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These are the user uploaded subtitles that are being translated: 1 00:00:04,103 --> 00:00:07,793 ROWE: Orbiting the magnificent ringed planet, Saturn, 2 00:00:07,896 --> 00:00:11,000 are a series of extraordinary moons. 3 00:00:13,896 --> 00:00:15,275 LANZA: The closer that we look, 4 00:00:15,379 --> 00:00:19,103 the more that we see its moons are like worlds of their own-- 5 00:00:19,172 --> 00:00:20,827 so dynamic, so Earth-like. 6 00:00:21,896 --> 00:00:25,000 ROWE: Almost a billion miles from the Sun, 7 00:00:25,068 --> 00:00:29,689 these icy worlds could be home for Life 2.0. 8 00:00:31,586 --> 00:00:34,689 The moons of Saturn offer possibly the best 9 00:00:34,689 --> 00:00:37,517 chance of finding extraterrestrial life 10 00:00:37,586 --> 00:00:38,827 in our solar system. 11 00:00:42,827 --> 00:00:45,931 ROWE: With each new mission, we get closer 12 00:00:46,000 --> 00:00:49,482 to unraveling the mysteries of Saturn's moons. 13 00:00:51,827 --> 00:00:53,379 [electricity sparking] 14 00:00:53,482 --> 00:00:57,413 [explosion blasts] 15 00:01:07,310 --> 00:01:09,310 ROWE: October 2019. 16 00:01:09,379 --> 00:01:13,103 Astronomers discover 20 new moons 17 00:01:13,172 --> 00:01:16,068 orbiting the gas giant, Saturn. 18 00:01:16,068 --> 00:01:21,000 These tiny, three-mile-wide objects 19 00:01:21,068 --> 00:01:24,896 bring the ringed planet's moon count to over 80, 20 00:01:27,000 --> 00:01:30,275 the most of any planet in our solar system. 21 00:01:32,793 --> 00:01:34,689 You hate to play favorites, but I'm gonna say it-- 22 00:01:34,689 --> 00:01:38,517 Saturn is my favorite planetary system. 23 00:01:38,586 --> 00:01:42,000 It is unbelievably beautiful, with this incredible system of 24 00:01:42,000 --> 00:01:43,482 rings and moons, 25 00:01:43,482 --> 00:01:48,000 and there's a lot of mystery kind of all bound up in there. 26 00:01:50,379 --> 00:01:52,000 ROWE: The Voyager spacecraft gave us our 27 00:01:52,068 --> 00:01:55,206 first close look at Saturn and its rings. 28 00:01:56,586 --> 00:02:01,517 Two decades later, Cassini got us even closer 29 00:02:01,586 --> 00:02:03,379 to many of Saturn's moons. 30 00:02:05,896 --> 00:02:09,206 There's Prometheus, Pandora, and Atlas. 31 00:02:10,379 --> 00:02:15,000 Its largest moon, Titan, is a moon that's shrouded 32 00:02:15,000 --> 00:02:17,172 in mystery. 33 00:02:17,275 --> 00:02:21,482 There's Mimas, that's fairly small, 34 00:02:21,482 --> 00:02:23,724 and then Tethys and Dione are a bit larger. 35 00:02:25,172 --> 00:02:27,620 There are a pair of moons-- Janus and Epimetheus-- 36 00:02:27,689 --> 00:02:29,482 that were perhaps one moon in the past. 37 00:02:31,172 --> 00:02:33,310 Iapetus, half of it's bright white. 38 00:02:33,379 --> 00:02:34,689 The other half of it is sort of as 39 00:02:34,793 --> 00:02:37,103 dark as coal, sort of yin and yang. 40 00:02:39,379 --> 00:02:42,482 Each of the moons of Saturn 41 00:02:42,586 --> 00:02:45,379 had remarkable stories to tell. 42 00:02:46,482 --> 00:02:49,517 ROWE: In 2005, Cassini discovered that 43 00:02:49,586 --> 00:02:53,793 one moon's story was particularly exciting. 44 00:02:53,793 --> 00:02:55,793 PLAIT: Yeah, Enceladus. 45 00:02:55,793 --> 00:02:58,793 Enceladus is one of Saturn's wee little moons. 46 00:02:58,793 --> 00:03:01,310 It's about 300 miles across-- for scale, 47 00:03:01,379 --> 00:03:03,482 it's roughly the size of Colorado. 48 00:03:06,206 --> 00:03:09,379 ROWE: The spacecraft's cameras spot plumes of 49 00:03:09,379 --> 00:03:12,586 water vapor shooting out from Enceladus 50 00:03:13,689 --> 00:03:15,413 at 800 miles an hour. 51 00:03:18,482 --> 00:03:20,275 Three times as powerful than 52 00:03:20,275 --> 00:03:22,931 all the hot springs in Yellowstone. 53 00:03:25,793 --> 00:03:29,068 RADENBAUGH: The discovery of geysers gushing out of tiny, 54 00:03:29,068 --> 00:03:31,586 little Enceladus that should have been cold and dead, 55 00:03:31,586 --> 00:03:34,517 completely changed our view of what that moon exactly was. 56 00:03:36,068 --> 00:03:38,586 DURDA: It's alive. That moon is alive. 57 00:03:38,586 --> 00:03:41,275 I'd like to be standing there on the surface of Enceladus to 58 00:03:41,275 --> 00:03:43,310 see with the-- this water vapor 59 00:03:43,379 --> 00:03:46,000 and ice crystals booming out of the surface 60 00:03:46,068 --> 00:03:47,689 at supersonic speeds. 61 00:03:55,896 --> 00:03:59,517 ROWE: Cassini's sensors probe deep beneath 62 00:03:59,586 --> 00:04:01,689 the frozen surface of Enceladus, 63 00:04:01,689 --> 00:04:06,000 detecting hints of a rocky core 64 00:04:06,103 --> 00:04:09,103 and something else even more remarkable. 65 00:04:11,172 --> 00:04:13,689 Underneath that thick layer of ice, 66 00:04:13,793 --> 00:04:16,275 there is liquid water ocean. 67 00:04:16,275 --> 00:04:20,103 CHRISTIANSEN: The measurements suggest his is a huge part of 68 00:04:20,172 --> 00:04:21,896 Enceladus's interior volume, 69 00:04:22,000 --> 00:04:25,310 about six miles deep, because it was making Enceladus 70 00:04:25,379 --> 00:04:26,793 wobble in its orbit. 71 00:04:26,896 --> 00:04:29,413 Imagine putting liquid inside a ball and rolling it. 72 00:04:29,482 --> 00:04:30,827 You see the natural wobble of 73 00:04:30,896 --> 00:04:32,827 the ball as the liquid sloshes around. 74 00:04:34,275 --> 00:04:38,689 ROWE: Giant liquid oceans on an alien world, 75 00:04:38,793 --> 00:04:41,586 opening up exciting new possibilities. 76 00:04:42,689 --> 00:04:46,413 Where you find water, you could possibly find life. 77 00:04:49,275 --> 00:04:52,206 If you had asked me 20 years ago where there might be life 78 00:04:52,275 --> 00:04:54,172 in the solar system besides Earth, 79 00:04:54,275 --> 00:04:56,793 I think Saturn's moons would have been the last place 80 00:04:56,896 --> 00:04:58,482 I would have picked. 81 00:04:58,586 --> 00:05:02,275 But against all odds, it's looking like this tiny icy 82 00:05:02,275 --> 00:05:03,827 moon orbiting Saturn 83 00:05:03,896 --> 00:05:06,827 nearly a billion miles from the Sun may be one of 84 00:05:06,896 --> 00:05:09,275 the best places to look for life. 85 00:05:10,724 --> 00:05:14,068 ROWE: July 2021. 86 00:05:15,103 --> 00:05:18,482 A new study reexamines Cassini's plume data 87 00:05:20,103 --> 00:05:22,793 and finds huge quantities of methane. 