1 00:00:00,000 --> 00:00:00,840 (dramatic music) 2 00:00:00,840 --> 00:00:04,563 Saturn is the jewel in the crown of the solar system. 3 00:00:04,563 --> 00:00:07,430 It's the truly beautiful, majestic planet. 4 00:00:07,430 --> 00:00:11,063 Saturn just makes us gasp at its beauty. 5 00:00:12,290 --> 00:00:15,760 The Saturnian system is an absolute wonderland. 6 00:00:15,760 --> 00:00:19,690 Saturn, second largest of the planets, 7 00:00:19,690 --> 00:00:24,690 nearly 800 times the volume of Earth, a true gas giant, 8 00:00:25,790 --> 00:00:30,790 adorned by and adored for its mysterious, captivating rings. 9 00:00:32,390 --> 00:00:34,700 The study of Saturn's rings has inspired 10 00:00:34,700 --> 00:00:37,453 great theoretical musings for centuries. 11 00:00:38,860 --> 00:00:42,420 Almost 300,000 kilometers in diameter, 12 00:00:42,420 --> 00:00:45,600 the ring system is just 20 meters thick. 13 00:00:45,600 --> 00:00:48,090 The rings capture the imagination 14 00:00:48,090 --> 00:00:51,750 to the point you have to understand where they came from 15 00:00:51,750 --> 00:00:53,400 and what do they mean? 16 00:00:53,400 --> 00:00:55,530 To try and answer these questions, 17 00:00:55,530 --> 00:00:58,470 humans designed, built, and launched 18 00:00:58,470 --> 00:01:01,703 some of the most advanced spacecraft ever conceived. 19 00:01:02,640 --> 00:01:05,470 It was and is the largest outerplanetary spacecraft 20 00:01:05,470 --> 00:01:07,330 that's ever been built. 21 00:01:07,330 --> 00:01:10,143 This is a massive piece of machinery. 22 00:01:11,120 --> 00:01:14,200 This is the story of the exploration of Saturn, 23 00:01:14,200 --> 00:01:19,200 its rings and moons, told by those who dared to do it, 24 00:01:19,320 --> 00:01:21,570 a place that turns out to be much more 25 00:01:21,570 --> 00:01:24,160 than just a celestial beauty spot. 26 00:01:24,160 --> 00:01:26,150 The building blocks of life could form 27 00:01:26,150 --> 00:01:29,420 in the interiors of these icy bodies. 28 00:01:29,420 --> 00:01:30,680 The kind of conditions we see 29 00:01:30,680 --> 00:01:33,090 are probably present on tens of billions 30 00:01:33,090 --> 00:01:35,263 of environments across the Milky Way. 31 00:01:37,270 --> 00:01:39,310 Saturn could hold the key 32 00:01:39,310 --> 00:01:43,620 to understanding our true place in the universe. 33 00:01:43,620 --> 00:01:44,970 It's definitely the most 34 00:01:44,970 --> 00:01:46,963 interesting place in the solar system. 35 00:01:51,308 --> 00:01:54,141 (title resonates) 36 00:01:55,530 --> 00:01:57,530 To the naked eye, the night sky 37 00:01:57,530 --> 00:02:00,010 is filled with points of light. 38 00:02:00,010 --> 00:02:04,040 Zoom into almost all of them and they remain just that: 39 00:02:04,040 --> 00:02:06,303 shining points in a dark universe. 40 00:02:07,220 --> 00:02:09,630 But one celestial object revealed 41 00:02:09,630 --> 00:02:13,410 to an Italian polymath that it was special. 42 00:02:13,410 --> 00:02:15,910 Galileo wasn't the inventor of the telescope, 43 00:02:15,910 --> 00:02:17,960 but he was one of the first people to use it 44 00:02:17,960 --> 00:02:20,090 for astronomical observations. 45 00:02:20,090 --> 00:02:23,943 It was 1610 when Galileo first observed the Saturn system. 46 00:02:24,930 --> 00:02:27,870 His drawing showed what were described 47 00:02:27,870 --> 00:02:31,800 as ears or jug handles either side of the planet. 48 00:02:31,800 --> 00:02:34,620 So Saturn's my face, it appeared that there 49 00:02:34,620 --> 00:02:36,533 were these weird globes. 50 00:02:37,640 --> 00:02:39,710 And so he thought well, these might be moons 51 00:02:39,710 --> 00:02:42,970 but stuck one on each side of the planet Saturn. 52 00:02:42,970 --> 00:02:45,620 He didn't know Newtonian mechanics, it hadn't been invented. 53 00:02:45,620 --> 00:02:47,510 He didn't know that moons have to go 54 00:02:47,510 --> 00:02:49,230 all away around a planet. 55 00:02:49,230 --> 00:02:51,340 When he went back to look at Saturn 56 00:02:51,340 --> 00:02:52,590 a couple of years later, 57 00:02:52,590 --> 00:02:56,045 he noticed that those features had gone. 58 00:02:56,045 --> 00:02:58,210 (spirited music) 59 00:02:58,210 --> 00:03:01,290 Galileo even suggested that Saturn had eaten 60 00:03:01,290 --> 00:03:04,310 his own children as in the ancient Greek myth, 61 00:03:04,310 --> 00:03:06,663 and that's why the moons had disappeared. 62 00:03:08,440 --> 00:03:11,000 Galileo lived in Italy, but he was aware 63 00:03:11,000 --> 00:03:13,000 of other major figures in his time, 64 00:03:13,000 --> 00:03:16,430 including Constantijn Huygens from the Netherlands, 65 00:03:16,430 --> 00:03:20,540 and in fact it was Huygens' son, Christiaan Huygens, 66 00:03:20,540 --> 00:03:22,160 who eventually solved the puzzle 67 00:03:22,160 --> 00:03:25,143 that was posed by the disappearing handles of Saturn. 68 00:03:26,530 --> 00:03:30,080 Christiaan Huygens turned his telescope towards Saturn. 69 00:03:30,080 --> 00:03:32,410 As technology develops, optics developed, 70 00:03:32,410 --> 00:03:34,160 and he was able to see more. 71 00:03:34,160 --> 00:03:36,900 And what he saw meant that he was able 72 00:03:36,900 --> 00:03:39,690 to come up with this radical idea 73 00:03:39,690 --> 00:03:43,553 that Saturn was surrounded by a ring system, 74 00:03:45,890 --> 00:03:48,910 and he was able to link back to what Galileo saw 75 00:03:48,910 --> 00:03:51,630 because if the ring system was tilted 76 00:03:51,630 --> 00:03:54,490 at an angle to our view from Earth, 77 00:03:54,490 --> 00:03:58,220 it means that sometimes you'll see the rings tilted 78 00:03:58,220 --> 00:04:00,220 and you'll see them sort of almost face-on, 79 00:04:00,220 --> 00:04:01,980 and other times when the planet has moved, 80 00:04:01,980 --> 00:04:03,360 they'll be edge-on. 81 00:04:03,360 --> 00:04:07,830 So at particular times, we'd look at the rings edge-on 82 00:04:07,830 --> 00:04:09,440 and they completely disappear. 83 00:04:09,440 --> 00:04:11,360 In fact even today when Hubble, 84 00:04:11,360 --> 00:04:14,850 the best optical telescope we have, looked at Saturn 85 00:04:14,850 --> 00:04:17,500 across through the ring plane, the rings disappeared. 86 00:04:20,580 --> 00:04:22,150 But not only that, Christiaan Huygens 87 00:04:22,150 --> 00:04:25,240 made another amazing discovery: 88 00:04:25,240 --> 00:04:28,940 that Saturn has a moon and it turns out 89 00:04:28,940 --> 00:04:32,260 that this moon is a really curious place, 90 00:04:32,260 --> 00:04:34,090 and is perhaps even more curious 91 00:04:34,090 --> 00:04:36,140 than the rings of Saturn itself. 92 00:04:36,140 --> 00:04:40,370 After the discovery by Huygens of Saturn's first moon, 93 00:04:40,370 --> 00:04:42,950 Giovanni Domenico Cassini discovered 94 00:04:42,950 --> 00:04:45,500 four more in the next decades, 95 00:04:45,500 --> 00:04:47,540 and moons continued to be discovered 96 00:04:47,540 --> 00:04:50,200 over the next few hundred years. 97 00:04:50,200 --> 00:04:51,190 Mimas. 98 00:04:51,190 --> 00:04:52,270 Enceladus. 99 00:04:52,270 --> 00:04:53,820 Hyperion. 100 00:04:53,820 --> 00:04:56,010 However, from the first there were 101 00:04:56,010 --> 00:04:59,450 big questions posed by Saturn's rings. 102 00:04:59,450 --> 00:05:02,470 What were the rings made of? 103 00:05:02,470 --> 00:05:03,873 How did they arise? 104 00:05:04,800 --> 00:05:07,663 What's the origin of the rings of Saturn? 105 00:05:08,610 --> 00:05:12,573 And why does Saturn have rings and not the other planets? 106 00:05:14,050 --> 00:05:15,630 The only way to answer that question 107 00:05:15,630 --> 00:05:19,063 is to actually get up close, we need to go to Saturn. 108 00:05:20,040 --> 00:05:22,820 But getting to planets in the outer solar system 109 00:05:22,820 --> 00:05:25,650 obviously requires a huge amount of fuel, 110 00:05:25,650 --> 00:05:27,390 but a large amount of fuel means 111 00:05:27,390 --> 00:05:29,260 you have an expensive mission 112 00:05:29,260 --> 00:05:32,580 because you're trying to launch a lot of mass into space 113 00:05:32,580 --> 00:05:35,170 and you need more fuel to be able to do that. 114 00:05:35,170 --> 00:05:37,160 So you start to think about, well, 115 00:05:37,160 --> 00:05:38,830 what are the other ways that you 116 00:05:38,830 --> 00:05:40,810 can accelerate your spacecraft 117 00:05:40,810 --> 00:05:42,960 without requiring lots of fuel? 118 00:05:42,960 --> 00:05:44,190 And one technique that's used 119 00:05:44,190 --> 00:05:46,810 is what's called a gravitational assist. 120 00:05:46,810 --> 00:05:49,851 (monitor beeping) 121 00:05:49,851 --> 00:05:51,270 (inquisitive music) 122 00:05:51,270 --> 00:05:53,430 As a spacecraft passes a planet 123 00:05:53,430 --> 00:05:56,200 that is itself moving around the sun, 124 00:05:56,200 --> 00:05:57,890 it would get dragged along 125 00:05:57,890 --> 00:06:01,390 and accelerated by the planets during the encounter, 126 00:06:01,390 --> 00:06:04,400 gaining extra speed like a skateboarder 127 00:06:04,400 --> 00:06:07,340 briefly holding onto a passing car. 128 00:06:07,340 --> 00:06:11,410 What's more, a huge opportunity suddenly presented itself. 