.965 we block out most of the light, 00:03:00.965 --> 00:03:03.981 we fly a space telescope in that shadow that's created, 00:03:03.981 --> 00:03:05.758 and boom, we get to see planets. 00:03:05.758 --> 00:03:08.421 Well that would look something like this. 00:03:08.421 --> 00:03:10.010 So there's that big screen, 00:03:10.010 --> 00:03:10.885 and there's no planets, 00:03:10.885 --> 00:03:13.389 because unfortunately it doesn't actually work very well, 00:03:13.389 --> 00:03:16.309 because the light waves of the light and waves 00:03:16.309 --> 00:03:17.989 diffracts around that screen 00:03:17.989 --> 00:03:19.773 the same way it did in the telescope. 00:03:19.773 --> 00:03:22.910 It's like water bending around a rock in a stream, 00:03:22.910 --> 00:03:24.700 and all that light just destroys the shadow. 00:03:24.700 --> 00:03:27.373 It's a terrible shadow. And we can't see planets. NOTE Paragraph 00:03:27.373 --> 00:03:29.140 But Spitzer actually knew the answer. 00:03:29.140 --> 00:03:31.645 If we can feather the edges, soften those edges 00:03:31.645 --> 00:03:33.411 so we can control diffraction, 00:03:33.411 --> 00:03:35.126 well then we can see a planet, 00:03:35.126 --> 00:03:36.925 and in the last 10 years or so we've come up 00:03:36.925 --> 00:03:38.969 with optimal solutions for doing that. 00:03:38.969 --> 00:03:42.501 It looks something like that. 00:03:42.501 --> 00:03:44.846 We call that our flower petal starshade. 00:03:44.846 --> 00:03:47.806 If we make the edges of those petals exactly right, 00:03:47.806 --> 00:03:49.230 if we control their shape, 00:03:49.230 --> 00:03:50.788 we can control diffraction, 00:03:50.788 --> 00:03:52.234 and now we have a great shadow. 00:03:52.234 --> 00:03:54.878 It's about 10 billion times dimmer than it was before, 00:03:54.878 --> 00:03:58.324 and we can see the planets beam out just like that. 00:03:58.324 --> 00:04:00.182 That, of course, has to be bigger than my thumb. 00:04:00.182 --> 00:04:01.640 That starshade is about 00:04:01.640 --> 00:04:03.216 the size of half a football field 00:04:03.216 --> 00:04:06.806 and it has to fly 50,000 kilometers away from the telescope 00:04:06.806 --> 00:04:08.866 that has to be held right in its shadow, 00:04:08.866 --> 00:04:10.830 and then we can see those planets. NOTE Paragraph 00:04:10.830 --> 00:04:12.238 This sounds formidable, 00:04:12.238 --> 00:04:15.246 but brilliant engineers, colleagues of mine at JPL, 00:04:15.246 --> 00:04:18.126 came up with a fabulous design for how to do that 00:04:18.126 --> 00:04:19.200 and it looks like this. 00:04:19.200 --> 00:04:20.988 It starts wrapped around a hub. 00:04:20.988 --> 00:04:22.967 It separates from the telescope. 00:04:22.967 --> 00:04:25.238 The petals unfurl, they open up, 00:04:25.238 --> 00:04:26.998 the telescope turns around. 00:04:26.998 --> 00:04:29.142 Then you'll see it flip and fly out 00:04:29.142 --> 00:04:32.357 that 50,000 kilometers away from the telescope. 00:04:32.357 --> 00:04:34.827 It's going to move in front of the star 00:04:34.827 --> 00:04:38.110 just like that, creates a wonderful shadow. 00:04:38.110 --> 00:04:41.914 Boom, we get planets orbiting about it. 00:04:41.914 --> 00:04:43.638 (Applause) 00:04:43.638 --> 00:04:45.997 Thank you. NOTE Paragraph 00:04:45.997 --> 00:04:47.950 That's not science fiction. 00:04:47.950 --> 00:04:50.513 We've been working on this for the last five or six years. 00:04:50.513 --> 00:04:53.116 Last summer, we did a really cool test 00:04:53.116 --> 00:04:55.555 out in California at Northrop Grumman. 00:04:55.555 --> 00:04:57.138 So those are four petals. 00:04:57.138 --> 00:04:58.850 This is a sub-scale star shade. 00:04:58.850 --> 00:05:01.347 It's about half the size of the one you just saw. 00:05:01.347 --> 00:05:02.807 You'll see the petals unfurl. 00:05:02.807 --> 00:05:04.874 Those four petals were built by four undergraduates 00:05:04.874 --> 00:05:07.289 doing a summer internship at JPL. 00:05:07.289 --> 00:05:08.535 Now you're seeing it deploy. 00:05:08.535 --> 00:05:10.517 Those petals have to rotate into place. 00:05:10.517 --> 00:05:11.687 The base of those petals 00:05:11.687 --> 00:05:14.060 has to go to the same place every time 00:05:14.060 --> 00:05:15.683 to within a tenth of a millimeter. 00:05:15.683 --> 00:05:17.443 We ran this test 16 times, 00:05:17.443 --> 00:05:20.282 and 16 times it went into the exact same place 00:05:20.282 --> 00:05:21.723 to a tenth of a millimeter. 00:05:21.723 --> 00:05:23.655 This has to be done very precisely, 00:05:23.655 --> 00:05:26.163 but if we can do this, if we can build this technology, 00:05:26.163 --> 00:05:27.647 if we can get it into space, 00:05:27.647 --> 00:05:29.448 you might see something like this. 00:05:29.448 --> 00:05:31.720 That's a picture of one our nearest neighbor stars 00:05:31.720 --> 00:05:34.314 taken with the Hubble Space Telescope. 00:05:34.314 --> 00:05:36.698 If we can take a similar space telescope, 00:05:36.698 --> 00:05:37.956 slightly larger, 00:05:37.956 --> 00:05:39.378 put it out there, 00:05:39.378 --> 00:05:40.764 fly an occulter in front of it, 00:05:40.764 --> 00:05:42.954 what we might see is something like that -- 00:05:42.954 --> 00:05:45.890 that's a family portrait of our solar system -- but not ours. 00:05:45.890 --> 00:05:48.412 We're hoping it'll be someone else's solar system 00:05:48.412 --> 00:05:50.044 as seen through an occulter, 00:05:50.044 --> 00:05:51.114 through a starshade like that. 00:05:51.114 --> 00:05:53.139 You can see Jupiter, you can see Saturn, 00:05:53.139 --> 00:05:55.762 Uranus, Neptune, and right there in the center, 00:05:55.762 --> 00:05:57.102 next to the residual light 00:05:57.102 --> 00:05:59.007 is that pale blue dot. That's Earth. 00:05:59.007 --> 00:06:01.381 We want to see that, see if there's water, 00:06:01.381 --> 00:06:02.786 oxygen, ozone, 00:06:02.786 --> 00:06:05.309 the things that might tell us that it could harbor life. NOTE Paragraph 00:06:05.309 --> 00:06:07.718 I think this is the coolest possible science. 00:06:07.718 --> 00:06:09.371 That's why I got into doing this, 00:06:09.371 --> 00:06:11.341 because I think that will change the world. 00:06:11.341 --> 00:06:13.779 That will change everything when we see that. NOTE Paragraph 00:06:13.779 --> 00:06:15.365 Thank you. NOTE Paragraph 00:06:15.365 --> 00:06:19.365 (Applause)