88 00:05:25,000 --> 00:05:26,275 This large amount can't be 89 00:05:26,275 --> 00:05:29,482 explained by just geochemical processes. 90 00:05:32,000 --> 00:05:35,275 The methane might be from primordial organic matter 91 00:05:35,275 --> 00:05:38,275 breaking down in Enceladus's oceans, 92 00:05:38,379 --> 00:05:47,896 or even processes we've never seen before. 93 00:05:48,000 --> 00:05:49,103 But it could be that 94 00:05:49,103 --> 00:05:53,103 living microorganisms helped generate the methane, 95 00:05:53,172 --> 00:05:55,620 just like they do on Earth. 96 00:05:57,000 --> 00:06:00,689 Enceladus might actually look a lot like early Earth in its 97 00:06:00,793 --> 00:06:02,896 deepest oceans, when life was first arising, 98 00:06:02,896 --> 00:06:05,206 because we know that there are some chemical pathways that are 99 00:06:05,275 --> 00:06:08,000 likely occurring on Enceladus that happened on Earth. 100 00:06:12,275 --> 00:06:14,206 ROWE: These chemical pathways start with 101 00:06:14,275 --> 00:06:16,896 hot, hydrothermal vents on Earth's 102 00:06:16,896 --> 00:06:21,620 cold sea floor, releasing important life-giving chemicals 103 00:06:21,689 --> 00:06:24,310 into the oceans. 104 00:06:24,379 --> 00:06:26,896 Having hydrothermal vents are a real 105 00:06:26,896 --> 00:06:29,172 boon to the evolution of life. 106 00:06:29,275 --> 00:06:32,172 PLAIT: These are cracks in the Earth's crust, where 107 00:06:32,172 --> 00:06:36,931 hot material can then spew out into the ocean. 108 00:06:37,000 --> 00:06:38,482 RADEBAUGH: And that's the energy 109 00:06:38,482 --> 00:06:39,793 that life needs to be able to form, 110 00:06:39,793 --> 00:06:42,103 and then water so everything is present, and things 111 00:06:42,172 --> 00:06:44,896 are able to just grab all these resources and energy 112 00:06:45,000 --> 00:06:47,620 and just start to evolve. 113 00:06:47,689 --> 00:06:51,689 ROWE: On Earth, hydrothermal vents produce methane, 114 00:06:51,793 --> 00:06:53,896 but only in small amounts. 115 00:06:53,896 --> 00:06:56,517 Microbial life 116 00:06:56,586 --> 00:06:59,620 living around the vents makes the rest. 117 00:07:03,620 --> 00:07:07,413 Maybe microorganisms do the same 118 00:07:07,482 --> 00:07:14,482 at the bottom of Enceladus's deep oceans. 119 00:07:14,482 --> 00:07:17,689 Hydrothermal vents on Enceladus could offer 120 00:07:17,793 --> 00:07:21,172 the perfect location for chemistry 121 00:07:21,172 --> 00:07:24,172 becoming biochemistry becoming life. 122 00:07:26,482 --> 00:07:29,413 ROWE: Hydrothermal vents normally require 123 00:07:29,482 --> 00:07:31,482 heat from a hot core. 124 00:07:36,379 --> 00:07:40,931 So what's going on inside Enceladus? 125 00:07:41,000 --> 00:07:46,068 This is an icy moon out there in the cold outer solar system. 126 00:07:46,068 --> 00:07:48,827 Where is all this heat coming from? 127 00:07:48,896 --> 00:07:52,206 ROWE: Cassini spotted Enceladus's plumes 128 00:07:52,275 --> 00:07:54,275 shooting out from parallel cracks 129 00:07:54,379 --> 00:07:57,482 in the surface, called tiger stripes. 130 00:08:02,517 --> 00:08:06,000 The cracks are a clue to the origin of the geysers 131 00:08:06,103 --> 00:08:08,068 and the energy that powers them. 132 00:08:11,000 --> 00:08:12,931 We look to the orbit of Enceladus itself. 133 00:08:13,000 --> 00:08:14,827 It's not in a perfectly circular orbit 134 00:08:14,896 --> 00:08:16,103 around the planet. 135 00:08:16,172 --> 00:08:18,586 It's on a slightly elliptical orbit, and that means that 136 00:08:18,689 --> 00:08:22,482 the tidal forces acting on the moon change over time. 137 00:08:22,482 --> 00:08:25,586 It's a little bit like the forces on a rubber ball. 138 00:08:25,689 --> 00:08:29,482 When the moon is closer to the planet, it's stretched out, 139 00:08:29,482 --> 00:08:31,275 and when the moon is farther from the planet, 140 00:08:31,275 --> 00:08:34,620 it's relaxed back a little bit, so you're gonna squeeze 141 00:08:34,689 --> 00:08:36,896 and deform and squish the body of 142 00:08:36,896 --> 00:08:39,793 that moon over time, which is gonna heat its interior. 143 00:08:43,793 --> 00:08:46,586 ROWE: The warm, rocky core heats up the ocean, 144 00:08:46,586 --> 00:08:49,931 which both powers the geysers as they burst 145 00:08:50,000 --> 00:08:51,068 through the surface 146 00:08:52,793 --> 00:08:56,931 and creates conditions that could support life. 147 00:09:00,413 --> 00:09:02,689 DURDA: We see the energy source kicking the water 148 00:09:02,793 --> 00:09:04,724 out of the Enceladus subsurface. 149 00:09:04,793 --> 00:09:07,068 You combine that energy source 150 00:09:07,068 --> 00:09:09,379 and liquid water, that harkens to putting 151 00:09:09,379 --> 00:09:11,482 us on the same path that early life 152 00:09:11,586 --> 00:09:13,206 may have taken here on the Earth. 153 00:09:13,275 --> 00:09:14,586 And if that's the case, 154 00:09:14,689 --> 00:09:17,068 there could be little beasties swimming underneath the surface 155 00:09:17,068 --> 00:09:18,586 of one of Saturn's moons. 156 00:09:20,586 --> 00:09:22,896 ROWE: Saturn's squeezing of Enceladus may 157 00:09:22,896 --> 00:09:25,586 have transformed it into a living world, 158 00:09:29,206 --> 00:09:31,310 but other moons weren't as lucky. 159 00:09:33,068 --> 00:09:36,827 They've been torn apart in vicious fights 160 00:09:36,896 --> 00:09:38,103 to the death. 161 00:09:56,517 --> 00:10:00,586 ROWE: There are a huge variety of moons orbiting Saturn, 162 00:10:01,793 --> 00:10:07,931 from Titan, a moon larger than the planet Mercury, 163 00:10:08,000 --> 00:10:11,206 to objects about the size of a sports stadium. 164 00:10:12,482 --> 00:10:14,413 RADEBAUGH: There must be something dramatic that happened 165 00:10:14,482 --> 00:10:15,793 to create a system 166 00:10:15,862 --> 00:10:17,586 that's so complicated and changing 167 00:10:17,689 --> 00:10:20,172 before our very eyes. 168 00:10:20,172 --> 00:10:23,896 ROWE: To understand such a marked difference in size, 169 00:10:24,000 --> 00:10:27,862 scientists look for clues in the moon's orbits around 170 00:10:27,862 --> 00:10:29,517 Saturn itself. 171 00:10:31,172 --> 00:10:34,689 Most of the moons of that system orbit in the same direction. 172 00:10:34,758 --> 00:10:36,793 That's obviously not a coincidence. 173 00:10:36,896 --> 00:10:39,275 That's motion left over from the formation 174 00:10:39,379 --> 00:10:40,620 of our solar system. 