129 00:06:11,410 --> 00:06:13,610 It was discovered that the outer planets 130 00:06:13,610 --> 00:06:15,240 would actually align in a way 131 00:06:15,240 --> 00:06:18,530 that they hadn't since Thomas Jefferson had been president. 132 00:06:18,530 --> 00:06:22,160 So we realized that you could fly past Jupiter, 133 00:06:22,160 --> 00:06:25,060 get a kick, go to Saturn, get a kick, 134 00:06:25,060 --> 00:06:27,793 go to Uranus, get a kick, go on to Neptune. 135 00:06:28,950 --> 00:06:32,776 This gravity assist trajectory was called The Grand Tour. 136 00:06:32,776 --> 00:06:34,120 And if we were gonna go and do this, 137 00:06:34,120 --> 00:06:36,000 take advantage of this alignment, 138 00:06:36,000 --> 00:06:39,200 we'd better get going and launch that spacecraft soon. 139 00:06:39,200 --> 00:06:42,010 NASA quickly responded to the opportunity 140 00:06:42,010 --> 00:06:44,850 by preparing some pathfinding spacecraft, 141 00:06:44,850 --> 00:06:46,650 one that would go to Jupiter 142 00:06:46,650 --> 00:06:48,710 and one that could use a gravity assist 143 00:06:48,710 --> 00:06:50,733 from Jupiter to go on to Saturn. 144 00:06:53,528 --> 00:06:55,713 And that was called Pioneer 11. 145 00:06:59,174 --> 00:07:03,035 (spacecraft beeping) 146 00:07:03,035 --> 00:07:05,785 (flames roaring) 147 00:07:07,230 --> 00:07:09,630 The primary purpose of those Pioneers 148 00:07:09,630 --> 00:07:12,433 was really to pave the way for later spacecraft. 149 00:07:14,000 --> 00:07:16,521 And that mission was called Voyager. 150 00:07:16,521 --> 00:07:19,104 (upbeat music) 151 00:07:23,690 --> 00:07:25,950 And the Voyager mission had two components, 152 00:07:25,950 --> 00:07:28,500 Voyager 1 and Voyager 2. 153 00:07:28,500 --> 00:07:30,690 Each of them would get a gravity assist 154 00:07:30,690 --> 00:07:33,190 from Jupiter to go on to Saturn. 155 00:07:33,190 --> 00:07:36,370 But that's then where the missions deviated, 156 00:07:36,370 --> 00:07:40,050 because Voyager 1 was given an extra special task. 157 00:07:40,050 --> 00:07:43,110 It was to go and visit the moon 158 00:07:43,110 --> 00:07:47,433 that Christiaan Huygens had discovered in 1655, Titan. 159 00:07:48,880 --> 00:07:50,570 Titan would become almost 160 00:07:50,570 --> 00:07:53,893 as important a destination as Saturn itself. 161 00:07:54,970 --> 00:07:57,770 Titan is a really intriguing moon. 162 00:07:57,770 --> 00:07:59,210 This is a massive moon, 163 00:07:59,210 --> 00:08:02,100 probably not worthy of the word moon. 164 00:08:02,100 --> 00:08:04,310 This is a body which is bigger than Mercury, 165 00:08:04,310 --> 00:08:06,070 so it's a big moon. 166 00:08:06,070 --> 00:08:07,780 Its mass is lower than that of Mercury, 167 00:08:07,780 --> 00:08:10,883 but in terms of size, it's bigger than our smallest planet. 168 00:08:12,070 --> 00:08:13,890 As we've been looking around the solar system, 169 00:08:13,890 --> 00:08:16,070 many people have been fixated on Mars 170 00:08:16,070 --> 00:08:19,750 as the place beyond the Earth most likely to hold life, 171 00:08:19,750 --> 00:08:21,290 but there's another place in the solar system 172 00:08:21,290 --> 00:08:22,940 which is probably just as exciting, 173 00:08:22,940 --> 00:08:26,013 and for some people even more so, and that's Titan. 174 00:08:28,120 --> 00:08:31,690 The atmosphere of Titan was hinted at a century ago 175 00:08:31,690 --> 00:08:34,040 and confirmed in the 1940s. 176 00:08:34,040 --> 00:08:36,690 It's the only satellite in the solar system 177 00:08:36,690 --> 00:08:38,270 with a dense atmosphere. 178 00:08:38,270 --> 00:08:39,860 In fact, its atmosphere is actually 179 00:08:39,860 --> 00:08:42,143 denser than our atmosphere here on Earth. 180 00:08:43,310 --> 00:08:44,680 Titan is the most interesting moon 181 00:08:44,680 --> 00:08:47,300 in the solar system, hands-down. 182 00:08:47,300 --> 00:08:48,720 But getting to Titan 183 00:08:48,720 --> 00:08:50,950 meant a change of direction, 184 00:08:50,950 --> 00:08:53,483 curtailing the exploration of the outer plants. 185 00:08:54,640 --> 00:08:57,950 So Voyager 1 going off to visit Titan 186 00:08:57,950 --> 00:08:59,700 meant that it was no longer able 187 00:08:59,700 --> 00:09:02,890 to slingshot on to visit Uranus and Neptune. 188 00:09:02,890 --> 00:09:05,160 If Voyager 1 had not been able 189 00:09:05,160 --> 00:09:07,740 to achieve that objective for whatever reason, 190 00:09:07,740 --> 00:09:11,460 Voyager 2 was going to be diverted to do that job 191 00:09:11,460 --> 00:09:14,205 at the expense of going on to Uranus and Neptune. 192 00:09:14,205 --> 00:09:16,630 (upbeat music) 193 00:09:16,630 --> 00:09:19,637 But that's how they felt about Titan, the importance. 194 00:09:21,236 --> 00:09:24,080 7-4-6-S-1-9. 195 00:09:24,080 --> 00:09:24,913 15 seconds. 196 00:09:24,913 --> 00:09:28,200 When Pioneer 11 eventually arrived at Saturn 197 00:09:28,200 --> 00:09:30,960 six years after flying by Jupiter, 198 00:09:30,960 --> 00:09:33,890 it was an immense, exciting moment. 199 00:09:33,890 --> 00:09:37,560 Five, four, three, two, one. 200 00:09:39,396 --> 00:09:40,329 We made it! (people cheering) 201 00:09:40,329 --> 00:09:41,317 Hooray! 202 00:09:41,317 --> 00:09:44,234 (intriguing music) 203 00:09:46,400 --> 00:09:50,660 The rings of Saturn were big and beautiful in our pictures 204 00:09:50,660 --> 00:09:53,743 and we stood in awe at the closeup views. 205 00:09:55,260 --> 00:09:59,160 My task was to see if we might discover any new rings, 206 00:09:59,160 --> 00:10:02,220 and amazingly, I watched the first images 207 00:10:02,220 --> 00:10:04,190 appear on the television screen 208 00:10:04,190 --> 00:10:07,373 and there was clearly a new ring of Saturn. 209 00:10:12,350 --> 00:10:14,920 The rings of Saturn had originally 210 00:10:14,920 --> 00:10:18,550 been named A, B, and C, in order 211 00:10:18,550 --> 00:10:21,330 from the outermost known ring to the innermost, 212 00:10:21,330 --> 00:10:24,410 but in the 20th century, we began to discover 213 00:10:24,410 --> 00:10:27,570 new rings which were then assigned alphabetically 214 00:10:27,570 --> 00:10:30,590 in the order of discovery, first the D Ring, 215 00:10:30,590 --> 00:10:35,540 then the E Ring, so the next available letter was F, 216 00:10:35,540 --> 00:10:38,807 and so I named that ring Ring F of Saturn. 217 00:10:38,807 --> 00:10:41,307 (tense music) 218 00:10:44,630 --> 00:10:49,240 Pioneer 11 passed Titan by quite a large distance, 219 00:10:49,240 --> 00:10:51,023 couple hundred thousand miles away. 220 00:10:55,680 --> 00:10:57,980 And really all it told us about Titan 221 00:10:57,980 --> 00:10:59,430 was that it was very, very cold, 222 00:10:59,430 --> 00:11:02,680 too cold for life as we know it to exist. 223 00:11:02,680 --> 00:11:04,310 But actually we needed to go back 224 00:11:04,310 --> 00:11:06,820 and look at this thing in much more detail. 225 00:11:06,820 --> 00:11:09,520 Fortunately, two more spacecraft 226 00:11:09,520 --> 00:11:11,690 were already on their way. 227 00:11:11,690 --> 00:11:15,810 4-7-4-7-4-6-U-S-4-9. 228 00:11:15,810 --> 00:11:18,760 The Pioneers had told us it was safe, 229 00:11:18,760 --> 00:11:20,165 it's okay, we can go there. 230 00:11:20,165 --> 00:11:21,930 (triumphant music) 231 00:11:21,930 --> 00:11:24,650 So just a year later, Voyager 1, 232 00:11:24,650 --> 00:11:27,280 equipped with better instruments and better cameras 233 00:11:27,280 --> 00:11:31,223 was preparing to take a look at Saturn and its rings. 234 00:11:34,970 --> 00:11:37,890 The encounter was an amazingly thrilling 235 00:11:37,890 --> 00:11:39,540 and rapid experience, 236 00:11:39,540 --> 00:11:41,730 all happened within a matter of a few days, 237 00:11:41,730 --> 00:11:43,860 and even before you could explain 238 00:11:43,860 --> 00:11:45,620 some of the new phenomena we saw, 239 00:11:45,620 --> 00:11:49,280 Voyager was off on its way out of the solar system. 240 00:11:49,280 --> 00:11:51,470 (people cheering) (people applauding) 241 00:11:51,470 --> 00:11:54,810 Many people referred to that flood of data, 242 00:11:54,810 --> 00:11:57,310 the camera pictures and other observations, 243 00:11:57,310 --> 00:12:00,062 as like drinking from a fire hose. 244 00:12:00,062 --> 00:12:02,846 The estimate is. 245 00:12:02,846 --> 00:12:05,649 (people chattering) 246 00:12:05,649 --> 00:12:07,585 (people cheering) (people applauding) 247 00:12:07,585 --> 00:12:11,090 Do you guys have any questions? 248 00:12:11,090 --> 00:12:13,470 After the Voyager flybys, we knew there were 249 00:12:13,470 --> 00:12:15,930 thousands of rings, and it's that moment 250 00:12:15,930 --> 00:12:18,130 that we stopped naming them with letters. 251 00:12:18,130 --> 00:12:21,260 It was just impossible, exceeded the alphabet. 252 00:12:21,260 --> 00:12:24,610 We saw waves propagating through the rings, 253 00:12:24,610 --> 00:12:27,710 we saw the edges of the rings wiggling. 254 00:12:27,710 --> 00:12:31,590 A ring could be maintained between two moons, 255 00:12:31,590 --> 00:12:33,943 one outside the ring and one inside the ring. 256 00:12:35,430 --> 00:12:38,680 And that's the beauty of this idea of moonlets 257 00:12:38,680 --> 00:12:40,290 that are sitting within the rings, 258 00:12:40,290 --> 00:12:42,560 shepherding the gravitational motion 259 00:12:42,560 --> 00:12:44,043 of the particles within it. 260 00:12:45,203 --> 00:12:49,220 (intriguing music) (people chattering) 261 00:12:49,220 --> 00:12:51,060 Maybe it's a scientific prerequisite 262 00:12:51,060 --> 00:12:52,840 to start with a simple idea, 263 00:12:52,840 --> 00:12:55,800 but we had imagined the rings were ancient, 264 00:12:55,800 --> 00:12:59,260 unchanging, and completely uniform, 265 00:12:59,260 --> 00:13:02,550 and this picture of the rings was completely shattered. 