1 00:00:00,719 --> 00:00:04,160 All right. Okay. We'll go ahead and get started. So this is our 2 00:00:04,160 --> 00:00:07,280 two o'clock press conference: Welcome to Bennu. 3 00:00:07,280 --> 00:00:11,599 So our participants today are Jeff Grossman from NASA Headquarters; 4 00:00:11,599 --> 00:00:15,360 Dante Lauretta from the University of Arizona; Michael Nolan also from the 5 00:00:15,360 --> 00:00:20,400 University of Arizona; and Amy Simon from NASA Goddard Space Flight Center 6 00:00:20,400 --> 00:00:41,300 [No Audio] 7 00:00:41,840 --> 00:00:45,760 -[Jeff] OSIRIS-REx is the third mission in NASA's New Frontiers Program. 8 00:00:45,760 --> 00:00:50,000 These missions are competed missions 9 00:00:50,000 --> 00:00:53,920 and led by principal investigators from the community, and they cost in the range 10 00:00:53,920 --> 00:00:58,399 of a billion dollars each mission. OSIRIS-REx is the third mission that 11 00:00:58,399 --> 00:01:02,719 joins New Horizons which is going to encounter a distant 12 00:01:02,719 --> 00:01:06,479 Kuiper Belt object, Ultimate Thule, on new year's day, and 13 00:01:06,479 --> 00:01:10,080 Juno which is currently orbiting Jupiter and studying its 14 00:01:10,080 --> 00:01:14,400 atmosphere, and another mission to be announced next summer, it's 15 00:01:14,400 --> 00:01:20,320 scheduled to be announced. So that's the New Frontiers Program. 16 00:01:20,320 --> 00:01:24,320 The New Frontiers Program is one component of NASA's planetary mission fleet. 17 00:01:24,320 --> 00:01:28,680 These missions range from all stages of development. 18 00:01:28,680 --> 00:01:31,520 Some of them are just being developed others are in 19 00:01:31,520 --> 00:01:35,119 primary operations, like OSIRIS-REx, and others 20 00:01:35,119 --> 00:01:41,280 have completed, like the Dawn Mission and a few others, and they span the 21 00:01:41,280 --> 00:01:46,880 whole solar system. these missions are NASA run, 22 00:01:46,880 --> 00:01:50,159 and many of them have international partners, and a few of them shown here 23 00:01:50,159 --> 00:01:55,600 are international missions that NASA participates in. 24 00:01:55,600 --> 00:01:58,960 You may notice that there's many of these missions, 25 00:01:58,960 --> 00:02:02,399 if you recognize them, are going to the small bodies 26 00:02:02,399 --> 00:02:08,560 in our solar system. Small bodies, rather than planets or their large moons, 27 00:02:08,560 --> 00:02:12,800 small bodies are bodies that range in size from 28 00:02:12,800 --> 00:02:16,720 only a few meters across to hundreds of kilometers, like the 29 00:02:16,720 --> 00:02:20,239 largest asteroids. The one that OSIRIS-REx is going to, 30 00:02:20,239 --> 00:02:24,480 Asteroid Bennu, is about 500 meters across which is 31 00:02:24,480 --> 00:02:28,720 about three city blocks in diameter. 32 00:02:28,720 --> 00:02:34,400 These bodies are mostly fairly primitive bodies. They never 33 00:02:34,400 --> 00:02:38,720 manage to form into large planets, and they tell us 34 00:02:38,720 --> 00:02:42,480 many things about the early solar system and other things 35 00:02:42,480 --> 00:02:48,239 about our solar system. The small bodies missions are spanning 36 00:02:48,239 --> 00:02:52,560 our solar system, exploring it from one end to the other: 37 00:02:52,560 --> 00:02:55,840 from out at Ultimate Thule where New Horizons is 38 00:02:55,840 --> 00:02:58,879 in the Kuiper Belt which is about 40 times as far 39 00:02:58,879 --> 00:03:05,040 from the sun as the Earth is, to Lucy which will be looking at 40 00:03:05,040 --> 00:03:08,800 small bodies that share Jupiter's orbit when it goes out 41 00:03:08,800 --> 00:03:13,120 there in the next decade, to a few missions in the main belt of 42 00:03:13,120 --> 00:03:16,400 asteroids, including the completed Dawn Mission, 43 00:03:16,400 --> 00:03:19,920 and the upcoming Psyche Mission, and several missions that 44 00:03:19,920 --> 00:03:23,519 are studying objects in the inner solar system like OSIRIS-REx. 45 00:03:23,519 --> 00:03:26,879 And the great thing about studying an inner solar system, 46 00:03:26,879 --> 00:03:32,720 near-earth asteroid like Bennu, is that it's accessible, and that 47 00:03:32,720 --> 00:03:38,879 enables OSIRIS-REx to do something great which is to bring a sample back to Earth. 48 00:03:40,480 --> 00:03:44,000 The topics that these .... There are many problems that these 49 00:03:44,000 --> 00:03:47,840 missions are attempting to solve. 50 00:03:48,000 --> 00:03:51,040 These range from how our solar system formed, 51 00:03:51,040 --> 00:03:54,159 to how the solar system got to be the way it is, 52 00:03:54,159 --> 00:03:57,760 to what the properties and processes in the solar system are now, 53 00:03:57,760 --> 00:04:01,120 to the hazards and resources that asteroids 54 00:04:01,120 --> 00:04:07,599 pose to Earth or provide to explorers, and critically for OSIRIS-REx, 55 00:04:07,599 --> 00:04:11,120 one of the things we hope to learn is about the inventory of volatile elements 56 00:04:11,120 --> 00:04:14,799 and organic matter that may be present in the solar system. 57 00:04:14,799 --> 00:04:21,600 And OSIRIS-REx, as you can see on this chart, 58 00:04:21,600 --> 00:04:25,120 has a lot of its potential to answer questions 59 00:04:25,120 --> 00:04:28,560 like that. And I think what we now know 60 00:04:28,560 --> 00:04:32,880 and we'll hear in this press conference, is that we've gone to the right place to 61 00:04:32,880 --> 00:04:36,560 answer these questions, and that Bennu is proving to be just the 62 00:04:36,560 --> 00:04:40,280 asteroid we hoped it would be. And now we'll find out why. 63 00:04:40,280 --> 00:04:45,440 -[Dante] Thank you, Jeff. 64 00:04:45,440 --> 00:04:49,120 So I'm Dante Lauretta, professor of planetary science at the University of 65 00:04:49,120 --> 00:04:52,960 Arizona and the principal investigator for the OSIRIS-REx Mission, 66 00:04:52,960 --> 00:04:56,320 and also very excited to be here today, so thank you 67 00:04:56,320 --> 00:05:00,800 for this opportunity. So we are here. We have arrived at Bennu. 68 00:05:00,800 --> 00:05:04,560 Arrival was officially December 3rd of 2018, 69 00:05:04,560 --> 00:05:08,320 and that was the morning I woke up and saw an event on my calendar that I put 70 00:05:08,320 --> 00:05:12,320 there a decade ago, so it was truly a great day for us. 71 00:05:12,320 --> 00:05:16,000 And a lot of the uncertainty has been removed about 72 00:05:16,000 --> 00:05:19,680 this mission, right? One of the things that's characteristic of OSIRIS-REx is 73 00:05:19,680 --> 00:05:22,160 that we're going to a target that we've only seen through our 74 00:05:22,160 --> 00:05:26,400 telescopes. And we're using that telescopic knowledge to design the 75 00:05:26,400 --> 00:05:29,360 mission, and understand the risk posture, but 76 00:05:29,360 --> 00:05:33,039 really we were going to a new world, and we were going to reveal that world, 77 00:05:33,039 --> 00:05:35,759 and then assess, in this early campaign of the mission, 78 00:05:35,759 --> 00:05:40,479 the challenges that lie ahead. So here you can see, so far, the best 79 00:05:40,479 --> 00:05:42,720 resolution image of the asteroid that we've 80 00:05:42,720 --> 00:05:47,440 obtained so far. This was right before the arrival on December 2nd 81 00:05:47,440 --> 00:05:50,639 when we were using our PolyCam high resolution imager 82 00:05:50,640 --> 00:05:54,900 that was built at the University of Arizona, to get 33 centimeter 83 00:05:54,900 --> 00:05:59,120 per pixel images, and then this is a multi-image mosaic that's 84 00:05:59,120 --> 00:06:02,880 stitched together, to show the overall asteroid texture. 85 00:06:02,880 --> 00:06:05,520 And there's a couple really interesting features here. 86 00:06:05,520 --> 00:06:09,199 We'll hear more about the shape when Mike Nolan gets up and talks to us, 87 00:06:09,199 --> 00:06:12,240 but we did relatively accurately predict the shape 88 00:06:12,240 --> 00:06:15,840 of the object. We are looking at a bouldery surface. 89 00:06:15,840 --> 00:06:19,360 Remembering that this is a sample return mission, we are going to have to send our 90 00:06:19,360 --> 00:06:22,479 spacecraft down to make a brief, five-second, 91 00:06:22,479 --> 00:06:25,280 touch-and-go contact with the asteroid to collect 92 00:06:25,280 --> 00:06:29,039 material on the order of centimeter sized particles. 93 00:06:29,039 --> 00:06:34,800 We are seeing some basins or depressions, and we're discussing the nature of those 94 00:06:34,800 --> 00:06:38,720 and the origin of those. Some of those look like traditional impact craters, 95 00:06:38,720 --> 00:06:42,160 others may be expressions of the interior structure or the evolution of 96 00:06:42,160 --> 00:06:45,840 the asteroid. So there's a lot of excitement here, and 97 00:06:45,840 --> 00:06:49,080 I just want to emphasize these are really early days in the mission. 98 00:06:49,080 --> 00:06:53,120 This is kind of our first look at the asteroid, and we have a long 99 00:06:53,120 --> 00:06:56,880 time to explore this and make the critical operational decisions about 100 00:06:56,880 --> 00:07:00,400 where to go on the asteroid surface to get that sample. 