1 00:00:00,550 --> 00:00:04,900 In the asteroid belt is a huge dwarf planet. 2 00:00:04,900 --> 00:00:06,190 It's called Ceres. 3 00:00:06,190 --> 00:00:10,680 Does it have an ocean underneath its icy crust? 4 00:00:10,680 --> 00:00:11,870 Let's find out. 5 00:00:11,870 --> 00:00:16,730 Hi, I'm Jim Green, Chief Scientist at NASA and this is Gravity Assist. 6 00:00:16,730 --> 00:00:21,900 On this season of Gravity Assist, we're looking for life beyond Earth. 7 00:00:21,900 --> 00:00:27,859 I'm here with Dr. Britney Schmidt, who is an astrobiologist, and an associate professor 8 00:00:27,859 --> 00:00:33,690 in the earth and atmospheric sciences department at Georgia Institute of Technology in Atlanta. 9 00:00:33,690 --> 00:00:36,280 Britney, welcome to Gravity Assist. 10 00:00:36,280 --> 00:00:37,280 Thanks very much. 11 00:00:37,280 --> 00:00:38,280 Excited to be here. 12 00:00:38,280 --> 00:00:40,130 So where is Ceres in our solar system? 13 00:00:40,130 --> 00:00:41,560 And how big is it? 14 00:00:41,560 --> 00:00:44,420 So Ceres is in the main asteroid belt. 15 00:00:44,420 --> 00:00:45,781 Just about smack dab in the middle of it. 16 00:00:45,781 --> 00:00:49,620 It is kind of halfway between the orbits of Mars and Jupiter. 17 00:00:49,620 --> 00:00:53,039 The kind of neat thing about it is actually how big it is, you know, when you think of 18 00:00:53,039 --> 00:00:57,250 asteroids, you might think of something small, maybe the size of your house, but actually, 19 00:00:57,250 --> 00:01:01,559 Ceres is about the size of the state of Texas. 20 00:01:01,559 --> 00:01:03,769 So it's absolutely gigantic. 21 00:01:03,769 --> 00:01:06,040 So what makes it so special? 22 00:01:06,040 --> 00:01:10,390 It's one of the only planets that's really made of this kind of frozen ground on the 23 00:01:10,390 --> 00:01:11,390 on the outside. 24 00:01:11,390 --> 00:01:13,940 So I kind of like to call it a permafrost planet, if you will. 25 00:01:13,940 --> 00:01:18,961 So if you think about the Arctic on the earth, where the ground is frozen, year round, it's 26 00:01:18,961 --> 00:01:20,060 the same thing on Ceres. 27 00:01:20,060 --> 00:01:22,670 So it's kind of this frozen mud up on top. 28 00:01:22,670 --> 00:01:23,800 So that's kind of special. 29 00:01:23,800 --> 00:01:26,130 And it's really a weird object in that way. 30 00:01:26,130 --> 00:01:32,570 Well, you know, NASA's Dawn spacecraft, which first visited Vesta, and then left Vesta and 31 00:01:32,570 --> 00:01:34,040 went out to Ceres. 32 00:01:34,040 --> 00:01:40,270 It spent more than three years orbiting that dwarf planet and took spectacular images and 33 00:01:40,270 --> 00:01:41,670 other measurements. 34 00:01:41,670 --> 00:01:43,751 Tell us a little bit about what we learned from Dawn. 35 00:01:43,751 --> 00:01:46,040 Dawn was a fantastic mission. 36 00:01:46,040 --> 00:01:50,740 It's really a testament to doing as much as you can with any mission. 37 00:01:50,740 --> 00:01:54,750 So as you're zooming in on a planet getting closer and closer- those first images where 38 00:01:54,750 --> 00:01:58,580 it becomes more than a point of light, it starts to become a real place. 39 00:01:58,580 --> 00:02:05,360 I remember those first images because we could start to see every rotation, this kind of 40 00:02:05,360 --> 00:02:08,090 brightness that would kind of show up. 41 00:02:08,090 --> 00:02:12,130 And then as we zoomed in and we got closer and closer, you could see that there was almost 42 00:02:12,130 --> 00:02:16,220 it looked like a flashlight and some of the images coming from this crater. 43 00:02:16,220 --> 00:02:20,840 And as we got closer, we could see that what it was is that though Ceres is very, very 44 00:02:20,840 --> 00:02:27,650 dark, there's also these really bright deposits in this crater called Occator crater. 45 00:02:27,650 --> 00:02:32,870 And those bright deposits were reflecting a huge amount of light back at us. 46 00:02:32,870 --> 00:02:36,980 And when we got up close, what we could see is that these are definitely salts. 47 00:02:36,980 --> 00:02:41,780 And so salts are created in the interaction between water and rock. 48 00:02:41,780 --> 00:02:42,850 It happens on the Earth. 49 00:02:42,850 --> 00:02:44,970 It happens on other planets. 50 00:02:44,970 --> 00:02:51,810 And so what we think is that that is briny material, material from deeper inside Ceres 51 00:02:51,810 --> 00:02:52,810 that has come up. 52 00:02:52,810 --> 00:02:59,110 Well, as you say, that liquid water, in fact, must have some aspect to do with these these 53 00:02:59,110 --> 00:03:01,500 briny salty deposits. 54 00:03:01,500 --> 00:03:08,740 So do we think that Ceres has an ocean inside it or liquid water at some layer? 55 00:03:08,740 --> 00:03:13,420 It looks like there probably is the gravity data is consistent with that. 56 00:03:13,420 --> 00:03:19,090 It's very, very round, which is really hard for solid materials to do that very well. 57 00:03:19,090 --> 00:03:23,700 So liquids, but ice is another good way to make something kind of round, it can relax 58 00:03:23,700 --> 00:03:24,709 over time. 59 00:03:24,709 --> 00:03:29,280 So there is some evidence to suggest that deep down there might be some liquid layers, 60 00:03:29,280 --> 00:03:35,210 there's certainly evidence to suggest there might be brine pockets or former brine pockets, 61 00:03:35,210 --> 00:03:39,209 so a little bit of heat from an impact or something could really warm those up. 62 00:03:39,209 --> 00:03:42,740 So it's one of those questions that we think there's really good evidence for it. 63 00:03:42,740 --> 00:03:48,680 But it's not clear whether that's constantly liquid now or was recently liquid in the past. 64 00:03:48,680 --> 00:03:52,870 Studying places like Ceres, even if they don't have bugs crawling around right now means 65 00:03:52,870 --> 00:03:59,560 that it's a really neat opportunity to understand planets as they form or as they existed just 66 00:03:59,560 --> 00:04:00,980 before life took hold.