266 00:13:02,550 --> 00:13:06,100 The rings were changing in time, changing in space, 267 00:13:06,100 --> 00:13:09,080 they're dynamically changing with waves 268 00:13:09,080 --> 00:13:13,500 lapping across the rings, so this idea of symmetry, 269 00:13:13,500 --> 00:13:15,830 of constant persistence of the rings, 270 00:13:15,830 --> 00:13:18,056 all were immediately questioned. 271 00:13:18,056 --> 00:13:19,481 (people chattering) 272 00:13:19,481 --> 00:13:21,220 (inquisitive music) 273 00:13:21,220 --> 00:13:23,610 But what was the origin of the rings? 274 00:13:23,610 --> 00:13:25,283 Where did they come from? 275 00:13:27,180 --> 00:13:29,330 When an object gets closer to the planet 276 00:13:29,330 --> 00:13:32,280 it gets stretched out, and so a basketball might look 277 00:13:32,280 --> 00:13:35,470 more like an American football under this stress. 278 00:13:35,470 --> 00:13:37,800 The question is, can that stress 279 00:13:37,800 --> 00:13:39,773 be withstood by the object? 280 00:13:42,200 --> 00:13:45,360 For most competent objects, including humans, 281 00:13:45,360 --> 00:13:47,490 we can withstand that stress. 282 00:13:47,490 --> 00:13:51,330 For objects that are piles of rubble or dust 283 00:13:51,330 --> 00:13:55,000 or are big, say larger than 50 or 100 kilometers, 284 00:13:55,000 --> 00:13:57,353 they cannot withstand that force. 285 00:13:59,160 --> 00:14:01,100 If a large moon had once strayed 286 00:14:01,100 --> 00:14:04,800 too close to Saturn, this destructive force 287 00:14:04,800 --> 00:14:07,993 would've been enough to tear it into tiny pieces. 288 00:14:11,010 --> 00:14:12,890 So Saturn once had a moon, 289 00:14:12,890 --> 00:14:15,400 say an object about the size of Titan, 290 00:14:15,400 --> 00:14:18,260 if it were dragged in toward the planet by friction, 291 00:14:18,260 --> 00:14:20,240 first the ice would shatter 292 00:14:20,240 --> 00:14:22,890 and then later the core, which is made of metal, 293 00:14:22,890 --> 00:14:25,260 would shatter or might even end up inside the planet, 294 00:14:25,260 --> 00:14:28,503 and the pieces of ice formed a ring around Saturn. 295 00:14:29,520 --> 00:14:30,630 And now the mission 296 00:14:30,630 --> 00:14:32,710 turned to the prize that was worth 297 00:14:32,710 --> 00:14:35,417 missing out Neptune and Uranus: Titan. 298 00:14:38,648 --> 00:14:41,900 (tense music) 299 00:14:41,900 --> 00:14:44,340 The scientific community and the public 300 00:14:44,340 --> 00:14:47,900 watched with great interest as Voyager 1 301 00:14:47,900 --> 00:14:49,703 made the first flyby of Titan. 302 00:14:49,703 --> 00:14:53,623 What Voyager 1 encountered was still this mysterious veil. 303 00:14:54,650 --> 00:14:58,060 There was an organic haze that encircled the surface 304 00:14:58,060 --> 00:15:00,393 and you couldn't see the surface as a result. 305 00:15:01,680 --> 00:15:03,950 That atmosphere is simultaneously 306 00:15:03,950 --> 00:15:07,270 the bane of my research because it blocks the surface, 307 00:15:07,270 --> 00:15:10,823 but it's also the reason why Titan is so interesting. 308 00:15:12,490 --> 00:15:14,730 All of those hazes that mean that you and I 309 00:15:14,730 --> 00:15:16,360 can't actually see the surface 310 00:15:16,360 --> 00:15:18,440 with light that our eyes can see, 311 00:15:18,440 --> 00:15:21,963 make Titan this organic chemistry wonderland. 312 00:15:26,290 --> 00:15:28,186 One of the other things we figured out was that there was 313 00:15:28,186 --> 00:15:30,510 methane present in the atmosphere of Titan. 314 00:15:30,510 --> 00:15:32,290 Now this is important because 315 00:15:32,290 --> 00:15:34,380 both pressure and temperature measurements 316 00:15:34,380 --> 00:15:37,180 that Voyager 1 took indicated that 317 00:15:37,180 --> 00:15:40,860 it gets incredibly close to the triple point of methane. 318 00:15:40,860 --> 00:15:44,430 This opened the really, really tantalizing possibility 319 00:15:44,430 --> 00:15:47,193 for lakes and oceans on the surface. 320 00:15:48,560 --> 00:15:51,690 Some people think if we look in these methane lakes, 321 00:15:51,690 --> 00:15:54,410 perhaps we'll find a different way of organizing matter, 322 00:15:54,410 --> 00:15:55,960 a different way of organizing life. 323 00:15:55,960 --> 00:15:58,360 (monkey calls) 324 00:15:58,360 --> 00:16:00,660 Titan was still hiding all its mysteries from us, 325 00:16:00,660 --> 00:16:02,800 so that laid down the gauntlet of the challenge. 326 00:16:02,800 --> 00:16:05,543 We must now go to the surface of Titan. 327 00:16:07,510 --> 00:16:09,330 Fortunately, Voyager 1 made 328 00:16:09,330 --> 00:16:11,210 excellent observations of Titan, 329 00:16:11,210 --> 00:16:13,930 so thankfully Voyager 2 was allowed 330 00:16:13,930 --> 00:16:17,513 to go on to the next planet, Uranus, and then to Neptune. 331 00:16:17,513 --> 00:16:19,870 (triumphant music) 332 00:16:19,870 --> 00:16:21,580 The Uranian rings had been discovered 333 00:16:21,580 --> 00:16:24,350 from the ground om 1977, 334 00:16:24,350 --> 00:16:28,220 Voyager itself discovered the ring of Jupiter in 1979, 335 00:16:28,220 --> 00:16:31,160 and while we were on our way to the planet Uranus, 336 00:16:31,160 --> 00:16:33,870 the rings of Neptune were also discovered. 337 00:16:33,870 --> 00:16:36,870 So by the time the Voyager mission had completed, 338 00:16:36,870 --> 00:16:40,130 we knew that all of the giant planets had rings, 339 00:16:40,130 --> 00:16:42,610 just the opposite of what the question had been 340 00:16:42,610 --> 00:16:46,110 before those missions of why only Saturn has rings, 341 00:16:46,110 --> 00:16:50,870 but leaving us with deeper questions about Saturn's rings. 342 00:16:50,870 --> 00:16:52,060 What were they made of? 343 00:16:52,060 --> 00:16:54,060 How old were they? 344 00:16:54,060 --> 00:16:57,820 And why are Saturn's rings so particularly different, 345 00:16:57,820 --> 00:17:00,440 so big and so bright compared to 346 00:17:00,440 --> 00:17:03,710 the narrower, less massive, darker rings 347 00:17:03,710 --> 00:17:05,563 of Jupiter, Uranus, and Neptune? 348 00:17:06,980 --> 00:17:10,980 The rapid flybys that Voyager provided were insufficient 349 00:17:10,980 --> 00:17:13,970 to answer these questions in more detail, 350 00:17:13,970 --> 00:17:17,240 but then those failings could be addressed 351 00:17:17,240 --> 00:17:19,770 by a mission that went into orbit around Saturn 352 00:17:19,770 --> 00:17:21,601 and stayed for many years. 353 00:17:21,601 --> 00:17:22,750 (people chattering) 354 00:17:22,750 --> 00:17:26,497 We already knew that the value of orbiting a system 355 00:17:26,497 --> 00:17:28,990 and the amount of understanding you can gain 356 00:17:28,990 --> 00:17:31,100 by being there for a long period of time 357 00:17:31,100 --> 00:17:33,040 is so amazing that the next step 358 00:17:33,040 --> 00:17:35,530 was clearly gonna be an orbital mission. 359 00:17:35,530 --> 00:17:38,510 And if we're going to send another mission to Saturn 360 00:17:38,510 --> 00:17:41,520 that stays there, it should have a part of it 361 00:17:41,520 --> 00:17:43,323 that lands on the surface of Titan. 362 00:17:44,410 --> 00:17:46,830 Planning began in 1982 363 00:17:46,830 --> 00:17:49,810 for a mission that will be more ambitious and advanced 364 00:17:49,810 --> 00:17:52,290 than anything that had gone before, 365 00:17:52,290 --> 00:17:54,763 a mission called Cassini Huygens. 366 00:18:02,010 --> 00:18:06,430 The spacecraft was about the size of a school bus. 367 00:18:06,430 --> 00:18:08,270 If you saw it when they were putting it together, 368 00:18:08,270 --> 00:18:10,520 it was pretty impressive, you just looked up. 369 00:18:10,520 --> 00:18:11,913 It was a monster. 370 00:18:13,740 --> 00:18:16,560 It was and is the largest outerplanetary spacecraft 371 00:18:16,560 --> 00:18:19,050 that's ever been built, and may, 372 00:18:19,050 --> 00:18:21,398 in my lifetime, ever be built. 373 00:18:21,398 --> 00:18:22,870 Pressures are excellent. 374 00:18:22,870 --> 00:18:24,350 T plus 20 seconds. 375 00:18:24,350 --> 00:18:25,860 The mission was a collaboration 376 00:18:25,860 --> 00:18:28,050 with the European Space Agency, 377 00:18:28,050 --> 00:18:31,433 who designed and built a lander called Huygens. 378 00:18:32,300 --> 00:18:34,900 And this was the vehicle to take us 379 00:18:34,900 --> 00:18:38,049 down through the clouds, down to the surface of Titan. 380 00:18:38,049 --> 00:18:41,070 (dramatic music) 381 00:18:41,070 --> 00:18:42,340 The Huygens probe was actually 382 00:18:42,340 --> 00:18:44,330 designed to be able to float in liquid 383 00:18:44,330 --> 00:18:46,330 as well as land on a solid surface 384 00:18:46,330 --> 00:18:48,720 because we didn't know at the time whether it was going to 385 00:18:48,720 --> 00:18:51,600 land in a liquid or on a solid surface. 