101 00:07:00,400 --> 00:07:04,639 So the good news is, when when you're working with NASA on a mission like this, 102 00:07:04,639 --> 00:07:07,759 you like to have very clear and well-defined mission success criteria, 103 00:07:07,759 --> 00:07:11,199 and we made sure that there would be no doubt as to whether or 104 00:07:11,199 --> 00:07:15,360 not OSIRIS-REx was a success. And we're proud to announce today that 105 00:07:15,360 --> 00:07:18,240 the first mission success criterion has been achieved. 106 00:07:18,240 --> 00:07:22,400 We have rendezvoused with Asteroid Bennu, and we have begun our exploration of 107 00:07:22,400 --> 00:07:26,800 this fascinating small world. The next one is probably the grand 108 00:07:26,800 --> 00:07:30,080 challenge of the mission which is to contact the surface of the asteroid 109 00:07:30,080 --> 00:07:33,440 and collect that sample. And then, of course, the mission 110 00:07:33,440 --> 00:07:37,840 culminates in 2023 with the safe return of that material to Earth, 111 00:07:37,840 --> 00:07:41,440 ultimate delivery to the NASA Johnson Space Center, and to the astromaterials 112 00:07:41,440 --> 00:07:44,540 curation facility where it will then become available worldwide 113 00:07:44,540 --> 00:07:50,180 to researchers across the planet. We have a phenomenal payload suite. 114 00:07:50,180 --> 00:07:52,080 Our scientific instruments are truly 115 00:07:52,080 --> 00:07:55,280 world class. In addition to the camera system that was provided by the 116 00:07:55,280 --> 00:07:59,599 University of Arizona, I showed you the PolyCam imagery from right at the end of 117 00:07:59,599 --> 00:08:04,560 our approach phase, we also have MapCam data and SamCam. 118 00:08:04,560 --> 00:08:08,160 MapCam is our global mapper and it has the color filters, and we'll be showing 119 00:08:08,160 --> 00:08:11,039 some color imaging data. And then SamCam is there to 120 00:08:11,039 --> 00:08:14,319 document the sample collection activity. 121 00:08:14,319 --> 00:08:19,199 The Goddard Space Flight Center and my colleague, Dr. Amy Simon, is the 122 00:08:19,199 --> 00:08:23,580 deputy instrument scientist for the visible and infrared spectrometer. 123 00:08:23,580 --> 00:08:24,800 And we'll be hearing some more 124 00:08:24,800 --> 00:08:28,080 information about what that instrument has detected. 125 00:08:28,080 --> 00:08:32,080 Arizona State University provided the OSIRIS-REx thermal emission spectrometer, 126 00:08:32,080 --> 00:08:36,399 the OTES instrument, which is right here, and our Canadian Space Agency partners 127 00:08:36,399 --> 00:08:41,039 provided the OSIRIS-REx laser altimeter which did just get its first data a few 128 00:08:41,039 --> 00:08:44,000 days ago when we entered preliminary survey and started our 129 00:08:44,000 --> 00:08:46,720 north polar pass. And we're still actually assessing 130 00:08:46,720 --> 00:08:49,200 the nature of that information and processing that. 131 00:08:49,200 --> 00:08:52,399 And then we're also really proud to fly a student collaboration experiment, 132 00:08:52,399 --> 00:08:56,000 that's the regolith X-ray imaging spectrometer, the REXUS 133 00:08:56,000 --> 00:08:59,839 instrument, from students at MIT and Harvard University, to look at 134 00:08:59,839 --> 00:09:03,839 X-ray fluorescence from the surface and tell us about the elements that are 135 00:09:03,839 --> 00:09:07,519 there. And they're also still in checkout and calibration phase, and we don't have 136 00:09:07,519 --> 00:09:11,760 any information about the nature of the asteroid from them yet. 137 00:09:11,760 --> 00:09:15,279 So with that, I'm going to hand it over to Dr. Simon to tell us about the 138 00:09:15,279 --> 00:09:18,399 spectral analysis results from the mission. 139 00:09:18,400 --> 00:09:30,600 [No audio] 140 00:09:31,120 --> 00:09:34,560 -[Amy] Okay, so, as Dante said, we're all extremely excited to be here and to 141 00:09:34,560 --> 00:09:37,600 finally be at the asteroid. And I'm representing the two 142 00:09:37,600 --> 00:09:41,519 spectrometer instruments today. And so that's OVIRS, the visible and 143 00:09:41,519 --> 00:09:45,360 infrared spectrometer, and OTES, the thermal emission spectrometer. 144 00:09:45,360 --> 00:09:48,399 And the thing to remember about both of these instruments, is that they're not 145 00:09:48,400 --> 00:09:51,360 imagers. They're point spectrometers. So whatever spot 146 00:09:51,360 --> 00:09:54,420 we're looking at on the surface, we're seeing that ... 147 00:09:54,420 --> 00:09:57,120 we're not making an image. We're seeing the spectrum of everything in 148 00:09:57,120 --> 00:10:01,200 that spot at the same time. And so we started our observations on 149 00:10:01,200 --> 00:10:05,440 approach to the asteroid on Sovember 2nd. So about 200 kilometers away is when we 150 00:10:05,440 --> 00:10:11,279 got our first look at the asteroid. So for OVIRS, this is what we saw. 151 00:10:11,279 --> 00:10:14,399 We have this beautiful spectrum, and you can see that the asteroid does 152 00:10:14,399 --> 00:10:17,600 not fill our field of view. It only filled about 45 percent of the field of 153 00:10:17,600 --> 00:10:20,800 view, actually. And so we were seeing the entire surface 154 00:10:20,800 --> 00:10:25,040 on that side of the asteroid, plus dark space around it all at the same time. 155 00:10:25,040 --> 00:10:28,480 And even so, we were able to make our first detection of a real spectral 156 00:10:28,480 --> 00:10:31,120 signature that relates to the asteroid surface, 157 00:10:31,120 --> 00:10:34,720 and that's the feature you see here at 2.7 microns. 158 00:10:34,720 --> 00:10:38,240 And if you're wondering what that feature is - it's one of the things we 159 00:10:38,240 --> 00:10:41,680 were hoping to find. So we're super excited and happy to say 160 00:10:41,680 --> 00:10:45,760 that we saw the evidence of hydrated minerals on the surface of Bennu. 161 00:10:45,760 --> 00:10:49,920 We saw this in every single one of the spectra we have taken to date. 162 00:10:49,920 --> 00:10:53,360 And so that means we're seeing this widespread, hydrated minerals throughout 163 00:10:53,360 --> 00:10:56,200 the surface which is really great news. 164 00:10:56,200 --> 00:10:59,920 It's very similar to what we see in meteorites that have been analyzed here on Earth 165 00:10:59,920 --> 00:11:03,120 in the laboratory. And once we got a little bit closer, we 166 00:11:03,120 --> 00:11:06,320 were able to use OTES which has a bigger field of view, and also get a 167 00:11:06,320 --> 00:11:10,160 strong signal. And again, they also see evidence of 168 00:11:10,160 --> 00:11:14,640 hydrated minerals on the surface. So this is both spectrometers working in 169 00:11:14,640 --> 00:11:17,920 concert to confirm what each other is seeing, and we're seeing great matches 170 00:11:17,920 --> 00:11:22,560 with some of the meteorites. And so, why is this important? And that's 171 00:11:22,560 --> 00:11:26,240 because, to get hydrated minerals in the first place, to get clays, you have to 172 00:11:26,240 --> 00:11:30,240 have water interacting with regular minerals. Once you've made the clays, they 173 00:11:30,240 --> 00:11:33,920 can actually bond and store some of that water in there, make it water bearing. 174 00:11:33,920 --> 00:11:37,360 So these hydrated minerals have evidence of liquid water in Bennu's 175 00:11:37,360 --> 00:11:41,519 past. So this is really big news, and this is a great surprise. 176 00:11:41,519 --> 00:11:44,640 So with that I'm going to pass it over to Mike Nolan to talk about 177 00:11:44,640 --> 00:11:47,760 the shape model. 178 00:11:48,240 --> 00:11:51,839 -[Mike] All right, so, I'm Mike Nolan. I'm the science team chief, and I'm at the 179 00:11:51,839 --> 00:11:57,360 University of Arizona, and I deducted the shape model. So in 1999, almost 20 180 00:11:57,360 --> 00:12:01,120 years ago, I was a junior scientist at the Arecibo Observatory in Arecibo 181 00:12:01,120 --> 00:12:04,880 Puerto Rico, working at this very large telescope, 182 00:12:04,880 --> 00:12:11,040 and one of the ideas that we had going into this was 183 00:12:11,040 --> 00:12:13,839 that we might be able to make observations that would someday be used 184 00:12:13,839 --> 00:12:19,200 in planning space missions. And so here's the data I took on the 185 00:12:19,200 --> 00:12:22,720 left of the actual radar image data from Arecibo. You can 186 00:12:22,720 --> 00:12:26,240 see they're noisy and speckly, but then it was three million 187 00:12:26,240 --> 00:12:29,200 kilometers away, so that's still pretty good. 188 00:12:29,200 --> 00:12:34,079 And from that we made ... using a computer model we made the shape 189 00:12:34,079 --> 00:12:38,160 model on the right which you can see up here on the table too. 190 00:12:38,160 --> 00:12:41,360 We made this shape model. It's sort of a lumpy round thing. 191 00:12:41,360 --> 00:12:44,720 And let's see if we get that to play again. 192 00:12:44,720 --> 00:12:50,720 We did see one sort of obvious boulder feature and said 193 00:12:50,720 --> 00:12:53,519 that we thought that was probably 10 or 20 meters across, 194 00:12:53,519 --> 00:12:57,200 but then we couldn't really see any below that ... 195 00:12:57,200 --> 00:13:00,320 the size of our pixels here is about 15 meters. 