1 00:00:00,000 --> 00:00:02,160 NARRATOR: Flying through space, 2 00:00:02,320 --> 00:00:04,160 a high-tech view from above 3 00:00:04,320 --> 00:00:07,320 uncovers a strange expanse on the surface of Mars. 4 00:00:08,520 --> 00:00:11,960 CYLITA GUY: This find is potentially huge for the future of space travel. 5 00:00:12,120 --> 00:00:14,120 - (beep) NARRATOR: Cutting-edge technology 6 00:00:14,280 --> 00:00:16,000 looking down from space 7 00:00:16,160 --> 00:00:19,240 reveals a centuries-old legend in Earth's oceans. 8 00:00:19,400 --> 00:00:22,120 TORRI YATES-ORR: Something weird is definitely going on here. 9 00:00:22,280 --> 00:00:24,920 NARRATOR: NASA probes spot a vast hexagon 10 00:00:25,080 --> 00:00:27,080 swirling around Saturn's north pole. 11 00:00:27,240 --> 00:00:29,880 DAN RISKIN: This is honestly one of the weirdest things in the universe. 12 00:00:30,040 --> 00:00:32,720 NARRATOR: And satellites capture a perfect doughnut-shaped lake 13 00:00:32,880 --> 00:00:34,560 carved into the landscape. 14 00:00:34,720 --> 00:00:37,280 GUY WALTERS: This is really weird. So what happened here? 15 00:00:37,440 --> 00:00:39,440 - (boom) 16 00:00:40,480 --> 00:00:42,680 NARRATOR: Everywhere we look on our planet, 17 00:00:42,840 --> 00:00:45,240 there's evidence of the past. 18 00:00:45,400 --> 00:00:47,200 In nature. 19 00:00:47,360 --> 00:00:49,640 In buildings. 20 00:00:49,800 --> 00:00:52,160 In relics. 21 00:00:52,320 --> 00:00:54,160 Each holds a mystery 22 00:00:54,320 --> 00:00:57,600 that technology now allows us to see from above. 23 00:00:57,760 --> 00:00:59,880 - (dramatic music) 24 00:01:00,040 --> 00:01:02,720 NARRATOR: What new secrets are revealed? 25 00:01:05,760 --> 00:01:07,760 - (optimistic music) 26 00:01:09,760 --> 00:01:11,520 NARRATOR: In the 21st century, 27 00:01:11,680 --> 00:01:14,240 the view from above has reached ever greater heights... 28 00:01:15,960 --> 00:01:18,080 ..uncovering mysteries not just on Earth 29 00:01:18,240 --> 00:01:20,240 but across our solar system. 30 00:01:21,600 --> 00:01:25,520 As we search for clues on Earth to solve these cosmic enigmas, 31 00:01:25,680 --> 00:01:27,680 technology reveals that outer space 32 00:01:27,840 --> 00:01:31,040 holds answers to some of our own abiding secrets 33 00:01:31,200 --> 00:01:34,560 and may even hold the key to the future of human space travel. 34 00:01:35,920 --> 00:01:38,120 - (tense music) 35 00:01:38,280 --> 00:01:40,280 NARRATOR: The Red Planet Mars 36 00:01:40,440 --> 00:01:42,640 is Earth's most tempting neighbouring planet. 37 00:01:44,040 --> 00:01:46,040 DAN RISKIN: Mars really does feel like 38 00:01:46,200 --> 00:01:48,440 the next frontier in space exploration. 39 00:01:49,360 --> 00:01:51,360 TORRI YATES-ORR: Since the 1960s, 40 00:01:51,520 --> 00:01:54,480 we've sent probes and orbiters to explore the planet from above, 41 00:01:54,640 --> 00:01:56,640 searching for clues about its history 42 00:01:56,800 --> 00:01:58,720 and what it can reveal about planet Earth. 43 00:01:58,880 --> 00:02:01,880 GEORGE KOUROUNIS: Today, there are even rovers on the surface, 44 00:02:02,040 --> 00:02:04,640 and space scientists are looking forward to the day 45 00:02:04,800 --> 00:02:06,640 humans can fly a mission to Mars. 46 00:02:07,640 --> 00:02:10,800 PETER SOROYE: To chase that dream, scientists investigate 47 00:02:10,960 --> 00:02:13,880 the Martian surface with the images and data captured from above 48 00:02:14,040 --> 00:02:16,080 to find places where humans could land. 49 00:02:16,240 --> 00:02:18,240 TORRI YATES-ORR: A landing site needs to be close 50 00:02:18,400 --> 00:02:20,080 to major areas of interest, 51 00:02:20,240 --> 00:02:22,720 including where signs of alien life could be found 52 00:02:22,880 --> 00:02:25,800 and any resources that could support a human mission. 53 00:02:26,720 --> 00:02:29,040 NARRATOR: And one team of researchers examining 54 00:02:29,200 --> 00:02:32,640 a possible Martian landing site finds something astonishing. 55 00:02:32,800 --> 00:02:34,800 - (tense music) 56 00:02:34,960 --> 00:02:37,680 DAN RISKIN: It's amazing. I mean, you think of Mars, 57 00:02:37,840 --> 00:02:41,080 you expect this boring desert of flat, orange nothing. 58 00:02:41,240 --> 00:02:43,360 But this is stunning. 59 00:02:43,520 --> 00:02:45,920 NARRATOR: Images captured of the Martian surface 60 00:02:46,080 --> 00:02:48,080 reveal an unexpected bright area. 61 00:02:48,240 --> 00:02:50,080 GEORGE KOUROUNIS: This is wild 62 00:02:50,240 --> 00:02:53,080 because you just don't expect anything on Mars to look like this! 63 00:02:53,240 --> 00:02:56,040 It's just completely the wrong shape and colour. 64 00:02:56,200 --> 00:02:59,240 DAN RISKIN: It's not the jagged black of volcanic rock 65 00:02:59,400 --> 00:03:02,440 and it's not the red waves of iron-rich sand dunes. 66 00:03:02,600 --> 00:03:07,000 So what's happening on Mars to make these light tones? 67 00:03:07,160 --> 00:03:09,120 PETER SOROYE: And this is pretty big. 68 00:03:09,280 --> 00:03:12,400 It's around six kilometres long and four kilometres wide. 69 00:03:12,560 --> 00:03:15,120 That's seven times bigger than Central Park. 70 00:03:15,280 --> 00:03:18,680 NARRATOR: Millions of kilometres further away from the sun, 71 00:03:18,840 --> 00:03:20,520 in the Kuiper Belt, 72 00:03:20,680 --> 00:03:23,440 advanced space technology looking down from above 73 00:03:23,600 --> 00:03:25,360 may uncover a clue. 74 00:03:25,520 --> 00:03:27,520 - (intriguing music) 75 00:03:27,680 --> 00:03:29,480 TORRI YATES-ORR: In the summer of 2015, 76 00:03:29,640 --> 00:03:31,480 the New Horizons probe reached Pluto, 77 00:03:31,640 --> 00:03:34,520 over nine years after it was launched from Earth. 78 00:03:34,680 --> 00:03:36,720 CYLITA GUY: Until this major milestone, 79 00:03:36,880 --> 00:03:39,920 the best view we had of Pluto was from the Hubble Space Telescope. 80 00:03:40,080 --> 00:03:42,840 So when the first images of the dwarf planet finally reached us, 81 00:03:43,000 --> 00:03:45,080 the difference was staggering. 82 00:03:45,240 --> 00:03:47,920 DAN RISKIN: New Horizons captured 83 00:03:48,080 --> 00:03:50,640 a huge bright feature on the side of the planet 84 00:03:50,800 --> 00:03:52,520 that looks like a heart. 