386 00:18:51,600 --> 00:18:53,080 So we designed the mission to cope 387 00:18:53,080 --> 00:18:55,323 with as many characteristics as possible. 388 00:18:56,290 --> 00:18:58,980 No one's ever tried to measure the depths of an ocean 389 00:18:58,980 --> 00:19:00,010 and how hard a rock is 390 00:19:00,010 --> 00:19:01,870 depending on which one you're gonna land on. 391 00:19:01,870 --> 00:19:04,500 We knew from Hubble images that there 392 00:19:04,500 --> 00:19:06,420 probably wasn't a global ocean, 393 00:19:06,420 --> 00:19:10,520 but whether there were other liquids was still not known. 394 00:19:10,520 --> 00:19:12,080 Huygens' team had to prepare for that 395 00:19:12,080 --> 00:19:15,600 but also a very hard landing, or maybe you can imagine 396 00:19:15,600 --> 00:19:19,083 a very squish surface full of organic goop. 397 00:19:19,083 --> 00:19:22,530 (liquid gurgling) 398 00:19:22,530 --> 00:19:23,810 20 seconds and counting. 399 00:19:23,810 --> 00:19:25,740 This is Titan Launch Control. 400 00:19:25,740 --> 00:19:28,630 Without any doubt, the most risky element 401 00:19:28,630 --> 00:19:32,020 of any space mission is the launch. 402 00:19:32,020 --> 00:19:33,540 T minus 15 seconds. 403 00:19:33,540 --> 00:19:36,130 It was a nighttime launch, so you had to get on the bus 404 00:19:36,130 --> 00:19:38,520 something like two in the morning or something to go out, 405 00:19:38,520 --> 00:19:40,610 and we did that, and we went out to the launch site, 406 00:19:40,610 --> 00:19:43,680 and the first opportunity, the launch was scrubbed. 407 00:19:43,680 --> 00:19:46,750 And so we did the same thing again two days later. 408 00:19:46,750 --> 00:19:47,983 T minus 10. 409 00:19:47,983 --> 00:19:49,980 When you've put eight years of your life 410 00:19:49,980 --> 00:19:52,360 into designing and building and testing something 411 00:19:52,360 --> 00:19:53,990 which is going to go into space-- 412 00:19:53,990 --> 00:19:55,320 Nine, eight, seven. 413 00:19:55,320 --> 00:19:57,660 And then seeing on the top of a rocket 414 00:19:57,660 --> 00:20:00,960 that's being vibrated on its way to Saturn, 415 00:20:00,960 --> 00:20:02,300 it is quite a feeling. 416 00:20:02,300 --> 00:20:03,133 One. 417 00:20:03,133 --> 00:20:07,950 (explosion booms) (dramatic music) 418 00:20:07,950 --> 00:20:11,109 When it did go off, it created a huge amount of light, 419 00:20:11,109 --> 00:20:13,010 (flames crackling) 420 00:20:13,010 --> 00:20:15,490 and then the rocket went behind the cloud. 421 00:20:15,490 --> 00:20:17,720 When it went behind that cloud, it was very impressive. 422 00:20:17,720 --> 00:20:19,490 The whole cloud lit up. 423 00:20:19,490 --> 00:20:22,478 We all thought oh goodness, has something gone wrong? 424 00:20:22,478 --> 00:20:24,100 United Station, our fly ring data. 425 00:20:24,100 --> 00:20:25,630 And then the nose cone came out 426 00:20:25,630 --> 00:20:30,630 and you were getting all, phew. 427 00:20:36,847 --> 00:20:39,847 (inquisitive music) 428 00:20:49,659 --> 00:20:52,026 (people chattering) 429 00:20:52,026 --> 00:20:53,309 Wait, do I come? 430 00:20:53,309 --> 00:20:55,374 Go ahead Aswar, come. 431 00:20:55,374 --> 00:20:56,420 One of the things you have to do 432 00:20:56,420 --> 00:20:58,080 when you arrive at a big planetary body 433 00:20:58,080 --> 00:20:59,710 is slam the brakes on pretty quick. 434 00:20:59,710 --> 00:21:03,230 You need to slow yourself down and get yourself into orbit. 435 00:21:03,230 --> 00:21:04,750 You typically do this by going 436 00:21:04,750 --> 00:21:06,380 very close to the planet to slow you down, 437 00:21:06,380 --> 00:21:09,870 so you get captured by the gravitational pull of Saturn. 438 00:21:09,870 --> 00:21:13,050 It was an incredibly complex sequence 439 00:21:13,050 --> 00:21:15,483 that we had basically worked on for two years. 440 00:21:16,900 --> 00:21:20,590 Even after Pioneer and Voyager, we didn't know enough 441 00:21:20,590 --> 00:21:23,243 about the possible dangers of the Saturn system. 442 00:21:24,990 --> 00:21:27,430 And because the Cassini spacecraft was moving 443 00:21:27,430 --> 00:21:29,750 at about 10 miles per second, 444 00:21:29,750 --> 00:21:32,360 even hitting a grain of sand or a chunk of ice 445 00:21:32,360 --> 00:21:34,050 could be deadly to the spacecraft, 446 00:21:34,050 --> 00:21:37,034 and so we took a number of ways to remove that risk, 447 00:21:37,034 --> 00:21:38,660 (dramatic music) 448 00:21:38,660 --> 00:21:40,477 and the best was to turn so that 449 00:21:40,477 --> 00:21:43,993 the spacecraft antennae was facing forward. 450 00:21:45,080 --> 00:21:46,700 The high-gain antennae, which is a thing 451 00:21:46,700 --> 00:21:48,330 which communicates back to Earth, 452 00:21:48,330 --> 00:21:50,270 was actually protecting it from 453 00:21:50,270 --> 00:21:53,340 potentially being hit by dust particles, 454 00:21:53,340 --> 00:21:56,293 so it couldn't be in communication with Earth at that time. 455 00:21:59,830 --> 00:22:01,790 This was an incredibly nervous 456 00:22:01,790 --> 00:22:04,713 and dangerous maneuver to do given the unknowns. 457 00:22:07,230 --> 00:22:08,610 Once Cassini had crossed 458 00:22:08,610 --> 00:22:10,530 the plane of Saturn's rings, 459 00:22:10,530 --> 00:22:13,570 the spacecraft had to reorient itself again. 460 00:22:13,570 --> 00:22:15,550 The thrusters had to be turned 461 00:22:15,550 --> 00:22:19,010 so that they would point in the direction of motion 462 00:22:19,010 --> 00:22:21,400 to be able to capture it into orbit. 463 00:22:21,400 --> 00:22:22,570 During the 90 minutes 464 00:22:22,570 --> 00:22:24,690 that Cassini's engines were firing, 465 00:22:24,690 --> 00:22:28,250 the spacecraft was completely shielded from Earth. 466 00:22:28,250 --> 00:22:30,740 At its closest approach, the spacecraft 467 00:22:30,740 --> 00:22:34,893 was just 20,000 kilometers from the cloud tops of Saturn. 468 00:22:36,010 --> 00:22:39,460 All the mission controllers on Earth could do was wait. 469 00:22:39,460 --> 00:22:43,123 We all held our breath waiting for the signal to return. 470 00:22:44,630 --> 00:22:47,460 But then we got a signal which was dead-on. 471 00:22:47,460 --> 00:22:48,340 The doppler has landed. 472 00:22:48,340 --> 00:22:49,810 And we knew at that moment we had 473 00:22:49,810 --> 00:22:52,637 successfully gone into orbit, and there was a huge cheer. 474 00:22:52,637 --> 00:22:57,590 (people cheering) (people applauding) 475 00:22:57,590 --> 00:22:59,320 It was really a fist pump moment. 476 00:22:59,320 --> 00:23:01,397 People were jumping up and hugging. 477 00:23:01,397 --> 00:23:04,910 (people cheering) (people applauding) 478 00:23:04,910 --> 00:23:06,340 I was watching it in the middle of the night 479 00:23:06,340 --> 00:23:09,610 via the internet, and I must've went into a huge cheer 480 00:23:09,610 --> 00:23:11,903 which woke everybody else up in the house. 481 00:23:14,030 --> 00:23:14,970 When the burn was completed, 482 00:23:14,970 --> 00:23:18,640 we knew we were in orbit, so we turned away from the Earth 483 00:23:18,640 --> 00:23:21,070 and photographed the dark side of the rings 484 00:23:21,070 --> 00:23:22,830 and then after we come back through 485 00:23:22,830 --> 00:23:23,850 the ring plane crossing again, 486 00:23:23,850 --> 00:23:26,360 we turn back to the Earth to start play back that data, 487 00:23:26,360 --> 00:23:28,660 and those images I'll never forget them. 488 00:23:28,660 --> 00:23:31,750 We've had much prettier images but my gosh, 489 00:23:31,750 --> 00:23:34,150 to see the ripples and the structure in those rings, 490 00:23:34,150 --> 00:23:36,966 it was absolutely, like I said, I'll never forget it. 491 00:23:36,966 --> 00:23:40,452 (triumphant music) 492 00:23:40,452 --> 00:23:43,580 It's one of those moments you'll take to your grave. 493 00:23:43,580 --> 00:23:45,340 Cassini Huygens had arrived 494 00:23:45,340 --> 00:23:49,120 at the Saturnian system, an enormous gas giant 495 00:23:49,120 --> 00:23:50,055 with 82 moons at present count, 496 00:23:50,055 --> 00:23:55,055 orbiting on the outside and within 497 00:23:55,270 --> 00:23:59,870 the hundreds of rings of varying shades and colors. 498 00:23:59,870 --> 00:24:02,630 We could now truly start to appreciate 499 00:24:02,630 --> 00:24:06,693 the awesome beauty and complexity of this planetary system. 500 00:24:07,987 --> 00:24:10,570 (gentle music) 501 00:24:13,710 --> 00:24:16,150 From a mission engineer's point of view, 502 00:24:16,150 --> 00:24:18,790 the rings are a hazard. (laughs) 503 00:24:18,790 --> 00:24:21,370 But once we've discovered that the environment's safe, 504 00:24:21,370 --> 00:24:23,580 then we can start to open up the stops a little bit 505 00:24:23,580 --> 00:24:24,733 to allow more activity. 506 00:24:26,230 --> 00:24:29,360 We knew that we'd have long, consecutive pieces of data 507 00:24:29,360 --> 00:24:32,380 to test our theories, but we didn't realize 508 00:24:32,380 --> 00:24:35,840 that because we could orbit Saturn hundreds of time, 509 00:24:35,840 --> 00:24:39,040 the same aspect could be seen over multiple times 510 00:24:39,040 --> 00:24:41,070 by all the 12 instruments, 511 00:24:41,070 --> 00:24:44,380 and that hit us in the head sometimes. 512 00:24:44,380 --> 00:24:47,690 Oh, this is something unexpected that's happening. 