196 00:13:00,320 --> 00:13:03,839 But so we knew there was one big one, and we got our overall shape, and people 197 00:13:03,839 --> 00:13:06,800 always ask me, "how much do you believe this shape?" and I said, "well, I believe 198 00:13:06,800 --> 00:13:09,519 that boulder's there; I think the sizes are about right; 199 00:13:09,519 --> 00:13:13,200 some of those little wiggly details I'm not so sure about." 200 00:13:13,200 --> 00:13:17,279 So then we got our ground-based model. 201 00:13:17,280 --> 00:13:22,300 So on the right is the model that I just showed you that we made, 202 00:13:22,300 --> 00:13:26,020 and on the left is the actual imagery that we got. 203 00:13:26,020 --> 00:13:29,360 And so, as far as I can tell, every 204 00:13:29,360 --> 00:13:32,880 single one of these little features on here has some meaningful 205 00:13:32,880 --> 00:13:36,959 signature on the asteroid. The model works remarkably well. 206 00:13:36,959 --> 00:13:40,160 There's ... it's missing some of the surface detail because it was a little 207 00:13:40,160 --> 00:13:42,480 coarser than, of course, we would have liked, 208 00:13:42,480 --> 00:13:45,199 we always like to do better, but everything in this model 209 00:13:45,199 --> 00:13:48,959 is in, you can see in the picture... so there's there's our little bump, 210 00:13:48,959 --> 00:13:52,240 and there's a boulder. Even this smaller boulder 211 00:13:52,240 --> 00:13:57,440 is revealed there. This little valley you can see in the images. 212 00:13:57,440 --> 00:14:00,560 So it worked remarkably well which is important because we made a lot 213 00:14:00,560 --> 00:14:03,440 of our decisions about how to go forward with this mission based on this 214 00:14:03,440 --> 00:14:07,199 model. And so the fact.... And people say, "are you sure?" I said, "I'm as 215 00:14:07,199 --> 00:14:10,959 sure as I can be, and let's go do it." And we went and did it. 216 00:14:10,959 --> 00:14:15,519 And yep, it really worked. So now we have, of course, now that 217 00:14:15,519 --> 00:14:18,720 we're there, we're using images to make a new shape model. 218 00:14:18,720 --> 00:14:22,160 And so on the right you can see the new shape model of 219 00:14:22,160 --> 00:14:26,320 Bennu made from those images on the left. And so it's got a lot more detail. 220 00:14:26,320 --> 00:14:29,360 It's a little more.... We have the models here. You can see that the real asteroid 221 00:14:29,360 --> 00:14:32,160 is a little more squashed, perhaps, than the model we made. 222 00:14:32,160 --> 00:14:34,240 And in fact, that was the one thing I said that 223 00:14:34,240 --> 00:14:37,360 really might be true. When you look at what radar can do, it might be a little 224 00:14:37,360 --> 00:14:39,760 different. But it worked remarkably well and what 225 00:14:39,760 --> 00:14:43,120 that means is that pretty much all of those decisions we made about how to go 226 00:14:43,120 --> 00:14:46,240 forward are really going to be.... We're accurate enough that we can really 227 00:14:46,240 --> 00:14:50,560 use them and say, "Yes, we can. That's really what Bennu looks like, and 228 00:14:50,560 --> 00:14:53,760 now let's go get our sample." 229 00:14:54,399 --> 00:14:58,240 -[Dante] Thank you. So before I go on, let me just say, 230 00:14:58,240 --> 00:15:01,680 the findings that Amy talked about are really, 231 00:15:01,680 --> 00:15:06,560 really exciting for us. I mean, we targeted Bennu precisely because we 232 00:15:06,560 --> 00:15:10,000 thought it had water-bearing minerals, and by analogy 233 00:15:10,000 --> 00:15:12,639 with the carbonaceous chondrite meteorites that we've been studying, 234 00:15:12,639 --> 00:15:16,000 organic material. That still remains to be seen. We have not detected the 235 00:15:16,000 --> 00:15:18,320 organics, but it definitely looks like we've gone 236 00:15:18,320 --> 00:15:22,320 to the right place. Both the OVIRS instrument, with the detection of the 2.7 237 00:15:22,320 --> 00:15:24,959 micron feature, and the OTES instrument, with the 238 00:15:24,959 --> 00:15:30,000 spectral matches to the CI and CM carbonaceous chondrites, really 239 00:15:30,000 --> 00:15:34,800 is exciting. I mean, I know when Amy and Dr. Vicky Hamilton, who leads the 240 00:15:34,800 --> 00:15:38,639 spectral analysis working group, first called me with the 2.7 micron results, 241 00:15:38,639 --> 00:15:42,720 we were so excited, and it just was everything we hoped had come to pass. 242 00:15:42,720 --> 00:15:44,880 Very early in the mission we had found out 243 00:15:44,880 --> 00:15:48,480 that, in fact, Bennu is going to be able to provide the type of material that we 244 00:15:48,480 --> 00:15:50,720 want to return and get back into our laboratories 245 00:15:50,720 --> 00:15:53,839 to answer these fundamental questions about whether these carbonaceous 246 00:15:53,839 --> 00:15:56,880 asteroids might have delivered these compounds to the surface of the early 247 00:15:56,880 --> 00:15:59,199 Earth and led to habitability and maybe even 248 00:15:59,199 --> 00:16:02,720 the origin of life. So let me go over a couple other results. 249 00:16:02,720 --> 00:16:07,120 I talked about the MapCam. That's the color imager. It has four 250 00:16:07,120 --> 00:16:10,560 different band pass filters in the red, green, blue, 251 00:16:10,560 --> 00:16:13,600 and infrared. And when we're looking at Bennu, one of 252 00:16:13,600 --> 00:16:16,800 the other things that struck us early on, when some of the images were coming in 253 00:16:16,800 --> 00:16:19,680 from PolyCam, like the one that we see over here on the right, 254 00:16:19,680 --> 00:16:23,519 these are at really low phase angles, which basically means that the sun was 255 00:16:23,519 --> 00:16:26,240 kind of right behind us, so there's very little shadows, 256 00:16:26,240 --> 00:16:30,079 and all of those color variations or contrast variations that you see on the 257 00:16:30,079 --> 00:16:33,600 surface are real. So we're seeing a lot of different kinds 258 00:16:33,600 --> 00:16:37,680 of reflectivity in the surface material, probably related 259 00:16:37,680 --> 00:16:42,079 to the composition. So we are seeing a fair bit of compositional diversity 260 00:16:42,079 --> 00:16:45,279 which wasn't something, necessarily, that we would have predicted or expected from 261 00:16:45,279 --> 00:16:48,880 the ground-based data. In fact, as we had watched Bennu rotate 262 00:16:48,880 --> 00:16:52,560 in various telescopes and with spectrometers attached to them, 263 00:16:52,560 --> 00:16:55,839 we didn't see a lot of spectral variation or even reflectance variation. 264 00:16:55,839 --> 00:16:59,759 So to see this wide range of reflectance properties is really surprising. 265 00:16:59,759 --> 00:17:04,079 And we see it in the color. So over there on the left is a MapCam red/green/blue 266 00:17:04,079 --> 00:17:08,559 color composite image. You can see the dark spots showing up really nicely. 267 00:17:08,559 --> 00:17:12,319 Bennu is bluish. We had thought that from the beginning. It's a B-type 268 00:17:12,319 --> 00:17:15,520 asteroid, and that means it reflects more blue light than red light. 269 00:17:15,520 --> 00:17:19,039 And we are seeing that color variation that we expected showing 270 00:17:19,039 --> 00:17:21,520 up in the ratios, and there'll be more 271 00:17:21,520 --> 00:17:24,880 information about the implications of the color variations 272 00:17:24,880 --> 00:17:28,559 during our presentations tomorrow morning. 273 00:17:28,559 --> 00:17:32,799 We also care a lot about the thermal properties of the asteroids, so we tied.... 274 00:17:32,799 --> 00:17:35,200 Mike mentioned, you know, thinking about planning a 275 00:17:35,200 --> 00:17:38,260 spacecraft mission based on his data processing. Well, a lot of 276 00:17:38,260 --> 00:17:41,600 the safety of the spacecraft and how we design the spacecraft was 277 00:17:41,600 --> 00:17:44,640 based on that information. And we took his shape model 278 00:17:44,640 --> 00:17:48,240 along with observations made by the Spitzer Space Telescope, and came up with 279 00:17:48,240 --> 00:17:51,200 what we thought the thermal profile would be of the asteroid. 280 00:17:51,200 --> 00:17:54,320 And then you design the spacecraft hardware to be able to survive those 281 00:17:54,320 --> 00:17:57,679 thermal regimes, particularly during the sample acquisition event. 282 00:17:57,679 --> 00:18:02,559 And what the graphs over there on the right show is the OVIRS data 283 00:18:02,559 --> 00:18:06,080 at four microns, so out in the infrared part of that 284 00:18:06,080 --> 00:18:09,679 instrument's capabilities, compared to what we predicted 285 00:18:09,679 --> 00:18:13,440 the thermal flux, or the infrared radiation, coming off the surface of the 286 00:18:13,440 --> 00:18:16,640 asteroid would be based on the ground-based shape model. 287 00:18:16,640 --> 00:18:20,000 And then you see the similar kind of plot down below this is the 288 00:18:20,000 --> 00:18:23,760 OTES 14 micron channel, so farther out into the mid-infrared 289 00:18:23,760 --> 00:18:27,039 where you're really getting a lot of the thermal emission, or heat flux, off the 290 00:18:27,040 --> 00:18:31,080 surface of the asteroid, those are the blue circles compared to 291 00:18:31,080 --> 00:18:34,600 the prediction using the asteroid shaped model in the red curve. 