85 00:03:52,680 --> 00:03:55,760 GEORGE KOUROUNIS: The size of this is staggering, 86 00:03:55,920 --> 00:03:58,400 about 16-hundred kilometres across. 87 00:03:58,560 --> 00:04:01,320 That's over three times longer than the Grand Canyon. 88 00:04:02,720 --> 00:04:06,200 NARRATOR: But what is making this huge light-coloured shape on Pluto? 89 00:04:06,360 --> 00:04:09,120 PETER SOROYE: Pluto is over three billion kilometres 90 00:04:09,280 --> 00:04:11,880 from the sun on average, making it pretty chilly... 91 00:04:12,040 --> 00:04:13,880 an unbelievably frigid 92 00:04:14,040 --> 00:04:17,320 minus 232 degrees Celsius. 93 00:04:17,480 --> 00:04:20,240 CYLITA GUY: It's so cold that nitrogen, methane 94 00:04:20,400 --> 00:04:24,320 and carbon monoxide in its thin atmosphere can actually freeze. 95 00:04:25,160 --> 00:04:27,400 DAN RISKIN: And this deep-space ice 96 00:04:27,560 --> 00:04:29,240 collects on unique terrain. 97 00:04:29,400 --> 00:04:31,600 Most of the heart is this massive basin 98 00:04:31,760 --> 00:04:34,840 that's filled in with a thick layer of these weird kinds of ice. 99 00:04:36,400 --> 00:04:38,200 NARRATOR: Could the bright area on Mars 100 00:04:38,360 --> 00:04:41,200 be a vast ice field like Pluto's heart 101 00:04:41,360 --> 00:04:44,720 and will these secrets bring humans closer to exploring Mars? 102 00:04:46,080 --> 00:04:49,240 DAN RISKIN: Mars's atmosphere is more than 95% carbon dioxide. 103 00:04:49,400 --> 00:04:51,080 So would it be possible for that 104 00:04:51,240 --> 00:04:53,160 to solidify into an ice patch on the surface? 105 00:04:53,320 --> 00:04:57,640 CYLITA GUY: Mars does sometimes have ice and frost made of CO2, 106 00:04:57,800 --> 00:05:00,040 but it doesn't always stick around. 107 00:05:00,200 --> 00:05:02,160 ROMA AGRAWAL: Mars isn't as cold as Pluto. 108 00:05:02,320 --> 00:05:04,720 For carbon dioxide to stay solid as ice, 109 00:05:04,880 --> 00:05:06,560 it needs to be pretty cold... 110 00:05:06,720 --> 00:05:10,160 around negative 125 degrees Celsius. 111 00:05:10,320 --> 00:05:12,800 GEORGE KOUROUNIS: At the poles or overnight... 112 00:05:12,960 --> 00:05:16,400 no problem. Temperatures can drop to minus 130 113 00:05:16,560 --> 00:05:19,920 or even minus 150 Celsius in winter at the poles. 114 00:05:20,080 --> 00:05:22,280 But when the sun hits... 115 00:05:22,440 --> 00:05:24,440 everything changes. 116 00:05:24,600 --> 00:05:26,480 PETER SOROYE: On Earth, we know 117 00:05:26,640 --> 00:05:29,080 frozen or solid carbon dioxide as dry ice. 118 00:05:29,240 --> 00:05:31,320 And if you think about what happens to that 119 00:05:31,480 --> 00:05:33,160 when it hits normal temperatures, 120 00:05:33,320 --> 00:05:35,320 you can start to visualise what happens on Mars 121 00:05:35,480 --> 00:05:38,040 every time the sun starts to warm up the surface. 122 00:05:38,200 --> 00:05:40,480 DAN RISKIN: It's something called sublimation. 123 00:05:40,640 --> 00:05:43,440 It's when something goes from a frozen solid to a gas 124 00:05:43,600 --> 00:05:46,480 so fast that it just skips the liquid stage altogether. 125 00:05:46,640 --> 00:05:49,400 CYLITA GUY: And this weird light area on Mars 126 00:05:49,560 --> 00:05:51,280 is right by the equator. 127 00:05:51,440 --> 00:05:54,640 While it can get down to below minus 70 degrees Celsius at night, 128 00:05:54,800 --> 00:05:57,200 this isn't quite cold enough for CO2 ice. 129 00:05:57,360 --> 00:06:01,240 DAN RISKIN: And at noon, It can get up to a balmy 20 degrees Celsius 130 00:06:01,400 --> 00:06:03,160 at the surface. 131 00:06:03,320 --> 00:06:05,320 But even then, because of the thin atmosphere, 132 00:06:05,480 --> 00:06:07,880 if you go up just one-and-a-half metres above the ground, 133 00:06:08,040 --> 00:06:11,280 you're already down to zero degrees Celsius. 134 00:06:11,440 --> 00:06:14,560 - That's far too warm for any CO2 ice to really stick around. 135 00:06:16,160 --> 00:06:18,280 GEORGE KOUROUNIS: So what else could be going on? 136 00:06:18,440 --> 00:06:20,120 What other clues can we find? 137 00:06:20,280 --> 00:06:22,880 NARRATOR: A closer look at the NASA images 138 00:06:23,040 --> 00:06:25,120 suggests something surprising. 139 00:06:25,280 --> 00:06:27,280 - (intriguing music) 140 00:06:27,440 --> 00:06:30,680 TORRI YATES-ORR: This bright area on Mars is full of geographic features 141 00:06:30,840 --> 00:06:32,960 that look shockingly familiar. 142 00:06:33,120 --> 00:06:35,800 NARRATOR: There may be a clue closer to home 143 00:06:35,960 --> 00:06:38,080 here on Earth in Iceland. 144 00:06:38,240 --> 00:06:41,080 GEORGE KOUROUNIS: Iceland is known as the land of fire and ice - 145 00:06:41,240 --> 00:06:45,080 and for good reason. It has some of the world's most active volcanoes 146 00:06:45,240 --> 00:06:47,040 and some of the largest glaciers. 147 00:06:49,280 --> 00:06:51,120 NARRATOR: This is Vatnajokull, 148 00:06:51,280 --> 00:06:53,320 one of the largest ice caps in Europe. 149 00:06:53,480 --> 00:06:57,120 DAN RISKIN: This massive chunk of slow-flowing ice 150 00:06:57,280 --> 00:07:00,960 covers over 75-hundred square kilometres. 151 00:07:01,120 --> 00:07:03,480 CYLITA GUY: There is more to this chilling beauty 152 00:07:03,640 --> 00:07:05,320 than meets the eye. 153 00:07:05,480 --> 00:07:08,280 Active volcanoes are hiding under the ice. 154 00:07:08,440 --> 00:07:10,840 TORRI YATES-ORR: But it's the glaciers that hold the clue 155 00:07:11,000 --> 00:07:13,000 to the strange bright region on Mars... 156 00:07:13,160 --> 00:07:17,720 particularly the dramatic Svínafellsjokull glacial tongue. 157 00:07:19,400 --> 00:07:21,400 DAN RISKIN: If you look at the glacier tongue, 158 00:07:21,560 --> 00:07:23,240 where it hits the sea, 159 00:07:23,400 --> 00:07:26,560 you can see some cracks in the ice that are starting to spread outward. 160 00:07:26,720 --> 00:07:28,720 And if you look at the shapes, 161 00:07:28,880 --> 00:07:31,480 they look an awful lot like the ones on Mars. 162 00:07:31,640 --> 00:07:33,840 CYLITA GUY: There are also bands of 163 00:07:34,000 --> 00:07:36,360 earth and rock in these really long wavy piles. 