1 00:00:04,100 --> 00:00:07,767 ROWE: Orbiting the magnificent ringed planet, Saturn, 2 00:00:07,867 --> 00:00:11,000 are a series of extraordinary moons. 3 00:00:13,867 --> 00:00:15,266 LANZA: The closer that we look, 4 00:00:15,367 --> 00:00:19,100 the more that we see its moons are like worlds of their own -- 5 00:00:19,166 --> 00:00:20,800 so dynamic, so Earth-like. 6 00:00:21,867 --> 00:00:25,000 ROWE: Almost a billion miles from the Sun, 7 00:00:25,066 --> 00:00:29,667 these icy worlds could be home for Life 2.0. 8 00:00:31,567 --> 00:00:34,667 The moons of Saturn offer possibly the best 9 00:00:34,667 --> 00:00:37,500 chance of finding extraterrestrial life 10 00:00:37,567 --> 00:00:38,800 in our solar system. 11 00:00:42,800 --> 00:00:45,900 ROWE: With each new mission, we get closer 12 00:00:46,000 --> 00:00:49,467 to unraveling the mysteries of Saturn's moons. 13 00:00:51,800 --> 00:00:53,367 [electricity sparking] 14 00:00:53,467 --> 00:00:57,400 [explosion blasts] 15 00:01:07,300 --> 00:01:09,300 ROWE: October 2019. 16 00:01:09,367 --> 00:01:13,100 Astronomers discover 20 new moons 17 00:01:13,166 --> 00:01:16,066 orbiting the gas giant, Saturn. 18 00:01:16,066 --> 00:01:21,000 These tiny, three-mile-wide objects 19 00:01:21,066 --> 00:01:24,867 bring the ringed planet's moon count to over 80, 20 00:01:26,967 --> 00:01:30,000 the most of any planet in our solar system. 21 00:01:30,000 --> 00:01:30,266 the most of any planet in our solar system. 22 00:01:32,767 --> 00:01:34,667 You hate to play favorites, but I'm gonna say it -- 23 00:01:34,667 --> 00:01:38,500 Saturn is my favorite planetary system. 24 00:01:38,567 --> 00:01:41,967 It is unbelievably beautiful, with this incredible system of 25 00:01:41,967 --> 00:01:43,467 rings and moons, 26 00:01:43,467 --> 00:01:48,000 and there's a lot of mystery kind of all bound up in there. 27 00:01:50,367 --> 00:01:52,000 ROWE: The Voyager spacecraft gave us our 28 00:01:52,066 --> 00:01:55,200 first close look at Saturn and its rings. 29 00:01:56,567 --> 00:02:00,000 Two decades later, Cassini got us even closer 30 00:02:00,000 --> 00:02:01,500 Two decades later, Cassini got us even closer 31 00:02:01,567 --> 00:02:03,367 to many of Saturn's moons. 32 00:02:05,867 --> 00:02:09,200 There's Prometheus, Pandora, and Atlas. 33 00:02:10,367 --> 00:02:14,967 Its largest moon, Titan, is a moon that's shrouded 34 00:02:14,967 --> 00:02:17,166 in mystery. 35 00:02:17,266 --> 00:02:21,467 There's Mimas, that's fairly small, 36 00:02:21,467 --> 00:02:23,700 and then Tethys and Dione are a bit larger. 37 00:02:25,166 --> 00:02:27,600 There are a pair of moons -- Janus and Epimetheus -- 38 00:02:27,667 --> 00:02:29,467 that were perhaps one moon in the past. 39 00:02:31,166 --> 00:02:33,300 Iapetus, half of it's bright white. 40 00:02:33,367 --> 00:02:34,667 The other half of it is sort of as 41 00:02:34,767 --> 00:02:37,100 dark as coal, sort of yin and yang. 42 00:02:39,367 --> 00:02:42,467 Each of the moons of Saturn 43 00:02:42,567 --> 00:02:45,367 had remarkable stories to tell. 44 00:02:46,467 --> 00:02:49,500 ROWE: In 2005, Cassini discovered that 45 00:02:49,567 --> 00:02:53,767 one moon's story was particularly exciting. 46 00:02:53,767 --> 00:02:55,767 PLAIT: Yeah, Enceladus. 47 00:02:55,767 --> 00:02:58,767 Enceladus is one of Saturn's wee little moons. 48 00:02:58,767 --> 00:03:00,000 It's about 300 miles across -- for scale, 49 00:03:00,000 --> 00:03:01,300 It's about 300 miles across -- for scale, 50 00:03:01,367 --> 00:03:03,467 it's roughly the size of Colorado. 51 00:03:06,200 --> 00:03:09,367 ROWE: The spacecraft's cameras spot plumes of 52 00:03:09,367 --> 00:03:12,567 water vapor shooting out from Enceladus 53 00:03:13,667 --> 00:03:15,400 at 800 miles an hour. 54 00:03:18,467 --> 00:03:20,266 Three times as powerful than 55 00:03:20,266 --> 00:03:22,900 all the hot springs in Yellowstone. 56 00:03:25,767 --> 00:03:29,066 RADENBAUGH: The discovery of geysers gushing out of tiny, 57 00:03:29,066 --> 00:03:30,000 little Enceladus that should have been cold and dead, 58 00:03:30,000 --> 00:03:31,567 little Enceladus that should have been cold and dead, 59 00:03:31,567 --> 00:03:34,500 completely changed our view of what that moon exactly was. 60 00:03:36,066 --> 00:03:38,567 DURDA: It's alive. That moon is alive. 61 00:03:38,567 --> 00:03:41,266 I'd like to be standing there on the surface of Enceladus to 62 00:03:41,266 --> 00:03:43,300 see with the -- this water vapor 63 00:03:43,367 --> 00:03:46,000 and ice crystals booming out of the surface 64 00:03:46,066 --> 00:03:47,667 at supersonic speeds. 65 00:03:55,867 --> 00:03:59,500 ROWE: Cassini's sensors probe deep beneath 66 00:03:59,567 --> 00:04:00,000 the frozen surface of Enceladus, 67 00:04:00,000 --> 00:04:01,667 the frozen surface of Enceladus, 68 00:04:01,667 --> 00:04:06,000 detecting hints of a rocky core 69 00:04:06,100 --> 00:04:09,100 and something else even more remarkable. 70 00:04:11,166 --> 00:04:13,667 Underneath that thick layer of ice, 71 00:04:13,767 --> 00:04:16,266 there is liquid water ocean. 72 00:04:16,266 --> 00:04:20,100 CHRISTIANSEN: The measurements suggest his is a huge part of 73 00:04:20,166 --> 00:04:21,867 Enceladus's interior volume, 74 00:04:21,967 --> 00:04:25,300 about six miles deep, because it was making Enceladus 75 00:04:25,367 --> 00:04:26,767 wobble in its orbit. 76 00:04:26,867 --> 00:04:29,400 Imagine putting liquid inside a ball and rolling it. 77 00:04:29,467 --> 00:04:30,000 You see the natural wobble of 78 00:04:30,000 --> 00:04:30,800 You see the natural wobble of 79 00:04:30,867 --> 00:04:32,800 the ball as the liquid sloshes around. 80 00:04:34,266 --> 00:04:38,667 ROWE: Giant liquid oceans on an alien world, 81 00:04:38,767 --> 00:04:41,567 opening up exciting new possibilities. 82 00:04:42,667 --> 00:04:46,400 Where you find water, you could possibly find life. 83 00:04:49,266 --> 00:04:52,200 If you had asked me 20 years ago where there might be life 84 00:04:52,266 --> 00:04:54,166 in the solar system besides Earth, 85 00:04:54,266 --> 00:04:56,767 I think Saturn's moons would have been the last place 86 00:04:56,867 --> 00:04:58,467 I would have picked. 87 00:04:58,567 --> 00:05:00,000 But against all odds, it's looking like this tiny icy 88 00:05:00,000 --> 00:05:02,266 But against all odds, it's looking like this tiny icy 89 00:05:02,266 --> 00:05:03,800 moon orbiting Saturn 90 00:05:03,867 --> 00:05:06,800 nearly a billion miles from the Sun may be one of 91 00:05:06,867 --> 00:05:09,266 the best places to look for life. 92 00:05:10,700 --> 00:05:14,066 ROWE: July 2021. 93 00:05:15,100 --> 00:05:18,467 A new study reexamines Cassini's plume data 94 00:05:20,100 --> 00:05:22,767 and finds huge quantities of methane. 95 00:05:25,000 --> 00:05:26,266 This large amount can't be 96 00:05:26,266 --> 00:05:29,467 explained by just geochemical processes. 