292 00:18:34,600 --> 00:18:37,679 So the good news is, again, the shape model, 293 00:18:37,679 --> 00:18:42,240 Mike and his team at Arecibo, and also using Goldstone planetary radar system 294 00:18:42,240 --> 00:18:45,679 in California, really nailed it. The planning that 295 00:18:45,679 --> 00:18:50,000 we did, the design of the spacecraft, the observation profile, they're all spot-on. 296 00:18:50,000 --> 00:18:54,080 We are ready to go. There is nothing about this asteroid 297 00:18:54,080 --> 00:18:56,320 that is going to prevent us moving forward into the 298 00:18:56,320 --> 00:19:01,039 intensive science mapping campaign that we have planned for 2019. 299 00:19:01,039 --> 00:19:03,440 And then I just want to highlight a couple of the really interesting 300 00:19:03,440 --> 00:19:08,000 geologic features. So I would say, Mike, the one thing was that 10 meter 301 00:19:08,000 --> 00:19:11,120 size boulder turned out to be substantially larger, on the order of 50 302 00:19:11,120 --> 00:19:13,760 meters. And there's a fair number of 10 303 00:19:13,760 --> 00:19:17,200 meter-sized boulders, and the boulder geology is fascinating. I definitely 304 00:19:17,200 --> 00:19:20,640 can't go into all of it here. This is one area 305 00:19:20,640 --> 00:19:25,039 that looks like it's a disaggregated breccia, 306 00:19:25,039 --> 00:19:28,160 and that's something I'll talk about during my presentation tomorrow. 307 00:19:28,160 --> 00:19:32,320 But we're looking at a wide variety of the reflectance variations even as we 308 00:19:32,320 --> 00:19:36,640 get down into the tens of centimeter scales. We're seeing clasts or rocks 309 00:19:36,640 --> 00:19:40,320 that look very bright, connected to some that are very dark, and then when we look 310 00:19:40,320 --> 00:19:43,600 at a feature like this, they look like they're maybe falling apart due to some 311 00:19:43,600 --> 00:19:47,180 kind of thermal stresses, or fracturing, or weathering pattern. 312 00:19:47,180 --> 00:19:51,200 We do see rocks that appear to be outcrops, that they're 313 00:19:51,200 --> 00:19:55,200 some just tip-of-the-iceberg reflection of something that appears to 314 00:19:55,200 --> 00:19:58,559 extend much deeper down into the interior of the asteroid, like this 315 00:19:58,559 --> 00:20:01,679 feature here. And it's got a lot of linear features 316 00:20:01,679 --> 00:20:04,159 associated with it which also may [be] due to thermal 317 00:20:04,159 --> 00:20:08,159 stressing and fracturing on the asteroid surface. 318 00:20:08,159 --> 00:20:11,120 And then we also see these perch boulders. There's some that, like 319 00:20:11,120 --> 00:20:14,799 especially the big one, that we even saw on the ground-based radar data and 320 00:20:14,799 --> 00:20:19,440 and several others, that are 10 meters or larger, 10 to 50 meter size range, 321 00:20:19,440 --> 00:20:23,760 and they appear to just be resting right on top of the asteroid surface like they 322 00:20:23,760 --> 00:20:28,159 fell back on, or something weathered around them and left them exposed. 323 00:20:28,159 --> 00:20:32,000 So the bottom line is this is an interesting world from a geologic 324 00:20:32,000 --> 00:20:35,520 perspective. There's a lot going on here in terms of processes on the 325 00:20:35,520 --> 00:20:38,640 surface of the asteroid, modification of the material, 326 00:20:38,640 --> 00:20:41,840 and that's something we want to get a good handle on because as we're going 327 00:20:41,840 --> 00:20:45,280 through our sample site selection process, we want to understand 328 00:20:45,280 --> 00:20:48,799 where do we have the best opportunity to get this most primitive, 329 00:20:48,799 --> 00:20:52,320 oldest material from the dawn of the solar system, and where might we get 330 00:20:52,320 --> 00:20:55,120 material that would tell us about the geology of the asteroid and the 331 00:20:55,120 --> 00:20:57,919 processing that happens on the surface of the asteroid. 332 00:20:57,919 --> 00:21:01,760 In the best world we would get both kinds of material, or multiple kinds of 333 00:21:01,760 --> 00:21:05,520 material, depending on what we see on the surface of this asteroid. 334 00:21:05,520 --> 00:21:08,960 And then we were starting to look at where we might be able to go get a 335 00:21:08,960 --> 00:21:12,620 sample. I know it's very early days here, but as the PI of the mission, 336 00:21:12,620 --> 00:21:15,520 I have to think about that second mission success criteria: 337 00:21:15,520 --> 00:21:20,080 safely contact the asteroid sample... asteroid surface and collect a sample. 338 00:21:20,080 --> 00:21:22,400 And it's a little early, but we are seeing these 339 00:21:22,400 --> 00:21:25,600 basins and possible impact craters. This one here, 340 00:21:25,600 --> 00:21:30,000 it's over here on the left of the image, is about 20 meters in diameter 341 00:21:30,000 --> 00:21:34,159 which is of order of our navigation capability in terms of accurate 342 00:21:34,159 --> 00:21:36,480 targeting a location on the asteroid surface. 343 00:21:36,480 --> 00:21:40,640 And we are seeing the finest grain material seeming to accumulate in these 344 00:21:40,640 --> 00:21:44,080 low basins here. We haven't mapped the entire asteroid surface yet. 345 00:21:44,080 --> 00:21:47,760 We've only been at this for a week, and our team is going through this in a 346 00:21:47,760 --> 00:21:51,039 very systematic manner, and this is just the preliminary survey 347 00:21:51,039 --> 00:21:55,520 data. When we get to the detailed survey next year, when we're in our site 348 00:21:55,520 --> 00:21:58,400 selection campaign, we're going to get about a factor of 349 00:21:58,400 --> 00:22:04,440 six to seven times better resolution. So right now we're at 33 centimeters per pixel. 350 00:22:04,440 --> 00:22:06,799 When we do the global mapping campaign, 351 00:22:06,799 --> 00:22:10,559 what we call our "baseball diamond" which refers to the different look angles so 352 00:22:10,559 --> 00:22:13,280 we can get stereo imaging and different shadowing features, 353 00:22:13,280 --> 00:22:16,400 we'll be getting down to five centimeter per pixel resolution. 354 00:22:16,400 --> 00:22:19,360 And then once we've got regions of interest selected on the asteroid 355 00:22:19,360 --> 00:22:21,840 surface, and we get into this reconnaissance phase, 356 00:22:21,840 --> 00:22:25,520 we'll be doing low altitude flyovers of potential sample sites, 357 00:22:25,520 --> 00:22:29,280 and we'll be getting sub centimeter per pixel resolution of these 358 00:22:29,280 --> 00:22:32,480 regions of interest and potential sample sites. So we are 359 00:22:32,480 --> 00:22:36,400 going to take our time. Right now we're still in the navigation campaign of the 360 00:22:36,400 --> 00:22:39,520 mission, which means we're learning to fly. One of 361 00:22:39,520 --> 00:22:43,760 the big challenges of OSIRIS-REx is accurate navigation of the spacecraft in 362 00:22:43,760 --> 00:22:48,240 this microgravity environment. It's more akin to docking than it is to 363 00:22:48,240 --> 00:22:52,480 landing, when we go in to get that sample. So a lot of the expertise from NASA 364 00:22:52,480 --> 00:22:56,320 and from our partners at Lockheed Martin that relate to space situational 365 00:22:56,320 --> 00:23:00,159 awareness or rendezvous with a target in Earth orbit, like the 366 00:23:00,159 --> 00:23:04,240 International Space Station, come into play with OSIRIS-REx. So we 367 00:23:04,240 --> 00:23:07,200 want to take our time and make sure that we know how to fly, and that's what the 368 00:23:07,200 --> 00:23:09,600 navigation campaign is about. We're getting quick, 369 00:23:09,600 --> 00:23:14,320 early-look data in preliminary survey. We're planning an orbital insertion in 370 00:23:14,320 --> 00:23:16,559 orbit A, and we actually do have an estimate on 371 00:23:16,559 --> 00:23:19,840 the mass, and I'll be talking about that in the presentation tomorrow as well as 372 00:23:19,840 --> 00:23:23,039 our radio science team and Dan Shearer's presentation, 373 00:23:23,039 --> 00:23:27,679 but in orbit (and that'll be a record for the smallest object ever orbited by 374 00:23:27,679 --> 00:23:31,120 a spacecraft) we'll really transition over to 375 00:23:31,120 --> 00:23:34,159 what we call landmark tracking optical navigation, where we look at 376 00:23:34,159 --> 00:23:37,200 features on the surface of the asteroid, and use that to determine the spacecraft 377 00:23:37,200 --> 00:23:39,440 position. So it really won't be till the end of 378 00:23:39,440 --> 00:23:43,360 February where the science campaign, what we call the site selection campaign 379 00:23:43,360 --> 00:23:46,720 of the mission, starts. And the science team is kind of in charge of where the 380 00:23:46,720 --> 00:23:49,520 spacecraft is pointing and the data that we're collecting, 381 00:23:49,520 --> 00:23:53,520 processing all of that information. And once even we have a site, 382 00:23:53,520 --> 00:23:57,760 which we anticipate by the end of 2019, we're going to spend about six months 383 00:23:57,760 --> 00:24:01,120 designing the descent down to the asteroid surface and rehearsing various 384 00:24:01,120 --> 00:24:03,360 approaches to make sure we do it in a safe and 385 00:24:03,360 --> 00:24:06,559 systematic manner, so that we go and get that sample 386 00:24:06,559 --> 00:24:12,240 approximately July of 2020. We're confident in mission success. 