164 00:07:36,520 --> 00:07:38,280 These are called moraines - 165 00:07:38,440 --> 00:07:40,120 material that's either been picked up 166 00:07:40,280 --> 00:07:42,760 by the sides of the glacier or pushed together by the front. 167 00:07:42,920 --> 00:07:45,120 ROMA AGRAWAL: And they create shapes 168 00:07:45,280 --> 00:07:48,040 nearly identical to the strange area on Mars. 169 00:07:48,200 --> 00:07:51,960 GEORGE KOUROUNIS: And this wasn't the only icy clue in Europe. 170 00:07:52,120 --> 00:07:55,480 NARRATOR: Around 26-hundred kilometres to the southeast 171 00:07:55,640 --> 00:07:57,520 is another stunning ice form, 172 00:07:57,680 --> 00:08:00,000 high in the Austrian Alps. 173 00:08:00,160 --> 00:08:01,840 - (tense music) 174 00:08:02,000 --> 00:08:04,120 NARRATOR: This is the Pasterze Glacier. 175 00:08:05,040 --> 00:08:06,680 PETER SOROYE: Climate change is chasing 176 00:08:06,840 --> 00:08:08,520 this epic glacier into the past. 177 00:08:08,680 --> 00:08:10,800 It's been receding since the 1850s. 178 00:08:10,960 --> 00:08:14,120 100 years ago, it was over 11 kilometres long. 179 00:08:14,280 --> 00:08:16,840 Today, it's less than eight kilometres long, 180 00:08:17,000 --> 00:08:19,400 and it's dropped in mass by over 50%. 181 00:08:19,560 --> 00:08:21,240 - (dramatic music) 182 00:08:21,400 --> 00:08:24,120 DAN RISKIN: But for now it still holds clues to the Martian mystery. 183 00:08:25,680 --> 00:08:28,000 NARRATOR: Its stunning crevasse-like shapes 184 00:08:28,160 --> 00:08:31,280 reveal signs of the flow of water and ice over the terrain. 185 00:08:31,440 --> 00:08:33,120 DAN RISKIN: Circular crevasses 186 00:08:33,280 --> 00:08:35,080 with these concentric rings of cracks 187 00:08:35,240 --> 00:08:37,600 can happen when there's water flowing under 188 00:08:37,760 --> 00:08:40,600 or on top of or even within the glacier. 189 00:08:40,760 --> 00:08:42,440 These wear away at the ice, 190 00:08:42,600 --> 00:08:44,280 and then the ice gets weak spots, 191 00:08:44,440 --> 00:08:46,680 and when it gets unstable enough, it collapses. 192 00:08:47,640 --> 00:08:49,160 - And these cracks that look like hash marks 193 00:08:49,320 --> 00:08:51,480 are called tic-tac-toe crevasses. 194 00:08:51,640 --> 00:08:53,320 They occur when the glacier ice 195 00:08:53,480 --> 00:08:55,800 flows on top of a higher area in the landscape, 196 00:08:55,960 --> 00:08:58,200 which stresses it in different directions, 197 00:08:58,360 --> 00:09:00,120 creating this unique crack pattern. 198 00:09:00,280 --> 00:09:02,760 TORRI YATES-ORR: And when you look at them side by side, 199 00:09:02,920 --> 00:09:04,800 these look uncannily like the fracture shapes 200 00:09:04,960 --> 00:09:06,640 on the Martian surface. 201 00:09:06,800 --> 00:09:08,920 GEORGE KOUROUNIS: The weird shape on Mars 202 00:09:09,080 --> 00:09:11,560 has the hallmark features of a glacier. 203 00:09:12,760 --> 00:09:14,560 NARRATOR: Could a glacier be the secret 204 00:09:14,720 --> 00:09:17,440 to this unexpected feature on the Martian surface? 205 00:09:18,360 --> 00:09:20,040 GEORGE KOUROUNIS: If we're able 206 00:09:20,200 --> 00:09:22,400 to find a source of water, even if it's frozen ice, 207 00:09:22,560 --> 00:09:24,760 that would make further explorations of Mars, 208 00:09:24,920 --> 00:09:27,840 especially by humans, so much easier. 209 00:09:28,000 --> 00:09:30,000 It could change everything. 210 00:09:32,080 --> 00:09:34,280 DAN RISKIN: Water could be used for everything, 211 00:09:34,440 --> 00:09:36,120 from drinking to feeding plants. 212 00:09:36,280 --> 00:09:38,440 It could even be converted into rocket fuel. 213 00:09:38,600 --> 00:09:40,840 NARRATOR: But there's a problem. 214 00:09:41,840 --> 00:09:44,840 ROMA AGRAWAL: The satellites and probes that look at Mars from above 215 00:09:45,000 --> 00:09:47,360 have found signs of water ice glaciers. 216 00:09:47,520 --> 00:09:49,520 But there's a key difference. 217 00:09:49,680 --> 00:09:51,360 DAN RISKIN: Any glaciers at the surface 218 00:09:51,520 --> 00:09:53,080 are nowhere near the equator, 219 00:09:53,240 --> 00:09:55,400 and that is because of sublimation. 220 00:09:55,560 --> 00:09:57,800 CYLITA GUY: Water is really unstable on Mars, 221 00:09:57,960 --> 00:10:00,120 and that's because of its thin atmosphere. 222 00:10:00,280 --> 00:10:03,480 The atmospheric pressure is more than 100 times less 223 00:10:03,640 --> 00:10:05,320 than here on Earth. 224 00:10:05,480 --> 00:10:08,280 PETER SOROYE: Because of the low atmospheric pressure on Mars, 225 00:10:08,440 --> 00:10:10,720 instead of liquid water boiling at 100 degrees Celsius, 226 00:10:10,880 --> 00:10:12,560 like it does on Earth, 227 00:10:12,720 --> 00:10:15,280 it actually turns into gas at around ten degrees Celsius. 228 00:10:15,440 --> 00:10:19,760 Basically, if it's not frozen, it's boiling or evaporating away. 229 00:10:19,920 --> 00:10:22,600 TORRI YATES-ORR: So if it can't be a surface water glacier, 230 00:10:22,760 --> 00:10:24,640 what's going on? 231 00:10:24,800 --> 00:10:26,480 NARRATOR: What clues can be found 232 00:10:26,640 --> 00:10:29,680 by the advanced probes searching Mars from above? 233 00:10:29,840 --> 00:10:33,120 TORRI YATES-ORR: The Mars Reconnaissance Orbiter, or MRO, 234 00:10:33,280 --> 00:10:37,200 has been flying high above the Red Planet for over 17 years. 235 00:10:37,360 --> 00:10:40,600 Packed with high-tech equipment, it offers a crucial clue. 236 00:10:41,480 --> 00:10:44,240 ROMA AGRAWAL: When the researchers looked at the data from the MRO, 237 00:10:44,400 --> 00:10:46,200 they found that the light area 238 00:10:46,360 --> 00:10:48,360 was actually a kind of salt. 239 00:10:48,520 --> 00:10:50,440 - (dramatic music) 240 00:10:50,600 --> 00:10:53,120 NARRATOR: But how did this salt appear? 241 00:10:53,280 --> 00:10:54,960 - And how can salt on Mars 242 00:10:55,120 --> 00:10:57,600 make shapes just like those we see in glaciers here on Earth? 243 00:10:57,760 --> 00:10:59,520 NARRATOR: A mystery whose answer 244 00:10:59,680 --> 00:11:02,640 may still hold the key to human missions to Mars. 245 00:11:03,840 --> 00:11:05,920 - (dramatic music) 246 00:11:06,080 --> 00:11:07,760 - There's a clue on Earth that provides 247 00:11:07,920 --> 00:11:09,760 the final piece of the puzzle. 