513 00:24:47,690 --> 00:24:51,260 It's very easy to think of the system as isolated parts, 514 00:24:51,260 --> 00:24:53,100 especially when you're working with a spacecraft mission 515 00:24:53,100 --> 00:24:54,180 and you target this feature 516 00:24:54,180 --> 00:24:55,550 and then you target the satellite. 517 00:24:55,550 --> 00:24:58,560 Any speculation, any idea we had had from the years 518 00:24:58,560 --> 00:25:01,463 between Voyager and Cassini, could now be tested. 519 00:25:02,640 --> 00:25:05,537 And as for the origins of the rings and moons, 520 00:25:05,537 --> 00:25:08,382 the Cassini team made a further discovery. 521 00:25:08,382 --> 00:25:11,132 (dramatic music) 522 00:25:12,260 --> 00:25:14,260 As we have seen quite clearly, 523 00:25:14,260 --> 00:25:17,220 Saturn's rings are made out of ice, 524 00:25:17,220 --> 00:25:21,843 which is the fragments of shattered icy moons. 525 00:25:27,840 --> 00:25:29,840 But the alternate is also true. 526 00:25:29,840 --> 00:25:32,740 Cassini showed us that the pieces of the ring 527 00:25:32,740 --> 00:25:34,900 are sticking together to make new moons. 528 00:25:34,900 --> 00:25:38,570 So the rings are collecting in places to make moons, 529 00:25:38,570 --> 00:25:41,590 and the moons are being shattered to make new rings. 530 00:25:41,590 --> 00:25:45,723 So this is sort of a cosmic recycling of material. 531 00:25:47,290 --> 00:25:49,440 So not only are the rings of Saturn 532 00:25:49,440 --> 00:25:54,440 most likely made of moons, but they also make new moons. 533 00:25:54,680 --> 00:25:57,240 One of the best measurements that Cassini made 534 00:25:57,240 --> 00:25:59,920 was to measure the total mass of the rings. 535 00:25:59,920 --> 00:26:03,550 This determines how long this recycling process could go on. 536 00:26:03,550 --> 00:26:06,453 The amount of pollution, the amount of meteoric dust, 537 00:26:07,360 --> 00:26:09,500 the combination of those two facts 538 00:26:09,500 --> 00:26:13,870 say that the rings are about 100 million years old. 539 00:26:13,870 --> 00:26:17,150 This can be extended, perhaps, to a billion years or two, 540 00:26:17,150 --> 00:26:19,240 but the current one is the rings 541 00:26:19,240 --> 00:26:22,131 that the dinosaurs would've seen. 542 00:26:22,131 --> 00:26:24,881 (dinosaur roars) 543 00:26:37,463 --> 00:26:40,046 (gentle music) 544 00:26:45,526 --> 00:26:47,320 (intriguing music) 545 00:26:47,320 --> 00:26:48,890 If we were to look closely, 546 00:26:48,890 --> 00:26:53,200 many of the ring particles would appear fluffy to your hand. 547 00:26:53,200 --> 00:26:56,823 They're fairy castle structures sort of like snow. 548 00:26:59,260 --> 00:27:01,920 You would see a range in particle sizes 549 00:27:01,920 --> 00:27:06,440 continually colliding, but at a relatively low velocity, 550 00:27:06,440 --> 00:27:08,970 maybe a millimeter a second, 551 00:27:08,970 --> 00:27:11,590 which is gentle enough that the surfaces 552 00:27:11,590 --> 00:27:13,723 might be slightly compressed. 553 00:27:15,890 --> 00:27:18,350 But occasionally, particles will hit each other 554 00:27:18,350 --> 00:27:21,770 at a much higher velocity, which will knock off 555 00:27:21,770 --> 00:27:25,340 a spray of small particles of snow and ice 556 00:27:25,340 --> 00:27:28,740 which eventually are recaptured by other clumps, 557 00:27:28,740 --> 00:27:33,470 so the equilibrium, the balance between these two processes, 558 00:27:33,470 --> 00:27:38,470 leads to a distribution of sizes from dust to mountains, 559 00:27:38,550 --> 00:27:42,350 and each of the objects being like a pile of rubble 560 00:27:42,350 --> 00:27:44,783 with a coating of snow on the top. 561 00:27:48,219 --> 00:27:49,930 (inquisitive music) 562 00:27:49,930 --> 00:27:51,680 After six months in orbit, 563 00:27:51,680 --> 00:27:55,030 Cassini was scheduled to deploy the Huygens lander 564 00:27:55,030 --> 00:27:57,473 on December the 25th, 2004. 565 00:27:59,210 --> 00:28:01,090 We had Christmas dinner at my home 566 00:28:01,090 --> 00:28:03,740 and had a lot of the European and American contingent 567 00:28:03,740 --> 00:28:06,040 because we were all spending Christmas at JPL. 568 00:28:08,780 --> 00:28:10,480 My whole family was here. 569 00:28:10,480 --> 00:28:13,470 I made them come to JPL and they watched 570 00:28:13,470 --> 00:28:15,743 as we released the probe that night. 571 00:28:18,603 --> 00:28:19,731 (people chattering) 572 00:28:19,731 --> 00:28:22,620 (people cheering) (people applauding) 573 00:28:22,620 --> 00:28:23,780 A few days later we turned around 574 00:28:23,780 --> 00:28:26,553 to take a picture of where the probe was supposed to be. 575 00:28:27,959 --> 00:28:30,750 It's a little speck and it's not very exciting, 576 00:28:30,750 --> 00:28:33,310 but it was a genuine confirmation 577 00:28:33,310 --> 00:28:35,533 it was exactly where we thought it was going to be. 578 00:28:36,980 --> 00:28:38,330 Because what happens with a probe 579 00:28:38,330 --> 00:28:39,760 is essentially when you release it, 580 00:28:39,760 --> 00:28:41,674 you've turned on a little three-week egg timer. 581 00:28:41,674 --> 00:28:43,390 (dramatic music) (timer ticking) 582 00:28:43,390 --> 00:28:46,020 Your worst nightmare is silence. 583 00:28:46,020 --> 00:28:48,847 That's happened too many times to people in space missions 584 00:28:48,847 --> 00:28:50,773 and it's just a punch in the gut. 585 00:28:52,510 --> 00:28:54,490 But three weeks later, right on schedule, 586 00:28:54,490 --> 00:28:55,640 we get the signal back. 587 00:28:57,570 --> 00:28:58,770 When we arrive at Titan, 588 00:28:58,770 --> 00:29:01,400 we're traveling at incredible speeds, 589 00:29:01,400 --> 00:29:05,110 and what you gotta do is go from ballistic, 590 00:29:05,110 --> 00:29:07,720 incredibly fast speeds at the top of the atmosphere 591 00:29:07,720 --> 00:29:09,560 to zero speed at the bottom 592 00:29:09,560 --> 00:29:11,430 of the atmosphere on the surface, 593 00:29:11,430 --> 00:29:13,310 and this is pretty hard to do. 594 00:29:13,310 --> 00:29:14,720 There are several elements in order 595 00:29:14,720 --> 00:29:16,380 to get yourself down to the surface. 596 00:29:16,380 --> 00:29:18,043 The first is a heat shield. 597 00:29:19,910 --> 00:29:21,620 Titan has a huge atmosphere, 598 00:29:21,620 --> 00:29:23,453 and Huygens was just screaming in. 599 00:29:24,338 --> 00:29:25,342 And if we were to send the probe 600 00:29:25,342 --> 00:29:28,808 in without protection, it will burn immediately. 601 00:29:28,808 --> 00:29:30,470 So you have the sacrificial heat shield 602 00:29:30,470 --> 00:29:33,820 in front of the probe, so the fireball that's created 603 00:29:33,820 --> 00:29:37,420 as the probe slows down doesn't destroy the lander itself. 604 00:29:37,420 --> 00:29:38,720 And in the case of Huygens, 605 00:29:38,720 --> 00:29:41,163 the heat shield was made of many of those tile. 606 00:29:42,550 --> 00:29:43,560 While the heat shield 607 00:29:43,560 --> 00:29:45,470 was slowing the probe down, 608 00:29:45,470 --> 00:29:49,810 Huygens experienced a deceleration of 15G. 609 00:29:49,810 --> 00:29:53,310 Once it had got to an altitude of 170 kilometers 610 00:29:53,310 --> 00:29:56,980 and was only traveling at a mere 400 meters per second, 611 00:29:56,980 --> 00:30:00,233 Huygens deployed the first of its three parachutes. 612 00:30:01,850 --> 00:30:04,450 The drogue parachute stabilized the probe 613 00:30:04,450 --> 00:30:06,660 and pulled off the back cover, 614 00:30:06,660 --> 00:30:09,520 which deployed the main parachute, 615 00:30:09,520 --> 00:30:13,205 at which point the spent heat shield was discarded. 616 00:30:13,205 --> 00:30:15,872 (clock ticking) 617 00:30:16,970 --> 00:30:19,330 But Titan's atmosphere is so thick 618 00:30:19,330 --> 00:30:21,660 that if we kept that parachute on, 619 00:30:21,660 --> 00:30:23,900 the batteries would've run out before it got to the surface. 620 00:30:23,900 --> 00:30:24,920 It was gonna go a little slowly. 621 00:30:24,920 --> 00:30:26,850 So it actually deployed that parachute 622 00:30:26,850 --> 00:30:28,320 and then dropped the last chute 623 00:30:28,320 --> 00:30:31,053 which allowed it to descend at a more reasonable pace. 624 00:30:32,080 --> 00:30:33,960 You get horizontal winds coming across 625 00:30:33,960 --> 00:30:35,560 and swinging the probe about, 626 00:30:35,560 --> 00:30:37,120 so as it descends through the atmosphere 627 00:30:37,120 --> 00:30:40,703 it's not perfectly still, it's swinging like a pendulum. 628 00:30:42,040 --> 00:30:46,470 The images from descent show channels on the surface 629 00:30:46,470 --> 00:30:48,790 and there was no doubt, there were no questions, 630 00:30:48,790 --> 00:30:51,400 it was obvious what we were seeing. 631 00:30:51,400 --> 00:30:54,620 And it was just so spectacular to see something 632 00:30:54,620 --> 00:30:57,190 and know what it was on the surface of Titan 633 00:30:57,190 --> 00:31:00,161 and for it to be river channels. 634 00:31:00,161 --> 00:31:03,328 (introspective music) 635 00:31:14,768 --> 00:31:16,240 It then landed on the surface 636 00:31:16,240 --> 00:31:18,350 and it started transmitting back to Cassini, 637 00:31:18,350 --> 00:31:20,350 which was way up overhead. 