387 00:24:12,240 --> 00:24:15,600 One of the other things we did along those lines in terms of our readiness 388 00:24:15,600 --> 00:24:17,520 for TAG, or the Touch And Go sample 389 00:24:17,520 --> 00:24:21,679 acquisition event, is to extend the robotic arm that's called TAGSAM, 390 00:24:21,679 --> 00:24:25,600 the Touch And Go Sample Acquisition Mechanism, that was provided by our team 391 00:24:25,600 --> 00:24:28,760 members at Lockheed Martin. And we got it out in front of the 392 00:24:28,760 --> 00:24:31,520 SamCam. And the image that you see over here on the right is an 393 00:24:31,520 --> 00:24:35,279 in-flight image, one of my favorite images, because you can actually see 394 00:24:35,279 --> 00:24:39,360 sunlight passing through the filter screen. This is basically an air filter, 395 00:24:39,360 --> 00:24:43,039 and I call TAGSAM a space vacuum cleaner. We're actually going to blow 396 00:24:43,039 --> 00:24:46,320 high purity nitrogen down into the regolith of the asteroid, 397 00:24:46,320 --> 00:24:50,400 and push it up into this filter. And the fact that we can see the shadow of the 398 00:24:50,400 --> 00:24:54,000 filter screen on the inner portion of the TAGSAM, 399 00:24:54,000 --> 00:24:57,240 makes me look forward to that day in 2020 when we take the same image after 400 00:24:57,240 --> 00:25:00,760 the sample acquisition event and we can see outlines of grains there. 401 00:25:00,760 --> 00:25:04,159 So, fingers crossed. After sample acquisition, these images 402 00:25:04,159 --> 00:25:08,320 from SamCam will help us verify successful sampling, and then we 403 00:25:08,320 --> 00:25:11,520 can start thinking about stowing that in the sample return capsule, 404 00:25:11,520 --> 00:25:16,400 and bringing it back to Earth, which will occur in September of 2023. 405 00:25:16,400 --> 00:25:20,240 So, this is kind of our report card. For those of you who don't know, the name 406 00:25:20,240 --> 00:25:24,799 OSIRIS-REx, as I like to say, is an awesome acronym that 407 00:25:24,799 --> 00:25:28,400 describes the scientific objectives of the mission. So the first one, 408 00:25:28,400 --> 00:25:32,320 Origins, looks like we've got to the target that is like our 409 00:25:32,320 --> 00:25:35,520 most volatile and organic rich carbonaceous meteorites. 410 00:25:35,520 --> 00:25:38,559 From the spectral interpretation we thought there would be clay minerals on 411 00:25:38,559 --> 00:25:42,640 the surface of this asteroid, and as Amy said, that we have found, both in 412 00:25:42,640 --> 00:25:45,760 OVIRS and OTES data, strong convincing evidence that the 413 00:25:45,760 --> 00:25:48,320 surface is dominated by these clay minerals. 414 00:25:48,320 --> 00:25:51,600 From the resource identification and, kind of the feed forward to asteroid 415 00:25:51,600 --> 00:25:54,480 mining, Bennu appears to be a very water-rich target. 416 00:25:54,480 --> 00:25:58,480 And water is the most interesting, and possibly lucrative, 417 00:25:58,480 --> 00:26:01,919 commodity that you would mine from an asteroid. So you could process it into 418 00:26:01,919 --> 00:26:05,919 rocket fuel in-situ, in space, and from security which relates to the 419 00:26:05,919 --> 00:26:08,880 fact that Bennu is a potentially hazardous asteroid 420 00:26:08,880 --> 00:26:12,480 with a non-negligible probability of impacting the Earth 421 00:26:12,480 --> 00:26:16,559 well into the 22nd century. We have already, from our initial preliminary 422 00:26:16,559 --> 00:26:20,400 survey flybys, characterized the mass. Combining that with the shape model we 423 00:26:20,400 --> 00:26:22,960 have a constraint on the asteroid density. 424 00:26:22,960 --> 00:26:26,799 And then the orbit of the asteroid, and folding all of that information into 425 00:26:26,800 --> 00:26:29,840 predicting the likelihood of an Earth impact, that's still work to go as we 426 00:26:29,840 --> 00:26:32,960 move forward. I would say the one area that we were 427 00:26:32,960 --> 00:26:36,220 surprised by the asteroid, and where the challenge ahead lies, 428 00:26:36,220 --> 00:26:39,000 is that we were working towards one boulder 429 00:26:39,000 --> 00:26:41,919 on the order of 10 meters, we've got hundreds of boulders on the 430 00:26:41,919 --> 00:26:45,679 order of 10 meters. The average grain size was predicted to 431 00:26:45,679 --> 00:26:48,960 be on the centimeter size scale. That's still to be determined as we get into 432 00:26:48,960 --> 00:26:52,080 the higher resolution imaging campaigns, but 433 00:26:52,080 --> 00:26:55,440 certainly, it's a little more rugged of an environment than we had expected 434 00:26:55,440 --> 00:27:00,080 based on our mission planning and the ground-based observational data analysis. 435 00:27:00,080 --> 00:27:04,320 So I will leave you there with this portrait of Asteroid Bennu, 436 00:27:04,320 --> 00:27:08,220 and I think we're ready to move on. 437 00:27:08,220 --> 00:27:11,039 -[Moderator] Okay so, questions. Please remember to 438 00:27:11,039 --> 00:27:12,560 state your name and affiliation. 439 00:27:12,560 --> 00:27:16,320 Hi, Sid Perkins, I'm a freelancer, and 440 00:27:16,320 --> 00:27:20,000 related to your last point in looking at the population 441 00:27:20,000 --> 00:27:24,159 distribution of boulders and sizes on the surface, 442 00:27:24,160 --> 00:27:28,000 is that what you would expect? Are you seeing something of a Brazil nut effect 443 00:27:28,000 --> 00:27:31,120 where the big stuff rises and the small things kind of 444 00:27:31,120 --> 00:27:34,380 settle, or what what can you say about that 445 00:27:34,380 --> 00:27:36,580 versus your expectations if you had any? 446 00:27:36,580 --> 00:27:39,039 -[Dante] Right, well, certainly our expectation was 447 00:27:39,039 --> 00:27:41,600 that there would not be as many boulders of 448 00:27:41,600 --> 00:27:44,159 this size scale on the surface of the asteroid. So that is the the big 449 00:27:44,159 --> 00:27:46,960 surprise so far that we've encountered with the asteroid. 450 00:27:46,960 --> 00:27:49,679 In terms of what's causing the boulder distribution, it looks like there's 451 00:27:49,679 --> 00:27:53,279 multiple processes at work here, and like I said it's really early days. 452 00:27:53,279 --> 00:27:55,360 We've literally had seven days to think about it. 453 00:27:55,360 --> 00:27:58,880 Plus getting ready for all these events that are going on here at the AGU. 454 00:27:58,880 --> 00:28:02,720 So, I almost say come to the talks tomorrow because we've got 455 00:28:02,720 --> 00:28:06,159 three different presentations on boulders and geology, plus posters 456 00:28:06,159 --> 00:28:09,679 on Wednesday afternoon. There's a lot going on to explain the boulder 457 00:28:09,679 --> 00:28:16,000 distribution and their morphologies on the surface of this asteroid. 458 00:28:16,000 --> 00:28:19,520 Seth Borenstein, AP. Two quick questions: 459 00:28:19,520 --> 00:28:22,720 first, the mass of Bennu, if you can give us that, 460 00:28:22,720 --> 00:28:29,279 and second, have you seen anything that's different than, for example, 461 00:28:29,279 --> 00:28:33,039 Ceres and Vesta, you know, which would be the ones you'd be compared to 462 00:28:33,039 --> 00:28:36,240 in terms of past missions. Is there something that you've 463 00:28:36,240 --> 00:28:38,559 seen on Bennu that we haven't seen on any 464 00:28:38,559 --> 00:28:41,420 other asteroid yet? 465 00:28:41,420 --> 00:28:43,679 -[Dante] Sure so, in terms of the mass of 466 00:28:43,679 --> 00:28:47,360 the asteroid we work in units called GM which is the gravitational 467 00:28:47,360 --> 00:28:51,200 coefficient times the mass of the object. From the ground we had predicted about a 468 00:28:51,200 --> 00:28:55,120 value of 5.2, and we're seeing a little lower than 469 00:28:55,120 --> 00:28:58,000 that, around 4.9. Probably a better value is 470 00:28:58,000 --> 00:29:01,279 the density, and the density's coming in at just 471 00:29:01,279 --> 00:29:06,080 under 1200 kilograms per cubic meter, remembering that your average rock is 472 00:29:06,080 --> 00:29:10,240 around 3 000. So it's really got a lower density than even these 473 00:29:10,240 --> 00:29:14,080 carbonaceous chondrite meteorites, which tells us that it probably is made 474 00:29:14,080 --> 00:29:17,600 of these hydrated minerals which are generally low density, but it's also got 475 00:29:17,600 --> 00:29:21,279 some porosity or cave like structures in its interior 476 00:29:21,279 --> 00:29:23,660 to the tune of maybe 40 percent of that asteroid 477 00:29:23,660 --> 00:29:25,360 may be void space in the interior to get 478 00:29:25,360 --> 00:29:29,279 down to such a low density. In terms of comparison to Vesta and 479 00:29:29,279 --> 00:29:33,279 Ceres, it's really not fair because this would be a boulder on the 480 00:29:33,279 --> 00:29:36,799 surface of those objects. Those are really planetary scale bodies. 