175 00:10:41,896 --> 00:10:44,310 ROWE: This suggests the moons formed around 176 00:10:44,379 --> 00:10:46,379 the same time as Saturn did. 177 00:10:47,379 --> 00:10:49,793 4.6 billion years ago, 178 00:10:49,896 --> 00:10:53,000 the ringless gas giant grows from gas, 179 00:10:53,103 --> 00:10:56,586 rock, and ice in the protoplanetary disk, 180 00:10:56,689 --> 00:10:58,689 along with a family of moons. 181 00:11:01,517 --> 00:11:05,206 This origin story works for most of Saturn's moons, 182 00:11:08,000 --> 00:11:11,275 but not for the recently discovered objects orbiting 183 00:11:11,379 --> 00:11:14,896 in the opposite direction of the planet's rotation. 184 00:11:16,103 --> 00:11:19,482 If there's a moon orbiting in the other direction, 185 00:11:19,586 --> 00:11:21,413 it couldn't have formed with the planet. 186 00:11:22,482 --> 00:11:24,620 It must have come from somewhere else. 187 00:11:26,068 --> 00:11:28,103 ROWE: Saturn captured these moons. 188 00:11:29,689 --> 00:11:31,172 But from where? 189 00:11:35,172 --> 00:11:37,586 WALSH: We think there was a huge upheaval in the solar system 190 00:11:37,586 --> 00:11:38,931 over four billion years ago, 191 00:11:39,000 --> 00:11:40,793 where the giant planets 192 00:11:40,896 --> 00:11:44,000 went from a close and compact configuration, started 193 00:11:44,103 --> 00:11:45,689 having interactions with each other, 194 00:11:45,793 --> 00:11:48,275 moved each other around to end up into the orbits 195 00:11:48,379 --> 00:11:49,413 that they find today. 196 00:11:49,482 --> 00:11:51,896 During that process, a lot of smaller bodies, 197 00:11:52,000 --> 00:11:53,413 like asteroids from the distant part 198 00:11:53,482 --> 00:11:54,862 of the solar system got scattered 199 00:11:54,862 --> 00:11:56,793 every which direction. 200 00:11:58,482 --> 00:12:00,931 ROWE: During this ancient upheaval, 201 00:12:01,000 --> 00:12:03,517 Saturn grabs some of the scattered objects. 202 00:12:06,413 --> 00:12:09,862 Many bodies now crowd the region around the planet, 203 00:12:11,413 --> 00:12:13,862 and that means collisions. 204 00:12:17,482 --> 00:12:19,482 Some are destructive. 205 00:12:19,482 --> 00:12:21,793 Others form new moons. 206 00:12:23,172 --> 00:12:24,620 In the cosmic pinball, 207 00:12:24,689 --> 00:12:27,000 some moons are thrown out of the system, 208 00:12:29,000 --> 00:12:31,413 and others, into Saturn. 209 00:12:31,482 --> 00:12:34,620 Only one large moon survives the carnage. 210 00:12:36,275 --> 00:12:37,793 WALSH: And all of a sudden, most of the mass 211 00:12:37,862 --> 00:12:40,000 of all the satellites is in that single moon, Titan. 212 00:12:43,000 --> 00:12:46,275 ROWE: Titan may have formed from the material in 213 00:12:46,275 --> 00:12:50,000 the protoplanetary disk at the same time as Saturn, 214 00:12:50,068 --> 00:12:54,275 but then gorged on the debris created in the later 215 00:12:54,379 --> 00:12:59,379 lunar collisions. 216 00:12:59,379 --> 00:13:05,068 It amassed 96 percent of the material orbiting Saturn 217 00:13:05,068 --> 00:13:08,689 and grew so large that it developed a dense atmosphere. 218 00:13:13,000 --> 00:13:15,103 CHRISTIANSEN: When Voyager photographed Titan, 219 00:13:15,172 --> 00:13:17,793 it clearly showed that Titan had a thick atmosphere, 220 00:13:17,896 --> 00:13:20,275 which was so incredibly exciting, 221 00:13:20,275 --> 00:13:22,172 but it was so dense and impenetrable, 222 00:13:22,172 --> 00:13:24,793 that was all we could see. 223 00:13:26,275 --> 00:13:28,413 ROWE: Two decades after Voyager, 224 00:13:28,482 --> 00:13:31,275 the Huygens Probe launched from Cassini 225 00:13:32,689 --> 00:13:36,689 and plunged through the murky depths of Titan's atmosphere. 226 00:13:42,793 --> 00:13:44,517 DARTNELL: Our first images of what 227 00:13:44,586 --> 00:13:47,000 the Titanic landscape was like 228 00:13:47,103 --> 00:13:52,172 were utterly and truly mind-blowing. 229 00:13:52,172 --> 00:13:53,586 HOWETT: It showed there were mountains 230 00:13:53,586 --> 00:13:54,620 and there was sort of erosion 231 00:13:54,689 --> 00:13:56,586 on those mountains that looked like liquid 232 00:13:56,689 --> 00:13:59,793 had fallen down the mountains and brought material with it. 233 00:14:01,103 --> 00:14:03,172 That liquid must have come from somewhere. 234 00:14:03,275 --> 00:14:05,068 And where else than rain, 235 00:14:05,068 --> 00:14:06,275 the weather on Titan? 236 00:14:07,931 --> 00:14:10,689 ROWE: We've only found two places in the solar system 237 00:14:10,793 --> 00:14:13,896 with rivers and rain-- 238 00:14:13,896 --> 00:14:17,758 Earth and Titan. 239 00:14:17,758 --> 00:14:20,068 Out of this thick gloom, 240 00:14:20,068 --> 00:14:24,206 this is the most similar place to Earth we've ever seen. 241 00:14:24,275 --> 00:14:27,275 ROWE: Similar, but not identical. 242 00:14:29,103 --> 00:14:34,068 That rain filling lakes and rivers on Titan isn't water. 243 00:14:35,103 --> 00:14:36,482 It's liquid methane. 244 00:14:37,896 --> 00:14:41,310 It's like if every oil well, if every gas station on 245 00:14:41,379 --> 00:14:43,379 Earth started leaking all over the place, 246 00:14:43,482 --> 00:14:46,068 that is what we see on this world. 247 00:14:48,896 --> 00:14:50,758 ROWE: The methane is a liquid on Titan 248 00:14:50,758 --> 00:14:55,413 because the surface temperature is 290 degrees below zero, 249 00:14:56,689 --> 00:14:59,103 which is a big problem for life 250 00:14:59,172 --> 00:15:01,103 as we understand it. 251 00:15:02,620 --> 00:15:05,517 We don't know of any organism that can really survive past 252 00:15:05,586 --> 00:15:08,000 negative 4 degrees Fahrenheit, and that's just because 253 00:15:08,103 --> 00:15:10,689 cells will tend to freeze there. 254 00:15:10,758 --> 00:15:12,379 HOWETT: The cells that we have, 255 00:15:12,482 --> 00:15:15,310 what they're made up from, these proteins and fatty 256 00:15:15,379 --> 00:15:19,689 material, stop working, and everything would die. 257 00:15:19,758 --> 00:15:24,379 ROWE: That's what happens to Earth's water-based cells. 258 00:15:27,068 --> 00:15:32,172 But could methane-based life survive in extreme cold? 259 00:15:34,896 --> 00:15:38,482 The ALMA telescope spotted a clue in Titan's nitrogen- 260 00:15:38,586 --> 00:15:41,379 and-methane-rich atmosphere. 