97 00:05:32,000 --> 00:05:35,266 The methane might be from primordial organic matter 98 00:05:35,266 --> 00:05:38,266 breaking down in Enceladus's oceans, 99 00:05:38,367 --> 00:05:47,867 or even processes we've never seen before. 100 00:05:47,967 --> 00:05:49,066 But it could be that 101 00:05:49,100 --> 00:05:53,100 living microorganisms helped generate the methane, 102 00:05:53,166 --> 00:05:55,600 just like they do on Earth. 103 00:05:56,967 --> 00:06:00,000 Enceladus might actually look a lot like early Earth in its 104 00:06:00,000 --> 00:06:00,667 Enceladus might actually look a lot like early Earth in its 105 00:06:00,767 --> 00:06:02,867 deepest oceans, when life was first arising, 106 00:06:02,867 --> 00:06:05,200 because we know that there are some chemical pathways that are 107 00:06:05,266 --> 00:06:08,000 likely occurring on Enceladus that happened on Earth. 108 00:06:12,266 --> 00:06:14,200 ROWE: These chemical pathways start with 109 00:06:14,266 --> 00:06:16,867 hot, hydrothermal vents on Earth's 110 00:06:16,867 --> 00:06:21,600 cold sea floor, releasing important life-giving chemicals 111 00:06:21,667 --> 00:06:24,300 into the oceans. 112 00:06:24,367 --> 00:06:26,867 Having hydrothermal vents are a real 113 00:06:26,867 --> 00:06:29,166 boon to the evolution of life. 114 00:06:29,266 --> 00:06:30,000 PLAIT: These are cracks in the Earth's crust, where 115 00:06:30,000 --> 00:06:32,166 PLAIT: These are cracks in the Earth's crust, where 116 00:06:32,166 --> 00:06:36,900 hot material can then spew out into the ocean. 117 00:06:37,000 --> 00:06:38,467 RADEBAUGH: And that's the energy 118 00:06:38,467 --> 00:06:39,767 that life needs to be able to form, 119 00:06:39,767 --> 00:06:42,100 and then water so everything is present, and things 120 00:06:42,166 --> 00:06:44,867 are able to just grab all these resources and energy 121 00:06:44,967 --> 00:06:47,600 and just start to evolve. 122 00:06:47,667 --> 00:06:51,667 ROWE: On Earth, hydrothermal vents produce methane, 123 00:06:51,767 --> 00:06:53,867 but only in small amounts. 124 00:06:53,867 --> 00:06:56,500 Microbial life 125 00:06:56,567 --> 00:06:59,600 living around the vents makes the rest. 126 00:07:03,600 --> 00:07:07,400 Maybe microorganisms do the same 127 00:07:07,467 --> 00:07:14,467 at the bottom of Enceladus's deep oceans. 128 00:07:14,467 --> 00:07:17,667 Hydrothermal vents on Enceladus could offer 129 00:07:17,767 --> 00:07:21,166 the perfect location for chemistry 130 00:07:21,166 --> 00:07:24,166 becoming biochemistry becoming life. 131 00:07:26,467 --> 00:07:29,400 ROWE: Hydrothermal vents normally require 132 00:07:29,467 --> 00:07:30,000 heat from a hot core. 133 00:07:30,000 --> 00:07:31,467 heat from a hot core. 134 00:07:36,367 --> 00:07:40,900 So what's going on inside Enceladus? 135 00:07:41,000 --> 00:07:46,066 This is an icy moon out there in the cold outer solar system. 136 00:07:46,066 --> 00:07:48,800 Where is all this heat coming from? 137 00:07:48,867 --> 00:07:52,200 ROWE: Cassini spotted Enceladus's plumes 138 00:07:52,266 --> 00:07:54,266 shooting out from parallel cracks 139 00:07:54,367 --> 00:07:57,467 in the surface, called tiger stripes. 140 00:08:02,500 --> 00:08:06,000 The cracks are a clue to the origin of the geysers 141 00:08:06,100 --> 00:08:08,066 and the energy that powers them. 142 00:08:11,000 --> 00:08:12,900 We look to the orbit of Enceladus itself. 143 00:08:13,000 --> 00:08:14,800 It's not in a perfectly circular orbit 144 00:08:14,867 --> 00:08:16,100 around the planet. 145 00:08:16,166 --> 00:08:18,567 It's on a slightly elliptical orbit, and that means that 146 00:08:18,667 --> 00:08:22,467 the tidal forces acting on the moon change over time. 147 00:08:22,467 --> 00:08:25,567 It's a little bit like the forces on a rubber ball. 148 00:08:25,667 --> 00:08:29,467 When the moon is closer to the planet, it's stretched out, 149 00:08:29,467 --> 00:08:30,000 and when the moon is farther from the planet, 150 00:08:30,000 --> 00:08:31,266 and when the moon is farther from the planet, 151 00:08:31,266 --> 00:08:34,600 it's relaxed back a little bit, so you're gonna squeeze 152 00:08:34,667 --> 00:08:36,867 and deform and squish the body of 153 00:08:36,867 --> 00:08:39,767 that moon over time, which is gonna heat its interior. 154 00:08:43,767 --> 00:08:46,567 ROWE: The warm, rocky core heats up the ocean, 155 00:08:46,567 --> 00:08:49,900 which both powers the geysers as they burst 156 00:08:50,000 --> 00:08:51,066 through the surface 157 00:08:52,767 --> 00:08:56,900 and creates conditions that could support life. 158 00:09:00,400 --> 00:09:02,667 DURDA: We see the energy source kicking the water 159 00:09:02,767 --> 00:09:04,700 out of the Enceladus subsurface. 160 00:09:04,767 --> 00:09:07,066 You combine that energy source 161 00:09:07,066 --> 00:09:09,367 and liquid water, that harkens to putting 162 00:09:09,367 --> 00:09:11,467 us on the same path that early life 163 00:09:11,567 --> 00:09:13,200 may have taken here on the Earth. 164 00:09:13,266 --> 00:09:14,567 And if that's the case, 165 00:09:14,667 --> 00:09:17,066 there could be little beasties swimming underneath the surface 166 00:09:17,066 --> 00:09:18,567 of one of Saturn's moons. 167 00:09:20,567 --> 00:09:22,867 ROWE: Saturn's squeezing of Enceladus may 168 00:09:22,867 --> 00:09:25,567 have transformed it into a living world, 169 00:09:29,200 --> 00:09:30,000 but other moons weren't as lucky. 170 00:09:30,000 --> 00:09:31,300 but other moons weren't as lucky. 171 00:09:33,066 --> 00:09:36,800 They've been torn apart in vicious fights 172 00:09:36,867 --> 00:09:38,100 to the death. 173 00:09:54,667 --> 00:09:58,700 ROWE: There are a huge variety of moons orbiting Saturn, 174 00:09:59,967 --> 00:10:06,100 from Titan, a moon larger than the planet Mercury, 175 00:10:06,166 --> 00:10:09,367 to objects about the size of a sports stadium. 176 00:10:10,667 --> 00:10:12,567 RADEBAUGH: There must be something dramatic that happened 177 00:10:12,667 --> 00:10:13,900 to create a system 178 00:10:14,000 --> 00:10:15,767 that's so complicated and changing 179 00:10:15,767 --> 00:10:16,919 before our very eyes. 180 00:10:16,919 --> 00:10:18,300 before our very eyes. 181 00:10:18,367 --> 00:10:22,066 ROWE: To understand such a marked difference in size, 182 00:10:22,066 --> 00:10:26,000 scientists look for clues in the moon's orbits around 183 00:10:26,066 --> 00:10:27,667 Saturn itself. 184 00:10:29,367 --> 00:10:32,800 Most of the moons of that system orbit in the same direction. 185 00:10:32,867 --> 00:10:34,967 That's obviously not a coincidence. 186 00:10:34,967 --> 00:10:37,467 That's motion left over from the formation 187 00:10:37,467 --> 00:10:38,767 of our solar system. 188 00:10:40,000 --> 00:10:42,467 ROWE: This suggests the moons formed around 189 00:10:42,567 --> 00:10:44,500 the same time as Saturn did. 190 00:10:45,500 --> 00:10:46,919 4.6 billion years ago, 191 00:10:46,919 --> 00:10:47,967 4.6 billion years ago, 192 00:10:47,967 --> 00:10:51,166 the ringless gas giant grows from gas, 193 00:10:51,266 --> 00:10:54,767 rock, and ice in the protoplanetary disk, 194 00:10:54,767 --> 00:10:56,867 along with a family of moons. 