248 00:11:09,920 --> 00:11:11,600 - (intriguing music) 249 00:11:11,760 --> 00:11:13,960 NARRATOR: Hiding only a few decades in the past, 250 00:11:14,120 --> 00:11:17,080 in the bright red waters of Bolivia's Laguna Colorada 251 00:11:17,240 --> 00:11:18,920 is a staggering secret. 252 00:11:19,080 --> 00:11:21,600 GEORGE KOUROUNIS: The lakes of this region, 253 00:11:21,760 --> 00:11:24,320 in the high plateau known as the Altiplano, 254 00:11:24,480 --> 00:11:26,280 are extremely salt and form 255 00:11:26,440 --> 00:11:29,200 large and dramatic salt islands in the brilliant waters. 256 00:11:29,360 --> 00:11:31,320 ROMA AGRAWAL: But in the 1980s 257 00:11:31,480 --> 00:11:33,480 scientists discovered something incredible 258 00:11:33,640 --> 00:11:36,280 hiding in these salty shells. 259 00:11:36,440 --> 00:11:38,480 Ancient ice. 260 00:11:38,640 --> 00:11:42,080 CYLITA GUY: The researchers believed that this ice was formed 261 00:11:42,240 --> 00:11:44,960 during the Little Ice Age, which started in the Middle Ages. 262 00:11:45,120 --> 00:11:49,320 DAN RISKIN: This thick layer of salt insulated this ice against melting, 263 00:11:49,480 --> 00:11:52,560 so it could stick around for decades or even centuries, even though 264 00:11:52,720 --> 00:11:54,480 in the bright sunlight the summer temperatures 265 00:11:54,640 --> 00:11:56,320 get to, like, 16 degrees Celsius. 266 00:11:56,480 --> 00:11:59,040 PETER SOROYE: And these aren't just little ice cubes. 267 00:11:59,200 --> 00:12:03,440 These ice-cored salt islands were as large as 1.5 kilometres across 268 00:12:03,600 --> 00:12:06,200 and seven metres high. 269 00:12:06,360 --> 00:12:08,640 TORRI YATES-ORR: It's unknown if the ice persists to this day, 270 00:12:08,800 --> 00:12:10,480 but the hidden ice implies 271 00:12:10,640 --> 00:12:13,000 something staggering about the shape on Mars. 272 00:12:14,200 --> 00:12:17,040 NARRATOR: Could the salt and the glacial-looking terrain 273 00:12:17,200 --> 00:12:21,520 at this strange bright area on Mars be a sign of ice hiding below? 274 00:12:21,680 --> 00:12:24,880 DAN RISKIN: Experts believe there is a way this could happen. 275 00:12:25,040 --> 00:12:28,520 First, a long time ago, a Martian volcano could have erupted 276 00:12:28,680 --> 00:12:31,440 right next to a water ice glacier. 277 00:12:32,480 --> 00:12:34,960 GEORGE KOUROUNIS: The hot ash would have instantly melted 278 00:12:35,120 --> 00:12:38,200 the top of the ice, and - as it evaporated away - 279 00:12:38,360 --> 00:12:41,720 it would have left a layer of salt behind, hidden by the dark ash. 280 00:12:42,840 --> 00:12:45,760 CYLITA GUY: Eventually, Martian winds would have blown the ash away, 281 00:12:45,920 --> 00:12:47,920 leaving behind the bright salt layer, 282 00:12:48,080 --> 00:12:50,360 which would hold the shape of the glacier beneath. 283 00:12:50,520 --> 00:12:53,640 GEORGE KOUROUNIS: Even though this isn't 100% confirmation, 284 00:12:53,800 --> 00:12:57,280 it's really important because, if it is there on the surface, 285 00:12:57,440 --> 00:12:59,240 that changes everything. 286 00:13:01,800 --> 00:13:03,480 - (tense music) 287 00:13:03,640 --> 00:13:05,960 ROMA AGRAWAL: Glaciers have been found on Mars before, 288 00:13:06,120 --> 00:13:10,160 but in the unfriendly and extreme environments at the Martian poles, 289 00:13:10,320 --> 00:13:12,640 where the icy temperatures and long winter nights 290 00:13:12,800 --> 00:13:15,960 would wreak havoc on humans and electronics alike. 291 00:13:16,120 --> 00:13:18,680 PETER SOROYE: And at such cold temperatures, 292 00:13:18,840 --> 00:13:20,840 simply turning that ice into liquid water 293 00:13:21,000 --> 00:13:22,720 could be a near-impossible task. 294 00:13:22,880 --> 00:13:26,800 CYLITA GUY: But this glacier is at the much more accessible 295 00:13:26,960 --> 00:13:28,960 warm and sunny equator. 296 00:13:29,120 --> 00:13:31,640 And digging through a crust of salt is going to be far easier 297 00:13:31,800 --> 00:13:35,920 than trying to break up polar ice in negative 50-degree Celsius weather. 298 00:13:36,760 --> 00:13:39,760 GEORGE KOUROUNIS: If there really is ice hiding under this salt, 299 00:13:39,920 --> 00:13:41,640 it'll be a total game changer. 300 00:13:41,800 --> 00:13:43,520 - (tense music) 301 00:13:43,680 --> 00:13:46,960 NARRATOR: This shocking discovery on Mars is just the beginning. 302 00:13:47,120 --> 00:13:48,920 CYLITA GUY: This find is potentially 303 00:13:49,080 --> 00:13:51,000 huge for the future of space travel. 304 00:13:51,160 --> 00:13:54,640 The possibility of accessible frozen water 305 00:13:54,800 --> 00:13:57,520 makes the logistics of a mission to the Red Planet a little simpler. 306 00:13:57,680 --> 00:13:59,600 Mind you, not simple, 307 00:13:59,760 --> 00:14:02,280 but just a little bit easier. 308 00:14:02,440 --> 00:14:05,080 GEORGE KOUROUNIS: What we're seeing here in this view from above, 309 00:14:05,240 --> 00:14:07,000 even though it's on another planet, 310 00:14:07,160 --> 00:14:09,840 could change the direction of human history. 311 00:14:15,240 --> 00:14:17,560 NARRATOR: Advanced satellite technology in space, 312 00:14:17,720 --> 00:14:19,400 looking down from above, 313 00:14:19,560 --> 00:14:22,040 captures planet Earth like never before. 314 00:14:22,200 --> 00:14:23,880 - (dramatic music) 315 00:14:24,040 --> 00:14:26,840 DAN RISKIN: The US has all kinds of cutting-edge equipment in space, 316 00:14:27,000 --> 00:14:29,240 and a couple of satellites have something called 317 00:14:29,400 --> 00:14:34,760 the Visible Infrared Imaging Radiometer Suite, or VIIRS. 318 00:14:34,920 --> 00:14:36,920 CYLITA GUY: It's amazing. 319 00:14:37,080 --> 00:14:39,640 Sensors collect visible and infrared images, 320 00:14:39,800 --> 00:14:42,600 which can be used to do everything from predicting the weather 321 00:14:42,760 --> 00:14:46,440 to tracking fires and even sensing changes in the ocean colour. 