1 00:00:06,360 --> 00:00:10,240 The landscapes of Earth have been shaped by volcanoes. 2 00:00:13,360 --> 00:00:16,800 We've long been in awe of their destructive beauty. 3 00:00:18,200 --> 00:00:23,880 But only recently have we discovered that volcanism exists beyond Earth. 4 00:00:27,360 --> 00:00:31,640 The planets and moons of the solar system have volcanoes that are even 5 00:00:31,640 --> 00:00:35,080 more extraordinary than those on our home planet. 6 00:00:36,760 --> 00:00:40,080 Rivers of lava once raced across our moon. 7 00:00:40,080 --> 00:00:43,880 It's an amazing thought that you could have been standing on Earth 8 00:00:43,880 --> 00:00:46,920 and looked up at the moon, and seen these massive eruptions happening. 9 00:00:50,280 --> 00:00:53,160 The largest volcano of the solar system, 10 00:00:53,160 --> 00:00:56,960 three times the height of Everest, is on Mars. 11 00:00:59,080 --> 00:01:03,120 The most violent volcano is on a moon of Jupiter. 12 00:01:06,480 --> 00:01:12,880 Huge, icy geysers fountain out into space from a moon orbiting Saturn. 13 00:01:12,880 --> 00:01:16,760 We have not closed the book on volcanism across the solar system by any means. 14 00:01:18,760 --> 00:01:23,000 But what's most remarkable is what volcanic activity elsewhere in 15 00:01:23,000 --> 00:01:27,480 the solar system has told scientists about our own planet, Earth. 16 00:01:31,120 --> 00:01:34,640 What the Earth was like at its birth, 17 00:01:34,640 --> 00:01:37,640 why we have the geology and the atmosphere we do. 18 00:01:40,000 --> 00:01:44,440 And even how life on Earth, and possibly elsewhere, originated. 19 00:01:58,360 --> 00:02:00,800 Way back in the ninth century AD, 20 00:02:00,800 --> 00:02:03,520 a band of Vikings discovered Iceland. 21 00:02:05,080 --> 00:02:08,120 They experienced volcanic eruptions for the first time. 22 00:02:13,000 --> 00:02:15,000 To explain their devastation, 23 00:02:15,000 --> 00:02:19,840 they evoked the terrible wrath of gods such as Surtr, the fire giant. 24 00:02:21,120 --> 00:02:25,640 A Viking poet wrote, "In the beginning, all was cold and grim. 25 00:02:26,800 --> 00:02:29,640 "Then came Surtr with a crashing noise. 26 00:02:32,280 --> 00:02:36,240 "Bright and burning, he bore a flaming sword." 27 00:02:44,280 --> 00:02:48,280 A millennium later, and a team of international scientists has also 28 00:02:48,280 --> 00:02:51,160 travelled to the land of fire and ice. 29 00:02:58,000 --> 00:03:00,720 This small country has more types of 30 00:03:00,720 --> 00:03:04,240 volcanoes and geological wonders packed into it 31 00:03:04,240 --> 00:03:05,840 than anywhere else in the world. 32 00:03:11,280 --> 00:03:15,360 For the team, it allows them to compare the volcanism of Earth with 33 00:03:15,360 --> 00:03:17,800 volcanoes found elsewhere in the solar system. 34 00:03:20,560 --> 00:03:23,720 You've got these continual cycles of glaciers and volcanoes. 35 00:03:23,720 --> 00:03:26,120 Absolutely brilliant. 36 00:03:26,120 --> 00:03:29,000 Yeah, you have a really diverse range of volcanic features here, 37 00:03:29,000 --> 00:03:32,000 and I think it's a good place to see the importance of volcanism. 38 00:03:37,680 --> 00:03:39,720 For geologist Jim Head, 39 00:03:39,720 --> 00:03:41,360 Iceland is a familiar landscape. 40 00:03:44,280 --> 00:03:46,040 In the 1960s, 41 00:03:46,040 --> 00:03:48,920 he was teaching the Apollo astronauts all about rocks 42 00:03:48,920 --> 00:03:50,880 before they headed off to the moon. 43 00:03:52,440 --> 00:03:53,960 We took them everywhere we could 44 00:03:53,960 --> 00:03:55,960 that would give them geological information. 45 00:03:55,960 --> 00:03:58,400 Iceland was clearly one of those. 46 00:03:58,400 --> 00:04:01,600 And I think it's completely perfect, actually, 47 00:04:01,600 --> 00:04:05,320 that we are here today in Iceland, studying the volcanoes that 48 00:04:05,320 --> 00:04:07,760 actually propelled the astronauts to go to the moon. 49 00:04:10,840 --> 00:04:16,920 Five, four, three, two, one. 50 00:04:16,920 --> 00:04:19,840 The Apollo missions weren't just about the space race. 51 00:04:21,760 --> 00:04:25,840 They were also the most ambitious geological field trips of all time. 52 00:04:28,280 --> 00:04:30,560 A key aim was to discover if volcanoes 53 00:04:30,560 --> 00:04:32,320 had helped create the moon. 54 00:04:34,160 --> 00:04:36,440 And, if so, were any still active? 55 00:04:37,800 --> 00:04:39,440 Before the Apollo programme, 56 00:04:39,440 --> 00:04:41,480 we didn't even know whether the moon had volcanism. 57 00:04:41,480 --> 00:04:43,760 For example, some people thought it was a cold moon, 58 00:04:43,760 --> 00:04:45,600 some people thought it was a warm moon, 59 00:04:45,600 --> 00:04:47,360 which had heating inside and volcanism. 60 00:04:47,360 --> 00:04:50,000 So this is a big question - was it even volcanic rock? 61 00:04:50,000 --> 00:04:52,240 2,000 feet, 2,000 feet. 62 00:04:52,240 --> 00:04:55,120 47 degrees. Roger. 63 00:04:57,520 --> 00:05:00,320 These dark-looking plains of the moon 64 00:05:00,320 --> 00:05:03,720 were particularly tantalising to scientists. 65 00:05:03,720 --> 00:05:07,280 They're called the seas, or the maria. 66 00:05:10,120 --> 00:05:12,560 Beautiful view! Isn't that something? 67 00:05:12,560 --> 00:05:14,400 Magnificent desolation. 68 00:05:14,400 --> 00:05:16,800 To find out exactly what they were, 69 00:05:16,800 --> 00:05:20,480 the first Apollo landing was to Mare Tranquillitatis, 70 00:05:20,480 --> 00:05:22,160 the Sea of Tranquillity. 71 00:05:22,160 --> 00:05:24,120 OK, ready for me to come out? 72 00:05:24,120 --> 00:05:26,560 All set. 73 00:05:26,560 --> 00:05:29,880 As the astronauts explored the dusty and rocky surface, 74 00:05:29,880 --> 00:05:34,880 they recognised basalt - the most common volcanic rock found on Earth. 75 00:05:37,520 --> 00:05:38,560 And lots of it. 76 00:05:39,600 --> 00:05:43,840 When you erupt molten rock on a moon, liquid rock on the moon, 77 00:05:43,840 --> 00:05:45,880 it actually is one sixth gravity, 78 00:05:45,880 --> 00:05:48,080 so it's much less gravity than we see on the Earth. 79 00:05:48,080 --> 00:05:51,360 It looks like a collection of just about 80 00:05:51,360 --> 00:05:54,320 every variety of rock you could find. 81 00:05:54,320 --> 00:05:59,520 If the lava is coming up from great depths, given the gravity, etc, 82 00:05:59,520 --> 00:06:01,600 you'll get a lot of lava coming up, 83 00:06:01,600 --> 00:06:03,680 commonly much more than you see on the Earth, 84 00:06:03,680 --> 00:06:05,200 and so it flows great distances, 85 00:06:05,200 --> 00:06:09,000 and so we have lava flows that go over 1000 kilometres, 86 00:06:09,000 --> 00:06:10,840 like, incredible, it would go 87 00:06:10,840 --> 00:06:13,080 halfway across the United States, no problem. 88 00:06:14,320 --> 00:06:17,320 Another mysterious feature found on the moon 89 00:06:17,320 --> 00:06:20,800 was these winding canyons, or sinuous rilles. 90 00:06:23,280 --> 00:06:28,240 These channels were up to 400 metres deep and over 100km long. 91 00:06:30,360 --> 00:06:33,840 Clues as to what created them can be found back on Earth. 92 00:06:42,040 --> 00:06:47,240 Under the south-west of Iceland are curious tunnels through solid rock. 93 00:06:47,240 --> 00:06:49,440 They appear almost man-made. 94 00:06:53,200 --> 00:06:55,960 Gro Pedersen is exploring one. 95 00:06:57,760 --> 00:06:59,600 In the depths of the tunnel, 96 00:06:59,600 --> 00:07:02,840 she hopes to find evidence of what used to flow through it. 97 00:07:04,040 --> 00:07:08,720 You can actually see how the lava has been running along the wall here, 98 00:07:08,720 --> 00:07:12,000 and you can see also that it was very hot in here, 99 00:07:12,000 --> 00:07:14,240 because some of this lava re-melted, 100 00:07:14,240 --> 00:07:17,600 and basically was dribbling down the wall. You see that here. 101 00:07:19,520 --> 00:07:24,600 It's a lava tube and, long ago, lava was surging through these tunnels. 102 00:07:26,440 --> 00:07:29,720 One of the very exciting things people found on the moon 103 00:07:29,720 --> 00:07:32,320 was these sinuous rilles and, 104 00:07:32,320 --> 00:07:35,160 of course, before people actually had been on the moon, 105 00:07:35,160 --> 00:07:39,000 they were thought to potentially be water eroded. 