195 00:10:59,667 --> 00:11:03,367 This origin story works for most of Saturn's moons, 196 00:11:06,166 --> 00:11:09,467 but not for the recently discovered objects orbiting 197 00:11:09,467 --> 00:11:13,000 in the opposite direction of the planet's rotation. 198 00:11:14,266 --> 00:11:16,919 If there's a moon orbiting in the other direction, 199 00:11:16,919 --> 00:11:17,667 If there's a moon orbiting in the other direction, 200 00:11:17,667 --> 00:11:19,567 it couldn't have formed with the planet. 201 00:11:20,667 --> 00:11:22,767 It must have come from somewhere else. 202 00:11:24,200 --> 00:11:26,266 ROWE: Saturn captured these moons. 203 00:11:27,800 --> 00:11:29,300 But from where? 204 00:11:33,367 --> 00:11:35,700 WALSH: We think there was a huge upheaval in the solar system 205 00:11:35,767 --> 00:11:37,100 over four billion years ago, 206 00:11:37,166 --> 00:11:38,967 where the giant planets 207 00:11:38,967 --> 00:11:42,166 went from a close and compact configuration, started 208 00:11:42,266 --> 00:11:43,867 having interactions with each other, 209 00:11:43,867 --> 00:11:46,467 moved each other around to end up into the orbits 210 00:11:46,467 --> 00:11:46,919 that they find today. 211 00:11:46,919 --> 00:11:47,567 that they find today. 212 00:11:47,567 --> 00:11:50,066 During that process, a lot of smaller bodies, 213 00:11:50,066 --> 00:11:51,567 like asteroids from the distant part 214 00:11:51,667 --> 00:11:53,000 of the solar system got scattered 215 00:11:53,066 --> 00:11:54,967 every which direction. 216 00:11:56,600 --> 00:11:59,100 ROWE: During this ancient upheaval, 217 00:11:59,166 --> 00:12:01,667 Saturn grabs some of the scattered objects. 218 00:12:04,567 --> 00:12:08,000 Many bodies now crowd the region around the planet, 219 00:12:09,567 --> 00:12:12,000 and that means collisions. 220 00:12:15,667 --> 00:12:16,919 Some are destructive. 221 00:12:16,919 --> 00:12:17,600 Some are destructive. 222 00:12:17,667 --> 00:12:19,900 Others form new moons. 223 00:12:21,367 --> 00:12:22,767 In the cosmic pinball, 224 00:12:22,867 --> 00:12:25,166 some moons are thrown out of the system, 225 00:12:27,166 --> 00:12:29,567 and others, into Saturn. 226 00:12:29,667 --> 00:12:32,767 Only one large moon survives the carnage. 227 00:12:34,467 --> 00:12:35,900 WALSH: And all of a sudden, most of the mass 228 00:12:36,000 --> 00:12:38,166 of all the satellites is in that single moon, Titan. 229 00:12:41,166 --> 00:12:44,400 ROWE: Titan may have formed from the material in 230 00:12:44,467 --> 00:12:46,919 the protoplanetary disk at the same time as Saturn, 231 00:12:46,919 --> 00:12:48,166 the protoplanetary disk at the same time as Saturn, 232 00:12:48,166 --> 00:12:52,467 but then gorged on the debris created in the later 233 00:12:52,467 --> 00:12:57,500 lunar collisions. 234 00:12:57,567 --> 00:13:03,200 It amassed 96 percent of the material orbiting Saturn 235 00:13:03,266 --> 00:13:06,800 and grew so large that it developed a dense atmosphere. 236 00:13:11,166 --> 00:13:13,266 CHRISTIANSEN: When Voyager photographed Titan, 237 00:13:13,367 --> 00:13:15,967 it clearly showed that Titan had a thick atmosphere, 238 00:13:15,967 --> 00:13:16,919 which was so incredibly exciting, 239 00:13:16,919 --> 00:13:18,400 which was so incredibly exciting, 240 00:13:18,467 --> 00:13:20,300 but it was so dense and impenetrable, 241 00:13:20,367 --> 00:13:22,900 that was all we could see. 242 00:13:24,467 --> 00:13:26,567 ROWE: Two decades after Voyager, 243 00:13:26,667 --> 00:13:29,400 the Huygens Probe launched from Cassini 244 00:13:30,867 --> 00:13:34,800 and plunged through the murky depths of Titan's atmosphere. 245 00:13:40,967 --> 00:13:42,667 DARTNELL: Our first images of what 246 00:13:42,767 --> 00:13:45,166 the Titanic landscape was like 247 00:13:45,266 --> 00:13:46,919 were utterly and truly mind-blowing. 248 00:13:46,919 --> 00:13:50,300 were utterly and truly mind-blowing. 249 00:13:50,367 --> 00:13:51,700 HOWETT: It showed there were mountains 250 00:13:51,767 --> 00:13:52,767 and there was sort of erosion 251 00:13:52,867 --> 00:13:54,767 on those mountains that looked like liquid 252 00:13:54,767 --> 00:13:57,900 had fallen down the mountains and brought material with it. 253 00:13:59,266 --> 00:14:01,367 That liquid must have come from somewhere. 254 00:14:01,367 --> 00:14:03,200 And where else than rain, 255 00:14:03,266 --> 00:14:04,467 the weather on Titan? 256 00:14:06,100 --> 00:14:08,867 ROWE: We've only found two places in the solar system 257 00:14:08,867 --> 00:14:12,000 with rivers and rain -- 258 00:14:12,100 --> 00:14:15,867 Earth and Titan. 259 00:14:15,967 --> 00:14:16,919 Out of this thick gloom, 260 00:14:16,919 --> 00:14:18,200 Out of this thick gloom, 261 00:14:18,266 --> 00:14:22,367 this is the most similar place to Earth we've ever seen. 262 00:14:22,467 --> 00:14:25,467 ROWE: Similar, but not identical. 263 00:14:27,266 --> 00:14:32,200 That rain filling lakes and rivers on Titan isn't water. 264 00:14:33,266 --> 00:14:34,600 It's liquid methane. 265 00:14:36,066 --> 00:14:39,467 It's like if every oil well, if every gas station on 266 00:14:39,567 --> 00:14:41,567 Earth started leaking all over the place, 267 00:14:41,567 --> 00:14:44,200 that is what we see on this world. 268 00:14:47,066 --> 00:14:48,867 ROWE: The methane is a liquid on Titan 269 00:14:48,967 --> 00:14:53,567 because the surface temperature is 290 degrees below zero, 270 00:14:54,867 --> 00:14:57,266 which is a big problem for life 271 00:14:57,367 --> 00:14:59,266 as we understand it. 272 00:15:00,767 --> 00:15:03,667 We don't know of any organism that can really survive past 273 00:15:03,767 --> 00:15:06,166 negative 4 degrees Fahrenheit, and that's just because 274 00:15:06,266 --> 00:15:08,800 cells will tend to freeze there. 275 00:15:08,867 --> 00:15:10,567 HOWETT: The cells that we have, 276 00:15:10,567 --> 00:15:13,467 what they're made up from, these proteins and fatty 277 00:15:13,567 --> 00:15:16,919 material, stop working, and everything would die. 278 00:15:16,919 --> 00:15:17,800 material, stop working, and everything would die. 279 00:15:17,867 --> 00:15:22,500 ROWE: That's what happens to Earth's water-based cells. 280 00:15:25,200 --> 00:15:30,300 But could methane-based life survive in extreme cold? 281 00:15:33,066 --> 00:15:36,667 The ALMA telescope spotted a clue in Titan's nitrogen- 282 00:15:36,667 --> 00:15:39,500 and-methane-rich atmosphere. 283 00:15:39,567 --> 00:15:43,367 With sunlight hitting the atmosphere of Titan, 284 00:15:43,467 --> 00:15:46,667 things like methane and nitrogen can get broken apart 285 00:15:46,667 --> 00:15:46,919 and reassembled, like playing with LEGO blocks, 286 00:15:46,919 --> 00:15:50,867 and reassembled, like playing with LEGO blocks, 287 00:15:50,967 --> 00:15:54,166 and then these molecules recombine to 288 00:15:54,266 --> 00:15:57,166 make new ones, like vinyl cyanide. 