261 00:15:41,379 --> 00:15:45,206 With sunlight hitting the atmosphere of Titan, 262 00:15:45,275 --> 00:15:48,482 things like methane and nitrogen can get broken apart 263 00:15:48,586 --> 00:15:52,758 and reassembled, like playing with LEGO blocks, 264 00:15:52,758 --> 00:15:56,000 and then these molecules recombine to 265 00:15:56,103 --> 00:15:59,000 make new ones, like vinyl cyanide. 266 00:16:01,068 --> 00:16:03,000 Artist depiction. 267 00:16:03,103 --> 00:16:08,620 ROWE: Used on Earth to make plastics, vinyl cyanide can 268 00:16:08,689 --> 00:16:11,000 build long chains of molecules, 269 00:16:11,000 --> 00:16:14,586 the type you need to build cell membranes. 270 00:16:20,620 --> 00:16:23,310 But unlike Earth's water-based cells, 271 00:16:23,379 --> 00:16:26,206 the extreme cold wouldn't destroy them. 272 00:16:28,793 --> 00:16:31,000 HOWETT: It could survive at those low temperatures. 273 00:16:31,000 --> 00:16:35,000 So on Titan, it could be that this vinyl cyanide is able 274 00:16:35,103 --> 00:16:36,586 to form the membranes 275 00:16:36,586 --> 00:16:38,379 that are required for cells to develop, 276 00:16:38,379 --> 00:16:41,068 which are required for life to happen. 277 00:16:44,862 --> 00:16:47,000 ROWE: And good news-- 278 00:16:47,103 --> 00:16:50,068 there's a lot of this stuff on Titan right now. 279 00:16:52,689 --> 00:16:57,172 There's as much as 10 billion tons of this vinyl cyanide 280 00:16:57,172 --> 00:16:58,620 in just one of the lakes. 281 00:16:58,689 --> 00:17:00,689 If you want to start making creatures out of it-- 282 00:17:00,793 --> 00:17:02,586 say, I don't know, a giant squid-- 283 00:17:02,689 --> 00:17:04,103 do you like giant squids? 284 00:17:04,172 --> 00:17:07,586 I hope so, because you could make billions 285 00:17:07,689 --> 00:17:13,103 of giant squids out of this vinyl cyanide. 286 00:17:13,172 --> 00:17:16,000 ROWE: Saturn's geyser moon, Enceladus, 287 00:17:16,068 --> 00:17:18,517 could have life as we know it. 288 00:17:18,586 --> 00:17:23,586 Titan might have something truly alien. 289 00:17:23,586 --> 00:17:27,068 It is an unrelentingly brutal, 290 00:17:27,068 --> 00:17:30,068 cold place compared to Earth. 291 00:17:30,068 --> 00:17:33,482 But for Titanic life, it might just be ideal. 292 00:17:35,103 --> 00:17:36,620 COOPER: As we search for life beyond Earth, 293 00:17:36,689 --> 00:17:40,103 it still comes with a bias of life as we know it. 294 00:17:40,172 --> 00:17:42,275 And so it's great, as we continue 295 00:17:42,275 --> 00:17:45,172 to explore and continue to evolve our definitions, 296 00:17:45,172 --> 00:17:50,103 we can expand our view of how to search for life. 297 00:17:50,172 --> 00:17:54,275 Maybe the Saturn system has two living worlds. 298 00:17:56,689 --> 00:18:00,689 ROWE: But for life to thrive on Titan's surface, 299 00:18:00,793 --> 00:18:04,586 it must survive a storm of deadly particles 300 00:18:04,689 --> 00:18:06,689 racing out of the Sun 301 00:18:06,793 --> 00:18:08,862 at over a million miles an hour. 302 00:18:26,275 --> 00:18:29,241 ROWE: The sun provides light and warmth... 303 00:18:33,034 --> 00:18:37,689 and something else, something very dangerous-- 304 00:18:37,793 --> 00:18:38,793 the solar wind. 305 00:18:42,275 --> 00:18:45,448 These lethal solar particles can strip away 306 00:18:45,448 --> 00:18:48,655 atmosphere from planets and moons. 307 00:18:52,000 --> 00:18:54,000 Without an atmosphere, 308 00:18:54,068 --> 00:18:56,448 Earth would be a barren desert, right? 309 00:18:56,448 --> 00:18:59,068 There wouldn't be any water, it would just all boil away. 310 00:18:59,137 --> 00:19:01,275 There wouldn't be any life, 311 00:19:02,379 --> 00:19:06,379 ROWE: Luckily, Earth has a built-in defense system. 312 00:19:07,793 --> 00:19:09,103 SUTTER: In the center of our Earth, 313 00:19:09,172 --> 00:19:13,551 we have a solid iron core, and surrounding that is liquid iron 314 00:19:13,551 --> 00:19:17,689 that is constantly moving and swirling and convecting, 315 00:19:17,793 --> 00:19:19,275 and these complex motions 316 00:19:19,344 --> 00:19:23,275 power up a global-scale magnetic field 317 00:19:26,965 --> 00:19:28,896 PLAIT: And this acts like a force field 318 00:19:28,965 --> 00:19:31,482 against the solar wind, pushes it away, 319 00:19:31,586 --> 00:19:33,344 pushes it around us so it doesn't hit us. 320 00:19:35,000 --> 00:19:38,103 ROWE: We think that Saturn's moon, Titan, 321 00:19:38,172 --> 00:19:40,758 has no molten iron core 322 00:19:43,275 --> 00:19:47,482 and therefore no protective magnetic field. 323 00:19:47,586 --> 00:19:50,172 So it's at the mercy of the solar wind. 324 00:19:51,379 --> 00:19:53,896 It kind of begs the question, why does Titan 325 00:19:54,000 --> 00:19:56,482 have such a thick, dense atmosphere? 326 00:19:56,551 --> 00:20:01,068 ROWE: Titan retaining an atmosphere without 327 00:20:01,137 --> 00:20:03,965 a protective shield makes no sense. 328 00:20:06,689 --> 00:20:08,793 SUTTER: Titan doesn't have a magnetic field, 329 00:20:08,896 --> 00:20:11,241 but Saturn does. 330 00:20:11,241 --> 00:20:14,000 So maybe there's some sort of interaction between 331 00:20:14,068 --> 00:20:18,689 the atmosphere of Titan and Saturn's giant magnetic field. 332 00:20:20,448 --> 00:20:23,862 ROWE: The gas giant Saturn generates a magnetic field 333 00:20:23,862 --> 00:20:26,896 around 600 times larger than Earth's, 334 00:20:29,344 --> 00:20:33,068 large enough to shield Titan from the solar wind. 335 00:20:35,379 --> 00:20:38,758 So Titan by itself is vulnerable. 336 00:20:38,758 --> 00:20:40,586 Saturn is like the mother ship. 337 00:20:40,689 --> 00:20:43,172 It has this giant force field 338 00:20:43,275 --> 00:20:44,689 that it can use to protect Titan. 339 00:20:46,103 --> 00:20:52,000 ROWE: Despite Saturn's embrace, Titan still loses 340 00:20:52,068 --> 00:20:56,275 some of its atmosphere, because occasionally, 341 00:20:56,344 --> 00:21:00,896 the moon wanders away from its protective parent. 342 00:21:00,965 --> 00:21:04,344 Titan orbits inside of that magnetic field... 343 00:21:04,344 --> 00:21:06,965 mostly, most of the time. 344 00:21:07,000 --> 00:21:08,689 Its orbit isn't perfectly circular. 345 00:21:08,793 --> 00:21:10,379 It's slightly elliptical. 346 00:21:12,137 --> 00:21:15,344 So as Titan orbits the planet, for a little bit of time, 347 00:21:15,344 --> 00:21:16,689 about 5 percent of its orbit, 348 00:21:16,758 --> 00:21:19,137 it's actually slightly outside the magnetic field 349 00:21:19,137 --> 00:21:20,793 before dipping back in again. 