106 00:07:39,000 --> 00:07:41,280 But then people have gone to the moon, 107 00:07:41,280 --> 00:07:44,680 and it has been studied much more and we've found out that these 108 00:07:44,680 --> 00:07:49,360 sinuous rilles were always connected with the maria, 109 00:07:49,360 --> 00:07:52,600 the moon lava that we have up there. 110 00:07:53,840 --> 00:07:58,320 Perhaps these sinuous rilles were once enclosed lava tubes. 111 00:08:00,440 --> 00:08:03,000 So one of the things that you see here, obviously, 112 00:08:03,000 --> 00:08:05,400 is that we have what we call skylights, 113 00:08:05,400 --> 00:08:07,240 so the roof has collapsed. 114 00:08:07,240 --> 00:08:10,680 If all of the roof collapses, you will end up with a valley, 115 00:08:10,680 --> 00:08:13,120 like something you see on the moon. 116 00:08:13,120 --> 00:08:18,520 But you can also see the tubes on the moon by a string of skylights, 117 00:08:18,520 --> 00:08:22,280 just as we see here, one hole after the other, and you just follow them, 118 00:08:22,280 --> 00:08:25,920 you trace them down and you can see that these are within lava flows. 119 00:08:27,960 --> 00:08:31,120 But when did these eruptions take place? 120 00:08:31,120 --> 00:08:32,840 And why did they eventually stop? 121 00:08:37,600 --> 00:08:41,120 The answer would come in small bags of volcanic rocks 122 00:08:41,120 --> 00:08:42,800 brought home by the astronauts. 123 00:08:45,040 --> 00:08:48,280 On Earth, they could be accurately dated. 124 00:08:48,280 --> 00:08:51,240 So when the moon rocks were brought back, it's, like, unbelievable. 125 00:08:51,240 --> 00:08:55,000 OK, this we can tell, four-billion-year-old rocks. 126 00:08:55,000 --> 00:08:57,480 These are the keys to the understanding of the solar system. 127 00:08:59,840 --> 00:09:02,400 Like other planetary bodies made of rock, 128 00:09:02,400 --> 00:09:06,480 the moon was a mass of hot molten magma as it was forming. 129 00:09:06,480 --> 00:09:12,040 It's an amazing thought that you could have been standing on Earth 130 00:09:12,040 --> 00:09:14,880 and looked up at the moon and seen these massive eruptions happening. 131 00:09:17,720 --> 00:09:19,960 But all the time, it was cooling - 132 00:09:19,960 --> 00:09:24,640 being relatively small, a quarter the diameter of the Earth, 133 00:09:24,640 --> 00:09:26,400 the moon cooled down quickly. 134 00:09:28,280 --> 00:09:30,320 By three billion years ago, 135 00:09:30,320 --> 00:09:34,080 almost all the lava and interior magma had solidified 136 00:09:34,080 --> 00:09:36,360 into one big lump of cold rock. 137 00:09:37,440 --> 00:09:38,600 No more volcanoes. 138 00:09:45,760 --> 00:09:47,400 But you see the remnants of it. 139 00:09:47,400 --> 00:09:50,040 I mean, when you look at the sky and you look at the moon, 140 00:09:50,040 --> 00:09:52,760 you see the evidence of the volcanism, 141 00:09:52,760 --> 00:09:55,240 because you see the dark areas, the basalt, 142 00:09:55,240 --> 00:09:56,680 which has filled in the craters. 143 00:09:59,360 --> 00:10:02,800 Understanding how the moon lost its volcanoes 144 00:10:02,800 --> 00:10:05,800 helps explain why Earth remains so active. 145 00:10:09,320 --> 00:10:13,200 Being larger allowed the Earth to retain much of its original heat. 146 00:10:16,880 --> 00:10:21,280 And so today, our planet is a dynamic and ever-changing world, 147 00:10:21,280 --> 00:10:23,440 rather than a dead one. 148 00:10:23,440 --> 00:10:26,600 So, the discovery on the moon of lava flows 149 00:10:26,600 --> 00:10:29,560 gave us pause to think about how this worked 150 00:10:29,560 --> 00:10:30,840 on other planetary bodies. 151 00:10:30,840 --> 00:10:32,680 How does volcanism work on Mars? 152 00:10:35,520 --> 00:10:38,160 So, the lunar exploration really opened up 153 00:10:38,160 --> 00:10:40,840 a field of, really, planetary volcanology. 154 00:10:45,280 --> 00:10:47,920 Exploring our neighbour, Mars, 155 00:10:47,920 --> 00:10:50,680 also reveals secrets about Earth's geology. 156 00:10:52,920 --> 00:10:55,480 When probes first reached the red planet, 157 00:10:55,480 --> 00:10:58,680 one feature stood out above swirling sandstorms. 158 00:10:59,880 --> 00:11:02,320 The volcano Olympus Mons. 159 00:11:06,480 --> 00:11:10,400 Olympus Mons is enormous, it's about 25km high. 160 00:11:10,400 --> 00:11:14,640 On Earth, you would be looking at something ridiculously high. 161 00:11:14,640 --> 00:11:19,240 Most commercial aircraft fly 10-15 kilometres. 162 00:11:19,240 --> 00:11:22,040 So you're looking at something that is towering way above 163 00:11:22,040 --> 00:11:23,920 what commercial aircraft might fly. 164 00:11:29,720 --> 00:11:32,840 Its base covers an area the size of France. 165 00:11:34,560 --> 00:11:37,280 It's three times the height of Mount Everest. 166 00:11:39,120 --> 00:11:43,160 Making it the largest volcano ever discovered in the solar system. 167 00:11:48,640 --> 00:11:51,520 Finding out how it grew to be so colossal 168 00:11:51,520 --> 00:11:54,400 tells scientists more about the volcanoes of Earth. 169 00:12:00,400 --> 00:12:04,480 That's why three of the team have come together to study this volcano. 170 00:12:07,960 --> 00:12:12,760 Icelanders call it Skjaldbreidur, which means "broad shield", 171 00:12:12,760 --> 00:12:15,880 as side on, it's reminiscent of a Viking shield. 172 00:12:19,520 --> 00:12:23,000 Although small in stature, it's of great significance. 173 00:12:25,760 --> 00:12:29,040 This shield volcano is the one over... 174 00:12:29,040 --> 00:12:33,600 about which all the other volcanoes of this type are called, 175 00:12:33,600 --> 00:12:35,600 in the solar system and on the Earth. 176 00:12:35,600 --> 00:12:37,800 So this is the first one, in many senses, 177 00:12:37,800 --> 00:12:40,160 the first one to be named the shield. 178 00:12:42,360 --> 00:12:44,920 It's only 1,000 metres high, 179 00:12:44,920 --> 00:12:47,760 a 25th the height of Olympus Mons, 180 00:12:47,760 --> 00:12:51,840 but crucially, it's the same type of shield volcano. 181 00:12:54,600 --> 00:12:56,360 At the summit is the crater. 182 00:12:58,120 --> 00:12:59,760 Wow, now you can see the crater. 183 00:12:59,760 --> 00:13:02,560 Yeah. Fantastic. Wow! 184 00:13:02,560 --> 00:13:04,360 That's very nice. 185 00:13:04,360 --> 00:13:08,040 I mean, you could even have come skiing up here. Oh, wow. Yeah. 186 00:13:08,040 --> 00:13:11,120 Then we can imagine, like, a lava lake. 187 00:13:11,120 --> 00:13:12,720 Yeah, just round the top. 188 00:13:12,720 --> 00:13:16,000 Yeah. Dribbling over where we are now. Yeah. 189 00:13:16,000 --> 00:13:19,240 Around the rim are mysteriously-shaped rocks. 190 00:13:21,560 --> 00:13:24,200 They look almost like fossilised snakes. 191 00:13:27,120 --> 00:13:30,360 Yet they give a hint how this type of volcano forms, 192 00:13:30,360 --> 00:13:33,360 and what gives it the distinctive shield shape. 193 00:13:35,520 --> 00:13:38,560 This is a type of lava we call entrail, 194 00:13:38,560 --> 00:13:42,680 and it's a bit like the entrails from the inside of a human body 195 00:13:42,680 --> 00:13:44,440 or any animal body. 196 00:13:44,440 --> 00:13:46,280 They're characteristically quite thin. 197 00:13:46,280 --> 00:13:48,280 I mean, you can see from the shape of my hand, 198 00:13:48,280 --> 00:13:49,640 it's a couple of hand widths. 199 00:13:49,640 --> 00:13:52,560 Shield volcanoes comprise lavas that are very runny, 200 00:13:52,560 --> 00:13:54,200 because the shapes of them, 201 00:13:54,200 --> 00:13:56,440 this broad shield shape, tells us it has to have been. 202 00:13:56,440 --> 00:14:01,080 And we have the evidence in front of our eyes of these small tubes, 203 00:14:01,080 --> 00:14:03,720 these entrails running down the sides of the volcano, 204 00:14:03,720 --> 00:14:06,160 telling us that indeed, it had to be very runny. 205 00:14:11,800 --> 00:14:14,280 This fast-flowing lava creates 206 00:14:14,280 --> 00:14:16,720 the gentle slopes of all shield volcanoes, 207 00:14:16,720 --> 00:14:20,200 including the largest one of all, on Mars. 208 00:14:26,720 --> 00:14:29,120 But while shield volcanoes on Iceland 209 00:14:29,120 --> 00:14:31,560 have just one crater at the summit, 210 00:14:31,560 --> 00:14:35,080 Olympus Mons has six overlapping craters. 