638 00:31:20,350 --> 00:31:23,120 The spacecraft, meanwhile, is flying over the top 639 00:31:23,120 --> 00:31:24,780 and pointing at the point on 640 00:31:24,780 --> 00:31:27,880 the surface of Titan where the probe is. 641 00:31:27,880 --> 00:31:30,390 And eventually the spacecraft goes over the horizon. 642 00:31:30,390 --> 00:31:31,440 The batteries were still going 643 00:31:31,440 --> 00:31:33,513 even after we lost sight of it. 644 00:31:34,640 --> 00:31:35,890 The spacecraft turned back 645 00:31:35,890 --> 00:31:38,070 and started to play the data back. 646 00:31:38,070 --> 00:31:40,090 Imaging guys turned around an image 647 00:31:40,090 --> 00:31:41,863 of the surface very, very quickly. 648 00:31:43,320 --> 00:31:44,330 (keyboard keys clacking) 649 00:31:44,330 --> 00:31:46,000 And it flickered up on the screen. 650 00:31:46,000 --> 00:31:47,947 And everybody looks up and goes, 651 00:31:47,947 --> 00:31:49,110 "What's going on here?" 652 00:31:49,110 --> 00:31:51,410 It was almost like it was fake. 653 00:31:51,410 --> 00:31:53,500 To see something like that on a moon 654 00:31:53,500 --> 00:31:56,620 in the outer solar system, it was just spectacular. 655 00:31:56,620 --> 00:31:58,230 It still gives me goosebumps to think about 656 00:31:58,230 --> 00:31:59,940 all of that working so well. 657 00:31:59,940 --> 00:32:02,270 Seeing something that no human in history 658 00:32:02,270 --> 00:32:05,920 had ever seen before, it was truly awe-inspiring. 659 00:32:05,920 --> 00:32:08,143 It was a moment I will never, ever forget. 660 00:32:09,270 --> 00:32:10,980 It was sitting on this flat lake bed 661 00:32:10,980 --> 00:32:13,970 and the things that appeared as rocks in the background 662 00:32:13,970 --> 00:32:17,753 were actually pebbles of ice that had been frozen. 663 00:32:19,690 --> 00:32:22,110 Titan is an icy satellite. 664 00:32:22,110 --> 00:32:25,180 Its bedrock is made of water ice. 665 00:32:25,180 --> 00:32:27,440 But when we look at the surface of Titan 666 00:32:27,440 --> 00:32:30,900 with the spectrometer, it's actually really hard 667 00:32:30,900 --> 00:32:34,320 to find any pure water ice spectral signatures, 668 00:32:34,320 --> 00:32:36,440 and I think that the key there 669 00:32:36,440 --> 00:32:38,260 is all these atmospheric products 670 00:32:38,260 --> 00:32:41,090 that are continually falling out across the surface. 671 00:32:41,090 --> 00:32:42,650 Titan's atmosphere is actually 672 00:32:42,650 --> 00:32:44,980 mostly nitrogen like Earth's atmosphere, 673 00:32:44,980 --> 00:32:47,290 but it's cold in the outer solar system, 674 00:32:47,290 --> 00:32:50,240 and the next most common constituent in the atmosphere 675 00:32:50,240 --> 00:32:53,220 is methane, and methane in Titan's atmosphere 676 00:32:53,220 --> 00:32:56,260 plays a role very much like water on Earth. 677 00:32:56,260 --> 00:32:58,210 So the methane in the atmosphere 678 00:32:58,210 --> 00:32:59,640 can condense to form clouds, 679 00:32:59,640 --> 00:33:01,810 it can actually rain out onto the surface, 680 00:33:01,810 --> 00:33:04,610 it can run across the surface in rivers, 681 00:33:04,610 --> 00:33:08,180 form lakes and seas, and there may even be 682 00:33:08,180 --> 00:33:11,570 methane aquifers in the subsurface as well. 683 00:33:11,570 --> 00:33:14,560 So it really does have a complete hydrological cycle 684 00:33:14,560 --> 00:33:17,373 where methane plays the role that water does on Earth. 685 00:33:18,710 --> 00:33:22,970 Carl Sagan and his research partners, Khare and Thompson, 686 00:33:22,970 --> 00:33:25,190 gave us a really interesting insight 687 00:33:25,190 --> 00:33:27,750 by doing experiments where they mixed 688 00:33:27,750 --> 00:33:31,120 nitrogen with methane and then provided 689 00:33:31,120 --> 00:33:34,697 some free energy source, some light or some particles 690 00:33:34,697 --> 00:33:35,530 (light booms) 691 00:33:35,530 --> 00:33:37,540 to break them apart or to ionize them, 692 00:33:37,540 --> 00:33:40,330 and it led to this incredible organic chemistry 693 00:33:40,330 --> 00:33:42,640 that was beyond the wildest dreams, 694 00:33:42,640 --> 00:33:45,440 created this stuff in the laboratory the called tholins. 695 00:33:46,885 --> 00:33:49,270 The methane dissociates at the top of the atmosphere, 696 00:33:49,270 --> 00:33:52,090 recombines to form very complex molecules, 697 00:33:52,090 --> 00:33:55,880 and all of that material falls out onto the surface. 698 00:33:55,880 --> 00:33:58,120 How long that process has been going on 699 00:33:58,120 --> 00:34:00,170 is still not well understood, 700 00:34:00,170 --> 00:34:02,630 but if Titan has had an atmosphere like it has today 701 00:34:02,630 --> 00:34:05,140 for the entirety of the solar system, 702 00:34:05,140 --> 00:34:08,920 that's going to produce a volume of sediments 703 00:34:08,920 --> 00:34:13,830 that means that Titan's crust is not just water ice 704 00:34:13,830 --> 00:34:15,840 but also has a bunch of organic sediments 705 00:34:15,840 --> 00:34:17,540 that have been built up over time. 706 00:34:18,840 --> 00:34:20,950 All of these organic materials have been 707 00:34:20,950 --> 00:34:24,190 sitting around littering the surface of this moon 708 00:34:24,190 --> 00:34:26,800 where there's the opportunity, potentially, 709 00:34:26,800 --> 00:34:29,460 for them to have mixed with liquid water. 710 00:34:29,460 --> 00:34:32,580 If you react water with these precursor molecules, 711 00:34:32,580 --> 00:34:34,613 what's been demonstrated is these tholins 712 00:34:34,613 --> 00:34:37,920 that have been studied in a lab can form amino acids. 713 00:34:37,920 --> 00:34:40,240 And the universe provides us that mechanism 714 00:34:40,240 --> 00:34:43,219 when impacts hit the surface of Titan, 715 00:34:43,219 --> 00:34:45,720 (object whooshes) (impact booms) 716 00:34:45,720 --> 00:34:48,370 because every impact has enough kinetic energy 717 00:34:48,370 --> 00:34:50,040 to melt some of the crust. 718 00:34:50,040 --> 00:34:52,540 The bigger your impacter, the more kinetic energy 719 00:34:52,540 --> 00:34:54,920 you impart, and so the more melt you can generate. 720 00:34:54,920 --> 00:34:57,240 And then based on how much melt you generate, 721 00:34:57,240 --> 00:35:00,860 you have this pool of liquid in the near subsurface 722 00:35:00,860 --> 00:35:03,330 that's going to cool slowly over time, 723 00:35:03,330 --> 00:35:06,000 and based on the sizes of impact craters 724 00:35:06,000 --> 00:35:07,140 that we've seen on Titan, 725 00:35:07,140 --> 00:35:08,760 this can be anywhere from hundreds 726 00:35:08,760 --> 00:35:10,423 to tens of thousands of years. 727 00:35:12,170 --> 00:35:15,220 So we know that Titan has all the ingredients 728 00:35:15,220 --> 00:35:17,850 necessary for life as we know it, 729 00:35:17,850 --> 00:35:20,020 and it's been doing these chemistry experiments 730 00:35:20,020 --> 00:35:22,130 for hundreds of millions of years. 731 00:35:22,130 --> 00:35:25,120 You also have the opportunity for organic material 732 00:35:25,120 --> 00:35:27,010 to mix with a different solvent 733 00:35:27,010 --> 00:35:28,730 in the form of liquid methane, 734 00:35:28,730 --> 00:35:33,460 and so perhaps there are other prebiotic systems on Titan 735 00:35:33,460 --> 00:35:35,810 that have progressed that are completely alien 736 00:35:35,810 --> 00:35:38,523 to the water-based biology we have on Earth. 737 00:35:39,800 --> 00:35:42,340 It's hard to conceive how a methane-based 738 00:35:42,340 --> 00:35:46,070 form of life would work, but nature has repeatedly 739 00:35:46,070 --> 00:35:48,540 surprised us as demonstrated by all the findings 740 00:35:48,540 --> 00:35:51,490 of the Cassini mission, so I'm not willing to rule out 741 00:35:51,490 --> 00:35:54,850 the possibility of life in the liquid methane lakes. 742 00:35:54,850 --> 00:35:58,150 I'm personally skeptical that we would find that. 743 00:35:58,150 --> 00:36:00,910 There are some difficulties with that. 744 00:36:00,910 --> 00:36:03,900 So for example long-chained carbon molecules, 745 00:36:03,900 --> 00:36:06,660 organic molecules, tend not to dissolve very well 746 00:36:06,660 --> 00:36:09,260 in liquid methane, they'll precipitate out. 747 00:36:09,260 --> 00:36:12,730 So you could imagine an inverted structure almost 748 00:36:12,730 --> 00:36:14,390 where because cells are a mixture 749 00:36:14,390 --> 00:36:17,430 of insoluble and soluble parts, 750 00:36:17,430 --> 00:36:19,650 it's possible it could work the other way around, 751 00:36:19,650 --> 00:36:20,890 and I find it much more difficult 752 00:36:20,890 --> 00:36:23,570 to conceive how that could work. 753 00:36:23,570 --> 00:36:25,810 Certainly it would be very exotic 754 00:36:25,810 --> 00:36:28,070 and at present we have no indications 755 00:36:28,070 --> 00:36:29,900 in any of the current measurements 756 00:36:29,900 --> 00:36:33,160 from the Cassini or Huygens part of the mission 757 00:36:33,160 --> 00:36:35,060 that there's anything bizarre 758 00:36:35,060 --> 00:36:38,630 that we might need to attribute to the activity of life. 759 00:36:38,630 --> 00:36:40,810 But the only way to find out is to go and look, 760 00:36:40,810 --> 00:36:44,020 and so you have with Titan this wonderful possibility 761 00:36:44,020 --> 00:36:45,830 that we might find life as we know it 762 00:36:45,830 --> 00:36:47,900 or we might find life as we don't know it. 763 00:36:47,900 --> 00:36:49,720 In any case, just going to look around 764 00:36:49,720 --> 00:36:51,630 will be a fantastic thing to do, 765 00:36:51,630 --> 00:36:53,973 so what's not to like, really? 