289 00:15:59,200 --> 00:16:01,166 Artist depiction. 290 00:16:01,266 --> 00:16:06,767 ROWE: Used on Earth to make plastics, vinyl cyanide can 291 00:16:06,867 --> 00:16:09,100 build long chains of molecules, 292 00:16:09,166 --> 00:16:12,700 the type you need to build cell membranes. 293 00:16:18,767 --> 00:16:21,467 But unlike Earth's water-based cells, 294 00:16:21,567 --> 00:16:24,367 the extreme cold wouldn't destroy them. 295 00:16:26,900 --> 00:16:29,100 HOWETT: It could survive at those low temperatures. 296 00:16:29,166 --> 00:16:33,166 So on Titan, it could be that this vinyl cyanide is able 297 00:16:33,266 --> 00:16:34,700 to form the membranes 298 00:16:34,767 --> 00:16:36,500 that are required for cells to develop, 299 00:16:36,567 --> 00:16:39,200 which are required for life to happen. 300 00:16:43,000 --> 00:16:45,166 ROWE: And good news -- 301 00:16:45,266 --> 00:16:46,919 there's a lot of this stuff on Titan right now. 302 00:16:46,919 --> 00:16:48,200 there's a lot of this stuff on Titan right now. 303 00:16:50,867 --> 00:16:55,300 There's as much as 10 billion tons of this vinyl cyanide 304 00:16:55,367 --> 00:16:56,767 in just one of the lakes. 305 00:16:56,867 --> 00:16:58,867 If you want to start making creatures out of it -- 306 00:16:58,867 --> 00:17:00,767 say, I don't know, a giant squid -- 307 00:17:00,767 --> 00:17:02,266 do you like giant squids? 308 00:17:02,367 --> 00:17:05,767 I hope so, because you could make billions 309 00:17:05,767 --> 00:17:11,266 of giant squids out of this vinyl cyanide. 310 00:17:11,266 --> 00:17:14,166 ROWE: Saturn's geyser moon, Enceladus, 311 00:17:14,166 --> 00:17:16,667 could have life as we know it. 312 00:17:16,767 --> 00:17:16,919 Titan might have something truly alien. 313 00:17:16,919 --> 00:17:21,700 Titan might have something truly alien. 314 00:17:21,767 --> 00:17:25,200 It is an unrelentingly brutal, 315 00:17:25,266 --> 00:17:28,200 cold place compared to Earth. 316 00:17:28,266 --> 00:17:31,667 But for Titanic life, it might just be ideal. 317 00:17:33,266 --> 00:17:34,767 COOPER: As we search for life beyond Earth, 318 00:17:34,867 --> 00:17:38,266 it still comes with a bias of life as we know it. 319 00:17:38,367 --> 00:17:40,400 And so it's great, as we continue 320 00:17:40,467 --> 00:17:43,300 to explore and continue to evolve our definitions, 321 00:17:43,367 --> 00:17:46,919 we can expand our view of how to search for life. 322 00:17:46,919 --> 00:17:48,266 we can expand our view of how to search for life. 323 00:17:48,367 --> 00:17:52,400 Maybe the Saturn system has two living worlds. 324 00:17:54,800 --> 00:17:58,867 ROWE: But for life to thrive on Titan's surface, 325 00:17:58,867 --> 00:18:02,767 it must survive a storm of deadly particles 326 00:18:02,767 --> 00:18:04,867 racing out of the Sun 327 00:18:04,867 --> 00:18:07,000 at over a million miles an hour. 328 00:18:22,600 --> 00:18:25,567 ROWE: The sun provides light and warmth... 329 00:18:29,367 --> 00:18:34,000 and something else, something very dangerous -- 330 00:18:34,100 --> 00:18:35,100 the solar wind. 331 00:18:38,567 --> 00:18:41,767 These lethal solar particles can strip away 332 00:18:41,767 --> 00:18:44,860 atmosphere from planets and moons. 333 00:18:44,860 --> 00:18:44,967 atmosphere from planets and moons. 334 00:18:48,300 --> 00:18:50,300 Without an atmosphere, 335 00:18:50,367 --> 00:18:52,767 Earth would be a barren desert, right? 336 00:18:52,767 --> 00:18:55,367 There wouldn't be any water, it would just all boil away. 337 00:18:55,467 --> 00:18:57,567 There wouldn't be any life, 338 00:18:58,700 --> 00:19:02,667 ROWE: Luckily, Earth has a built-in defense system. 339 00:19:04,100 --> 00:19:05,400 SUTTER: In the center of our Earth, 340 00:19:05,467 --> 00:19:09,867 we have a solid iron core, and surrounding that is liquid iron 341 00:19:09,867 --> 00:19:14,000 that is constantly moving and swirling and convecting, 342 00:19:14,100 --> 00:19:14,860 and these complex motions 343 00:19:14,860 --> 00:19:15,567 and these complex motions 344 00:19:15,667 --> 00:19:19,567 power up a global-scale magnetic field 345 00:19:23,266 --> 00:19:25,166 PLAIT: And this acts like a force field 346 00:19:25,266 --> 00:19:27,800 against the solar wind, pushes it away, 347 00:19:27,867 --> 00:19:29,667 pushes it around us so it doesn't hit us. 348 00:19:31,266 --> 00:19:34,400 ROWE: We think that Saturn's moon, Titan, 349 00:19:34,467 --> 00:19:37,066 has no molten iron core 350 00:19:39,567 --> 00:19:43,800 and therefore no protective magnetic field. 351 00:19:43,867 --> 00:19:44,860 So it's at the mercy of the solar wind. 352 00:19:44,860 --> 00:19:46,500 So it's at the mercy of the solar wind. 353 00:19:47,667 --> 00:19:50,200 It kind of begs the question, why does Titan 354 00:19:50,266 --> 00:19:52,767 have such a thick, dense atmosphere? 355 00:19:52,867 --> 00:19:57,367 ROWE: Titan retaining an atmosphere without 356 00:19:57,467 --> 00:20:00,266 a protective shield makes no sense. 357 00:20:03,000 --> 00:20:05,100 SUTTER: Titan doesn't have a magnetic field, 358 00:20:05,166 --> 00:20:07,567 but Saturn does. 359 00:20:07,567 --> 00:20:10,300 So maybe there's some sort of interaction between 360 00:20:10,367 --> 00:20:14,860 the atmosphere of Titan and Saturn's giant magnetic field. 361 00:20:14,860 --> 00:20:15,000 the atmosphere of Titan and Saturn's giant magnetic field. 362 00:20:16,767 --> 00:20:20,166 ROWE: The gas giant Saturn generates a magnetic field 363 00:20:20,166 --> 00:20:23,166 around 600 times larger than Earth's, 364 00:20:25,667 --> 00:20:29,367 large enough to shield Titan from the solar wind. 365 00:20:31,700 --> 00:20:35,066 So Titan by itself is vulnerable. 366 00:20:35,066 --> 00:20:36,900 Saturn is like the mother ship. 367 00:20:37,000 --> 00:20:39,500 It has this giant force field 368 00:20:39,567 --> 00:20:41,000 that it can use to protect Titan. 369 00:20:42,400 --> 00:20:44,860 ROWE: Despite Saturn's embrace, Titan still loses 370 00:20:44,860 --> 00:20:48,300 ROWE: Despite Saturn's embrace, Titan still loses 371 00:20:48,367 --> 00:20:52,567 some of its atmosphere, because occasionally, 372 00:20:52,667 --> 00:20:57,166 the moon wanders away from its protective parent. 373 00:20:57,266 --> 00:21:00,667 Titan orbits inside of that magnetic field... 374 00:21:00,667 --> 00:21:03,266 mostly, most of the time. 375 00:21:03,266 --> 00:21:05,000 Its orbit isn't perfectly circular. 376 00:21:05,100 --> 00:21:06,700 It's slightly elliptical. 377 00:21:08,467 --> 00:21:11,667 So as Titan orbits the planet, for a little bit of time, 378 00:21:11,667 --> 00:21:13,000 about 5 percent of its orbit, 379 00:21:13,066 --> 00:21:14,860 it's actually slightly outside the magnetic field 380 00:21:14,860 --> 00:21:15,467 it's actually slightly outside the magnetic field 381 00:21:15,467 --> 00:21:17,100 before dipping back in again. 