211 00:14:37,840 --> 00:14:41,640 That's the key. We actually can use what we see in Iceland to say, 212 00:14:41,640 --> 00:14:44,600 what we see in Mars is similar, but also different. 213 00:14:44,600 --> 00:14:49,240 It has to be much, much longer lived with multiple phases of eruptions 214 00:14:49,240 --> 00:14:52,760 to produce these multiple summit craters we see on Olympus Mons. 215 00:14:57,280 --> 00:15:00,960 When this behemoth erupted, Mars shuddered. 216 00:15:07,840 --> 00:15:11,640 Rivers of lava swept down the massive flanks of the volcano. 217 00:15:16,120 --> 00:15:18,720 But Earth is twice the size of Mars, 218 00:15:18,720 --> 00:15:22,920 so why don't we have volcanoes as enormous as Olympus Mons? 219 00:15:28,160 --> 00:15:30,920 It's all to do with plate tectonics. 220 00:15:33,320 --> 00:15:36,280 Earth is made up of seven huge plates 221 00:15:36,280 --> 00:15:38,320 drifting above a sea of magma. 222 00:15:42,920 --> 00:15:46,920 The circulation of magma recycles rocks and gases, 223 00:15:46,920 --> 00:15:49,760 bringing them to the surface and then back down again. 224 00:15:54,680 --> 00:15:59,120 Iceland is the perfect place to witness plate tectonics in action. 225 00:16:00,960 --> 00:16:04,600 This rift is where the North American plate, to the left, 226 00:16:04,600 --> 00:16:07,640 divides from its Eurasian cousin, to the right. 227 00:16:10,680 --> 00:16:14,760 The rift is widening rapidly, at over two centimetres a year. 228 00:16:18,200 --> 00:16:21,960 We've got the best evidence of plate tectonics we can find here. 229 00:16:21,960 --> 00:16:25,520 You can see the tension of the plates moving apart from each other. 230 00:16:25,520 --> 00:16:29,080 Yeah, this is the only planet that we know that's got plate tectonics. 231 00:16:31,800 --> 00:16:36,840 Mars, like all other planets we know of, has no active plate tectonics. 232 00:16:41,800 --> 00:16:46,280 The entire crust of Mars remains locked in place, 233 00:16:46,280 --> 00:16:48,280 with repercussions for its volcanoes. 234 00:16:55,000 --> 00:16:57,960 Any upwelling magma continually breaks through 235 00:16:57,960 --> 00:16:59,440 at one fixed location. 236 00:17:02,280 --> 00:17:05,800 On Mars, it's just centred, the same spot, for so long, 237 00:17:05,800 --> 00:17:07,400 building up a huge volcano. 238 00:17:07,400 --> 00:17:13,640 So it's a very focused eruption of magma for billions of years. 239 00:17:13,640 --> 00:17:16,960 And what happens is you just end up with a huge volcano, 240 00:17:16,960 --> 00:17:18,520 the biggest in the solar system. 241 00:17:27,760 --> 00:17:31,120 While Mars is no longer volcanically active, 242 00:17:31,120 --> 00:17:36,000 it does share an important feature with Earth - the polar ice caps. 243 00:17:38,480 --> 00:17:40,680 The story of these ice caps 244 00:17:40,680 --> 00:17:43,720 has been revealed through unusually shaped volcanoes. 245 00:17:45,880 --> 00:17:49,440 They have steep sides and a flat top like a table. 246 00:17:51,640 --> 00:17:55,880 Scientists now believe they might have been formed when volcanoes 247 00:17:55,880 --> 00:17:58,560 exploded through an ancient ice sheet. 248 00:18:04,440 --> 00:18:08,320 To understand how ice can change the behaviour of lava, 249 00:18:08,320 --> 00:18:11,480 scientists are carrying out an extreme experiment. 250 00:18:15,720 --> 00:18:20,880 For this, Ingo Sonder and Tracy Gregg need to make their own lava... 251 00:18:24,040 --> 00:18:27,600 ..out of 50kg of basalt rock. 252 00:18:27,600 --> 00:18:29,440 We're turning it to its lava state, 253 00:18:29,440 --> 00:18:32,080 and the students have built a little ramp 254 00:18:32,080 --> 00:18:35,240 that the lava will pour down and pool at the end. 255 00:18:35,240 --> 00:18:39,200 And at the end of this lava stream, there will be a little pond of ice. 256 00:18:39,200 --> 00:18:42,040 So the lava's going to flow over the ice. 257 00:18:42,040 --> 00:18:43,760 We know this has happened on Earth. 258 00:18:43,760 --> 00:18:46,480 We think it's happened on Mars in the past. 259 00:18:46,480 --> 00:18:47,800 So we'll see what happens. 260 00:18:51,560 --> 00:18:55,640 The electrical furnace is running at 80,000 watts. 261 00:18:57,680 --> 00:19:03,080 By now, the molten rock is over 1,200 degrees Celsius. 262 00:19:03,080 --> 00:19:04,560 It's ready for the big pour. 263 00:19:12,200 --> 00:19:14,840 Look where it hits the ice, it's boiling! 264 00:19:14,840 --> 00:19:17,760 Because the ice is melting and it's flashing to steam. 265 00:19:17,760 --> 00:19:21,960 And it's creating all those bubbles there on the lava. 266 00:19:21,960 --> 00:19:24,040 Whoa! And now, this is what happens... 267 00:19:26,320 --> 00:19:29,760 ..when the lava melts the ice and there's enough water, 268 00:19:29,760 --> 00:19:31,760 we're getting some little steam explosions. 269 00:19:34,080 --> 00:19:37,080 Right, there's no more lava coming out of the furnace. 270 00:19:37,080 --> 00:19:39,680 But underneath that black crust, it's still liquid, 271 00:19:39,680 --> 00:19:42,080 it's slowly flowing down. 272 00:19:42,080 --> 00:19:45,400 And you can see where it's ponded over the ice, 273 00:19:45,400 --> 00:19:49,760 there's some heaving going on as gas is trying to escape. 274 00:19:49,760 --> 00:19:53,240 The experiment lets Tracy identify 275 00:19:53,240 --> 00:19:57,960 key features as molten rock interacts with ice. 276 00:19:57,960 --> 00:20:01,920 When the lava hit the ice, a couple of things happened really fast. 277 00:20:01,920 --> 00:20:03,680 The lava started to bubble, 278 00:20:03,680 --> 00:20:06,560 as the ice melted and then flashed to steam. 279 00:20:06,560 --> 00:20:09,160 And then, as more melt occurred, 280 00:20:09,160 --> 00:20:11,080 there were actually puddles of water 281 00:20:11,080 --> 00:20:13,080 that started to boil and spatter just like 282 00:20:13,080 --> 00:20:15,240 on your stove, right, the water spattering. 283 00:20:15,240 --> 00:20:19,640 Where the ice wasn't, we have nice, neat, organised flows, 284 00:20:19,640 --> 00:20:21,360 folds in the lava. 285 00:20:21,360 --> 00:20:22,960 And right where the ice starts, 286 00:20:22,960 --> 00:20:25,200 we get these bigger bubbles on the surface. 287 00:20:25,200 --> 00:20:27,520 Look, that one's broken open, you can see inside. 288 00:20:27,520 --> 00:20:30,080 That's the kind of thing we could look for on Mars. 289 00:20:30,080 --> 00:20:33,920 Right? To see if there was any lava-ice interactions on Mars. 290 00:20:33,920 --> 00:20:35,560 Can you hear it? 291 00:20:35,560 --> 00:20:37,400 As the lava cools, it contracts, 292 00:20:37,400 --> 00:20:40,400 and it makes little pops like breakfast cereal. 293 00:20:40,400 --> 00:20:41,880 Pop, pop. 294 00:20:41,880 --> 00:20:42,880 Yep. 295 00:20:45,560 --> 00:20:47,120 That's amazing. 296 00:20:51,520 --> 00:20:54,240 The artificial volcano confirms that 297 00:20:54,240 --> 00:20:58,040 lava behaves very differently when it meets ice. 298 00:21:00,360 --> 00:21:02,680 But what happens out in the real world? 299 00:21:09,280 --> 00:21:14,760 One of the most distinctive types of volcano in Iceland is called a tuya. 300 00:21:16,520 --> 00:21:19,640 The team believe they can help explain the mountains 301 00:21:19,640 --> 00:21:21,480 with a similar shape on Mars. 302 00:21:23,720 --> 00:21:26,360 Wherever we see volcanoes that look like this, 303 00:21:26,360 --> 00:21:28,880 on Iceland we know that the ice has been there, 304 00:21:28,880 --> 00:21:31,560 and if we see the same sorts of volcanoes on Mars, 305 00:21:31,560 --> 00:21:34,680 we've got a good idea or a very good idea that there was ice present. 306 00:21:36,520 --> 00:21:39,880 There are two polar ice caps on Mars today. 307 00:21:43,400 --> 00:21:45,040 But millions of years ago, 308 00:21:45,040 --> 00:21:46,880 they were far more extensive. 309 00:21:50,120 --> 00:21:53,080 Mapping the tuyas on Mars reveals 310 00:21:53,080 --> 00:21:56,600 the coverage and depth of the ancient ice sheets. 311 00:22:01,680 --> 00:22:04,720 That's amazing, that you can actually say something about 312 00:22:04,720 --> 00:22:07,600 ice thickness in the past on a different planet, 313 00:22:07,600 --> 00:22:09,440 after the ice has gone. 314 00:22:09,440 --> 00:22:12,280 Which may have been three and a half billion years ago, as well. 315 00:22:12,280 --> 00:22:15,720 Yeah. It's similar processes on different planets but it's yielding 316 00:22:15,720 --> 00:22:18,520 valuable information. It's telling us about what most planets... 