322 00:14:47,320 --> 00:14:49,320 ROMA AGRAWAL: And crucially, it has something called 323 00:14:49,480 --> 00:14:51,520 the Day Night Band Sensor, 324 00:14:51,680 --> 00:14:53,760 which can see in very low light conditions 325 00:14:53,920 --> 00:14:57,560 to capture things at night that we can't see with the naked eye. 326 00:14:58,920 --> 00:15:01,360 NARRATOR: And this new view from above 327 00:15:01,520 --> 00:15:04,240 captures a long-hidden secret in the nighttime darkness 328 00:15:04,400 --> 00:15:06,280 of Earth's oceans. 329 00:15:06,440 --> 00:15:09,560 In the summer of 2019, off the coast of Java, 330 00:15:09,720 --> 00:15:12,280 this technology reveals an eerie shape 331 00:15:12,440 --> 00:15:14,800 emerging from the black ocean waters. 332 00:15:14,960 --> 00:15:17,320 - (tense music) 333 00:15:17,480 --> 00:15:20,120 TORRI YATES-ORR: Something weird is definitely going on here. 334 00:15:20,280 --> 00:15:22,080 PETER SOROYE: From the satellite, it looks 335 00:15:22,240 --> 00:15:24,880 so otherworldly and ethereal. 336 00:15:25,040 --> 00:15:27,680 CYLITA GUY: This looks like an abstract work of art. 337 00:15:27,840 --> 00:15:30,240 I see this glowing cloud floating in the black. 338 00:15:31,240 --> 00:15:34,000 DAN RISKIN: It's paler than the city lights on the island of Java, 339 00:15:34,160 --> 00:15:36,920 but it's definitely brighter than the nighttime ocean should be. 340 00:15:37,080 --> 00:15:39,800 GEORGE KOUROUNIS: It's hard to tell exactly what's going on here, 341 00:15:39,960 --> 00:15:41,400 but it's huge. 342 00:15:42,680 --> 00:15:44,760 CYLITA GUY: This shape covers a massive area, 343 00:15:44,920 --> 00:15:47,080 100,000 square kilometres. 344 00:15:47,240 --> 00:15:48,960 That's like the size of Iceland. 345 00:15:49,120 --> 00:15:50,440 - (eerie music) 346 00:15:50,600 --> 00:15:52,440 NARRATOR: This strange vast shape 347 00:15:52,600 --> 00:15:55,840 moves over time and raises countless questions. 348 00:15:56,000 --> 00:15:58,080 TORRI YATES-ORR: What is causing 349 00:15:58,240 --> 00:16:00,040 this enormous glow-in-the-dark spectre? 350 00:16:00,840 --> 00:16:03,280 PETER SOROYE: Is this some kind of weird natural phenomenon 351 00:16:03,440 --> 00:16:05,120 or is it caused by humans? 352 00:16:05,280 --> 00:16:07,240 CYLITA GUY: How long has it been here? 353 00:16:07,400 --> 00:16:09,640 DAN RISKIN: Is there any other technology in space 354 00:16:09,800 --> 00:16:12,400 that could offer a hint as to what we're seeing here? 355 00:16:12,560 --> 00:16:15,440 NARRATOR: Over 8,000 kilometres to the northeast, 356 00:16:15,600 --> 00:16:17,400 off the coast of Siberia, 357 00:16:17,560 --> 00:16:19,240 satellites looking down from space 358 00:16:19,400 --> 00:16:21,160 capture a possible clue... 359 00:16:21,320 --> 00:16:23,080 in the Sea of Okhotsk. 360 00:16:23,240 --> 00:16:27,120 Familiar-looking shapes swirling in the water. 361 00:16:27,280 --> 00:16:29,000 - (tense music) 362 00:16:29,160 --> 00:16:31,160 CYLITA GUY: In 2023, NASA captured this, 363 00:16:31,320 --> 00:16:33,000 as thinning ice breaks up 364 00:16:33,160 --> 00:16:35,000 and starts to flow with the spinning ocean currents. 365 00:16:36,440 --> 00:16:38,320 DAN RISKIN: As sea ice melts, 366 00:16:38,480 --> 00:16:41,080 swirls of white spin off into the ocean. 367 00:16:41,240 --> 00:16:43,240 Here it covers hundreds of kilometres. 368 00:16:43,400 --> 00:16:45,400 PETER SOROYE: These happen here every year, 369 00:16:45,560 --> 00:16:47,360 and sometimes last for months. 370 00:16:47,520 --> 00:16:49,480 It's even appearing earlier and earlier 371 00:16:49,640 --> 00:16:51,880 as sea ice breaks up sooner, thanks to climate change. 372 00:16:53,560 --> 00:16:56,240 - This swirling ice, seen from space, 373 00:16:56,400 --> 00:16:59,400 looks a lot like the shape we see in the images from around Java. 374 00:17:00,400 --> 00:17:02,880 CYLITA GUY: Does that mean that forming or melting sea ice 375 00:17:03,040 --> 00:17:05,680 could be behind the mysterious swirl in the Indian Ocean? 376 00:17:07,080 --> 00:17:09,480 NARRATOR: Further investigation from above 377 00:17:09,640 --> 00:17:11,320 uncovers some shocking clues. 378 00:17:12,560 --> 00:17:15,600 This isn't the only place this strange phenomenon appears. 379 00:17:16,680 --> 00:17:20,000 ROMA AGRAWAL: The VIIRS equipment finds several more instances 380 00:17:20,160 --> 00:17:22,560 of these strange glowing patches of sea. 381 00:17:23,560 --> 00:17:25,600 NARRATION: These weird phenomena are spotted 382 00:17:25,760 --> 00:17:27,440 off the coast of East Africa 383 00:17:27,600 --> 00:17:29,520 and in the waters of Southeast Asia. 384 00:17:29,680 --> 00:17:32,400 DAN RISKIN: And there's something all of those sites have in common. 385 00:17:32,560 --> 00:17:36,000 They're all in warm tropical waters. 386 00:17:36,160 --> 00:17:38,080 PETER SOROYE: That means there's no way 387 00:17:38,240 --> 00:17:41,200 these could be caused by melting or forming sea ice. 388 00:17:41,360 --> 00:17:45,000 So what else could cause huge areas of the ocean to get so bright? 389 00:17:46,000 --> 00:17:48,520 NARRATOR: Perhaps a record-breaking event in Spain 390 00:17:48,680 --> 00:17:50,680 can reveal a clue. 391 00:17:50,840 --> 00:17:52,840 In January of 2020, 392 00:17:53,000 --> 00:17:56,600 the Mediterranean is hit by a major storm. 393 00:17:56,760 --> 00:17:58,760 - Winter storm Gloria batters Spain 394 00:17:58,920 --> 00:18:01,000 with unparalleled heavy rain, 395 00:18:01,160 --> 00:18:03,120 high winds and blizzards. 396 00:18:03,280 --> 00:18:05,920 NARRATOR: And the quiet seaside town of Tossa de Mar 397 00:18:06,080 --> 00:18:08,520 faces something staggering. 398 00:18:08,680 --> 00:18:11,440 DAN RISKIN: Storms can cause something called a storm surge, 399 00:18:11,600 --> 00:18:13,840 where the sea level rises up higher than normal 400 00:18:14,000 --> 00:18:16,080 and then floods coastal areas. 401 00:18:16,240 --> 00:18:19,320 CYLITA GUY: And Gloria's storm surge poured more than just water 402 00:18:19,480 --> 00:18:21,480 into the streets of Tossa de Mar. 403 00:18:21,640 --> 00:18:25,280 The town suddenly flooded with a staggering amount of foam. 404 00:18:25,440 --> 00:18:27,880 - (wind whistles) PETER SOROYE: Sea foam occurs 405 00:18:28,040 --> 00:18:30,200 all the time, and all around the globe. 