382 00:21:19,667 --> 00:21:21,100 ROWE: But these short forays into 383 00:21:21,166 --> 00:21:25,667 the firing line don't cause any lasting damage. 384 00:21:26,967 --> 00:21:30,166 What's really weird is that there's sort of a residual 385 00:21:30,266 --> 00:21:32,266 magnetic effect on Titan. 386 00:21:32,266 --> 00:21:34,567 When it leaves Saturn's protective field, 387 00:21:34,567 --> 00:21:37,000 it should just immediately drop to nothing. 388 00:21:37,066 --> 00:21:39,300 But there still is this residual field, 389 00:21:39,367 --> 00:21:41,867 protecting it from the solar wind. 390 00:21:41,867 --> 00:21:44,860 SUTTER: It can maintain the memory of that magnetic field 391 00:21:44,860 --> 00:21:45,100 SUTTER: It can maintain the memory of that magnetic field 392 00:21:45,166 --> 00:21:48,000 and still preserve some of that protection. 393 00:21:49,300 --> 00:21:52,100 It's almost like Saturn is trying to teach 394 00:21:52,166 --> 00:21:54,166 Titan how to have a magnetic field, 395 00:21:54,166 --> 00:21:56,000 and Titan can remember for a little bit, 396 00:21:56,066 --> 00:21:58,000 but then it needs to come back home. 397 00:21:59,867 --> 00:22:02,367 ROWE: This magnetic memory could help 398 00:22:02,467 --> 00:22:05,600 support any life on Titan's surface, 399 00:22:05,667 --> 00:22:09,667 providing a safe haven that's protected from the solar wind. 400 00:22:12,266 --> 00:22:14,200 And Cassini spots a way 401 00:22:14,266 --> 00:22:14,860 Saturn's magnetism might also allow 402 00:22:14,860 --> 00:22:17,367 Saturn's magnetism might also allow 403 00:22:17,467 --> 00:22:20,667 its moons to develop life. 404 00:22:20,667 --> 00:22:24,767 One of the most amazing discoveries around Saturn was 405 00:22:24,867 --> 00:22:26,500 that its magnetic field is not 406 00:22:26,567 --> 00:22:28,667 just transporting charged particles from, 407 00:22:28,767 --> 00:22:32,266 say, the sun, but it's also transporting material 408 00:22:32,367 --> 00:22:33,800 from one moon to another. 409 00:22:37,166 --> 00:22:39,567 ROWE: Saturn's magnetic field helps boost 410 00:22:39,567 --> 00:22:41,867 the chance of life on Titan 411 00:22:41,867 --> 00:22:44,860 by stealing material from its sister moon, Enceladus. 412 00:22:44,860 --> 00:22:46,867 by stealing material from its sister moon, Enceladus. 413 00:22:48,166 --> 00:22:50,667 Magnetism is a strong force, of course, 414 00:22:50,667 --> 00:22:53,567 but to act on a scale and a range 415 00:22:53,567 --> 00:22:56,300 like this and maybe transport matter from moon to moon, 416 00:22:56,367 --> 00:22:58,066 that's pretty cool. 417 00:22:59,800 --> 00:23:02,867 ROWE: Saturn's magnetic field smashes apart 418 00:23:02,967 --> 00:23:07,367 water molecules blasted out from Enceladus's geysers 419 00:23:07,467 --> 00:23:12,600 and carries the leftover oxygen to Titan. 420 00:23:12,667 --> 00:23:14,767 SUTTER: The magnetic field of Saturn 421 00:23:14,867 --> 00:23:18,100 acts like an inter-lunar highway 422 00:23:18,166 --> 00:23:21,667 in the Saturn system, transporting oxygen 423 00:23:21,667 --> 00:23:24,500 from Enceladus all the way to Titan. 424 00:23:24,567 --> 00:23:28,166 ROWE: But there's a problem when the oxygen tries to 425 00:23:28,266 --> 00:23:33,066 take the Titan exit off of this inter-lunar highway. 426 00:23:33,066 --> 00:23:36,200 Normally, this oxygen wouldn't survive 427 00:23:36,266 --> 00:23:37,567 in the atmosphere of Titan. 428 00:23:37,667 --> 00:23:40,467 It would react with the methane there and create carbon dioxide. 429 00:23:41,967 --> 00:23:43,700 ROWE: To get to the surface 430 00:23:43,767 --> 00:23:44,860 in one piece, oxygen hitches 431 00:23:44,860 --> 00:23:46,166 in one piece, oxygen hitches 432 00:23:46,166 --> 00:23:49,567 a ride with something called a fullerene. 433 00:23:54,467 --> 00:23:55,967 Fullerenes are these sort of 434 00:23:55,967 --> 00:23:58,500 soccer ball shaped molecules that are hollow. 435 00:23:58,567 --> 00:24:00,667 If the oxygen atom gets in there, 436 00:24:00,667 --> 00:24:03,867 it can be safely transported through Titan's atmosphere. 437 00:24:05,767 --> 00:24:09,600 ROWE: Once on the surface, the oxygen could help create 438 00:24:09,667 --> 00:24:11,467 amino acids, 439 00:24:11,467 --> 00:24:14,400 the essential building blocks of proteins, 440 00:24:14,467 --> 00:24:14,860 another stepping stone for life to emerge. 441 00:24:14,860 --> 00:24:19,100 another stepping stone for life to emerge. 442 00:24:22,367 --> 00:24:25,767 Think of all the complex coincidences 443 00:24:25,867 --> 00:24:27,567 that have to happen 444 00:24:27,667 --> 00:24:30,667 for these chemical reactions to take place. 445 00:24:30,667 --> 00:24:32,667 If Titan's orbit was any different, 446 00:24:32,767 --> 00:24:34,100 it simply wouldn't exist. 447 00:24:37,767 --> 00:24:42,367 ROWE: Saturn protects any potential life on its moons. 448 00:24:43,600 --> 00:24:44,860 And as it turns out, the moons 449 00:24:44,860 --> 00:24:46,166 And as it turns out, the moons 450 00:24:46,166 --> 00:24:50,667 return the favor by helping create 451 00:24:50,767 --> 00:24:57,000 and maintain Saturn's iconic rings. 452 00:25:10,467 --> 00:25:13,800 ROWE: At 170,000 miles in diameter, 453 00:25:15,000 --> 00:25:17,500 but only 30 feet thick in places, 454 00:25:17,567 --> 00:25:22,367 Saturn's beautiful rings have always stolen the show, 455 00:25:25,266 --> 00:25:29,367 but their origin is still a mystery. 456 00:25:29,467 --> 00:25:29,965 Saturn has these beautiful rings that really 457 00:25:29,965 --> 00:25:33,066 Saturn has these beautiful rings that really 458 00:25:33,066 --> 00:25:34,300 define it as a planet, 459 00:25:34,367 --> 00:25:36,467 but its unique in the solar system in the sense that no 460 00:25:36,567 --> 00:25:40,100 other planet has such a big ring system. 461 00:25:40,166 --> 00:25:44,100 THALLER: All of the other gas giants have remnants of a ring, 462 00:25:44,166 --> 00:25:47,967 kind of small, thin, dark rings, but nothing like Saturn. 463 00:25:47,967 --> 00:25:51,000 So something very different happened around Saturn. 464 00:25:53,000 --> 00:25:57,600 ROWE: A clue comes from the rings' composition. 465 00:25:57,667 --> 00:25:59,965 They're around 99 percent water ice, 466 00:25:59,965 --> 00:26:00,500 They're around 99 percent water ice, 467 00:26:00,567 --> 00:26:03,467 giving the rings their sparkling appearance. 468 00:26:05,000 --> 00:26:09,400 This leads astronomers to a bold theory. 469 00:26:09,467 --> 00:26:13,100 We do not know how Saturn's icy rings formed. 