317 00:22:18,520 --> 00:22:21,320 how they were evolving and what was happening at the time. 318 00:22:23,400 --> 00:22:28,840 Today, Mars and our own moon are cold and desolate planetary bodies. 319 00:22:30,760 --> 00:22:32,360 Geologically inert. 320 00:22:35,720 --> 00:22:39,080 While Earth has retained active volcanoes. 321 00:22:41,440 --> 00:22:43,520 To understand how we got here, 322 00:22:43,520 --> 00:22:47,640 we need to find out what Earth was like four billion years ago. 323 00:22:51,840 --> 00:22:55,920 And scientists think they've found the perfect place to look, 324 00:22:55,920 --> 00:22:58,760 a moon far out in the solar system. 325 00:23:11,400 --> 00:23:14,400 Ashley Davies is a top planetary volcanologist. 326 00:23:16,640 --> 00:23:20,480 He's fascinated by a moon of Jupiter called Io. 327 00:23:24,040 --> 00:23:28,440 One of the most important images that's ever been collected by any 328 00:23:28,440 --> 00:23:33,160 spacecraft was obtained by Voyager at Io. 329 00:23:36,360 --> 00:23:41,440 The image revealed this crescent rising above Io's surface, 330 00:23:41,440 --> 00:23:43,480 no-one knew quite what this was. 331 00:23:43,480 --> 00:23:48,520 Could it be another moon behind Io, or some artefact in the image? 332 00:23:48,520 --> 00:23:54,200 And then it was realised that this was actually a huge volcanic plume 333 00:23:54,200 --> 00:23:56,760 rising up from Io's surface. 334 00:23:59,360 --> 00:24:01,720 For me, this was 335 00:24:01,720 --> 00:24:05,400 an image that I think shaped the rest of my life, 336 00:24:05,400 --> 00:24:07,240 because from this point... 337 00:24:07,240 --> 00:24:11,720 I was a schoolboy and I realised this was a huge step in an unknown 338 00:24:11,720 --> 00:24:15,880 direction for astronomy and planetary science. 339 00:24:17,640 --> 00:24:22,280 And in a way, this actually put me on the path through school and into 340 00:24:22,280 --> 00:24:25,120 scientific research, and finally brought me here to study 341 00:24:25,120 --> 00:24:27,280 this absolutely astonishing little world. 342 00:24:31,480 --> 00:24:36,920 We now know that crammed into Io, the same size as our moon, 343 00:24:36,920 --> 00:24:39,920 are over 400 active volcanoes. 344 00:24:42,160 --> 00:24:46,040 Compare this to just 60 on the whole of Earth. 345 00:24:50,280 --> 00:24:54,480 The most powerful eruption was seen at a volcano called Surtr, 346 00:24:54,480 --> 00:24:59,240 which is actually named after an Icelandic giant. 347 00:24:59,240 --> 00:25:03,720 A fissure opened up and a huge volume of lava literally gushed out 348 00:25:03,720 --> 00:25:07,880 of the ground to form large lava fountains kilometres high. 349 00:25:07,880 --> 00:25:10,600 It must have been an absolutely incredible sight to see 350 00:25:10,600 --> 00:25:13,440 if you were there to witness it, but not from too close by. 351 00:25:14,680 --> 00:25:16,480 When Surtr roars, 352 00:25:16,480 --> 00:25:22,480 it sends plumes of lava and ash over 500km into space. 353 00:25:31,320 --> 00:25:33,680 Io proved for the first time 354 00:25:33,680 --> 00:25:37,000 that Earth wasn't alone in having active volcanoes. 355 00:25:42,320 --> 00:25:44,920 And, perhaps more importantly, 356 00:25:44,920 --> 00:25:47,480 Io offered a clue as to the conditions 357 00:25:47,480 --> 00:25:49,600 that existed as the Earth formed. 358 00:25:51,640 --> 00:25:54,480 But first, scientists needed to discover 359 00:25:54,480 --> 00:25:57,680 where the heat driving Io's volcanism came from. 360 00:25:59,960 --> 00:26:02,400 The reason why Io is so active 361 00:26:02,400 --> 00:26:09,360 is it's caught in this gravitational tug-of-war between Jupiter, Io, 362 00:26:09,360 --> 00:26:11,440 Europa and Ganymede, 363 00:26:11,440 --> 00:26:14,200 and this pumps a lot of energy into the system. 364 00:26:21,280 --> 00:26:25,480 What happens to a squash ball is just like Io, 365 00:26:25,480 --> 00:26:30,640 as it's pulled between gigantic Jupiter and her other moons. 366 00:26:32,960 --> 00:26:36,880 A thermal camera reveals the temperature of the squash ball 367 00:26:36,880 --> 00:26:38,480 as the rallies progress. 368 00:26:40,120 --> 00:26:44,360 We hit the ball against the wall and it heated up. 369 00:26:46,480 --> 00:26:48,920 And it heated up because it was being compressed, 370 00:26:48,920 --> 00:26:50,520 twisted and turned. 371 00:26:51,640 --> 00:26:54,400 And Io is very much like that. 372 00:26:55,840 --> 00:27:00,360 With Io, it's being twisted and turned and squeezed by gravitational 373 00:27:00,360 --> 00:27:03,520 forces, and the gravitational forces 374 00:27:03,520 --> 00:27:07,600 cause a lot of interior heating and the heating manifests at the surface 375 00:27:07,600 --> 00:27:09,440 as huge volcanoes. 376 00:27:14,200 --> 00:27:17,120 Io heats up so much that it might erupt 377 00:27:17,120 --> 00:27:21,400 an extremely rare and hot form of lava called ultramafic. 378 00:27:25,480 --> 00:27:30,280 Ultramafic lava was abundant 4.5 billion years ago, 379 00:27:30,280 --> 00:27:33,400 when the Earth formed, 380 00:27:33,400 --> 00:27:34,640 but no longer. 381 00:27:37,280 --> 00:27:40,080 To discover this primitive lava on Io 382 00:27:40,080 --> 00:27:43,360 would offer scientists a window on the past. 383 00:27:52,640 --> 00:27:57,400 Volcanologist Rosaly Lopes does her research in Hawaii. 384 00:27:57,400 --> 00:28:02,440 We're studying volcanoes on Hawaii not because of Hawaii itself, 385 00:28:02,440 --> 00:28:07,840 but because Hawaiian volcanoes are such a good analogue, 386 00:28:07,840 --> 00:28:12,400 or a mirror if you like, for volcanoes on Jupiter's moon, Io. 387 00:28:12,400 --> 00:28:16,520 And it's really understanding the volcanoes on Io 388 00:28:16,520 --> 00:28:18,680 that we are after. 389 00:28:23,760 --> 00:28:27,640 Hawaii has more active volcanoes than anywhere on Earth. 390 00:28:29,760 --> 00:28:33,520 In fact, the islands are a chain of shield volcanoes, 391 00:28:33,520 --> 00:28:35,520 built up from the ocean floor. 392 00:28:36,760 --> 00:28:39,600 Rosaly looks for the most active lava flows. 393 00:28:41,920 --> 00:28:44,360 It's challenging, it's beautiful. 394 00:28:44,360 --> 00:28:46,800 I think a volcano in activity 395 00:28:46,800 --> 00:28:51,000 is just the most beautiful thing that anyone can see. 396 00:28:53,120 --> 00:28:58,920 Io is like Dante's Inferno, it's absolutely volcanoes everywhere. 397 00:29:01,240 --> 00:29:04,520 Sulphur everywhere, hot lavas everywhere, 398 00:29:04,520 --> 00:29:08,040 it is a volcanologist's paradise, 399 00:29:08,040 --> 00:29:11,240 but it would be absolute hell if you were actually there. 400 00:29:19,040 --> 00:29:23,280 Rosaly will measure the cooling rate of the lava here in Hawaii, 401 00:29:23,280 --> 00:29:26,080 and then apply it to the volcanoes of Io. 402 00:29:28,200 --> 00:29:30,840 In this way she hopes to find out if 403 00:29:30,840 --> 00:29:34,280 Io has the especially hot ultramafic lava. 404 00:29:36,200 --> 00:29:38,160 The team use a thermal camera. 405 00:29:39,960 --> 00:29:43,200 These should be nice images. Very nice, very nice. 406 00:29:43,200 --> 00:29:45,240 And then just really hot in the middle, 407 00:29:45,240 --> 00:29:47,400 where that's cooling so fast. 408 00:29:47,400 --> 00:29:50,040 That's beautiful, just spectacular. 409 00:29:52,280 --> 00:29:55,160 The hottest lava is the moment it emerges. 410 00:29:56,400 --> 00:29:58,960 If Jenny manages to break through the surface, 411 00:29:58,960 --> 00:30:03,120 you are going to see the hot lava spilling out. 412 00:30:03,120 --> 00:30:07,320 Oh, there we go. So that's the heart of the lava flow. 413 00:30:09,400 --> 00:30:12,400 The thermal camera reveals how quickly 414 00:30:12,400 --> 00:30:13,880 the lava cools here on Earth. 415 00:30:15,120 --> 00:30:20,000 Even on the hottest parts, it was only about 910 Celsius. 