481 00:29:36,799 --> 00:29:40,000 And especially something like Vesta which has gone through planetary 482 00:29:40,000 --> 00:29:43,840 differentiation, core formation, volcanism on its surface, 483 00:29:43,840 --> 00:29:47,360 Bennu is a totally different creature compared to those objects. 484 00:29:47,360 --> 00:29:51,520 It really looks like a pile of rubble in the sense that it 485 00:29:51,520 --> 00:29:53,660 probably originated from a larger asteroid. 486 00:29:53,660 --> 00:29:55,700 We have some working hypotheses that it 487 00:29:55,700 --> 00:29:59,600 came from a much larger body, on the order of 100 kilometers in diameter. 488 00:29:59,600 --> 00:30:03,120 And that was probably shattered in a catastrophic collision, 489 00:30:03,120 --> 00:30:06,399 on the order of 800 million to a billion years ago. 490 00:30:06,400 --> 00:30:10,100 And Bennu is just an accumulation of rubble from that event. 491 00:30:10,100 --> 00:30:14,320 It's very different than Vesta, maybe more like Ceres in the fact that 492 00:30:14,320 --> 00:30:17,919 it's got these water-rich minerals and so on, but again Ceres is kind of a 493 00:30:17,919 --> 00:30:22,240 planetary scale object, and you're going to have a lot more active geology and 494 00:30:22,240 --> 00:30:25,440 you know, surface expressions and cryovolcanism, and things like that that 495 00:30:25,440 --> 00:30:28,700 you would never expect to see on Bennu. 496 00:30:28,700 --> 00:30:32,240 Harvey Lyford - Freelance 497 00:30:32,399 --> 00:30:36,960 I'm wondering first of all, whether this is the smallest 498 00:30:36,960 --> 00:30:40,960 object in space that we've orbited with a spacecraft, 499 00:30:40,960 --> 00:30:45,360 and secondly, how much gravity can it have 500 00:30:45,360 --> 00:30:49,039 for you to have a stable orbit around it. I wonder how that works. 501 00:30:49,039 --> 00:30:52,960 -[Dante] Sure, so it will be the smallest object ever orbited by a spacecraft. 502 00:30:52,960 --> 00:30:56,480 That will happen on New Year's Eve of this year, so pay attention for that 503 00:30:56,480 --> 00:31:01,100 exciting event. And the acceleration due to gravity 504 00:31:01,100 --> 00:31:04,320 at the surface of the asteroid is estimated at about 10 505 00:31:04,320 --> 00:31:09,519 micro g's. So 1g is the average acceleration at the surface of the Earth. 506 00:31:09,519 --> 00:31:15,919 So we are one divided by 100,000 times that. So it is a really low 507 00:31:15,919 --> 00:31:19,440 gravity environment, and I mentioned the navigation challenge, 508 00:31:19,440 --> 00:31:23,440 and that's the reason why. You've got a gravitational force on the spacecraft 509 00:31:23,440 --> 00:31:26,080 that is comparable to solar radiation pressure, 510 00:31:26,080 --> 00:31:29,519 as well as outgassing from the spacecraft, or even thermal radiation 511 00:31:29,519 --> 00:31:32,320 from the asteroid, so that's why the navigation team gets 512 00:31:32,320 --> 00:31:33,880 two months to learn how to fly 513 00:31:33,880 --> 00:31:37,060 as they get into orbit at the end of the year. 514 00:31:37,440 --> 00:31:39,279 Alex Witze with Nature. 515 00:31:39,279 --> 00:31:42,720 Just sticking with the Dante theme, I wanted to ask you to talk more about 516 00:31:42,720 --> 00:31:46,559 the grain sizes. You can sample only up to two 517 00:31:46,559 --> 00:31:50,480 centimeters. You've got a very, very rugged look here, as you pointed out. 518 00:31:50,480 --> 00:31:54,559 You're noting these basins as places with the small grain material to maybe 519 00:31:54,559 --> 00:31:57,519 try and sample. How much are you worried about that 520 00:31:57,519 --> 00:31:59,700 two centimeter sampling limit? 521 00:31:59,700 --> 00:32:01,039 -[Dante] Well, you know I don't worry about things 522 00:32:01,039 --> 00:32:04,399 that are out of my control, right? So we did everything we could to plan this 523 00:32:04,400 --> 00:32:07,820 mission. I am confident we're going to find some fine-grained 524 00:32:07,820 --> 00:32:10,960 regions. The challenge will be how large they are and what that 525 00:32:10,960 --> 00:32:14,240 means for our navigation accuracy as we go into to 526 00:32:14,240 --> 00:32:18,000 get the spacecraft precisely targeted to the location that we want on the surface 527 00:32:18,000 --> 00:32:20,559 of the asteroid. There's an interesting puzzle going on 528 00:32:20,559 --> 00:32:24,240 here, because one of the key pieces of evidence for the average grain size was 529 00:32:24,240 --> 00:32:27,679 a parameter we call thermal inertia, which basically tells 530 00:32:27,679 --> 00:32:31,600 you how fast the asteroid surface heats up and how fast it cools off. 531 00:32:31,600 --> 00:32:35,840 And usually lower thermal inertias correspond to smaller grain sizes. 532 00:32:35,840 --> 00:32:39,279 So that's one of the reasons we estimated the average grain size on the 533 00:32:39,279 --> 00:32:42,399 order of one or two centimeters. We're still seeing that low thermal 534 00:32:42,399 --> 00:32:45,519 inertia. I didn't go into it on the thermal plot, but when we looked at that 535 00:32:45,519 --> 00:32:49,360 profile, the thermal curve as Bennu rotates, 536 00:32:49,360 --> 00:32:50,960 it's very consistent with the thermal inertia 537 00:32:50,960 --> 00:32:52,559 that we estimated from the ground. 538 00:32:52,559 --> 00:32:56,799 So there's some physics that we need to go back and take a look at, and see... 539 00:32:56,799 --> 00:32:59,760 and maybe there still is that fine grain material. There's still plenty of 540 00:32:59,760 --> 00:33:02,000 unresolved regions on the asteroid surface, 541 00:33:02,000 --> 00:33:06,080 and it may be dominated by centimeter scale particles. Remembering our pixel 542 00:33:06,080 --> 00:33:09,360 is 33 centimeters at this point, so we don't know what's happening inside those 543 00:33:09,360 --> 00:33:12,720 single pixel regions. And as a point of reference, the pixel 544 00:33:12,720 --> 00:33:17,120 size is just about the same size as the diameter of the TAGSAM head. 545 00:33:17,120 --> 00:33:21,279 So we have to get TAGSAM to one pixel on this image, 546 00:33:21,279 --> 00:33:24,000 and there's plenty of regions that we don't know what's happening at that 547 00:33:24,000 --> 00:33:27,360 scale. So that's why we have the year ahead of us to do the detailed 548 00:33:27,360 --> 00:33:30,799 mapping and ultimately the high resolution reconnaissance. 549 00:33:30,799 --> 00:33:33,679 Christoph Siedler: Spiel Online 550 00:33:33,840 --> 00:33:38,080 Dante, you mentioned that it would be unfair to compare 551 00:33:38,080 --> 00:33:44,880 Bennu to Ceres, for example, or Vesta. Can you compare it to Ryugu, the asteroid 552 00:33:44,880 --> 00:33:47,880 that Hayabusa2 is currently at just to 553 00:33:47,880 --> 00:33:51,540 have a vague idea how these are similar or different? 554 00:33:51,540 --> 00:33:53,679 -[Dante] Does anybody want to take that? I've been answering a lot of questions. 555 00:33:53,679 --> 00:33:54,639 Anybody else? 556 00:33:54,639 --> 00:33:58,080 -[Amy] Well, I guess at least from the spectral point of view, we can 557 00:33:58,080 --> 00:34:01,200 say that, based on Ryugu, we weren't expecting to 558 00:34:01,200 --> 00:34:05,519 see these hydrated minerals so easily from so far away. So that was actually a 559 00:34:05,519 --> 00:34:08,399 big surprise that it was such a strong signal 560 00:34:08,399 --> 00:34:11,760 immediately, without even a full field of view filled in. 561 00:34:11,760 --> 00:34:15,359 So, I think we probably do have more hydrated minerals than they do. 562 00:34:15,359 --> 00:34:18,800 We'll know a lot more once we enter that science mapping phase and can look at 563 00:34:18,800 --> 00:34:21,839 variations on the surface and get better ideas of where things are 564 00:34:21,839 --> 00:34:23,140 concentrated. 565 00:34:23,140 --> 00:34:27,760 -[Mike] Okay, one other thing is, so we knew Bennu looked like this. We've 566 00:34:27,760 --> 00:34:30,720 known Bennu looked like this for a long time, but we didn't know Ryugu looked 567 00:34:30,720 --> 00:34:33,520 like it does. And so when we saw those images of Ryugu, 568 00:34:33,520 --> 00:34:35,860 we were looking at those, and say well, that is likely... 569 00:34:35,860 --> 00:34:38,720 since overall they look kind of the same, we expect maybe they'll look 570 00:34:38,720 --> 00:34:41,599 the same in detail. And then when they're actually so 571 00:34:41,599 --> 00:34:44,159 different, that was even more exciting, 572 00:34:44,159 --> 00:34:47,679 that you have these things that are superficially very similar, 573 00:34:47,679 --> 00:34:50,720 but then in detail they're really quite different. And so that's another 574 00:34:50,720 --> 00:34:54,960 exciting aspect of going forward here. 575 00:34:54,960 --> 00:35:00,320 -[Moderator] I believe we have a question on the chat 576 00:35:00,320 --> 00:35:03,839 [inaudible] 577 00:35:04,320 --> 00:35:08,400 Hello? Okay cool, we're on. I have a question from vickisnath 578 00:35:08,400 --> 00:35:13,839 with hotpoprobot.com. The question is, "Currently, Bennu is the second most 579 00:35:13,839 --> 00:35:18,160 hazardous object, in terms of possible collision with Earth, according to NASA's 580 00:35:18,160 --> 00:35:22,000 Palermo Technical Hazard Scale. How will the mission help us in improving the 581 00:35:22,000 --> 00:35:25,280 risk index associated with asteroid Bennu? 