470 00:26:13,166 --> 00:26:14,767 We're not even sure how old they are, 471 00:26:14,767 --> 00:26:18,266 but one idea is that they formed from ice that was 472 00:26:18,367 --> 00:26:20,567 existing previously on a moon. 473 00:26:20,667 --> 00:26:23,400 How amazing is that? 474 00:26:23,467 --> 00:26:28,467 ROWE: Several billion years ago, Saturn may have been ringless, 475 00:26:29,667 --> 00:26:29,965 with a large, icy moon. 476 00:26:29,965 --> 00:26:32,166 with a large, icy moon. 477 00:26:32,266 --> 00:26:35,867 The moon was big enough that its gravity drew heavier 478 00:26:35,967 --> 00:26:37,767 stuff like rock to its core 479 00:26:37,767 --> 00:26:40,467 and lighter stuff like ice floated to the top. 480 00:26:40,567 --> 00:26:47,266 ROWE: We think the moon strayed too close to Saturn. 481 00:26:47,266 --> 00:26:50,367 WALSH: The gravity from Saturn could tear it apart, 482 00:26:52,200 --> 00:26:55,266 and it could separate the ices from the rocky parts 483 00:26:55,266 --> 00:26:57,767 and the ices could stay in orbit and form our rings, 484 00:26:57,767 --> 00:26:59,965 and the rocky parts would get swallowed up by Saturn. 485 00:26:59,965 --> 00:27:00,667 and the rocky parts would get swallowed up by Saturn. 486 00:27:07,066 --> 00:27:10,667 The death of a large moon may have built the rings, 487 00:27:14,867 --> 00:27:18,967 but they owe their current appearance to the moons that 488 00:27:18,967 --> 00:27:20,900 are still alive. 489 00:27:21,000 --> 00:27:24,266 THALLER: When you go back to Saturn's rings, 490 00:27:24,266 --> 00:27:27,100 time and time again, they're all slightly different. 491 00:27:27,166 --> 00:27:29,166 They are changing, they are braiding in and out of 492 00:27:29,166 --> 00:27:29,965 each other -- we had no idea there would be 493 00:27:29,965 --> 00:27:32,000 each other -- we had no idea there would be 494 00:27:32,100 --> 00:27:34,567 so much beauty and so much mystery in the rings. 495 00:27:36,467 --> 00:27:40,266 ROWE: The behavior of two of Saturn's moons, 496 00:27:40,266 --> 00:27:42,567 Prometheus and Atlas, 497 00:27:42,667 --> 00:27:45,100 which are embedded in the rings 498 00:27:45,166 --> 00:27:47,300 is especially surprising. 499 00:27:47,367 --> 00:27:50,567 Some of these smallest moons 500 00:27:50,667 --> 00:27:53,467 are interspersed within the ring system. 501 00:27:53,567 --> 00:27:57,767 Some of them are doing something really bizarre. 502 00:27:57,867 --> 00:27:59,965 In some cases, it looks like the moons were shepherding 503 00:27:59,965 --> 00:28:01,266 In some cases, it looks like the moons were shepherding 504 00:28:01,266 --> 00:28:04,767 the edges of the rings and keeping them in their place. 505 00:28:06,000 --> 00:28:09,567 ROWE: The moon's gravity cleans up the rings, 506 00:28:10,867 --> 00:28:14,367 sometimes, sculpting shapes in their wake. 507 00:28:16,667 --> 00:28:19,567 Saturn's rings aren't static, and there's some really 508 00:28:19,567 --> 00:28:22,500 fascinating interactions where moons are clearly pushing on 509 00:28:22,567 --> 00:28:25,467 the rings and causing weird and cool waves, 510 00:28:25,567 --> 00:28:29,900 making the rings just that much more beautiful. 511 00:28:30,000 --> 00:28:33,367 HOWETT: The whole dance between Saturn and its moons, 512 00:28:33,367 --> 00:28:35,166 its rings, how they all 513 00:28:35,266 --> 00:28:37,900 are interconnected, is just completely fascinating. 514 00:28:40,100 --> 00:28:41,667 It's a dynamic, amazing, 515 00:28:41,767 --> 00:28:44,200 living, geologically vibrant place. 516 00:28:48,266 --> 00:28:51,266 ROWE: Saturn's moons may keep the rings orderly, 517 00:28:53,200 --> 00:28:58,166 but they can't explain why the rings are so clean, 518 00:28:58,166 --> 00:28:59,667 almost pristine. 519 00:29:02,100 --> 00:29:03,667 PLAIT: They're too shiny. 520 00:29:03,667 --> 00:29:06,100 If they were billions of years old, 521 00:29:06,166 --> 00:29:08,500 they should have collected a lot of dust by now 522 00:29:08,567 --> 00:29:09,767 and be a lot darker. 523 00:29:09,867 --> 00:29:12,767 The fact that they're shiny kind of implies that 524 00:29:12,767 --> 00:29:16,600 maybe they're a lot younger than we first thought. 525 00:29:16,667 --> 00:29:19,467 ROWE: Perhaps the rings we see today 526 00:29:19,467 --> 00:29:22,367 are a more recent upgrade. 527 00:29:23,867 --> 00:29:26,667 The rings might only be 100 million years old, 528 00:29:26,667 --> 00:29:28,800 about the time of the dinosaurs. 529 00:29:28,867 --> 00:29:29,965 So if the dinosaurs had invented telescopes, 530 00:29:29,965 --> 00:29:31,867 So if the dinosaurs had invented telescopes, 531 00:29:31,967 --> 00:29:34,867 they could have seen Saturn without rings. 532 00:29:34,867 --> 00:29:36,100 And it makes you wonder, is this 533 00:29:36,166 --> 00:29:38,166 the first ring system that Saturn had? 534 00:29:38,166 --> 00:29:39,967 Or was there another ring system 535 00:29:39,967 --> 00:29:42,000 that may be slowly eroded away? 536 00:29:42,100 --> 00:29:45,266 Perhaps a comet or a body came in too close to Saturn, 537 00:29:45,367 --> 00:29:47,367 and Saturn's gravity literally tore it apart, 538 00:29:47,367 --> 00:29:49,200 and then we got a brand-new ring system. 539 00:29:51,567 --> 00:29:54,300 The later dinosaurs could have watched the rings form, 540 00:29:55,467 --> 00:29:57,266 and then they would have been wiped out by an asteroid. 541 00:29:58,567 --> 00:29:59,965 Yeah, should have built better telescopes, 542 00:29:59,965 --> 00:30:00,367 Yeah, should have built better telescopes, 543 00:30:00,367 --> 00:30:02,867 dinosaurs, sucks to be you. 544 00:30:05,567 --> 00:30:08,600 ROWE: We still don't know why the rings of Saturn 545 00:30:08,667 --> 00:30:10,266 are so clean. 546 00:30:11,967 --> 00:30:14,166 It could be that the rings really are old, and they have 547 00:30:14,166 --> 00:30:15,500 some sort of cleaning system, 548 00:30:15,567 --> 00:30:17,000 which removes the dust from them, 549 00:30:17,066 --> 00:30:21,600 making them look young, or they may actually be young, and this 550 00:30:21,667 --> 00:30:24,867 may be the seventh or eighth or whatever generation rings. 551 00:30:24,867 --> 00:30:29,965 It is so different than any other planetary system. 552 00:30:29,965 --> 00:30:29,967 It is so different than any other planetary system. 553 00:30:29,967 --> 00:30:31,867 And those mysteries still exist. 554 00:30:31,967 --> 00:30:35,667 We have some idea what went on, 555 00:30:35,767 --> 00:30:38,066 but there's a lot that we don't know about Saturn. 556 00:30:40,867 --> 00:30:43,600 ROWE: Cassini is changing that. 557 00:30:46,000 --> 00:30:50,000 It's discovered a whole new moon-making process, 558 00:30:52,166 --> 00:30:55,000 with the rings taking the lead. 559 00:31:10,967 --> 00:31:13,767 ROWE: Midway through its 13-year mission to Saturn, 560 00:31:16,166 --> 00:31:19,000 Cassini captures an intriguing image, 561 00:31:21,667 --> 00:31:23,700 a bright feature at the edge 562 00:31:23,767 --> 00:31:26,000 of one of Saturn's outermost rings, 563 00:31:27,066 --> 00:31:29,000 something we'd never seen before. 564 00:31:31,400 --> 00:31:34,600 I was really excited when we saw these images of Saturn's 565 00:31:34,667 --> 00:31:36,967 rings, and it looked like there was a lump, 566 00:31:36,967 --> 00:31:41,600 maybe a moon forming there, which they nicknamed Peggy. 