416 00:30:20,000 --> 00:30:24,640 The melting temperature of this rock is about 1,200 Celsius, 417 00:30:24,640 --> 00:30:30,520 so that tells you that even in those red hot parts, the lava has cooled, 418 00:30:30,520 --> 00:30:34,200 you know, more than a couple of hundred Celsius, 419 00:30:34,200 --> 00:30:36,480 so lava cools very, very fast. 420 00:30:39,000 --> 00:30:42,120 Rosaly suspects this also happens on Io. 421 00:30:44,760 --> 00:30:49,360 Space probes to Io have revealed that the surface hot spots 422 00:30:49,360 --> 00:30:50,760 are 1,200 degrees. 423 00:30:52,480 --> 00:30:55,920 When we get measurements of the temperatures on Io, 424 00:30:55,920 --> 00:30:58,800 we know that those temperatures likely have cooled 425 00:30:58,800 --> 00:31:02,200 by at least a couple of hundred degrees Celsius. 426 00:31:04,040 --> 00:31:08,760 It means the temperature of the lava just below the surface of Io 427 00:31:08,760 --> 00:31:11,400 must be around 1,400 degrees. 428 00:31:14,080 --> 00:31:17,840 Lava this hot is strong evidence it's ultramafic. 429 00:31:24,960 --> 00:31:26,840 An exciting finding, 430 00:31:26,840 --> 00:31:30,840 as it means Io could hold the secrets of the Earth's past. 431 00:31:34,760 --> 00:31:37,160 Io is a model of the early Earth, 432 00:31:37,160 --> 00:31:42,640 because the lavas on Io may be of the ultramafic type, 433 00:31:42,640 --> 00:31:45,280 and those are lavas that are very hot, 434 00:31:45,280 --> 00:31:49,000 very primitive and they erupted on Earth billions of years ago. 435 00:31:54,000 --> 00:31:56,040 The more we research Io, 436 00:31:56,040 --> 00:32:00,280 the more we find out what the Earth was like as it was forming - 437 00:32:00,280 --> 00:32:03,280 the type of lava flows, the form of volcanism, 438 00:32:03,280 --> 00:32:05,720 the tremendous density of volcanoes. 439 00:32:08,640 --> 00:32:10,000 By studying Io, 440 00:32:10,000 --> 00:32:14,320 we look at volcanism on a scale that has not happened on Earth 441 00:32:14,320 --> 00:32:15,800 for billions of years. 442 00:32:16,800 --> 00:32:20,200 So, Io reveals what primitive Earth was like... 443 00:32:23,040 --> 00:32:25,280 ..Dante's volcanic Inferno. 444 00:32:35,000 --> 00:32:37,200 Volcanoes have played a key role 445 00:32:37,200 --> 00:32:40,600 in the evolution of planets in another way - 446 00:32:40,600 --> 00:32:42,160 by creating their atmosphere. 447 00:32:44,600 --> 00:32:46,920 And the best way of looking at that 448 00:32:46,920 --> 00:32:50,840 is the most extreme example of all - Venus. 449 00:32:52,120 --> 00:32:54,320 The planet Venus is a very hot climate. 450 00:32:54,320 --> 00:32:56,880 The atmosphere is dense 451 00:32:56,880 --> 00:32:59,840 and its primary constituent is carbon dioxide. 452 00:33:04,800 --> 00:33:08,680 It has the densest atmosphere anywhere in the solar system. 453 00:33:12,840 --> 00:33:14,880 And one of the hottest. 454 00:33:17,240 --> 00:33:21,800 This extreme atmosphere was almost certainly created by volcanism. 455 00:33:23,800 --> 00:33:25,600 It pumps out these gases. 456 00:33:27,640 --> 00:33:29,520 But the thick atmosphere 457 00:33:29,520 --> 00:33:33,240 also hid what was happening on the planet's surface. 458 00:33:39,240 --> 00:33:42,080 So, we really didn't have much of an idea of what was beneath those 459 00:33:42,080 --> 00:33:43,800 clouds, and it was a bit of guesswork. 460 00:33:43,800 --> 00:33:46,320 You know, you send the probes down, are they going to survive, 461 00:33:46,320 --> 00:33:49,800 what's the atmospheric pressure going to be, how hot is it going to be? 462 00:33:50,800 --> 00:33:53,240 So when the first probes went down onto the surface, 463 00:33:53,240 --> 00:33:54,920 they didn't last very long. 464 00:34:01,240 --> 00:34:04,640 But a new generation of probes, armed with radar, 465 00:34:04,640 --> 00:34:07,480 eventually peered through the veil of Venus 466 00:34:07,480 --> 00:34:09,760 to reveal an astonishing landscape. 467 00:34:12,760 --> 00:34:14,800 More volcanic cones and craters 468 00:34:14,800 --> 00:34:17,440 than any other planet of the solar system. 469 00:34:19,640 --> 00:34:21,720 When they eventually got 470 00:34:21,720 --> 00:34:24,320 the correct sort of radar going through the clouds 471 00:34:24,320 --> 00:34:26,960 and seeing what was going on, then it got really exciting. 472 00:34:26,960 --> 00:34:30,360 Then we thought, "This is a planet with a lot of volcanoes on it, 473 00:34:30,360 --> 00:34:31,840 "and even more fascinating, 474 00:34:31,840 --> 00:34:33,920 "volcanoes unlike any we see on the Earth." 475 00:34:35,280 --> 00:34:37,920 These volcanoes are unique to Venus. 476 00:34:40,200 --> 00:34:43,200 Some are 65km across, 477 00:34:43,200 --> 00:34:46,480 surrounded by cliffs over 1000 metres high. 478 00:34:49,120 --> 00:34:53,560 Almost perfectly circular, they're known as pancake domes. 479 00:34:54,480 --> 00:34:56,360 The pancake domes were very much a mystery. 480 00:34:56,360 --> 00:35:00,560 What we saw on the surface of Venus were just large, basically pancakes, 481 00:35:00,560 --> 00:35:02,880 stuck on top of these flat plains. 482 00:35:02,880 --> 00:35:04,560 It was just, "What are these things?" 483 00:35:04,560 --> 00:35:07,760 They are so untypical of what else we saw on Venus, 484 00:35:07,760 --> 00:35:11,040 and that's when people started thinking, "Well, the sort of lava flows on Earth, 485 00:35:11,040 --> 00:35:13,280 "where we actually have these same features, 486 00:35:13,280 --> 00:35:15,920 "and these lava flows we have in places like Iceland." 487 00:35:19,360 --> 00:35:23,240 What could pancake domes tell us about volcanism on Earth? 488 00:35:26,200 --> 00:35:30,960 These are the extraordinary lava flows at Torfajokull in Iceland. 489 00:35:34,600 --> 00:35:36,440 They end in cliffs, 490 00:35:36,440 --> 00:35:40,320 similar to the pancake domes, but on a smaller scale. 491 00:35:40,320 --> 00:35:44,000 It's like walking across a mossy Venus, isn't it? 492 00:35:45,800 --> 00:35:48,240 Dave and Ian have come here to discover 493 00:35:48,240 --> 00:35:51,680 more about the lava that created these landscapes. 494 00:35:52,800 --> 00:35:55,920 One of the things I want to do quite soon 495 00:35:55,920 --> 00:36:00,920 is to find a nice piece of this lovely lava to hit with my hammer, 496 00:36:00,920 --> 00:36:03,840 so we can have a good look at what's inside it. 497 00:36:09,320 --> 00:36:10,960 I'm going to hit this bit here, OK? 498 00:36:18,840 --> 00:36:20,840 It makes a lovely noise as well, doesn't it? 499 00:36:20,840 --> 00:36:23,200 It does indeed. And a nice smell, actually. 500 00:36:23,200 --> 00:36:25,800 I love the smell of rhyolite in the afternoon! 501 00:36:25,800 --> 00:36:30,480 So, you can see lots of little white crystals actually aligned in that 502 00:36:30,480 --> 00:36:31,880 particular direction. 503 00:36:31,880 --> 00:36:34,520 These only line up when you've got something that's very, 504 00:36:34,520 --> 00:36:36,760 very sticky, and forcing crystals 505 00:36:36,760 --> 00:36:39,600 to actually line up in the one direction. 506 00:36:39,600 --> 00:36:41,840 And in this case, I know these crystals tell me 507 00:36:41,840 --> 00:36:43,640 this rock is very high in silica. 508 00:36:46,720 --> 00:36:51,200 Silica thickens the lava, and Dave and Ian believe this was what 509 00:36:51,200 --> 00:36:53,960 created the pancake domes of Venus. 510 00:36:56,360 --> 00:36:58,800 It behaves differently from thin lava. 511 00:37:02,400 --> 00:37:05,800 The most common type of lava we have in the solar system is basalt, 512 00:37:05,800 --> 00:37:09,080 and the entire surface of the moon and the entire surface of Mars 513 00:37:09,080 --> 00:37:10,680 is covered in basalt. 514 00:37:10,680 --> 00:37:13,960 I'm going to illustrate that by using oil. 515 00:37:17,800 --> 00:37:20,240 It spreads out where it wants to go, 516 00:37:20,240 --> 00:37:23,440 beautiful little fingers coming down thin and fast. 517 00:37:24,720 --> 00:37:29,400 However, in some parts of the Earth and these pancake domes on Venus, 518 00:37:29,400 --> 00:37:32,320 which is very exciting, we have this much thicker lava flow and I'm going 519 00:37:32,320 --> 00:37:35,760 to illustrate that with treacle, and let's see how that goes. 520 00:37:39,480 --> 00:37:41,080 Beautiful. 