350 00:21:23,344 --> 00:21:24,793 ROWE: But these short forays into 351 00:21:24,862 --> 00:21:29,379 the firing line don't cause any lasting damage. 352 00:21:30,655 --> 00:21:33,896 What's really weird is that there's sort of a residual 353 00:21:33,965 --> 00:21:35,965 magnetic effect on Titan. 354 00:21:36,000 --> 00:21:38,241 When it leaves Saturn's protective field, 355 00:21:38,241 --> 00:21:40,689 it should just immediately drop to nothing. 356 00:21:40,758 --> 00:21:43,000 But there still is this residual field, 357 00:21:43,068 --> 00:21:45,551 protecting it from the solar wind. 358 00:21:45,551 --> 00:21:48,793 SUTTER: It can maintain the memory of that magnetic field 359 00:21:48,862 --> 00:21:51,689 and still preserve some of that protection. 360 00:21:53,000 --> 00:21:55,793 It's almost like Saturn is trying to teach 361 00:21:55,862 --> 00:21:57,862 Titan how to have a magnetic field, 362 00:21:57,862 --> 00:21:59,689 and Titan can remember for a little bit, 363 00:21:59,758 --> 00:22:01,689 but then it needs to come back home. 364 00:22:03,586 --> 00:22:06,068 ROWE: This magnetic memory could help 365 00:22:06,137 --> 00:22:09,275 support any life on Titan's surface, 366 00:22:09,379 --> 00:22:13,379 providing a safe haven that's protected from the solar wind. 367 00:22:15,965 --> 00:22:17,896 And Cassini spots a way 368 00:22:18,000 --> 00:22:21,068 Saturn's magnetism might also allow 369 00:22:21,137 --> 00:22:24,344 its moons to develop life. 370 00:22:24,344 --> 00:22:28,482 One of the most amazing discoveries around Saturn was 371 00:22:28,551 --> 00:22:30,172 that its magnetic field is not 372 00:22:30,275 --> 00:22:32,379 just transporting charged particles from, 373 00:22:32,448 --> 00:22:36,000 say, the sun, but it's also transporting material 374 00:22:36,034 --> 00:22:37,482 from one moon to another. 375 00:22:40,896 --> 00:22:43,241 ROWE: Saturn's magnetic field helps boost 376 00:22:43,241 --> 00:22:45,551 the chance of life on Titan 377 00:22:45,551 --> 00:22:50,551 by stealing material from its sister moon, Enceladus. 378 00:22:51,896 --> 00:22:54,344 Magnetism is a strong force, of course, 379 00:22:54,344 --> 00:22:57,241 but to act on a scale and a range 380 00:22:57,241 --> 00:23:00,068 like this and maybe transport matter from moon to moon, 381 00:23:00,068 --> 00:23:01,758 that's pretty cool. 382 00:23:03,482 --> 00:23:06,586 ROWE: Saturn's magnetic field smashes apart 383 00:23:06,655 --> 00:23:11,068 water molecules blasted out from Enceladus's geysers 384 00:23:11,137 --> 00:23:16,275 and carries the leftover oxygen to Titan. 385 00:23:16,379 --> 00:23:18,482 SUTTER: The magnetic field of Saturn 386 00:23:18,551 --> 00:23:21,793 acts like an inter-lunar highway 387 00:23:21,896 --> 00:23:25,344 in the Saturn system, transporting oxygen 388 00:23:25,344 --> 00:23:28,172 from Enceladus all the way to Titan. 389 00:23:28,275 --> 00:23:31,896 ROWE: But there's a problem when the oxygen tries to 390 00:23:31,965 --> 00:23:36,758 take the Titan exit off of this inter-lunar highway. 391 00:23:36,758 --> 00:23:39,896 Normally, this oxygen wouldn't survive 392 00:23:40,000 --> 00:23:41,275 in the atmosphere of Titan. 393 00:23:41,344 --> 00:23:44,172 It would react with the methane there and create carbon dioxide. 394 00:23:45,655 --> 00:23:47,379 ROWE: To get to the surface 395 00:23:47,482 --> 00:23:49,862 in one piece, oxygen hitches 396 00:23:49,862 --> 00:23:53,275 a ride with something called a fullerene. 397 00:23:58,137 --> 00:23:59,655 Fullerenes are these sort of 398 00:23:59,655 --> 00:24:02,172 soccer ball shaped molecules that are hollow. 399 00:24:02,275 --> 00:24:04,344 If the oxygen atom gets in there, 400 00:24:04,344 --> 00:24:07,551 it can be safely transported through Titan's atmosphere. 401 00:24:09,482 --> 00:24:13,275 ROWE: Once on the surface, the oxygen could help create 402 00:24:13,379 --> 00:24:15,137 amino acids, 403 00:24:15,137 --> 00:24:18,103 the essential building blocks of proteins, 404 00:24:18,172 --> 00:24:22,793 another stepping stone for life to emerge. 405 00:24:26,034 --> 00:24:29,482 Think of all the complex coincidences 406 00:24:29,551 --> 00:24:31,275 that have to happen 407 00:24:31,344 --> 00:24:34,344 for these chemical reactions to take place. 408 00:24:34,344 --> 00:24:36,379 If Titan's orbit was any different, 409 00:24:36,448 --> 00:24:37,793 it simply wouldn't exist. 410 00:24:41,448 --> 00:24:46,068 ROWE: Saturn protects any potential life on its moons. 411 00:24:47,275 --> 00:24:49,862 And as it turns out, the moons 412 00:24:49,862 --> 00:24:54,379 return the favor by helping create 413 00:24:54,448 --> 00:25:00,689 and maintain Saturn's iconic rings. 414 00:25:16,000 --> 00:25:19,344 ROWE: At 170,000 miles in diameter, 415 00:25:20,482 --> 00:25:23,034 but only 30 feet thick in places, 416 00:25:23,103 --> 00:25:27,896 Saturn's beautiful rings have always stolen the show, 417 00:25:30,793 --> 00:25:34,896 but their origin is still a mystery. 418 00:25:35,000 --> 00:25:38,586 Saturn has these beautiful rings that really 419 00:25:38,655 --> 00:25:39,896 define it as a planet, 420 00:25:39,896 --> 00:25:42,000 but its unique in the solar system in the sense that no 421 00:25:42,068 --> 00:25:45,586 other planet has such a big ring system. 422 00:25:45,689 --> 00:25:49,586 THALLER: All of the other gas giants have remnants of a ring, 423 00:25:49,689 --> 00:25:53,482 kind of small, thin, dark rings, but nothing like Saturn. 424 00:25:53,551 --> 00:25:56,551 So something very different happened around Saturn. 425 00:25:58,551 --> 00:26:03,137 ROWE: A clue comes from the rings' composition. 426 00:26:03,137 --> 00:26:06,034 They're around 99 percent water ice, 427 00:26:06,103 --> 00:26:09,000 giving the rings their sparkling appearance. 428 00:26:10,482 --> 00:26:14,965 This leads astronomers to a bold theory. 429 00:26:15,000 --> 00:26:18,655 We do not know how Saturn's icy rings formed. 430 00:26:18,655 --> 00:26:20,275 We're not even sure how old they are, 431 00:26:20,344 --> 00:26:23,793 but one idea is that they formed from ice that was 432 00:26:23,896 --> 00:26:26,103 existing previously on a moon. 433 00:26:26,172 --> 00:26:28,965 How amazing is that? 434 00:26:29,000 --> 00:26:34,000 ROWE: Several billion years ago, Saturn may have been ringless, 435 00:26:35,172 --> 00:26:37,689 with a large, icy moon. 436 00:26:37,793 --> 00:26:41,379 The moon was big enough that its gravity drew heavier 437 00:26:41,482 --> 00:26:43,275 stuff like rock to its core 438 00:26:43,344 --> 00:26:46,000 and lighter stuff like ice floated to the top. 439 00:26:46,068 --> 00:26:52,793 ROWE: We think the moon strayed too close to Saturn. 