582 00:35:25,280 --> 00:35:28,800 -[Dante] So, one of the big uncertainties in the trajectory of the asteroid is a 583 00:35:28,800 --> 00:35:33,200 phenomenon called the Yarkovsky effect. And the Yarkovsky effect relates to the 584 00:35:33,200 --> 00:35:36,400 fact that the asteroid gets heated up by the sunlight, 585 00:35:36,400 --> 00:35:40,240 and then as it rotates into it's afternoon and it's evening, it releases 586 00:35:40,240 --> 00:35:44,880 that energy back out into space as heat. And it's a retrograde rotator which 587 00:35:44,880 --> 00:35:48,079 means it's afternoon is in the direction that it's moving on 588 00:35:48,079 --> 00:35:51,920 its orbit. So that emission of heat acts like a thruster 589 00:35:51,920 --> 00:35:54,400 and applies the brakes and slows the 590 00:35:54,400 --> 00:35:58,560 asteroid's orbital velocity down, therefore shrinking the semi-major axis 591 00:35:58,560 --> 00:36:01,680 of its orbit. We're going to study that phenomenon in 592 00:36:01,680 --> 00:36:04,240 unprecedented detail, and we're going to do it in two 593 00:36:04,240 --> 00:36:06,560 directions: from the top down and the bottom up. 594 00:36:06,560 --> 00:36:10,480 Mike talked about the radar data starting in 1999. 595 00:36:10,480 --> 00:36:14,920 We got even better data in 2005, and then in 2011 we were able to 596 00:36:14,920 --> 00:36:17,680 range to the asteroid, we didn't get the imaging resolution, but we 597 00:36:17,680 --> 00:36:21,040 were able to get its position relative to the Earth. And because of 598 00:36:21,040 --> 00:36:25,040 that 12-year arc, we actually measured the Yarkovsky effect in a 599 00:36:25,040 --> 00:36:28,800 change in the asteroid's orbit. And then we combine that with Spitzer 600 00:36:28,800 --> 00:36:31,520 Space Telescope observations to get the thermal emission, 601 00:36:31,520 --> 00:36:35,280 and that was how we got that asteroid mass estimated to begin with. 602 00:36:35,280 --> 00:36:40,079 So now we're going to be able to extend the baseline from 1999, to 2011, all the 603 00:36:40,079 --> 00:36:45,119 way to the end of our encounter in 2021, so we'll have 22 years of tracking on 604 00:36:45,119 --> 00:36:49,119 the asteroid's orbit, and that'll improve our understanding of 605 00:36:49,119 --> 00:36:52,800 how much the semi-major axis is changing as a result of this phenomenon. 606 00:36:52,800 --> 00:36:56,240 But in addition, because we're going to get this phenomenal 607 00:36:56,240 --> 00:37:00,240 5 centimeter resolution global shape model, and we're going to get the thermal 608 00:37:00,240 --> 00:37:04,240 emission from the OTES instrument, we're going to be able to evaluate the 609 00:37:04,240 --> 00:37:07,760 Yarkovsky effect from first principles. Do we understand 610 00:37:07,760 --> 00:37:10,720 the physics of thermal radiation and how it changes the 611 00:37:10,720 --> 00:37:13,680 asteroid's orbit. And that'll shrink the uncertainty, 612 00:37:13,680 --> 00:37:16,720 and therefore the impact probability will change. 613 00:37:16,720 --> 00:37:19,280 Don't know if it'll go up or down, but it'll change as a result of that 614 00:37:19,280 --> 00:37:20,880 improved knowledge. 615 00:37:20,880 --> 00:37:23,760 -[Jeff] I'd also like to add, that knowledge can 616 00:37:23,760 --> 00:37:27,680 be then applied to other asteroids, even ones that we 617 00:37:27,680 --> 00:37:30,160 haven't yet discovered, which may prove to be hazardous, 618 00:37:30,160 --> 00:37:34,640 and help understand the hazards posed by many asteroids. 619 00:37:34,640 --> 00:37:38,720 -[Moderator] Great. Do we have any other questions from reporters in the room? 620 00:37:42,320 --> 00:37:43,900 -[Questioner] I've got a really stupid question. 621 00:37:43,900 --> 00:37:46,020 What's to say that isn't just a giant 622 00:37:46,020 --> 00:37:49,140 chunk of impact breccia from a giant collision 623 00:37:49,140 --> 00:37:53,140 that just sort of came together... 624 00:37:55,120 --> 00:37:57,380 -[Dante] Okay, how do we know it's not an impact breccia? 625 00:37:57,380 --> 00:37:58,560 It may be an impact breccia. 626 00:37:58,560 --> 00:38:02,000 I mean it is... we expect a pile of rubble that 627 00:38:02,000 --> 00:38:05,119 coalesced after a catastrophic disruptive impact 628 00:38:05,119 --> 00:38:08,079 in the main asteroid belt hundreds of millions of years ago. 629 00:38:08,080 --> 00:38:11,720 And, in fact, when I showed you that disaggregated assemblage 630 00:38:11,720 --> 00:38:14,560 that looked like it was kind of breaking down in-situ. There's very 631 00:38:14,560 --> 00:38:20,079 different reflectivities there. So, it's definitely a pile of rubble, 632 00:38:20,079 --> 00:38:23,680 and whether or not it originated in an impact remains to be seen, 633 00:38:23,680 --> 00:38:33,839 but that's okay, right? So there's nothing wrong with that. 634 00:38:35,680 --> 00:38:38,960 Seth Borenstein again from AP. Just at the bottom right, 635 00:38:38,960 --> 00:38:43,839 you know, the bulge that you saw, Michael, you know decades ago, 636 00:38:43,839 --> 00:38:46,960 is that the 50 meter boulder you're talking about? 637 00:38:46,960 --> 00:38:51,180 -[Mike] Yes -[Seth] And and how big is the opposite one? 638 00:38:51,180 --> 00:38:54,160 -[Mike] The opposite ones, I recall... 639 00:38:54,160 --> 00:38:57,520 It's about the same size around but it's not as tall. So it's 640 00:38:57,520 --> 00:39:03,119 more like 20 tall, roughly. -[Seth] And is there a good... how do you 641 00:39:03,119 --> 00:39:06,800 describe this shape? I mean is there something similar 642 00:39:06,800 --> 00:39:09,920 in people's everyday life that this looks like to you? 643 00:39:09,920 --> 00:39:13,760 -[Mike] Well, I mean, to first order it's round, but I think of it as sort of 644 00:39:13,760 --> 00:39:18,079 two cones sitting on top of each other. That's sort of the way I think 645 00:39:18,079 --> 00:39:20,240 about it is right here's a cone and there's a cone, 646 00:39:20,240 --> 00:39:24,480 and with the bridge in the middle. That's the overall shape, and we think 647 00:39:24,480 --> 00:39:27,599 it's a round thing where the spin has basically formed this 648 00:39:27,599 --> 00:39:29,000 big bulge around the equator. 649 00:39:29,000 --> 00:39:33,780 -[Seth] Okay... because it's not quite that round. I mean it's that bulgy... 650 00:39:33,780 --> 00:39:35,040 -[Mike] You start with something round, and then 651 00:39:35,040 --> 00:39:39,040 then as it spins up, the bits at the equator kind of move out. 652 00:39:39,040 --> 00:39:42,720 and that's sort of how we think of it. We think of it as looking that way, 653 00:39:42,720 --> 00:39:46,720 and also, most likely, actually having formed that way. 654 00:39:46,720 --> 00:39:49,119 -[Dante] Yeah, I'd say the shape is a really interesting 655 00:39:49,119 --> 00:39:52,160 question right now because we thought it was related to the spin state 656 00:39:52,160 --> 00:39:55,200 and material migrating down to the pole, but we had the question earlier 657 00:39:55,200 --> 00:39:59,040 about the comparison to Ryugu. Ryugu is spinning much slower, 658 00:39:59,040 --> 00:40:02,320 by a factor of about two, and it has a more pronounced 659 00:40:02,320 --> 00:40:06,880 ridge and much sharper peak. And so that is counterintuitive to the rotation 660 00:40:06,880 --> 00:40:10,319 state model, unless there's been changes in the rotation state of those two 661 00:40:10,319 --> 00:40:13,760 asteroids. So I would say the team is having a field day right now because 662 00:40:13,760 --> 00:40:17,359 it's an asteroid geologist's dream to have a mystery like this to go and solve. 663 00:40:17,359 --> 00:40:21,040 So there's people throwing out all kinds of ideas about how these shapes and how 664 00:40:21,040 --> 00:40:23,680 these ridges form. So I would say, "stay tuned," because I 665 00:40:23,680 --> 00:40:26,079 think that the active debate is going to go on here. 666 00:40:26,079 --> 00:40:29,760 -[Seth] And just numbers of the distance from here, from Earth, 667 00:40:29,760 --> 00:40:32,760 and the spin rate for us please. 668 00:40:32,760 --> 00:40:36,240 -[Dante] So, Bennu is on an eccentric orbit 669 00:40:36,240 --> 00:40:38,720 that gets almost out to the orbit of Mars and actually 670 00:40:38,720 --> 00:40:42,160 comes inside the orbit of the Earth. So it's an earth crossing asteroid. 671 00:40:42,160 --> 00:40:45,920 It does a close approach to the Earth every 1.2 years. 672 00:40:45,920 --> 00:40:50,319 I believe we have a one-way light time on the order of seven minutes right now. 673 00:40:50,319 --> 00:40:53,599 So that's how we normally measure distance is how long it takes the signal 674 00:40:53,599 --> 00:40:56,240 to leave the Earth and get to the spacecraft, and then come back. 675 00:40:56,240 --> 00:41:01,119 The spin state is rotating once every 4.3 hours, and and we actually know it to 676 00:41:01,119 --> 00:41:02,600 something like 10 decimal places, 677 00:41:02,600 --> 00:41:05,640 but that's probably good enough for this. 678 00:41:05,640 --> 00:41:08,720 -[Moderator] Okay, I think we have some questions on the chat. 679 00:41:08,720 --> 00:41:12,400 Yeah we have a few questions. The first one is from Lisa Grossman with 680 00:41:12,400 --> 00:41:15,200 Science News. The question is, "Does Bennu look more or 681 00:41:15,200 --> 00:41:19,520 less boldery than Ryugu? Also, How did you feel 682 00:41:19,520 --> 00:41:22,110 when you first saw Bennu up close?" 