521 00:37:41,080 --> 00:37:43,840 See how slow and how thick it is? 522 00:37:43,840 --> 00:37:45,480 That's exactly what we expect to see 523 00:37:45,480 --> 00:37:47,400 when we have these thicker lava flows 524 00:37:47,400 --> 00:37:49,280 that are much richer in silica. 525 00:37:49,280 --> 00:37:50,800 The forward edge is very thick 526 00:37:50,800 --> 00:37:52,920 because everything is getting compressed 527 00:37:52,920 --> 00:37:55,160 and squeezed forward at that forward edge. 528 00:37:55,160 --> 00:37:57,440 If this was a real lava flow, 529 00:37:57,440 --> 00:38:01,240 you would actually see blocks falling off the front of it. 530 00:38:01,240 --> 00:38:03,040 On this sort of surface that's sloping, 531 00:38:03,040 --> 00:38:05,240 you will see something that looks a little elongate, 532 00:38:05,240 --> 00:38:08,360 as we can see here. But if you pour it onto a perfectly flat surface, 533 00:38:08,360 --> 00:38:11,240 you will get, basically, a pancake, a circular pancake. 534 00:38:22,600 --> 00:38:24,200 It's utterly fascinating, 535 00:38:24,200 --> 00:38:26,960 because until recently, I thought these planets 536 00:38:26,960 --> 00:38:29,120 were very, very boring, just had basalt, 537 00:38:29,120 --> 00:38:32,560 but having found this particular type of rock on Venus, 538 00:38:32,560 --> 00:38:33,880 it excites me personally, 539 00:38:33,880 --> 00:38:36,160 because I've been working on them for 30 years. 540 00:38:37,640 --> 00:38:40,880 But are any volcanoes on Venus still active? 541 00:38:42,960 --> 00:38:47,120 Some exciting circumstantial evidence has recently been discovered. 542 00:38:48,400 --> 00:38:53,520 They found that Venus had hot spots within it that occurred over quite 543 00:38:53,520 --> 00:38:57,000 a short time interval, and this was the first evidence we had of perhaps 544 00:38:57,000 --> 00:38:59,200 something active on Venus. 545 00:39:02,400 --> 00:39:08,240 This image of the planet's surface was taken on June 22nd 2008. 546 00:39:08,240 --> 00:39:10,760 The hottest parts are yellow and red. 547 00:39:12,080 --> 00:39:14,800 And the same area, just two days later. 548 00:39:15,960 --> 00:39:22,240 The best explanation of these new hot spots is erupting lava. 549 00:39:22,240 --> 00:39:26,400 We're also seeing unexplained spikes of sulphur in the atmosphere, 550 00:39:26,400 --> 00:39:29,280 which are probably related to these bursts of hot activity 551 00:39:29,280 --> 00:39:30,560 appearing on the surface. 552 00:39:32,000 --> 00:39:34,160 That really is quite exciting, to actually see these. 553 00:39:34,160 --> 00:39:36,600 It's these active volcanoes 554 00:39:36,600 --> 00:39:39,760 that create the dense atmosphere of Venus. 555 00:39:48,560 --> 00:39:52,760 But why haven't all the volcanoes of Earth led to a similar dense 556 00:39:52,760 --> 00:39:55,280 and hostile atmosphere on our own planet? 557 00:40:06,600 --> 00:40:10,120 Claire Cousins is an astrobiologist. 558 00:40:10,120 --> 00:40:13,040 She's been coming to Iceland for ten years, 559 00:40:13,040 --> 00:40:15,680 as this is the ideal place to find out 560 00:40:15,680 --> 00:40:18,160 how volcanoes can help support life. 561 00:40:20,400 --> 00:40:22,040 Claire and her colleagues 562 00:40:22,040 --> 00:40:24,480 are tapping into the gases of a volcanic vent. 563 00:40:29,360 --> 00:40:32,240 Oh, that's interesting. That looks good, that looks good. 564 00:40:32,240 --> 00:40:33,880 Nice. 565 00:40:36,320 --> 00:40:40,320 So what kind of volcanic gases do we typically get from these systems? 566 00:40:40,320 --> 00:40:43,280 It's about 2% CO2, carbon dioxide. 567 00:40:43,280 --> 00:40:46,200 About 1% H2S, hydrogen sulphide, 568 00:40:46,200 --> 00:40:48,440 and all of the other gases are in trace amounts. 569 00:40:49,880 --> 00:40:52,360 Many of these gases are highly toxic. 570 00:40:55,160 --> 00:41:00,440 So, we wear these gas masks while we're sampling these volcanic gases 571 00:41:00,440 --> 00:41:03,480 because they're what we call acidic gases, 572 00:41:03,480 --> 00:41:06,240 so they're things like carbon dioxide or hydrogen sulphide, 573 00:41:06,240 --> 00:41:09,160 and they're basically gases that we just don't want to be breathing in. 574 00:41:09,160 --> 00:41:10,600 They're really poisonous. 575 00:41:13,840 --> 00:41:18,560 But surprisingly, the most abundant gas is actually water vapour - 576 00:41:18,560 --> 00:41:21,160 97% at this site. 577 00:41:22,560 --> 00:41:26,960 Across the entire Earth, all these gases have a global effect. 578 00:41:28,880 --> 00:41:32,120 Volcanoes, they're not just destructive processes. 579 00:41:32,120 --> 00:41:35,280 In the long-term, especially, they produce a huge amount 580 00:41:35,280 --> 00:41:38,280 of essential ingredients for life, basically. 581 00:41:38,280 --> 00:41:39,640 Particularly water vapour, 582 00:41:39,640 --> 00:41:41,680 we're just surrounded at the moment by all this 583 00:41:41,680 --> 00:41:44,080 volcanic gas and the vast majority of it is water. 584 00:41:47,680 --> 00:41:52,640 Earth's early atmosphere and oceans were created by volcanism, 585 00:41:52,640 --> 00:41:55,520 pumping water and gas into the primeval sky. 586 00:41:57,880 --> 00:42:00,400 But because the tectonic plates of the Earth 587 00:42:00,400 --> 00:42:02,160 dragged so much of this water 588 00:42:02,160 --> 00:42:04,200 and gases back inside the planet... 589 00:42:05,960 --> 00:42:09,480 ..the right amount of atmosphere remained up above 590 00:42:09,480 --> 00:42:11,040 for life to evolve. 591 00:42:13,560 --> 00:42:15,080 Through this whole process, 592 00:42:15,080 --> 00:42:17,000 volcanoes actually deliver to the surface 593 00:42:17,000 --> 00:42:19,640 of the planet many fundamental ingredients required by life. 594 00:42:19,640 --> 00:42:23,720 In contrast, Venus, without plate tectonics, 595 00:42:23,720 --> 00:42:26,760 pumped ever more gases into her atmosphere. 596 00:42:29,000 --> 00:42:33,080 Over time, this dense atmosphere created a hell planet. 597 00:42:39,360 --> 00:42:42,520 All life that we know of needs heat, 598 00:42:42,520 --> 00:42:45,440 liquid water, and an energy-rich foodstuff. 599 00:42:47,720 --> 00:42:51,320 On Earth, volcanoes provide all three. 600 00:42:53,520 --> 00:42:55,840 If they can do this for life here, 601 00:42:55,840 --> 00:42:59,680 volcanoes might support life beyond Earth. 602 00:43:02,080 --> 00:43:04,560 At a volcanic hot spot in Iceland, 603 00:43:04,560 --> 00:43:08,160 Claire is searching for unusual life forms that can survive here. 604 00:43:14,920 --> 00:43:19,560 Our perspective of what's extreme is incredibly human-centric. 605 00:43:19,560 --> 00:43:22,400 We think that living at, you know, 20 Celsius 606 00:43:22,400 --> 00:43:24,320 in an oxygen-rich atmosphere is, 607 00:43:24,320 --> 00:43:25,520 that's what we like, 608 00:43:25,520 --> 00:43:29,320 and we see anything that's different to that as, you know, extreme. 609 00:43:29,320 --> 00:43:31,000 But in reality, 610 00:43:31,000 --> 00:43:33,120 that's just what we've evolved to live in, 611 00:43:33,120 --> 00:43:34,600 and microbes that live in these 612 00:43:34,600 --> 00:43:37,160 very hot or very acidic environments, 613 00:43:37,160 --> 00:43:38,480 they've evolved to live here 614 00:43:38,480 --> 00:43:41,320 and they wouldn't actually grow in our conditions. 615 00:43:45,600 --> 00:43:49,640 Mars had very similar environments where volcanism met ice. 616 00:43:52,080 --> 00:43:56,120 This makes it a good candidate for evidence of extraterrestrial life. 617 00:44:01,400 --> 00:44:04,480 Iceland acts as a useful parallel, 618 00:44:04,480 --> 00:44:06,840 and here Claire tests the water for sulphur, 619 00:44:06,840 --> 00:44:08,920 which certain bacteria can feed on. 620 00:44:12,040 --> 00:44:14,200 The intensity of the blue tells you 621 00:44:14,200 --> 00:44:17,040 how much sulphide is dissolved in the water. 622 00:44:17,040 --> 00:44:19,320 How much food there is for the microbes to eat. 623 00:44:19,320 --> 00:44:24,360 And we also get microbes which actually store the sulphur inside 624 00:44:24,360 --> 00:44:26,320 their cells for future use, 625 00:44:26,320 --> 00:44:28,760 like packing a sandwich into your bag for later. 626 00:44:28,760 --> 00:44:30,240 And they use that sulphur when 627 00:44:30,240 --> 00:44:32,480 they can't find any sulphur in the environment. 