440 00:26:52,862 --> 00:26:55,896 WALSH: The gravity from Saturn could tear it apart, 441 00:26:57,758 --> 00:27:00,793 and it could separate the ices from the rocky parts 442 00:27:00,862 --> 00:27:03,275 and the ices could stay in orbit and form our rings, 443 00:27:03,344 --> 00:27:06,172 and the rocky parts would get swallowed up by Saturn. 444 00:27:12,586 --> 00:27:16,172 The death of a large moon may have built the rings, 445 00:27:20,379 --> 00:27:24,482 but they owe their current appearance to the moons that 446 00:27:24,551 --> 00:27:26,448 are still alive. 447 00:27:26,448 --> 00:27:29,793 THALLER: When you go back to Saturn's rings, 448 00:27:29,862 --> 00:27:32,655 time and time again, they're all slightly different. 449 00:27:32,655 --> 00:27:34,689 They are changing, they are braiding in and out of 450 00:27:34,758 --> 00:27:37,551 each other-- we had no idea there would be 451 00:27:37,551 --> 00:27:40,068 so much beauty and so much mystery in the rings. 452 00:27:42,000 --> 00:27:45,793 ROWE: The behavior of two of Saturn's moons, 453 00:27:45,862 --> 00:27:48,103 Prometheus and Atlas, 454 00:27:48,172 --> 00:27:50,586 which are embedded in the rings 455 00:27:50,689 --> 00:27:52,862 is especially surprising. 456 00:27:52,862 --> 00:27:56,103 Some of these smallest moons 457 00:27:56,172 --> 00:27:59,000 are interspersed within the ring system. 458 00:27:59,068 --> 00:28:03,275 Some of them are doing something really bizarre. 459 00:28:03,379 --> 00:28:06,793 In some cases, it looks like the moons were shepherding 460 00:28:06,862 --> 00:28:10,275 the edges of the rings and keeping them in their place. 461 00:28:11,551 --> 00:28:15,103 ROWE: The moon's gravity cleans up the rings, 462 00:28:16,379 --> 00:28:19,896 sometimes, sculpting shapes in their wake. 463 00:28:22,172 --> 00:28:25,068 Saturn's rings aren't static, and there's some really 464 00:28:25,137 --> 00:28:28,034 fascinating interactions where moons are clearly pushing on 465 00:28:28,103 --> 00:28:31,000 the rings and causing weird and cool waves, 466 00:28:31,068 --> 00:28:35,448 making the rings just that much more beautiful. 467 00:28:35,448 --> 00:28:38,896 HOWETT: The whole dance between Saturn and its moons, 468 00:28:38,965 --> 00:28:40,689 its rings, how they all 469 00:28:40,793 --> 00:28:43,448 are interconnected, is just completely fascinating. 470 00:28:45,586 --> 00:28:47,172 It's a dynamic, amazing, 471 00:28:47,275 --> 00:28:49,758 living, geologically vibrant place. 472 00:28:53,793 --> 00:28:56,793 ROWE: Saturn's moons may keep the rings orderly, 473 00:28:58,758 --> 00:29:03,689 but they can't explain why the rings are so clean, 474 00:29:03,758 --> 00:29:05,172 almost pristine. 475 00:29:07,655 --> 00:29:09,172 PLAIT: They're too shiny. 476 00:29:09,241 --> 00:29:11,655 If they were billions of years old, 477 00:29:11,655 --> 00:29:14,034 they should have collected a lot of dust by now 478 00:29:14,103 --> 00:29:15,275 and be a lot darker. 479 00:29:15,379 --> 00:29:18,275 The fact that they're shiny kind of implies that 480 00:29:18,344 --> 00:29:22,137 maybe they're a lot younger than we first thought. 481 00:29:22,137 --> 00:29:25,000 ROWE: Perhaps the rings we see today 482 00:29:25,034 --> 00:29:27,896 are a more recent upgrade. 483 00:29:29,379 --> 00:29:32,172 The rings might only be 100 million years old, 484 00:29:32,241 --> 00:29:34,344 about the time of the dinosaurs. 485 00:29:34,344 --> 00:29:37,379 So if the dinosaurs had invented telescopes, 486 00:29:37,482 --> 00:29:40,379 they could have seen Saturn without rings. 487 00:29:40,448 --> 00:29:41,655 And it makes you wonder, is this 488 00:29:41,655 --> 00:29:43,689 the first ring system that Saturn had? 489 00:29:43,758 --> 00:29:45,482 Or was there another ring system 490 00:29:45,551 --> 00:29:47,551 that may be slowly eroded away? 491 00:29:47,551 --> 00:29:50,793 Perhaps a comet or a body came in too close to Saturn, 492 00:29:50,896 --> 00:29:52,896 and Saturn's gravity literally tore it apart, 493 00:29:52,965 --> 00:29:54,758 and then we got a brand-new ring system. 494 00:29:57,068 --> 00:29:59,862 The later dinosaurs could have watched the rings form, 495 00:30:01,000 --> 00:30:02,793 and then they would have been wiped out by an asteroid. 496 00:30:04,068 --> 00:30:05,896 Yeah, should have built better telescopes, 497 00:30:05,965 --> 00:30:08,379 dinosaurs, sucks to be you. 498 00:30:11,068 --> 00:30:14,137 ROWE: We still don't know why the rings of Saturn 499 00:30:14,137 --> 00:30:15,793 are so clean. 500 00:30:17,482 --> 00:30:19,689 It could be that the rings really are old, and they have 501 00:30:19,758 --> 00:30:21,034 some sort of cleaning system, 502 00:30:21,103 --> 00:30:22,482 which removes the dust from them, 503 00:30:22,586 --> 00:30:27,137 making them look young, or they may actually be young, and this 504 00:30:27,137 --> 00:30:30,379 may be the seventh or eighth or whatever generation rings. 505 00:30:30,448 --> 00:30:35,482 It is so different than any other planetary system. 506 00:30:35,551 --> 00:30:37,379 And those mysteries still exist. 507 00:30:37,482 --> 00:30:41,172 We have some idea what went on, 508 00:30:41,275 --> 00:30:43,586 but there's a lot that we don't know about Saturn. 509 00:30:46,379 --> 00:30:49,137 ROWE: Cassini is changing that. 510 00:30:51,482 --> 00:30:55,482 It's discovered a whole new moon-making process, 511 00:30:57,689 --> 00:31:00,551 with the rings taking the lead. 512 00:31:18,275 --> 00:31:21,137 ROWE: Midway through its 13-year mission to Saturn, 513 00:31:23,482 --> 00:31:26,344 Cassini captures an intriguing image, 514 00:31:29,000 --> 00:31:31,068 a bright feature at the edge 515 00:31:31,137 --> 00:31:33,379 of one of Saturn's outermost rings, 516 00:31:34,379 --> 00:31:36,344 something we'd never seen before. 517 00:31:38,793 --> 00:31:42,000 I was really excited when we saw these images of Saturn's 518 00:31:42,034 --> 00:31:44,275 rings, and it looked like there was a lump, 519 00:31:44,379 --> 00:31:49,000 maybe a moon forming there, which they nicknamed Peggy. 