406 00:18:30,360 --> 00:18:33,120 It's made when the agitation of wind and waves 407 00:18:33,280 --> 00:18:37,000 stirs up the organic material, pollutants, surfactants 408 00:18:37,160 --> 00:18:40,400 and general bits and bobs that are found in seawater. 409 00:18:41,280 --> 00:18:43,440 DAN RISKIN: To get sea foam in these large quantities, 410 00:18:43,600 --> 00:18:45,840 there has to be a lot of dissolved organic material, 411 00:18:46,000 --> 00:18:48,600 like a big algal bloom, getting broken down. 412 00:18:48,760 --> 00:18:51,240 And you have to pair that with choppy ocean waters, 413 00:18:51,400 --> 00:18:53,840 like a big cyclonic storm. 414 00:18:54,000 --> 00:18:56,600 NARRATOR: Could the churning ocean waves 415 00:18:56,760 --> 00:19:00,520 make a giant island of sea foam visible from space 416 00:19:00,680 --> 00:19:03,760 or is there something else hiding in the ocean depths? 417 00:19:03,920 --> 00:19:05,600 TORRI YATES-ORR: Maybe it's not a sign 418 00:19:05,760 --> 00:19:07,680 of organic material breaking down. 419 00:19:07,840 --> 00:19:10,560 Maybe there's something alive down there. 420 00:19:10,720 --> 00:19:12,720 - (tense music) 421 00:19:14,640 --> 00:19:16,360 NARRATOR: There may be a clue 422 00:19:16,520 --> 00:19:18,200 in an old maritime legend. 423 00:19:19,200 --> 00:19:22,480 TORRI YATES-ORR: Over centuries, there have been reports from sailors 424 00:19:22,640 --> 00:19:24,400 of a very weird phenomenon... 425 00:19:24,560 --> 00:19:26,680 something they called "milky seas". 426 00:19:26,840 --> 00:19:28,840 GEORGE KOUROUNIS: Researchers poring over 427 00:19:29,000 --> 00:19:33,640 ships logs and other historical records found over 200 reports 428 00:19:33,800 --> 00:19:35,480 of vast stretches of ocean 429 00:19:35,640 --> 00:19:38,000 emitting a starling white or green glow. 430 00:19:39,200 --> 00:19:41,640 - When those are mapped alongside the 12 instances 431 00:19:41,800 --> 00:19:43,800 captured by modern satellites, 432 00:19:43,960 --> 00:19:46,160 you can see that it continues a pattern. 433 00:19:46,320 --> 00:19:50,160 CYLITA GUY: These rare glowing ocean waters are most often found 434 00:19:50,320 --> 00:19:52,920 in the Arabian Sea and Indian Ocean. 435 00:19:53,840 --> 00:19:56,120 TORRI YATES-ORR: So are these ocean hazes seen on satellite 436 00:19:56,280 --> 00:19:58,600 the milky seas of maritime legend 437 00:19:58,760 --> 00:20:00,440 and are there any contemporary 438 00:20:00,600 --> 00:20:02,520 on-the-ground sightings that could back this up? 439 00:20:02,680 --> 00:20:04,400 - (tense music) 440 00:20:04,560 --> 00:20:07,080 NARRATOR: In an unbelievable moment of luck, 441 00:20:07,240 --> 00:20:09,760 the vessel Ganesha happened to pass through 442 00:20:09,920 --> 00:20:12,960 the tail of ocean haze captured by satellite. 443 00:20:13,920 --> 00:20:17,200 And what they record from the ocean surface is astonishing. 444 00:20:18,880 --> 00:20:21,520 - The crew described a vast and steady glow 445 00:20:21,680 --> 00:20:23,800 coming from beneath the ocean surface. 446 00:20:23,960 --> 00:20:25,960 GEORGE KOUROUNIS: Even more amazing... 447 00:20:26,120 --> 00:20:27,920 they catch it on camera. 448 00:20:28,080 --> 00:20:30,480 And that gives another huge clue to what's happening. 449 00:20:31,480 --> 00:20:34,600 CYLITA GUY: The crew see the ocean glow as a pale white or green 450 00:20:34,760 --> 00:20:36,480 because their perception of colour is affected 451 00:20:36,640 --> 00:20:38,200 by the dark and moonless night. 452 00:20:38,360 --> 00:20:42,760 The human eye contains two types of receptor cells - rods and cones. 453 00:20:42,920 --> 00:20:44,600 Cones help us to see colour, 454 00:20:44,760 --> 00:20:48,240 while rods work in low light to help us see in grayscale. 455 00:20:48,400 --> 00:20:50,440 Cone cells need lots and lots of light to work, 456 00:20:50,600 --> 00:20:52,720 which is why colour vision decreases at night 457 00:20:52,880 --> 00:20:54,560 or in other dark conditions. 458 00:20:54,720 --> 00:20:56,520 DAN RISKIN: But the cameras on the ship 459 00:20:56,680 --> 00:20:58,680 aren't affected the same way human eyes are. 460 00:20:58,840 --> 00:21:00,840 So they capture the truth. 461 00:21:01,000 --> 00:21:03,520 A glowing, greenish-blue haze 462 00:21:03,680 --> 00:21:05,960 that spreads out for miles. 463 00:21:06,120 --> 00:21:09,760 NARRATOR: It's a critical revelation and raises the question... 464 00:21:09,920 --> 00:21:13,320 what on Earth can make the ocean glow from below? 465 00:21:14,200 --> 00:21:17,080 GEORGE KOUROUNIS: There are some other glowing ocean phenomena 466 00:21:17,240 --> 00:21:18,920 that can give us a clue. 467 00:21:19,080 --> 00:21:20,760 PETER SOROYE: There are parts of the world 468 00:21:20,920 --> 00:21:22,560 where the impact of the waves on the shore 469 00:21:22,720 --> 00:21:24,920 can make a magical blue sparkle. 470 00:21:25,080 --> 00:21:27,800 Even the motion of fish or dolphins swimming in the water 471 00:21:27,960 --> 00:21:30,400 can create the same kind of glow. 472 00:21:30,560 --> 00:21:33,320 - These stunning phenomena are caused by a type of plankton. 473 00:21:33,480 --> 00:21:36,400 Tiny living things are producing light with their bodies 474 00:21:36,560 --> 00:21:38,360 through chemical reaction. 475 00:21:38,520 --> 00:21:40,760 They give off light when they're moved around. 476 00:21:40,920 --> 00:21:44,000 DAN RISKIN: But these creatures only emit little flashes of light, 477 00:21:44,160 --> 00:21:45,960 so it looks like it sparkles. 478 00:21:46,120 --> 00:21:48,120 That's not what we're seeing off the island of Java. 479 00:21:48,280 --> 00:21:51,040 So could it be another form of hidden life 480 00:21:51,200 --> 00:21:53,200 that's making the sea glow? 481 00:21:54,520 --> 00:21:57,520 NARRATOR: There may be a clue in Northern Iran 482 00:21:57,680 --> 00:21:59,480 where the salty Lake Urmia 483 00:21:59,640 --> 00:22:01,720 makes a statement visible from space. 484 00:22:01,880 --> 00:22:03,880 PETER SOROYE: In these satellite images, 485 00:22:04,040 --> 00:22:06,960 you can see that this lake actually changes colour. 486 00:22:07,120 --> 00:22:08,840 There is nothing subtle about it. 487 00:22:09,000 --> 00:22:11,680 CYLITA GUY: Scientists believe this stunning colour shift 488 00:22:11,840 --> 00:22:14,120 is caused by microscopic organisms... 