628 00:44:36,680 --> 00:44:40,400 She collects the microorganisms to study them more closely. 629 00:44:42,160 --> 00:44:45,360 We can read the DNA of these microorganisms and, you know, 630 00:44:45,360 --> 00:44:47,360 we can identify what they are, 631 00:44:47,360 --> 00:44:50,920 we can see what genes they have, you know, for certain lifestyles. 632 00:44:50,920 --> 00:44:53,400 Whether they can eat sulphur or not, for example. 633 00:44:53,400 --> 00:44:56,480 And we can really get a handle on the microbiology of these sites. 634 00:44:56,480 --> 00:45:00,760 Claire believes that life on Earth and possibly Mars 635 00:45:00,760 --> 00:45:05,200 could have originated in a volcanic hot spot just like this. 636 00:45:07,640 --> 00:45:10,600 But Mars is not the only planetary body 637 00:45:10,600 --> 00:45:13,480 where volcanism is closely linked to ice. 638 00:45:28,400 --> 00:45:32,880 Linda Spilker is head of the team that runs the Cassini probe that's 639 00:45:32,880 --> 00:45:35,680 been exploring Saturn and her moons. 640 00:45:36,880 --> 00:45:41,960 Linda is most interested in the moon called Enceladus. 641 00:45:41,960 --> 00:45:44,840 Enceladus is only about 500km across, 642 00:45:44,840 --> 00:45:48,200 and that's only about one seventh the size of our own moon. 643 00:45:48,200 --> 00:45:52,320 And that tiny moon, we think, should have been frozen solid. 644 00:45:52,320 --> 00:45:53,880 And if you look carefully, 645 00:45:53,880 --> 00:45:56,560 you notice it doesn't look like our moon at all. 646 00:45:56,560 --> 00:45:59,040 Our moon is covered with craters and it's dark, 647 00:45:59,040 --> 00:46:02,160 but this is bright, icy white, and very few craters. 648 00:46:03,920 --> 00:46:06,880 As the Cassini probe approached Enceladus, 649 00:46:06,880 --> 00:46:10,600 Linda observed something never seen before on a planetary body. 650 00:46:13,720 --> 00:46:17,400 If you look carefully, you can actually see individual geysers 651 00:46:17,400 --> 00:46:20,560 coming up and shooting out into space. 652 00:46:20,560 --> 00:46:22,600 And what a surprise. 653 00:46:22,600 --> 00:46:26,640 Everyone was in awe and amazement to see this level of activity. 654 00:46:31,240 --> 00:46:34,720 And we knew for the first time, this wasn't a dead moon. 655 00:46:34,720 --> 00:46:37,600 Enceladus was an active world. 656 00:46:50,680 --> 00:46:53,720 These eruptions are not molten rock. 657 00:46:56,560 --> 00:46:59,360 They are geysers, water and ice, 658 00:46:59,360 --> 00:47:03,200 fountaining over 700km into space. 659 00:47:05,560 --> 00:47:07,680 It means that liquid water 660 00:47:07,680 --> 00:47:11,960 deep below the surface is being forced upwards by heat. 661 00:47:14,000 --> 00:47:16,200 The material erupts so high 662 00:47:16,200 --> 00:47:20,160 that it's actually become part of Saturn's rings. 663 00:47:23,760 --> 00:47:28,400 So, all along, visible evidence of volcanic activity 664 00:47:28,400 --> 00:47:31,040 was present in the rings of Saturn, 665 00:47:31,040 --> 00:47:33,840 but scientists hadn't even realised. 666 00:47:38,200 --> 00:47:40,360 Coming out of the geysers, 667 00:47:40,360 --> 00:47:43,360 there's water vapour, there's tiny particles. 668 00:47:43,360 --> 00:47:46,640 If you'd stand near one of these cracks on Enceladus 669 00:47:46,640 --> 00:47:48,000 and put out your hand, 670 00:47:48,000 --> 00:47:50,120 it would almost be like it was snowing. 671 00:47:50,120 --> 00:47:52,440 These tiny particles would fall back down. 672 00:47:52,440 --> 00:47:54,840 And that's why there's no craters. 673 00:47:54,840 --> 00:47:59,320 That these particles go and fill in with fresh snow, on Enceladus, 674 00:47:59,320 --> 00:48:01,400 fill in all of the craters, 675 00:48:01,400 --> 00:48:06,560 and so, some pieces of Enceladus' surface are only minutes old. 676 00:48:06,560 --> 00:48:10,360 Covered by these tiny particles, falling in from space. 677 00:48:11,880 --> 00:48:16,680 So, how are these extraordinary geysers of ice and water formed? 678 00:48:21,920 --> 00:48:25,280 Again, Iceland provides a powerful analogy. 679 00:48:33,120 --> 00:48:34,840 This is the Strokkur geyser. 680 00:48:40,280 --> 00:48:42,880 Claire loves to witness its raw power. 681 00:48:45,600 --> 00:48:47,760 A great natural wonder of the world. 682 00:48:51,080 --> 00:48:52,320 So what we have here, 683 00:48:52,320 --> 00:48:55,160 rather than molten lava coming out of the ground, 684 00:48:55,160 --> 00:48:58,000 as you typically get for your regular volcano, 685 00:48:58,000 --> 00:49:00,200 what we have here is actually just water, 686 00:49:00,200 --> 00:49:02,760 just ground water which is within the ground. 687 00:49:02,760 --> 00:49:05,080 And it's being heated up by these magma chambers, 688 00:49:05,080 --> 00:49:07,720 which are actually much further, deeper underground. 689 00:49:07,720 --> 00:49:09,560 And this water gets superheated 690 00:49:09,560 --> 00:49:12,320 until it just can't stay underground any more, 691 00:49:12,320 --> 00:49:14,440 and all that steam and all that energy, 692 00:49:14,440 --> 00:49:16,040 just like in a normal volcano, 693 00:49:16,040 --> 00:49:18,080 will erupt all of that water to the surface. 694 00:49:23,160 --> 00:49:27,240 Just before the eruption, what we see is a kind of bubble forming, 695 00:49:27,240 --> 00:49:29,280 where we get this really beautiful, 696 00:49:29,280 --> 00:49:31,920 kind of almost glassy-looking dome of water, 697 00:49:31,920 --> 00:49:35,480 which is all this superheated water just coming up to the surface 698 00:49:35,480 --> 00:49:36,920 until it finally erupts. 699 00:49:38,000 --> 00:49:40,840 A thermal camera measures the heat of the water. 700 00:49:43,080 --> 00:49:45,520 What we can do when we look at the thermal camera here, 701 00:49:45,520 --> 00:49:49,360 we can get an idea of how high temperature the system is. 702 00:49:49,360 --> 00:49:51,600 It's about 70 Celsius. 703 00:49:51,600 --> 00:49:55,880 For me, Enceladus is one of the most exciting places, I think, 704 00:49:55,880 --> 00:49:57,920 in the solar system to go out and explore. It's... 705 00:49:57,920 --> 00:49:59,520 LOUD WHOOSH 706 00:49:59,520 --> 00:50:01,320 For reasons exactly like that, 707 00:50:01,320 --> 00:50:04,120 it's one of the other places in the solar system where we actually have 708 00:50:04,120 --> 00:50:08,840 this active hydrothermal activity, where we have these plumes which are 709 00:50:08,840 --> 00:50:11,120 massive in scale compared to what we have here. 710 00:50:16,600 --> 00:50:20,880 The geysers of Enceladus are so powerful, 711 00:50:20,880 --> 00:50:25,920 there must be an ocean of heated water hidden below the icy surface. 712 00:50:28,760 --> 00:50:33,080 Linda Spilker has ingeniously found out what's in this ocean. 713 00:50:35,280 --> 00:50:39,760 The Cassini spacecraft, since we can get so close to Enceladus, 714 00:50:39,760 --> 00:50:44,920 we can literally skim, fly through the jets and make measurements. 715 00:50:44,920 --> 00:50:48,720 We can measure the gas, we can measure the particles coming out, 716 00:50:48,720 --> 00:50:50,920 and figure out what they're made of. 717 00:50:50,920 --> 00:50:55,080 And the clues inside those particles, those composition, 718 00:50:55,080 --> 00:50:57,400 tells us about the ocean underneath. 719 00:50:59,520 --> 00:51:03,320 It is full of salts and organic compounds. 720 00:51:03,320 --> 00:51:06,080 Some of the key building blocks of life. 721 00:51:09,120 --> 00:51:13,280 So, we wonder, could Enceladus also have life 722 00:51:13,280 --> 00:51:16,520 very similar to the life on Earth? 723 00:51:16,520 --> 00:51:19,560 Is it like the same kind of life we have here on Earth? 724 00:51:19,560 --> 00:51:22,840 Is it something totally different that we can't imagine? 725 00:51:32,560 --> 00:51:34,600 We've had volcanism on Mars, 726 00:51:34,600 --> 00:51:38,280 we've had volcanism on Enceladus and its various different geysers. 727 00:51:38,280 --> 00:51:41,080 To find evidence of life on another planet would be... 728 00:51:41,080 --> 00:51:43,120 It would just be absolutely ground-breaking 729 00:51:43,120 --> 00:51:44,440 in terms of our understanding 730 00:51:44,440 --> 00:51:46,760 of our place, not just in the solar system, 731 00:51:46,760 --> 00:51:48,800 but in the universe as well, right? 