520 00:31:49,034 --> 00:31:51,034 ROWE: Named after the mother-in-law 521 00:31:51,103 --> 00:31:53,172 of the scientist who discovered it, 522 00:31:53,241 --> 00:31:56,586 Peggy was still too small to be considered 523 00:31:56,655 --> 00:32:02,275 a fully-formed moon, but nearby orbits 524 00:32:02,379 --> 00:32:06,689 a group of objects that are just big enough to be moons, 525 00:32:09,482 --> 00:32:11,689 and they are really weird. 526 00:32:13,275 --> 00:32:14,862 These moons are really unusual. 527 00:32:14,862 --> 00:32:17,862 We don't think of them as like anything else we've seen. 528 00:32:17,862 --> 00:32:21,551 They're kind of little fuzzy potatoes or maybe 529 00:32:21,551 --> 00:32:24,689 even like a ravioli is another one or a croissant. 530 00:32:24,793 --> 00:32:26,017 Why do we always come up with food? 531 00:32:26,017 --> 00:32:29,344 But at the same time, that's exactly what they look like. 532 00:32:29,344 --> 00:32:32,758 The most bizarrely-shaped moon of Saturn is Pan. 533 00:32:32,758 --> 00:32:34,586 It's got these crisscrossing cracks, 534 00:32:34,655 --> 00:32:37,482 just like bread, and then around the outside 535 00:32:37,551 --> 00:32:39,689 is a belly band, it's undulatory. 536 00:32:39,793 --> 00:32:41,344 How would this get there? 537 00:32:44,068 --> 00:32:46,655 ROWE: Cassini discovered a clue. 538 00:32:49,448 --> 00:32:51,586 Like Saturn's rings, 539 00:32:51,655 --> 00:32:55,482 these moons were made almost entirely of water ice. 540 00:32:58,551 --> 00:32:59,689 They must have grown from 541 00:32:59,793 --> 00:33:02,965 tiny lumps trapped within the rings. 542 00:33:04,034 --> 00:33:10,137 PLAIT: They're going to be extremely fragile, 543 00:33:10,137 --> 00:33:12,793 kind of like a snowflake orbiting Saturn. 544 00:33:12,862 --> 00:33:15,758 They can start drawing in material and then can grow. 545 00:33:15,758 --> 00:33:18,275 You can actually imagine rolling up a snowball 546 00:33:18,379 --> 00:33:21,172 and accumulating more and more particles on the outside. 547 00:33:21,275 --> 00:33:23,793 And in the same way, you could accumulate 548 00:33:23,862 --> 00:33:25,241 these clumps in the rings. 549 00:33:25,241 --> 00:33:27,241 And if they're near the edge of the rings, 550 00:33:27,241 --> 00:33:31,965 perhaps they actually break free and go out to form tiny moons. 551 00:33:34,586 --> 00:33:38,034 ROWE: The size of these space snowballs, 552 00:33:38,103 --> 00:33:41,241 tens of miles across or less, 553 00:33:41,241 --> 00:33:43,793 helps explain their unusual shapes. 554 00:33:47,172 --> 00:33:50,896 The size of the moon actually affects its shape in that once 555 00:33:51,000 --> 00:33:52,482 you get below a certain size threshold, 556 00:33:52,551 --> 00:33:54,275 you cannot be round anymore. 557 00:33:54,344 --> 00:33:56,172 That's because the strength of the rock or the ice 558 00:33:56,275 --> 00:33:59,000 in this case is too great to be overcome by gravity, 559 00:33:59,068 --> 00:34:02,103 and so the kind of oblong shapes can be maintained. 560 00:34:04,586 --> 00:34:06,655 ROWE: Add in a few collisions, 561 00:34:06,655 --> 00:34:10,793 and you get Saturn's ravioli- and croissant-shaped moons. 562 00:34:13,655 --> 00:34:16,034 It's a bizarre process but leads to a beautiful form. 563 00:34:16,103 --> 00:34:20,137 We know the moons affect the rings, but it looks 564 00:34:20,137 --> 00:34:22,793 like in this case, the rings affect the moons, too. 565 00:34:22,896 --> 00:34:24,896 They're connected in both directions. 566 00:34:30,758 --> 00:34:33,793 ROWE: The rings form a moon factory, 567 00:34:37,793 --> 00:34:41,862 capable of building countless generations of new worlds. 568 00:34:43,793 --> 00:34:47,344 This is a dance of physics. 569 00:34:49,379 --> 00:34:52,758 PLAIT: If moonlets can form by these icy ring particles, 570 00:34:52,758 --> 00:34:55,103 they'll grow, and then their natural gravitational 571 00:34:55,172 --> 00:34:57,689 interaction with the rings will make them move out. 572 00:34:57,758 --> 00:34:59,275 They keep growing as they move out. 573 00:34:59,344 --> 00:35:01,862 But then another moon forms where the first one was. 574 00:35:01,862 --> 00:35:04,793 So you keep getting these growing moons, right, 575 00:35:04,896 --> 00:35:07,172 and this process repeats like on a conveyor belt. 576 00:35:07,241 --> 00:35:09,793 And what you wind up with is bigger moons orbiting 577 00:35:09,896 --> 00:35:12,068 farther out from Saturn and smaller ones 578 00:35:12,137 --> 00:35:13,379 orbiting closer in. 579 00:35:16,241 --> 00:35:19,896 ROWE: But Saturn's conveyor belt will eventually break down. 580 00:35:24,551 --> 00:35:26,000 When ultraviolet light from 581 00:35:26,034 --> 00:35:30,344 the sun interacts with ring particles, 582 00:35:30,344 --> 00:35:34,586 it throws their steady orbit around Saturn out of whack. 583 00:35:36,793 --> 00:35:39,896 The sun energizes the rings, and it gives them a charge. 584 00:35:40,000 --> 00:35:41,482 This charge means they can get picked 585 00:35:41,586 --> 00:35:43,689 up by the magnetic field of Saturn. 586 00:35:43,793 --> 00:35:46,275 So these little tiny charged particles then are lifted 587 00:35:46,344 --> 00:35:47,655 out of the rings, 588 00:35:47,655 --> 00:35:49,793 follow along the magnetic field lines, 589 00:35:49,862 --> 00:35:51,896 rain down into Saturn's atmosphere. 590 00:35:54,551 --> 00:35:59,275 ROWE: The charged particles are tiny ice crystals. 591 00:35:59,344 --> 00:36:02,000 They rain down onto Saturn, 592 00:36:04,655 --> 00:36:07,896 enough to fill an Olympic-sized swimming pool 593 00:36:07,965 --> 00:36:09,000 every second. 594 00:36:12,862 --> 00:36:15,586 In less than 100 million years, 595 00:36:15,655 --> 00:36:19,689 Saturn's rings will be gone. 596 00:36:19,758 --> 00:36:25,000 There will be no material to build new moons. 597 00:36:25,068 --> 00:36:28,862 Saturn's moons and rings, 598 00:36:28,862 --> 00:36:31,068 they almost make me feel bittersweet, because they 599 00:36:31,137 --> 00:36:34,034 show you the beauty of what physics can create, 600 00:36:34,103 --> 00:36:36,103 But also the fleeting-ness. 601 00:36:36,172 --> 00:36:39,000 They'll be gone soon, and that makes me sad. 602 00:36:42,000 --> 00:36:44,000 ROWE: The closer we look, 603 00:36:44,034 --> 00:36:46,896 the more intriguing the Saturn system becomes. 604 00:36:53,275 --> 00:36:55,482 And now, scientists 605 00:36:55,551 --> 00:36:57,586 have an audacious new plan 606 00:37:00,965 --> 00:37:05,000 to fly a drone on one of Saturn's moons. 