489 00:22:14,280 --> 00:22:16,760 either algae or bacteria. 490 00:22:16,920 --> 00:22:18,880 In very bright and salty conditions, 491 00:22:19,040 --> 00:22:21,560 the algae, Dunaliella salina, 492 00:22:21,720 --> 00:22:25,800 turns from green to red as it makes these protective chemicals. 493 00:22:25,960 --> 00:22:29,280 DAN RISKIN: The bacteria, Halobacteriaceae, 494 00:22:29,440 --> 00:22:33,160 actually produce a red pigment that converts light into energy. 495 00:22:33,320 --> 00:22:35,280 So when they appear in large enough numbers, 496 00:22:35,440 --> 00:22:37,520 they make the water look red. 497 00:22:38,680 --> 00:22:41,400 PETER SOROYE: Lake Urmia shows us that there are microscopic creatures 498 00:22:41,560 --> 00:22:44,880 that can change the colour of water for extended periods. 499 00:22:45,040 --> 00:22:46,720 So could invisible bacteria 500 00:22:46,880 --> 00:22:49,080 be behind the glowing milky seas as well? 501 00:22:50,080 --> 00:22:51,920 CYLITA GUY: The latest research suggests 502 00:22:52,080 --> 00:22:55,840 that a bioluminescent bacteria known as Vibrio harveyi could be 503 00:22:56,000 --> 00:22:58,680 the secret ingredient behind these milky seas. 504 00:22:59,560 --> 00:23:02,280 DAN RISKIN: The bacteria can thrive under certain rare conditions, 505 00:23:02,440 --> 00:23:04,200 and when they grow to huge numbers, 506 00:23:04,360 --> 00:23:06,800 they collectively begin to glow. 507 00:23:07,680 --> 00:23:09,960 PETER SOROYE: Glowing is an adaptation that 508 00:23:10,120 --> 00:23:11,800 in other ocean creatures can be anything from 509 00:23:11,960 --> 00:23:16,800 a lure for food to a warning to a means of burning off UV radiation. 510 00:23:16,960 --> 00:23:19,640 NARRATOR: But what's driving these glowing bacteria 511 00:23:19,800 --> 00:23:21,560 is still a mystery. 512 00:23:21,720 --> 00:23:23,480 CYLITA GUY: Milky seas are rare enough 513 00:23:23,640 --> 00:23:25,880 that spotting them and getting to them quickly enough 514 00:23:26,040 --> 00:23:28,680 to test the waters for bacteria is tricky. 515 00:23:28,840 --> 00:23:30,320 So we won't know for sure 516 00:23:30,480 --> 00:23:32,160 if Vibrio harveyi is the culprit 517 00:23:32,320 --> 00:23:34,000 until more research is done. 518 00:23:34,160 --> 00:23:36,080 NARRATOR: And this maritime legend 519 00:23:36,240 --> 00:23:39,200 may hold hints of something even more staggering. 520 00:23:39,360 --> 00:23:41,960 TORRI YATES-ORR: Glowing bacteria may hold a clue 521 00:23:42,120 --> 00:23:44,680 not simply to Earth's milky seas mysteries 522 00:23:44,840 --> 00:23:47,080 but to life on other planets. 523 00:23:47,240 --> 00:23:49,120 DAN RISKIN: A lot of people think that 524 00:23:49,280 --> 00:23:50,960 since bioluminescence works so well 525 00:23:51,120 --> 00:23:53,640 and it's evolved so many times independently, 526 00:23:53,800 --> 00:23:56,120 it's one of the key things we should be looking for 527 00:23:56,280 --> 00:23:58,440 when we look for life on other worlds. 528 00:23:58,600 --> 00:24:02,240 GEORGE KOUROUNIS: With tools like VIIRS pointed toward outer space, 529 00:24:02,400 --> 00:24:05,920 could we uncover a milky sea on another planet? 530 00:24:06,080 --> 00:24:09,280 Only time will tell, but it's a tantalising possibility. 531 00:24:09,440 --> 00:24:11,440 - (dramatic music) 532 00:24:15,120 --> 00:24:17,120 LAUNCH ANNOUNCER: Three, two... 533 00:24:17,280 --> 00:24:19,880 NARRATOR: In 1997, the Cassini Orbiter 534 00:24:20,040 --> 00:24:22,680 launches into the skies... - (boom) 535 00:24:22,840 --> 00:24:27,720 ..beginning a 3.4-billion-kilometre journey through space. 536 00:24:27,880 --> 00:24:30,360 - (electronic hiss) GEORGE KOUROUNIS: Its mission? 537 00:24:30,520 --> 00:24:32,800 An in-depth examination of Saturn... 538 00:24:32,960 --> 00:24:35,040 from above. 539 00:24:35,200 --> 00:24:37,880 DAN RISKIN: As Cassini comes down over the north pole, 540 00:24:38,040 --> 00:24:40,560 it sees something truly incredible. 541 00:24:41,800 --> 00:24:43,800 CYLITA GUY: This is amazing. 542 00:24:43,960 --> 00:24:46,240 There's what looks like a perfect hexagon 543 00:24:46,400 --> 00:24:48,400 right at the top of the planet. 544 00:24:48,560 --> 00:24:51,400 DAN RISKIN: This is honestly one of the weirdest things in the universe. 545 00:24:51,560 --> 00:24:55,960 GEORGE KOUROUNIS: It seems too geometrically perfect to be real. 546 00:24:56,120 --> 00:24:58,600 And this thing is unbelievably massive. 547 00:24:58,760 --> 00:25:02,760 Each side is 13,800 kilometres long, 548 00:25:02,920 --> 00:25:06,000 and it's almost 25,000 kilometres across. 549 00:25:06,960 --> 00:25:08,920 - You could fit almost four Earths in there. 550 00:25:09,080 --> 00:25:10,920 GEORGE KOUROUNIS: How is it possible to have 551 00:25:11,080 --> 00:25:13,280 what looks to be a near perfect hexagon 552 00:25:13,440 --> 00:25:15,480 at the north pole of Saturn? 553 00:25:15,640 --> 00:25:17,720 TORRI YATES-ORR: I mean, what is going on here? 554 00:25:17,880 --> 00:25:20,320 What is this thing made of? 555 00:25:20,480 --> 00:25:22,160 - Why is it there? 556 00:25:22,320 --> 00:25:24,560 GEORGE KOUROUNIS: Saturn is over a billion kilometres 557 00:25:24,720 --> 00:25:29,720 away from Earth. So how can we investigate such a distant mystery? 558 00:25:29,880 --> 00:25:32,760 DAN RISKIN: When it comes to solving mysteries like this, 559 00:25:32,920 --> 00:25:35,320 sometimes you have to start a little closer to home. 560 00:25:35,480 --> 00:25:37,760 NARRATOR: Could clues to this strange phenomenon 561 00:25:37,920 --> 00:25:39,600 be found on Earth? 562 00:25:39,760 --> 00:25:41,880 CYLITA GUY: It seems odd to think about, 563 00:25:42,040 --> 00:25:44,400 but there are actually naturally occurring hexagons 564 00:25:44,560 --> 00:25:46,360 all over our planet. 565 00:25:46,520 --> 00:25:48,520 PETER SOROYE: From beehives to snowflakes, 566 00:25:48,680 --> 00:25:53,560 ancient rock formations to the pinpoint-lenses of dragonfly eyes. 567 00:25:53,720 --> 00:25:56,480 - But why does nature love this shape so much? 568 00:25:57,640 --> 00:25:59,640 NARRATOR: Perhaps a clue can be found 569 00:25:59,800 --> 00:26:02,440 in the heights of Bolivia's Altiplano, 570 00:26:02,600 --> 00:26:06,120 where a vast plain of white can be seen from space. 