567 00:31:41,667 --> 00:31:43,667 ROWE: Named after the mother-in-law 568 00:31:43,767 --> 00:31:45,800 of the scientist who discovered it, 569 00:31:45,867 --> 00:31:49,200 Peggy was still too small to be considered 570 00:31:49,266 --> 00:31:54,967 a fully-formed moon, but nearby orbits 571 00:31:54,967 --> 00:31:59,300 a group of objects that are just big enough to be moons, 572 00:32:02,166 --> 00:32:04,300 and they are really weird. 573 00:32:05,900 --> 00:32:07,467 These moons are really unusual. 574 00:32:07,567 --> 00:32:10,467 We don't think of them as like anything else we've seen. 575 00:32:10,567 --> 00:32:14,166 They're kind of little fuzzy potatoes or maybe 576 00:32:14,266 --> 00:32:17,367 even like a ravioli is another one or a croissant. 577 00:32:17,367 --> 00:32:18,567 Why do we always come up with food? 578 00:32:18,667 --> 00:32:22,000 But at the same time, that's exactly what they look like. 579 00:32:22,066 --> 00:32:25,367 The most bizarrely-shaped moon of Saturn is Pan. 580 00:32:25,467 --> 00:32:27,200 It's got these crisscrossing cracks, 581 00:32:27,266 --> 00:32:30,100 just like bread, and then around the outside 582 00:32:30,166 --> 00:32:32,367 is a belly band, it's undulatory. 583 00:32:32,367 --> 00:32:34,000 How would this get there? 584 00:32:36,700 --> 00:32:39,266 ROWE: Cassini discovered a clue. 585 00:32:42,100 --> 00:32:44,200 Like Saturn's rings, 586 00:32:44,266 --> 00:32:48,166 these moons were made almost entirely of water ice. 587 00:32:51,166 --> 00:32:52,367 They must have grown from 588 00:32:52,367 --> 00:32:55,567 tiny lumps trapped within the rings. 589 00:32:56,667 --> 00:33:00,158 PLAIT: They're going to be extremely fragile, 590 00:33:00,158 --> 00:33:02,767 PLAIT: They're going to be extremely fragile, 591 00:33:02,867 --> 00:33:05,400 kind of like a snowflake orbiting Saturn. 592 00:33:05,467 --> 00:33:08,367 They can start drawing in material and then can grow. 593 00:33:08,467 --> 00:33:10,967 You can actually imagine rolling up a snowball 594 00:33:10,967 --> 00:33:13,867 and accumulating more and more particles on the outside. 595 00:33:13,867 --> 00:33:16,400 And in the same way, you could accumulate 596 00:33:16,467 --> 00:33:17,867 these clumps in the rings. 597 00:33:17,967 --> 00:33:19,867 And if they're near the edge of the rings, 598 00:33:19,967 --> 00:33:24,567 perhaps they actually break free and go out to form tiny moons. 599 00:33:27,266 --> 00:33:30,158 ROWE: The size of these space snowballs, 600 00:33:30,158 --> 00:33:30,667 ROWE: The size of these space snowballs, 601 00:33:30,767 --> 00:33:33,867 tens of miles across or less, 602 00:33:33,967 --> 00:33:36,467 helps explain their unusual shapes. 603 00:33:39,800 --> 00:33:43,567 The size of the moon actually affects its shape in that once 604 00:33:43,567 --> 00:33:45,100 you get below a certain size threshold, 605 00:33:45,166 --> 00:33:46,900 you cannot be round anymore. 606 00:33:47,000 --> 00:33:48,867 That's because the strength of the rock or the ice 607 00:33:48,867 --> 00:33:51,667 in this case is too great to be overcome by gravity, 608 00:33:51,667 --> 00:33:54,767 and so the kind of oblong shapes can be maintained. 609 00:33:57,200 --> 00:33:59,266 ROWE: Add in a few collisions, 610 00:33:59,367 --> 00:34:00,158 and you get Saturn's ravioli- and croissant-shaped moons. 611 00:34:00,158 --> 00:34:03,467 and you get Saturn's ravioli- and croissant-shaped moons. 612 00:34:06,266 --> 00:34:08,667 It's a bizarre process but leads to a beautiful form. 613 00:34:08,767 --> 00:34:12,767 We know the moons affect the rings, but it looks 614 00:34:12,867 --> 00:34:15,467 like in this case, the rings affect the moons, too. 615 00:34:15,467 --> 00:34:17,500 They're connected in both directions. 616 00:34:23,367 --> 00:34:26,467 ROWE: The rings form a moon factory, 617 00:34:30,467 --> 00:34:34,467 capable of building countless generations of new worlds. 618 00:34:36,467 --> 00:34:40,000 This is a dance of physics. 619 00:34:42,000 --> 00:34:45,367 PLAIT: If moonlets can form by these icy ring particles, 620 00:34:45,467 --> 00:34:47,767 they'll grow, and then their natural gravitational 621 00:34:47,767 --> 00:34:50,300 interaction with the rings will make them move out. 622 00:34:50,367 --> 00:34:51,900 They keep growing as they move out. 623 00:34:52,000 --> 00:34:54,467 But then another moon forms where the first one was. 624 00:34:54,567 --> 00:34:57,467 So you keep getting these growing moons, right, 625 00:34:57,467 --> 00:34:59,800 and this process repeats like on a conveyor belt. 626 00:34:59,867 --> 00:35:00,158 And what you wind up with is bigger moons orbiting 627 00:35:00,158 --> 00:35:02,467 And what you wind up with is bigger moons orbiting 628 00:35:02,467 --> 00:35:04,700 farther out from Saturn and smaller ones 629 00:35:04,767 --> 00:35:06,000 orbiting closer in. 630 00:35:08,867 --> 00:35:12,567 ROWE: But Saturn's conveyor belt will eventually break down. 631 00:35:17,166 --> 00:35:18,600 When ultraviolet light from 632 00:35:18,667 --> 00:35:23,000 the sun interacts with ring particles, 633 00:35:23,066 --> 00:35:27,200 it throws their steady orbit around Saturn out of whack. 634 00:35:29,467 --> 00:35:30,158 The sun energizes the rings, and it gives them a charge. 635 00:35:30,158 --> 00:35:32,567 The sun energizes the rings, and it gives them a charge. 636 00:35:32,567 --> 00:35:34,166 This charge means they can get picked 637 00:35:34,166 --> 00:35:36,367 up by the magnetic field of Saturn. 638 00:35:36,367 --> 00:35:38,900 So these little tiny charged particles then are lifted 639 00:35:39,000 --> 00:35:40,266 out of the rings, 640 00:35:40,367 --> 00:35:42,400 follow along the magnetic field lines, 641 00:35:42,467 --> 00:35:44,567 rain down into Saturn's atmosphere. 642 00:35:47,166 --> 00:35:51,900 ROWE: The charged particles are tiny ice crystals. 643 00:35:52,000 --> 00:35:54,600 They rain down onto Saturn, 644 00:35:57,266 --> 00:36:00,158 enough to fill an Olympic-sized swimming pool 645 00:36:00,158 --> 00:36:00,500 enough to fill an Olympic-sized swimming pool 646 00:36:00,567 --> 00:36:01,667 every second. 647 00:36:05,467 --> 00:36:08,200 In less than 100 million years, 648 00:36:08,266 --> 00:36:12,300 Saturn's rings will be gone. 649 00:36:12,367 --> 00:36:17,667 There will be no material to build new moons. 650 00:36:17,667 --> 00:36:21,467 Saturn's moons and rings, 651 00:36:21,567 --> 00:36:23,700 they almost make me feel bittersweet, because they 652 00:36:23,767 --> 00:36:26,667 show you the beauty of what physics can create, 653 00:36:26,767 --> 00:36:28,767 But also the fleeting-ness. 654 00:36:28,767 --> 00:36:30,158 They'll be gone soon, and that makes me sad. 655 00:36:30,158 --> 00:36:31,600 They'll be gone soon, and that makes me sad. 656 00:36:34,667 --> 00:36:36,600 ROWE: The closer we look, 657 00:36:36,667 --> 00:36:39,567 the more intriguing the Saturn system becomes. 