766 00:36:56,100 --> 00:36:58,200 But as exciting as Titan was, 767 00:36:59,128 --> 00:37:02,203 there were even more intriguing discoveries to be made. 768 00:37:03,390 --> 00:37:06,300 When Cassini was approaching Saturn for the first time 769 00:37:06,300 --> 00:37:09,100 at the end of 2003, our experiment, 770 00:37:09,100 --> 00:37:11,010 the ultraviolet imagining spectrograph, 771 00:37:11,010 --> 00:37:12,990 was systematically scanning 772 00:37:12,990 --> 00:37:15,160 back and forth on the planet Saturn, 773 00:37:15,160 --> 00:37:17,470 and we were amazed to discover 774 00:37:17,470 --> 00:37:21,400 that the system was filled with molecules of oxygen, 775 00:37:21,400 --> 00:37:24,740 and the oxygen was completely unexpected 776 00:37:24,740 --> 00:37:28,210 and we mapped this out and we noticed 777 00:37:28,210 --> 00:37:30,260 that the peak in the distribution 778 00:37:30,260 --> 00:37:34,630 was just a distance four times Saturn's radius 779 00:37:34,630 --> 00:37:36,130 from the center of the system. 780 00:37:36,130 --> 00:37:38,390 We knew that the moon Enceladus 781 00:37:38,390 --> 00:37:40,490 was orbiting just at that distance. 782 00:37:40,490 --> 00:37:42,650 Enceladus is a tiny moon 783 00:37:42,650 --> 00:37:45,770 just 500 kilometers in diameter 784 00:37:45,770 --> 00:37:49,113 with a surface area slightly larger than Texas. 785 00:37:49,990 --> 00:37:51,840 It coexists with one of Saturn's 786 00:37:51,840 --> 00:37:53,963 fainter rings, the E Ring. 787 00:37:54,990 --> 00:37:57,180 The E Ring is just a ring 788 00:37:57,180 --> 00:37:59,700 of icy grains in the micron range. 789 00:37:59,700 --> 00:38:01,400 It was tenuous enough ring that we could 790 00:38:01,400 --> 00:38:03,470 fly through it and examine it. 791 00:38:03,470 --> 00:38:06,820 We had these tentative ideas that maybe 792 00:38:06,820 --> 00:38:10,650 there was a connection between the E Ring and Enceladus 793 00:38:10,650 --> 00:38:12,560 because they were pretty co-located, 794 00:38:12,560 --> 00:38:15,040 but we didn't really have any understanding 795 00:38:15,040 --> 00:38:17,270 of how they were playing together. 796 00:38:17,270 --> 00:38:19,920 Enceladus originally was on the itinerary, 797 00:38:19,920 --> 00:38:21,620 but only marginally so. 798 00:38:21,620 --> 00:38:24,170 It was another very interesting Saturn moon, 799 00:38:24,170 --> 00:38:26,990 small, very shiny, very white, very bright, 800 00:38:26,990 --> 00:38:29,673 but other than that too small to be interesting. 801 00:38:29,673 --> 00:38:32,423 (dramatic music) 802 00:38:37,670 --> 00:38:39,840 And it was in the first close flyby 803 00:38:39,840 --> 00:38:41,931 that the magnetometer team detected 804 00:38:41,931 --> 00:38:45,370 something interesting that they didn't expect. 805 00:38:45,370 --> 00:38:47,800 The magnetic field instrument observed 806 00:38:47,800 --> 00:38:50,260 that the magnetic field lines didn't quite 807 00:38:50,260 --> 00:38:51,930 come down to the moon the way they should. 808 00:38:51,930 --> 00:38:55,610 This significant deflection in the magnetic field 809 00:38:55,610 --> 00:38:58,440 was extremely unexpected. 810 00:38:58,440 --> 00:39:00,650 The magnetometer team said 811 00:39:00,650 --> 00:39:02,330 it looks like it has an atmosphere. 812 00:39:02,330 --> 00:39:05,100 Well, anybody that knows anything about moons 813 00:39:05,100 --> 00:39:07,020 says that's too tiny, can't have an atmosphere, 814 00:39:07,020 --> 00:39:09,550 it's way too small to hold onto anything. 815 00:39:09,550 --> 00:39:11,250 A moon as small as Enceladus 816 00:39:11,250 --> 00:39:13,760 has a tiny gravitational field, 817 00:39:13,760 --> 00:39:16,990 far too week to hold onto an atmosphere. 818 00:39:16,990 --> 00:39:19,860 What's more, the atmosphere that was there 819 00:39:19,860 --> 00:39:22,233 didn't seem to be evenly spread out. 820 00:39:23,197 --> 00:39:24,980 If you flew by the south pole 821 00:39:24,980 --> 00:39:26,500 it looked like there was an atmosphere, 822 00:39:26,500 --> 00:39:28,660 but if you flew by at the equator 823 00:39:28,660 --> 00:39:30,700 you didn't see anything at all. 824 00:39:30,700 --> 00:39:32,440 But then we went back again and again 825 00:39:32,440 --> 00:39:33,640 and explored with more instruments 826 00:39:33,640 --> 00:39:35,100 and then took some images, 827 00:39:35,100 --> 00:39:36,930 and all of the sudden realized 828 00:39:36,930 --> 00:39:38,577 that not only it had an atmosphere, 829 00:39:38,577 --> 00:39:40,270 it was an icy atmosphere, 830 00:39:40,270 --> 00:39:43,423 but it had these plumes coming out of the southern pole. 831 00:39:49,220 --> 00:39:52,962 And here's water geysers on a tiny moon. 832 00:39:52,962 --> 00:39:55,879 (intriguing music) 833 00:39:57,164 --> 00:39:59,630 And that water that was coming out of 834 00:39:59,630 --> 00:40:02,370 what we've later found out to be an interior ocean 835 00:40:02,370 --> 00:40:04,033 was what was forming the E Ring. 836 00:40:05,290 --> 00:40:07,260 We were able to measure the amount 837 00:40:07,260 --> 00:40:10,870 of water in those plumes exactly enough 838 00:40:10,870 --> 00:40:13,760 to explain the ring of oxygen around Saturn 839 00:40:13,760 --> 00:40:16,160 that we had seen before that approach. 840 00:40:16,160 --> 00:40:19,480 What an amazing development that the geysers 841 00:40:19,480 --> 00:40:22,300 on the moon Enceladus are continually erupting 842 00:40:22,300 --> 00:40:24,970 water molecules broken down by the sun 843 00:40:24,970 --> 00:40:28,560 to form atoms of oxygen that we could see 844 00:40:28,560 --> 00:40:32,013 even millions of miles away from the planet Saturn. 845 00:40:34,010 --> 00:40:36,320 And as we flew through these plumes 846 00:40:36,320 --> 00:40:39,220 coming out of the south pole, some of that plume material 847 00:40:39,220 --> 00:40:41,800 was captured by the instrument. 848 00:40:41,800 --> 00:40:43,050 And we used that to learn more 849 00:40:43,050 --> 00:40:45,690 about the interior ocean chemistry. 850 00:40:45,690 --> 00:40:48,020 Not only did it contain water vapor, 851 00:40:48,020 --> 00:40:52,920 but it had traces of ammonia, methane, H2, CO2, 852 00:40:52,920 --> 00:40:54,800 and then there was a whole host 853 00:40:54,800 --> 00:40:57,813 of organic compounds that we could also see. 854 00:40:58,680 --> 00:41:01,910 The experiment that we did here at Colorado 855 00:41:01,910 --> 00:41:03,720 is very similar to that. 856 00:41:03,720 --> 00:41:06,010 We didn't actually fly through the plume 857 00:41:06,010 --> 00:41:09,200 but we watched a star set through the plume. 858 00:41:09,200 --> 00:41:11,600 And now we can put all that information together 859 00:41:11,600 --> 00:41:14,380 to get a picture of the shape of the eruption 860 00:41:14,380 --> 00:41:15,900 and also the material that's being 861 00:41:15,900 --> 00:41:18,610 erupted from inside of Enceladus, 862 00:41:18,610 --> 00:41:21,350 and amazingly enough that material 863 00:41:21,350 --> 00:41:24,383 has the basic building blocks of life. 864 00:41:26,090 --> 00:41:28,570 We've been dominated as biologists 865 00:41:28,570 --> 00:41:31,480 with a fixation on the idea that all life on Earth 866 00:41:31,480 --> 00:41:33,360 is powered ultimately by the sun. 867 00:41:33,360 --> 00:41:36,620 Any formation of life going on on Enceladus 868 00:41:36,620 --> 00:41:38,740 is going to be happening beneath the icy crust 869 00:41:38,740 --> 00:41:40,460 and the oceans underneath where we see 870 00:41:40,460 --> 00:41:43,710 the same kind of hydrothermal vent systems 871 00:41:43,710 --> 00:41:46,350 releasing hydrogen gas into the oceans there, 872 00:41:46,350 --> 00:41:47,970 which we know for a fact would've 873 00:41:47,970 --> 00:41:50,070 been present on the early Earth, 874 00:41:50,070 --> 00:41:52,413 and they don't strictly require the sun. 875 00:41:53,400 --> 00:41:56,130 We think based on the types of molecules 876 00:41:56,130 --> 00:41:58,720 and other chemicals we're finding in the plume 877 00:41:58,720 --> 00:42:01,670 that this process called serpentinization is happening. 878 00:42:01,670 --> 00:42:04,620 Serpentinization is a geological process. 879 00:42:04,620 --> 00:42:06,680 It's a fancy way of saying how 880 00:42:06,680 --> 00:42:09,590 liquid water can react with rocks, 881 00:42:09,590 --> 00:42:11,340 and serpentinization is thought to be 882 00:42:11,340 --> 00:42:14,710 really important for supporting microorganisms 883 00:42:14,710 --> 00:42:17,620 and the base of an ecosystem outside of these 884 00:42:17,620 --> 00:42:21,270 hydrothermal vents because it makes abundant hydrogen, 885 00:42:21,270 --> 00:42:23,670 and hydrogen is sort of like rocket fuel 886 00:42:23,670 --> 00:42:26,380 for a microorganism, it's a great way 887 00:42:26,380 --> 00:42:30,473 to have a food that can be burned to provide energy. 