607 00:37:18,655 --> 00:37:21,758 Saturn is one of the most dynamic places 608 00:37:21,758 --> 00:37:24,413 in the solar system. 609 00:37:25,551 --> 00:37:27,379 We want to go back there, 610 00:37:27,448 --> 00:37:30,344 to explore its moons up close 611 00:37:30,413 --> 00:37:33,620 and hunt directly for Life 2.0. 612 00:37:36,137 --> 00:37:38,413 For so long, we've been emphasizing that to have 613 00:37:38,482 --> 00:37:39,724 a habitable planet, 614 00:37:39,724 --> 00:37:41,793 you have to be warm, you have to be close to your star. 615 00:37:43,034 --> 00:37:45,275 In fact, the most likely chance we have to find 616 00:37:45,344 --> 00:37:48,793 life maybe way in the outer solar system in Saturn's moons. 617 00:37:49,793 --> 00:37:52,482 But we won't know for sure until we send 618 00:37:52,551 --> 00:37:54,862 another mission there, specifically to look for life. 619 00:37:56,689 --> 00:37:58,517 ROWE: The Huygens Probe gave us 620 00:37:58,586 --> 00:38:01,206 a tantalizing glimpse of Titan's surface, 621 00:38:05,172 --> 00:38:08,241 but it wasn't equipped to search for life. 622 00:38:10,068 --> 00:38:14,517 Now, scientists are developing Dragonfly, 623 00:38:14,586 --> 00:38:19,206 a space helicopter that can search for life. 624 00:38:21,275 --> 00:38:23,413 Dragonfly is an amazing mission. 625 00:38:23,482 --> 00:38:25,586 We're sending this to Titan to better 626 00:38:25,655 --> 00:38:28,379 understand how life might arise in a very different 627 00:38:28,448 --> 00:38:29,413 context than Earth. 628 00:38:31,965 --> 00:38:33,896 One thing we know absolutely for certain 629 00:38:33,965 --> 00:38:37,586 is that Titan has interesting, complex chemistry. 630 00:38:37,655 --> 00:38:38,896 The question now is, 631 00:38:38,965 --> 00:38:42,172 does that chemistry actually turn into biology? 632 00:38:45,793 --> 00:38:49,551 The million-dollar question, is this a living world? 633 00:38:56,517 --> 00:38:59,862 ROWE: April 2021. 634 00:39:02,172 --> 00:39:05,655 We test the concept of a space helicopter. 635 00:39:10,275 --> 00:39:13,172 Ingenuity making the first remote flight on 636 00:39:13,241 --> 00:39:17,517 another world launches into the thin Martian atmosphere. 637 00:39:19,482 --> 00:39:21,586 Mars is a really difficult place to fly, 638 00:39:21,655 --> 00:39:25,482 because the atmosphere is 100 times thinner than Earth's. 639 00:39:25,551 --> 00:39:27,793 And remember, it's the atmosphere that provides 640 00:39:27,896 --> 00:39:31,000 the support and the lift for a helicopter to fly. 641 00:39:31,034 --> 00:39:32,448 So in order for Ingenuity to fly, 642 00:39:32,517 --> 00:39:34,689 it had to spin very fast in order 643 00:39:34,793 --> 00:39:36,172 to even get itself off the ground. 644 00:39:40,862 --> 00:39:43,896 ROWE: Fortunately, Titan's thick atmosphere 645 00:39:43,965 --> 00:39:46,379 is much more helicopter friendly. 646 00:39:48,862 --> 00:39:51,689 The contrast between Ingenuity and the Dragonfly mission 647 00:39:51,793 --> 00:39:52,689 is really funny, 648 00:39:52,689 --> 00:39:55,620 because Mars has almost no atmosphere, 649 00:39:55,689 --> 00:39:58,103 less than 1 percent the atmospheric pressure of Earth. 650 00:39:58,172 --> 00:40:01,344 On Titan, you have exactly the opposite. 651 00:40:01,413 --> 00:40:03,448 The air pressure near the surface of Titan can be 652 00:40:03,517 --> 00:40:06,034 four times as much as the air pressure on Earth. 653 00:40:06,103 --> 00:40:08,793 So for a helicopter or something like a drone, 654 00:40:08,896 --> 00:40:10,051 something like an octocopter, 655 00:40:10,051 --> 00:40:13,275 the lower the gravity is and the denser the atmosphere, 656 00:40:13,344 --> 00:40:14,551 the better you can fly. 657 00:40:15,413 --> 00:40:18,344 LANZA: So Titan just begs to be explored, because you get 658 00:40:18,413 --> 00:40:20,310 a lot of lift, and you can actually carry heavy 659 00:40:20,379 --> 00:40:21,344 instruments with you. 660 00:40:22,689 --> 00:40:25,275 It allows you to fly through the atmosphere, 661 00:40:25,344 --> 00:40:28,551 collect samples, and determine what the prebiotic chemistry 662 00:40:28,620 --> 00:40:29,724 is on that moon. 663 00:40:31,689 --> 00:40:34,241 If ever there was a world built for flying drones, 664 00:40:34,310 --> 00:40:36,310 it's Titan. 665 00:40:36,379 --> 00:40:40,241 ROWE: Dragonfly is scheduled to launch in 2027, 666 00:40:43,172 --> 00:40:46,000 arriving at Titan around seven years later, 667 00:40:46,034 --> 00:40:50,275 completing the journey of moon discovery that began 668 00:40:50,344 --> 00:40:52,758 with Voyager and Cassini. 669 00:40:55,241 --> 00:40:56,965 DURDA: We completely transformed 670 00:40:57,000 --> 00:41:00,344 our picture of the Saturn system, the rings and the moons. 671 00:41:00,413 --> 00:41:02,034 It's a far more complex 672 00:41:02,103 --> 00:41:04,344 environment than we ever dreamed possible. 673 00:41:04,413 --> 00:41:05,896 The moons have come alive, right? 674 00:41:06,000 --> 00:41:09,068 They're not boring, dead ice balls, and it just 675 00:41:09,137 --> 00:41:11,379 begs generation after generation of spacecraft follow up. 676 00:41:14,517 --> 00:41:15,965 ROWE: We're only just beginning to 677 00:41:16,000 --> 00:41:18,896 unravel the secrets of Saturn's moons. 678 00:41:21,275 --> 00:41:25,586 And with more than 80 to explore, the Saturn system is 679 00:41:25,655 --> 00:41:28,206 a gift that'll keep on giving. 680 00:41:31,103 --> 00:41:33,793 Saturn was the very first thing I ever 681 00:41:33,862 --> 00:41:35,758 saw through a telescope when I was a kid. 682 00:41:35,758 --> 00:41:39,689 And here I am-- clearly, I was inspired by Saturn, 683 00:41:39,758 --> 00:41:41,620 by its beauty. 684 00:41:41,689 --> 00:41:43,965 THALLER: Saturn has always been my favorite planet. 685 00:41:44,000 --> 00:41:45,275 Everything you want 686 00:41:45,344 --> 00:41:48,137 is there-- violence, colliding moons, 687 00:41:48,206 --> 00:41:51,689 how new rings form, new moons form over time. 688 00:41:53,068 --> 00:41:54,758 PLAIT: And there might be life there. 689 00:41:54,758 --> 00:41:58,172 There might be life in more than one place there. 690 00:41:58,241 --> 00:42:02,172 One destination, one planetary zip code, gives you all of that. 691 00:42:02,241 --> 00:42:03,689 I say go back to Saturn. 55493

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