683 00:41:22,110 --> 00:41:24,880 -[Dante] You're wanna take the boulder question? 684 00:41:24,880 --> 00:41:27,440 -[Mike] I'd say offhand, the largest 685 00:41:27,440 --> 00:41:31,119 boulders on Bennu are comparatively smaller than the largest 686 00:41:31,119 --> 00:41:34,160 boulders on Ryugu, and that things scale pretty well, and that's actually in one 687 00:41:34,160 --> 00:41:37,839 of the posters that you'll see on Wednesday. 688 00:41:37,839 --> 00:41:41,760 It's less bouldery, 689 00:41:41,760 --> 00:41:44,560 but they're comparable in some fairly 690 00:41:44,560 --> 00:41:47,280 straightforward ways. And there's there's a whole presentation 691 00:41:47,280 --> 00:41:48,300 on that on Wednesday. 692 00:41:48,300 --> 00:41:50,720 -[Dante] And how did you feel when we first saw Bennu? 693 00:41:50,720 --> 00:41:54,720 So I was pretty excited. It was like, "hey, we're there! 694 00:41:54,720 --> 00:41:57,839 And we have an awesome asteroid to explore." I mean, it was... 695 00:41:57,839 --> 00:42:01,839 it's a dream come true, and it's an honor and a privilege 696 00:42:01,839 --> 00:42:04,240 to be able to lead a program like this for NASA, and for 697 00:42:04,240 --> 00:42:07,280 the United States, and really for the world. 698 00:42:07,280 --> 00:42:12,000 And we are... we can't wait to spend the next year mapping this asteroid. 699 00:42:12,000 --> 00:42:16,960 It really is the culmination of a decade and a half of work on my part and 700 00:42:16,960 --> 00:42:21,440 this team which has worked together for years and years and years, just an 701 00:42:21,440 --> 00:42:25,680 amazing group of people. This is, obviously, a very small representation of 702 00:42:25,680 --> 00:42:29,200 the hundreds to thousands of people who have worked hard to make this mission a 703 00:42:29,200 --> 00:42:32,079 success. And I'm really proud of everybody and all the work that 704 00:42:32,079 --> 00:42:36,079 we've done to get here. So we have an amazing spacecraft with a 705 00:42:36,079 --> 00:42:39,599 world-class suite of instruments, and a fascinating world to explore, 706 00:42:39,599 --> 00:42:45,680 and all of that rushed into my mind as I got those first images of Bennu. 707 00:42:46,000 --> 00:42:49,160 -[Moderator] Do you have another one on the chat? -[Chat curator] Yes, we have a question from 708 00:42:49,160 --> 00:42:51,800 Dan Bamberger, Freelancer. 709 00:42:51,800 --> 00:42:54,880 "The radar modeling for Ryugu didn't show 710 00:42:54,880 --> 00:42:58,560 the equatorial ridge, while Bennu's shape was known better. 711 00:42:58,560 --> 00:43:02,400 still, this actual shape is more squashed at 712 00:43:02,400 --> 00:43:05,280 the poles. How reliable are radar shapes in general? 713 00:43:05,280 --> 00:43:09,359 -[Mike] So, we didn't have a radar shape model of Ryugu. We actually tried, but 714 00:43:09,359 --> 00:43:13,520 for various reasons, mostly including funding, we weren't able to get 715 00:43:13,520 --> 00:43:17,520 that shape model. I think that was in the early 2000s. Whereas, we had the radar 716 00:43:17,520 --> 00:43:20,160 shaped model of Bennu and actually, specifically knowing the 717 00:43:20,160 --> 00:43:24,079 squash, that was our biggest known uncertainty was how squashed it 718 00:43:24,079 --> 00:43:27,200 would be. And it's well within the uncertainties we estimated. 719 00:43:27,200 --> 00:43:30,800 So that's why we didn't come out 720 00:43:30,800 --> 00:43:36,640 the same is because we didn't actually have the model to start with. 721 00:43:36,640 --> 00:43:41,707 -[Chat Curator] Okay, one more question, from Leah Crane with New Scientist: 722 00:43:41,707 --> 00:43:44,040 "Do we have any ideas of why Bennu 723 00:43:44,040 --> 00:43:48,100 might have so much water?" -[Dante] Sure I'll take that one. 724 00:43:48,100 --> 00:43:53,760 So, we think that Bennu, the mineralogy on the asteroid formed 725 00:43:53,760 --> 00:43:55,520 basically at the dawn of the solar system 726 00:43:55,520 --> 00:43:59,119 over four and a half billion years ago when material was accreting from the 727 00:43:59,119 --> 00:44:03,200 protoplanetary disk, and the mineralogy is a remnant of that 728 00:44:03,200 --> 00:44:06,720 early phase. So as I've mentioned several times at 729 00:44:06,720 --> 00:44:10,720 this event, the asteroid is a fragment of a much 730 00:44:10,720 --> 00:44:13,920 larger body that originated in the main asteroid belt. 731 00:44:13,920 --> 00:44:18,400 And that body, when it formed, probably accreted, what we would say, anhydrous or 732 00:44:18,400 --> 00:44:21,680 dry minerals along with ice particles and then very 733 00:44:21,680 --> 00:44:24,640 early, within the first five to ten million years of the 734 00:44:24,640 --> 00:44:29,520 formation of that asteroid, that ice heated up and melted and then 735 00:44:29,520 --> 00:44:33,359 created, like a hydrothermal system in the interior of the asteroid, and that 736 00:44:33,359 --> 00:44:37,200 hot fluid reacted with the anhydrous minerals and 737 00:44:37,200 --> 00:44:40,319 formed the clays. And that is still preserved to this day. 738 00:44:40,319 --> 00:44:43,920 So that's one of the most exciting parts of studying samples like this 739 00:44:43,920 --> 00:44:47,280 is that you're actually looking at a rock that's four and a half billion 740 00:44:47,280 --> 00:44:50,000 years old, that's older than the Earth, it's older than anything that 741 00:44:50,000 --> 00:44:53,200 anybody could possibly touch or study. 742 00:44:53,200 --> 00:44:56,240 And you're peering back to the dawn of the solar system and trying to 743 00:44:56,240 --> 00:44:59,520 understand the chemical processes that played out, 744 00:44:59,520 --> 00:45:03,760 that led to the Earth being the habitable world that it is today. 745 00:45:03,760 --> 00:45:08,079 -[Moderator] Well, I think we have time for one more. 746 00:45:08,079 --> 00:45:12,080 -[Questioner] So to follow up with that, the idea that you've got hydrated minerals, 747 00:45:12,080 --> 00:45:17,680 the source of that water was not likely impacts with comets later, or 748 00:45:17,680 --> 00:45:21,119 how much could that have been a contributor to your hydration, or 749 00:45:21,119 --> 00:45:26,480 is it pretty firmly understood or expected that this was 750 00:45:26,480 --> 00:45:30,100 proto solar system? 751 00:45:30,100 --> 00:45:32,000 -[Dante] It's an interesting question, especially 752 00:45:32,000 --> 00:45:34,800 your reference to comets. One of the things that we've learned 753 00:45:34,800 --> 00:45:40,160 as planetary exploration has rolled out, and especially another 754 00:45:40,160 --> 00:45:43,440 NASA mission, a previous NASA mission called the Stardust Mission, actually 755 00:45:43,440 --> 00:45:46,880 went to the coma of a comet and brought back samples 756 00:45:46,880 --> 00:45:50,560 of that material, and one of the things we learned from that is that 757 00:45:50,560 --> 00:45:54,160 asteroids and comets are not like two distinctly different kinds of 758 00:45:54,160 --> 00:45:56,319 populations. There's kind of this continuum 759 00:45:56,319 --> 00:45:59,599 where you have really dry rocky and metallic stuff, 760 00:45:59,599 --> 00:46:02,800 and on the other end you have nearly pure icy bodies. 761 00:46:02,800 --> 00:46:06,640 And then you kind of can get any ratio of mixtures between the ice and rock 762 00:46:06,640 --> 00:46:10,319 in-between there. So Bennu probably was, at least the parent asteroid that 763 00:46:10,319 --> 00:46:12,800 Bennu came from, was comet-like at some point 764 00:46:12,800 --> 00:46:15,599 in its early history, and that it was a combination of rocky, 765 00:46:15,599 --> 00:46:20,800 metallic, icy, and organic material. And then all of that kind of accreted 766 00:46:20,800 --> 00:46:24,800 together and you had some limited geology taking place to establish the 767 00:46:24,800 --> 00:46:28,240 minerals that we have there. That's the working hypothesis, and I want 768 00:46:28,240 --> 00:46:30,319 to emphasize that, right. One of the great things 769 00:46:30,319 --> 00:46:35,040 is that we've laid out a hypothetical timeline for this asteroid, 770 00:46:35,040 --> 00:46:39,599 and I published this back in 2015. We're going to test all of that, right. 771 00:46:39,599 --> 00:46:42,319 We're not only going to test it with the asteroid encounter data, but we're going 772 00:46:42,319 --> 00:46:45,520 to bring a sample back and the sample is going to tell that story 773 00:46:45,520 --> 00:46:47,300 in great detail. 774 00:46:47,300 --> 00:46:50,400 -[Moderator] Okay. I think we're just about out of time, so 775 00:46:50,400 --> 00:46:54,000 that will conclude our press conference, and we'll reconvene at 3 o'clock. 776 00:46:54,000 --> 00:46:57,839 -[Dante] Thank you.