732 00:51:52,680 --> 00:51:55,320 The hunt for volcanoes elsewhere 733 00:51:55,320 --> 00:51:58,200 continues to produce amazing breakthroughs. 734 00:52:01,640 --> 00:52:05,560 This is one of the remotest and most distant parts of the solar system. 735 00:52:08,440 --> 00:52:09,520 Pluto. 736 00:52:11,960 --> 00:52:14,200 After a nine-year odyssey, 737 00:52:14,200 --> 00:52:18,840 the New Horizons probe finally reached Pluto in July 2015. 738 00:52:22,120 --> 00:52:24,560 What it discovered was astonishing. 739 00:52:27,200 --> 00:52:30,240 The New Horizons spacecraft that just visited Pluto 740 00:52:30,240 --> 00:52:34,320 found features that have every indication of being cryovolcanic, 741 00:52:34,320 --> 00:52:37,920 mountains, shield-like mountains, 742 00:52:37,920 --> 00:52:40,000 flows on the surface. 743 00:52:40,000 --> 00:52:41,560 Completely unexpected. 744 00:52:41,560 --> 00:52:43,680 And just an extraordinary discovery 745 00:52:43,680 --> 00:52:46,200 which just shows us how exciting the game can be. 746 00:52:47,520 --> 00:52:50,400 This is Wright Mons on Pluto. 747 00:52:52,200 --> 00:52:57,040 At 150km across, and 4km high, 748 00:52:57,040 --> 00:53:01,000 it's believed to be the largest cryovolcano of the solar system. 749 00:53:03,200 --> 00:53:08,760 It's driven by a similar process of mountain formation as on Earth, 750 00:53:08,760 --> 00:53:13,240 but instead of molten rock, it's built up from flowing ice. 751 00:53:16,160 --> 00:53:18,680 In the case of Pluto, it's so cold. 752 00:53:18,680 --> 00:53:20,440 It's not water ice, 753 00:53:20,440 --> 00:53:23,280 it's actually... can be nitrogen ice that can be there. 754 00:53:23,280 --> 00:53:24,720 Or methane ice. 755 00:53:24,720 --> 00:53:28,360 Other things that can be ice in that very cold environment of Pluto. 756 00:53:28,360 --> 00:53:30,720 And there are some tantalising features 757 00:53:30,720 --> 00:53:34,240 that perhaps are cryovolcanoes - maybe something has flowed out. 758 00:53:34,240 --> 00:53:37,240 You mix a little bit of water and ammonia together and it can actually 759 00:53:37,240 --> 00:53:39,120 flow on the surface. 760 00:53:40,320 --> 00:53:44,880 A rare event on Earth called frazil ice 761 00:53:44,880 --> 00:53:48,040 reveals how freezing water can sometimes behave 762 00:53:48,040 --> 00:53:49,880 in a similar way to lava. 763 00:53:51,520 --> 00:53:55,960 During winter, it's occasionally observed in Yosemite National Park. 764 00:53:58,240 --> 00:54:02,880 A slowly flowing river of chunks of ice, given the right conditions, 765 00:54:02,880 --> 00:54:05,320 suddenly freezes solid. 766 00:54:07,560 --> 00:54:09,800 What happens when we see frazil ice on Earth, 767 00:54:09,800 --> 00:54:12,040 is it is so close to its freezing point. 768 00:54:12,040 --> 00:54:14,000 That's why it's filled with ice crystals. 769 00:54:14,000 --> 00:54:18,240 And if it cools down just enough, just another half a degree Celsius, 770 00:54:18,240 --> 00:54:20,160 a quarter of a degree Celsius, 771 00:54:20,160 --> 00:54:24,560 suddenly all the water that's liquid between those ice crystals freezes, 772 00:54:24,560 --> 00:54:26,040 and it happens just like that. 773 00:54:27,680 --> 00:54:30,800 And it's entirely possible that that same process could be happening 774 00:54:30,800 --> 00:54:32,680 on the surface of Pluto. 775 00:54:40,800 --> 00:54:43,920 It's towards the end of the Iceland expedition, 776 00:54:43,920 --> 00:54:46,320 and the team gather to discuss their findings. 777 00:54:50,600 --> 00:54:53,480 Key to this is the fascinating paradox - 778 00:54:53,480 --> 00:54:57,360 volcanoes are a violent and destructive force, 779 00:54:57,360 --> 00:55:00,160 while also essential to life. 780 00:55:02,520 --> 00:55:04,360 Whenever we find volcanism on Earth, 781 00:55:04,360 --> 00:55:07,280 we find all sorts of kind of crazy chemistry, really, 782 00:55:07,280 --> 00:55:10,160 which can just support microbial life, as it is on Earth. 783 00:55:10,160 --> 00:55:11,680 And the real question is whether 784 00:55:11,680 --> 00:55:14,720 these same kinds of processes that happen on Mars or on Enceladus, 785 00:55:14,720 --> 00:55:17,640 whether those can actually support microbial life in the same way. 786 00:55:17,640 --> 00:55:20,800 There's a lot of similarities between this type of environment, 787 00:55:20,800 --> 00:55:23,840 that we've obviously got life in, we know that. 788 00:55:23,840 --> 00:55:27,680 So this is the type of environment that would be a great target 789 00:55:27,680 --> 00:55:30,000 to look for on Mars. Yeah. 790 00:55:34,200 --> 00:55:38,680 But volcanoes of the solar system also give us a window 791 00:55:38,680 --> 00:55:42,080 on what might happen to our own planet in the future. 792 00:55:44,040 --> 00:55:45,760 What I think is really fascinating, 793 00:55:45,760 --> 00:55:47,920 when you look throughout the solar system, 794 00:55:47,920 --> 00:55:52,480 is that you have this diversity of bodies, and each of these bodies, 795 00:55:52,480 --> 00:55:55,840 all of them, or most of them show volcanism. 796 00:55:55,840 --> 00:56:00,400 And then you see that they have been developing in different ways, 797 00:56:00,400 --> 00:56:01,960 each of the bodies. 798 00:56:03,960 --> 00:56:06,000 In about a billion years, 799 00:56:06,000 --> 00:56:10,440 it's predicted that the plate tectonics of Earth could end. 800 00:56:13,000 --> 00:56:15,360 A catastrophe for life here. 801 00:56:20,360 --> 00:56:22,920 Plate tectonics and volcanism replenish the atmosphere 802 00:56:22,920 --> 00:56:26,080 with what we need, but won't you just lose the atmosphere 803 00:56:26,080 --> 00:56:28,320 if you stop plate tectonics? 804 00:56:28,320 --> 00:56:31,160 If Earth just literally kind of grinds to a halt, then, yeah, 805 00:56:31,160 --> 00:56:34,800 eventually the atmosphere will be stripped away by the solar wind, 806 00:56:34,800 --> 00:56:37,480 it will be just lost into space and, yeah, 807 00:56:37,480 --> 00:56:40,320 basically I think we'll end up becoming very much like Mars, 808 00:56:40,320 --> 00:56:43,080 just a very cold and dry, barren, rocky planet. 809 00:56:45,920 --> 00:56:48,960 Earth as Mars is one option. 810 00:56:50,680 --> 00:56:52,680 But another scenario is possible. 811 00:56:57,360 --> 00:57:04,280 Even if plate tectonics ended, volcanism might continue unabated, 812 00:57:04,280 --> 00:57:07,720 and our atmosphere would become thicker and hotter. 813 00:57:07,720 --> 00:57:12,600 It could go the other way and end up like Venus, 814 00:57:12,600 --> 00:57:15,080 where we have all this carbon dioxide in the atmosphere, 815 00:57:15,080 --> 00:57:18,280 and, you know, either way, the options aren't looking that great. 816 00:57:18,280 --> 00:57:19,720 So the interesting thing is 817 00:57:19,720 --> 00:57:22,160 we've got these three planets next to each other, 818 00:57:22,160 --> 00:57:26,400 and they've all got these incredibly different scenes at the present day, 819 00:57:26,400 --> 00:57:30,920 that they may be telling us a lot about the potential futures for 820 00:57:30,920 --> 00:57:34,760 the Earth, as well, and volcanoes are a big part of that story. 821 00:57:34,760 --> 00:57:38,280 So you can see the higher life forms on Earth, like human beings, 822 00:57:38,280 --> 00:57:42,920 dying out as the conditions become much more difficult for them. 823 00:57:42,920 --> 00:57:44,680 Perhaps we'll lose our atmosphere, 824 00:57:44,680 --> 00:57:47,120 perhaps actually we start losing our water. 825 00:57:47,120 --> 00:57:50,120 It's going to be very difficult for human beings to adapt to those 826 00:57:50,120 --> 00:57:52,360 conditions, but the microbes will love them. Yeah. 827 00:57:52,360 --> 00:57:54,720 Microbes will inherit the Earth. 828 00:57:57,520 --> 00:58:00,680 Fortunately, all this is a billion years from now. 829 00:58:03,400 --> 00:58:08,000 Way back in the ninth century, Vikings discovered Iceland, 830 00:58:08,000 --> 00:58:10,840 its landscape sculpted by volcanoes. 831 00:58:14,680 --> 00:58:20,440 Today, a new generation of explorers are looking out into space, 832 00:58:20,440 --> 00:58:25,120 discovering how volcanoes have shaped not just our planet, 833 00:58:25,120 --> 00:58:27,760 but other extraordinary worlds.