888 00:42:31,550 --> 00:42:36,150 To me, Titan is less exciting than Enceladus 889 00:42:36,150 --> 00:42:39,240 because Enceladus has oceans 890 00:42:39,240 --> 00:42:43,290 with alkaline fluids from hydrothermal vents going into it, 891 00:42:43,290 --> 00:42:45,030 and therefore it's exactly analogous 892 00:42:45,030 --> 00:42:48,423 to how I think life started on Earth. 893 00:42:51,560 --> 00:42:54,650 This says to me that would be a good place to go, 894 00:42:54,650 --> 00:42:57,010 measure those plumes, maybe drill down 895 00:42:57,010 --> 00:42:59,443 and see if there's any form of life there. 896 00:43:00,700 --> 00:43:02,060 So Enceladus may have 897 00:43:02,060 --> 00:43:04,220 just the right conditions for life 898 00:43:04,220 --> 00:43:07,850 to get started far away from the sun, 899 00:43:07,850 --> 00:43:10,870 and the evidence for its mysterious inner workings 900 00:43:10,870 --> 00:43:14,183 can be seen in the enormous, diffuse E Ring. 901 00:43:16,200 --> 00:43:20,390 This is just another case of how the moons make rings, 902 00:43:20,390 --> 00:43:22,580 so by grinding of their surface, 903 00:43:22,580 --> 00:43:25,110 which throws dust into orbit around the planet, 904 00:43:25,110 --> 00:43:29,670 by erupting of geysers, or by shattering them to bits, 905 00:43:29,670 --> 00:43:33,290 the moons are the parents of the rings that we see, 906 00:43:33,290 --> 00:43:37,330 but also the children because the rings in some cases 907 00:43:37,330 --> 00:43:40,453 can collect up to form new moons. 908 00:43:43,529 --> 00:43:45,630 (whimsical music) 909 00:43:45,630 --> 00:43:46,660 Cassini would spend 910 00:43:46,660 --> 00:43:49,740 more than 13 years at the Saturnian system 911 00:43:49,740 --> 00:43:53,720 and completely 294 orbits of the planet, 912 00:43:53,720 --> 00:43:56,403 but eventually its fuel would run out. 913 00:43:58,340 --> 00:44:01,450 Everything has to end, including Cassini. 914 00:44:01,450 --> 00:44:02,850 (melancholic music) 915 00:44:02,850 --> 00:44:04,840 We went through this amazing time 916 00:44:04,840 --> 00:44:05,990 at the end of the mission, 917 00:44:05,990 --> 00:44:09,420 ending up with orbits which went inside Saturn's rings, 918 00:44:09,420 --> 00:44:10,900 but we knew at the end, of course, 919 00:44:10,900 --> 00:44:12,940 that the idea was to actually 920 00:44:12,940 --> 00:44:16,320 burn the spacecraft up in the atmosphere of Saturn, 921 00:44:16,320 --> 00:44:18,110 and that's to avoid it hitting these 922 00:44:18,110 --> 00:44:22,320 astrobiologically feasible places like Enceladus and Titan. 923 00:44:22,320 --> 00:44:23,630 The last thing we would want to do 924 00:44:23,630 --> 00:44:26,773 would be contaminate those with something sent from Earth. 925 00:44:32,800 --> 00:44:34,920 You can go where you've never been before. 926 00:44:34,920 --> 00:44:36,890 You can get science you will never have 927 00:44:36,890 --> 00:44:38,440 any other opportunity of getting, 928 00:44:38,440 --> 00:44:39,990 and you'll keep Enceladus safe. 929 00:44:41,320 --> 00:44:43,882 No brainer. (laughs) 930 00:44:43,882 --> 00:44:45,893 But the emotions were all over the map. 931 00:44:49,520 --> 00:44:52,523 All good things must come to an end, (laughs) right? 932 00:44:53,428 --> 00:44:55,653 Yes, it's sad in a way, but. 933 00:44:58,280 --> 00:45:00,620 The spacecraft was oriented so it could 934 00:45:00,620 --> 00:45:03,450 communicate with the deep space network here on Earth, 935 00:45:03,450 --> 00:45:06,420 but then the other axis was set 936 00:45:06,420 --> 00:45:08,830 so that the spacecraft could get the best measurements 937 00:45:08,830 --> 00:45:13,323 of Saturn's atmosphere as we plunged into it. 938 00:45:26,530 --> 00:45:31,447 We have loss of signal in X-ray band and CR-band. 939 00:45:35,127 --> 00:45:39,088 Total loss of signal at 11:55:46 940 00:45:39,088 --> 00:45:44,088 for the S-band, so that would be the end of the spacecraft. 941 00:45:44,720 --> 00:45:46,760 I don't think any of us were ready. 942 00:45:46,760 --> 00:45:49,020 If you ever had pets, and I've gone through 943 00:45:49,020 --> 00:45:50,960 eight cats and two dogs during 944 00:45:50,960 --> 00:45:53,000 the 23 years I worked on Cassini, 945 00:45:53,000 --> 00:45:55,990 and when you know it's time, it's time, 946 00:45:55,990 --> 00:45:58,730 and it was time to end the spacecraft. 947 00:45:58,730 --> 00:46:00,330 Now I, don't get me wrong, 948 00:46:00,330 --> 00:46:02,780 I'm very sentimental about it, but it wasn't a pet, 949 00:46:02,780 --> 00:46:05,870 it was just an amazing instrument, a robot, 950 00:46:05,870 --> 00:46:08,920 that did some incredible things at our behest. 951 00:46:08,920 --> 00:46:10,970 Signal from the spacecraft is gone 952 00:46:10,970 --> 00:46:14,903 and within the next 45 seconds, so will be the spacecraft. 953 00:46:16,520 --> 00:46:20,540 I hope you're all as deeply proud 954 00:46:20,540 --> 00:46:22,710 of this amazing accomplishment. 955 00:46:22,710 --> 00:46:24,570 Congratulations to you all. 956 00:46:24,570 --> 00:46:26,400 This has been an incredible mission, 957 00:46:26,400 --> 00:46:28,320 an incredible spacecraft, 958 00:46:28,320 --> 00:46:30,573 and you're all an incredible team. 959 00:46:31,530 --> 00:46:33,480 I'm gonna call this the end of mission. 960 00:46:34,470 --> 00:46:36,093 Project manager off the net. 961 00:46:36,927 --> 00:46:39,927 (people applauding) 962 00:46:45,350 --> 00:46:47,180 Cassini was only made possible 963 00:46:47,180 --> 00:46:51,360 by the hard work of hundreds of scientists and engineers 964 00:46:51,360 --> 00:46:53,960 from even before I was born, 965 00:46:53,960 --> 00:46:57,220 so to be able to be there with them 966 00:46:57,220 --> 00:47:01,130 for the end of the mission was supremely humbling 967 00:47:01,130 --> 00:47:04,220 because of the gift that they gave us. 968 00:47:04,220 --> 00:47:07,259 And I cried like a baby (laughs) the whole time. 969 00:47:07,259 --> 00:47:09,220 (inquisitive music) 970 00:47:09,220 --> 00:47:11,820 I've always loved the rings of Saturn. 971 00:47:11,820 --> 00:47:14,520 The Cassini exploration has allowed us 972 00:47:14,520 --> 00:47:18,923 to see them really close up, changing before our eyes. 973 00:47:20,030 --> 00:47:23,490 The idea of oceans beneath the ice 974 00:47:23,490 --> 00:47:28,090 that might support life is far from the old paradigm. 975 00:47:28,090 --> 00:47:31,070 It opens up a whole new idea of how life 976 00:47:31,070 --> 00:47:33,993 might form in solar systems in the cosmos. 977 00:47:35,200 --> 00:47:36,447 If you were to say to me, 978 00:47:36,447 --> 00:47:38,380 "Where would I most want to send a rocket?" 979 00:47:38,380 --> 00:47:40,170 it would be to Enceladus and it would be to look at 980 00:47:40,170 --> 00:47:43,350 the plumes and alkaline hydrothermal vents under the surface 981 00:47:43,350 --> 00:47:45,510 because to me, that's the environment 982 00:47:45,510 --> 00:47:48,570 that's most likely to drive the origin of life. 983 00:47:48,570 --> 00:47:50,700 Finding life on Enceladus 984 00:47:50,700 --> 00:47:52,460 or underneath the surface of Titan 985 00:47:52,460 --> 00:47:55,330 would drastically change our view of the universe 986 00:47:55,330 --> 00:47:58,670 and our place in it, and it's a future test 987 00:47:58,670 --> 00:48:01,060 to search out and find out if those ingredients 988 00:48:01,060 --> 00:48:04,873 have led to the evolution of life on those celestial bodies. 989 00:48:06,436 --> 00:48:08,580 In the summer of 2019, 990 00:48:08,580 --> 00:48:11,077 NASA announced that it had approved a mission 991 00:48:11,077 --> 00:48:15,663 called Dragonfly that would return to the surface of Titan. 992 00:48:16,670 --> 00:48:19,640 Dragonfly is a mission that's going to Titan 993 00:48:19,640 --> 00:48:21,963 to study its prebiotic chemistry. 994 00:48:23,800 --> 00:48:25,880 It's an octocopter. 995 00:48:25,880 --> 00:48:30,780 By being a mobile lander, Dragonfly is going to allow us 996 00:48:30,780 --> 00:48:34,053 to truly discover what the surface of Titan is like. 997 00:48:36,250 --> 00:48:38,440 And it would spend most of its time on the surface 998 00:48:38,440 --> 00:48:39,760 making scientific measurements, 999 00:48:39,760 --> 00:48:41,830 but then we'd be able to fly from place to place 1000 00:48:41,830 --> 00:48:43,350 so that we could measure the chemistry 1001 00:48:43,350 --> 00:48:45,893 in different environments. 1002 00:48:46,920 --> 00:48:51,920 Dragonfly's main goal is to taste the surface of Titan 1003 00:48:52,150 --> 00:48:54,410 and tell us what the end product 1004 00:48:54,410 --> 00:48:58,793 of all of this fantastic chemistry that Cassini revealed is. 1005 00:49:00,150 --> 00:49:02,130 And really understand how far 1006 00:49:02,130 --> 00:49:04,880 prebiotic chemistry can progress in an environment we know 1007 00:49:04,880 --> 00:49:06,730 has all the key ingredients for life. 1008 00:49:07,720 --> 00:49:08,960 Dragonfly is scheduled 1009 00:49:08,960 --> 00:49:12,810 to leave Earth for the Saturn system in 2026 1010 00:49:12,810 --> 00:49:16,470 and should arrive at Titan in 2034, 1011 00:49:16,470 --> 00:49:19,700 55 years after Pioneer 11 1012 00:49:19,700 --> 00:49:22,173 gave us our first encounter with Saturn. 1013 00:49:27,248 --> 00:49:30,165 (intriguing music)