658 00:36:45,900 --> 00:36:48,100 And now, scientists 659 00:36:48,166 --> 00:36:50,266 have an audacious new plan 660 00:36:53,567 --> 00:36:57,667 to fly a drone on one of Saturn's moons. 661 00:37:09,467 --> 00:37:12,567 Saturn is one of the most dynamic places 662 00:37:12,567 --> 00:37:15,200 in the solar system. 663 00:37:16,367 --> 00:37:18,166 We want to go back there, 664 00:37:18,266 --> 00:37:21,166 to explore its moons up close 665 00:37:21,166 --> 00:37:24,400 and hunt directly for Life 2.0. 666 00:37:26,967 --> 00:37:29,200 For so long, we've been emphasizing that to have 667 00:37:29,266 --> 00:37:30,351 a habitable planet, 668 00:37:30,351 --> 00:37:30,467 a habitable planet, 669 00:37:30,500 --> 00:37:32,600 you have to be warm, you have to be close to your star. 670 00:37:33,867 --> 00:37:36,100 In fact, the most likely chance we have to find 671 00:37:36,166 --> 00:37:39,567 life maybe way in the outer solar system in Saturn's moons. 672 00:37:40,600 --> 00:37:43,266 But we won't know for sure until we send 673 00:37:43,367 --> 00:37:45,667 another mission there, specifically to look for life. 674 00:37:47,467 --> 00:37:49,300 ROWE: The Huygens Probe gave us 675 00:37:49,367 --> 00:37:52,000 a tantalizing glimpse of Titan's surface, 676 00:37:56,000 --> 00:37:59,066 but it wasn't equipped to search for life. 677 00:38:00,867 --> 00:38:05,300 Now, scientists are developing Dragonfly, 678 00:38:05,367 --> 00:38:10,000 a space helicopter that can search for life. 679 00:38:12,100 --> 00:38:14,200 Dragonfly is an amazing mission. 680 00:38:14,266 --> 00:38:16,367 We're sending this to Titan to better 681 00:38:16,467 --> 00:38:19,166 understand how life might arise in a very different 682 00:38:19,266 --> 00:38:20,200 context than Earth. 683 00:38:22,767 --> 00:38:24,667 One thing we know absolutely for certain 684 00:38:24,767 --> 00:38:28,367 is that Titan has interesting, complex chemistry. 685 00:38:28,467 --> 00:38:29,667 The question now is, 686 00:38:29,767 --> 00:38:30,351 does that chemistry actually turn into biology? 687 00:38:30,351 --> 00:38:33,000 does that chemistry actually turn into biology? 688 00:38:36,567 --> 00:38:40,367 The million-dollar question, is this a living world? 689 00:38:47,300 --> 00:38:50,667 ROWE: April 2021. 690 00:38:53,000 --> 00:38:56,467 We test the concept of a space helicopter. 691 00:39:01,100 --> 00:39:04,000 Ingenuity making the first remote flight on 692 00:39:04,066 --> 00:39:08,300 another world launches into the thin Martian atmosphere. 693 00:39:10,266 --> 00:39:12,367 Mars is a really difficult place to fly, 694 00:39:12,467 --> 00:39:16,266 because the atmosphere is 100 times thinner than Earth's. 695 00:39:16,367 --> 00:39:18,600 And remember, it's the atmosphere that provides 696 00:39:18,667 --> 00:39:21,767 the support and the lift for a helicopter to fly. 697 00:39:21,867 --> 00:39:23,266 So in order for Ingenuity to fly, 698 00:39:23,266 --> 00:39:25,500 it had to spin very fast in order 699 00:39:25,567 --> 00:39:27,000 to even get itself off the ground. 700 00:39:31,667 --> 00:39:34,667 ROWE: Fortunately, Titan's thick atmosphere 701 00:39:34,767 --> 00:39:37,166 is much more helicopter friendly. 702 00:39:39,667 --> 00:39:42,500 The contrast between Ingenuity and the Dragonfly mission 703 00:39:42,567 --> 00:39:43,467 is really funny, 704 00:39:43,467 --> 00:39:46,400 because Mars has almost no atmosphere, 705 00:39:46,467 --> 00:39:48,900 less than 1 percent the atmospheric pressure of Earth. 706 00:39:49,000 --> 00:39:52,166 On Titan, you have exactly the opposite. 707 00:39:52,166 --> 00:39:54,266 The air pressure near the surface of Titan can be 708 00:39:54,266 --> 00:39:56,867 four times as much as the air pressure on Earth. 709 00:39:56,867 --> 00:39:59,600 So for a helicopter or something like a drone, 710 00:39:59,667 --> 00:40:00,351 something like an octocopter, 711 00:40:00,351 --> 00:40:00,800 something like an octocopter, 712 00:40:00,867 --> 00:40:04,100 the lower the gravity is and the denser the atmosphere, 713 00:40:04,166 --> 00:40:05,367 the better you can fly. 714 00:40:06,200 --> 00:40:09,166 LANZA: So Titan just begs to be explored, because you get 715 00:40:09,166 --> 00:40:11,100 a lot of lift, and you can actually carry heavy 716 00:40:11,166 --> 00:40:12,166 instruments with you. 717 00:40:13,500 --> 00:40:16,100 It allows you to fly through the atmosphere, 718 00:40:16,166 --> 00:40:19,367 collect samples, and determine what the prebiotic chemistry 719 00:40:19,367 --> 00:40:20,467 is on that moon. 720 00:40:22,467 --> 00:40:25,066 If ever there was a world built for flying drones, 721 00:40:25,066 --> 00:40:27,100 it's Titan. 722 00:40:27,166 --> 00:40:30,351 ROWE: Dragonfly is scheduled to launch in 2027, 723 00:40:30,351 --> 00:40:31,066 ROWE: Dragonfly is scheduled to launch in 2027, 724 00:40:34,000 --> 00:40:36,767 arriving at Titan around seven years later, 725 00:40:36,867 --> 00:40:41,100 completing the journey of moon discovery that began 726 00:40:41,166 --> 00:40:43,567 with Voyager and Cassini. 727 00:40:46,066 --> 00:40:47,767 DURDA: We completely transformed 728 00:40:47,767 --> 00:40:51,166 our picture of the Saturn system, the rings and the moons. 729 00:40:51,166 --> 00:40:52,867 It's a far more complex 730 00:40:52,867 --> 00:40:55,166 environment than we ever dreamed possible. 731 00:40:55,166 --> 00:40:56,700 The moons have come alive, right? 732 00:40:56,767 --> 00:40:59,867 They're not boring, dead ice balls, and it just 733 00:40:59,967 --> 00:41:00,351 begs generation after generation of spacecraft follow up. 734 00:41:00,351 --> 00:41:02,166 begs generation after generation of spacecraft follow up. 735 00:41:05,300 --> 00:41:06,767 ROWE: We're only just beginning to 736 00:41:06,767 --> 00:41:09,667 unravel the secrets of Saturn's moons. 737 00:41:12,100 --> 00:41:16,367 And with more than 80 to explore, the Saturn system is 738 00:41:16,467 --> 00:41:19,000 a gift that'll keep on giving. 739 00:41:21,900 --> 00:41:24,567 Saturn was the very first thing I ever 740 00:41:24,667 --> 00:41:26,567 saw through a telescope when I was a kid. 741 00:41:26,567 --> 00:41:30,351 And here I am -- clearly, I was inspired by Saturn, 742 00:41:30,351 --> 00:41:30,467 And here I am -- clearly, I was inspired by Saturn, 743 00:41:30,567 --> 00:41:32,400 by its beauty. 744 00:41:32,467 --> 00:41:34,767 THALLER: Saturn has always been my favorite planet. 745 00:41:34,767 --> 00:41:36,100 Everything you want 746 00:41:36,166 --> 00:41:38,967 is there -- violence, colliding moons, 747 00:41:38,967 --> 00:41:42,500 how new rings form, new moons form over time. 748 00:41:43,867 --> 00:41:45,567 PLAIT: And there might be life there. 749 00:41:45,567 --> 00:41:49,000 There might be life in more than one place there. 750 00:41:49,066 --> 00:41:53,000 One destination, one planetary zip code, gives you all of that. 751 00:41:53,066 --> 00:41:54,500 I say go back to Saturn.