571 00:26:06,280 --> 00:26:08,280 - This is the Salar de Uyuni. 572 00:26:08,440 --> 00:26:10,680 It covers over 10,000 square kilometres, 573 00:26:10,840 --> 00:26:13,000 making it the largest salt flat in the world. 574 00:26:13,160 --> 00:26:16,000 It's about the same size as the Big Island of Hawaii. 575 00:26:16,160 --> 00:26:18,160 NARRATOR: And viewed from above, 576 00:26:18,320 --> 00:26:22,520 stunning patterns in these ancient salts form a familiar shape. 577 00:26:22,680 --> 00:26:25,880 CYLITA GUY: There are hexagonal formations all across the surface, 578 00:26:26,040 --> 00:26:28,080 around one or two metres across. 579 00:26:28,240 --> 00:26:31,480 TORRI YATES-ORR: But what drives the salt into the hexagon shapes? 580 00:26:31,640 --> 00:26:34,400 PETER SOROYE: For years, scientists believed 581 00:26:34,560 --> 00:26:36,440 that the salt was forming hexagonal ridges 582 00:26:36,600 --> 00:26:39,480 from cracking under the pressure of contracting. 583 00:26:40,480 --> 00:26:43,360 ROMA AGRAWAL: This is something that can happen in cooling lava, 584 00:26:43,520 --> 00:26:46,120 and we can see the results in impressive rock formations 585 00:26:46,280 --> 00:26:48,440 like the Devils Tower in Wyoming 586 00:26:48,600 --> 00:26:50,720 and the Giant's Causeway in Ireland. 587 00:26:50,880 --> 00:26:53,200 CYLITA GUY: These kinds of shapes form because, 588 00:26:53,360 --> 00:26:55,400 as the lava cools, it contracts. 589 00:26:55,560 --> 00:26:58,080 These contractions stress the cooling rock, 590 00:26:58,240 --> 00:27:01,240 which cracks, forming these very efficient shapes. 591 00:27:01,400 --> 00:27:05,280 DAN RISKIN: And that just happens to be at 120-degree angles, 592 00:27:05,440 --> 00:27:07,560 and those are the angles that make a hexagon. 593 00:27:07,720 --> 00:27:09,400 - (dramatic music) 594 00:27:09,560 --> 00:27:11,360 PETER SOROYE: The latest research reveals 595 00:27:11,520 --> 00:27:13,720 the secret behind the salt flat hexagons 596 00:27:13,880 --> 00:27:16,640 is actually in the movement of water. 597 00:27:16,800 --> 00:27:19,320 DAN RISKIN: What's happening at the salt flats 598 00:27:19,480 --> 00:27:22,600 is really happening in the water underneath the crust 599 00:27:22,760 --> 00:27:24,320 in a phenomenon called convection. 600 00:27:24,480 --> 00:27:27,280 PETER SOROYE: Technically, convection is just the transfer 601 00:27:27,440 --> 00:27:29,840 of heat across a space by the movement of a fluid. 602 00:27:30,000 --> 00:27:32,800 CYLITA GUY: The warmer, less dense parts will rise, 603 00:27:32,960 --> 00:27:36,000 while the cooler, more dense material will sink down. 604 00:27:36,160 --> 00:27:37,840 NARRATOR: At the surface, 605 00:27:38,000 --> 00:27:40,800 water evaporates leaving behind ridges of salt 606 00:27:40,960 --> 00:27:45,000 that mirror the patterns of movement hidden under the surface. 607 00:27:45,160 --> 00:27:47,920 ROMA AGRAWAL: This movement tends to form polygonal shapes - 608 00:27:48,080 --> 00:27:50,080 and in perfect conditions, 609 00:27:50,240 --> 00:27:52,240 where there's nothing to interrupt the flow, 610 00:27:52,400 --> 00:27:55,360 convection loves to make hexagonal patterns. 611 00:27:55,520 --> 00:27:59,840 DAN RISKIN: So, could the same forces that make hexagons on Earth 612 00:28:00,000 --> 00:28:02,920 be what's happening on Saturn? 613 00:28:03,080 --> 00:28:05,840 CYLITA GUY: But Saturn's skies aren't made of water. 614 00:28:06,000 --> 00:28:09,720 DAN RISKIN: There isn't even land on Saturn. It's a gas giant. 615 00:28:09,880 --> 00:28:12,400 CYLITA GUY: Gas giants are huge planets 616 00:28:12,560 --> 00:28:15,640 made mainly of gases like helium and hydrogen, 617 00:28:15,800 --> 00:28:18,520 which surround a comparatively smaller solid core. 618 00:28:18,680 --> 00:28:20,600 TORRI YATES-ORR: So you've got to wonder 619 00:28:20,760 --> 00:28:22,440 if the same kind of motion in water on Earth 620 00:28:22,600 --> 00:28:24,280 can happen in gas... 621 00:28:24,440 --> 00:28:26,480 on a much larger scale. 622 00:28:26,640 --> 00:28:29,000 NARRATOR: Perhaps images from the Cassini Orbiter 623 00:28:29,160 --> 00:28:31,160 can provide a clue. 624 00:28:31,320 --> 00:28:33,680 To the naked eye, Saturn's hexagon 625 00:28:33,840 --> 00:28:35,840 appears pale yellow and blue. 626 00:28:36,000 --> 00:28:38,360 But the bright shades of the false colour images 627 00:28:38,520 --> 00:28:40,520 taken right above the pole 628 00:28:40,680 --> 00:28:43,920 uncovers depth and details inside this vast alien shape. 629 00:28:44,080 --> 00:28:45,760 DAN RISKIN: Those different colours 630 00:28:45,920 --> 00:28:48,080 indicate how deep you are in the hexagon. 631 00:28:48,240 --> 00:28:50,120 The redder colours are lower down, 632 00:28:50,280 --> 00:28:51,960 the blue is higher up. 633 00:28:52,120 --> 00:28:54,160 PETER SOROYE: So we can see that this isn't just right 634 00:28:54,320 --> 00:28:57,280 at the very top of the atmosphere. This has some real depth to it. 635 00:28:57,440 --> 00:29:01,120 DAN RISKIN: And crucially, looking straight down from above like this, 636 00:29:01,280 --> 00:29:04,440 Cassini also shows you that the hexagon is rotating. 637 00:29:04,600 --> 00:29:07,320 TORRI YATES-ORR: So how can a perfect shape like this 638 00:29:07,480 --> 00:29:10,000 hold together in the swirling gaseous atmosphere? 639 00:29:10,160 --> 00:29:13,720 NARRATOR: There may be a clue hidden in Earth's skies. 640 00:29:13,880 --> 00:29:16,920 DAN RISKIN: Just like in the water underneath the salt flats, 641 00:29:17,080 --> 00:29:19,400 convection also happens in the atmosphere. 642 00:29:19,560 --> 00:29:21,560 NARRATOR: Convection is behind 643 00:29:21,720 --> 00:29:24,160 the creation of clouds and thunderstorms. 644 00:29:24,320 --> 00:29:25,800 - (thunder cracks) 645 00:29:25,960 --> 00:29:28,040 - And it's the key driver of one of the most powerful 646 00:29:28,200 --> 00:29:30,000 phenomena on Earth... 647 00:29:30,160 --> 00:29:31,960 Hurricanes. - (wind howls) 648 00:29:32,120 --> 00:29:33,920 NARRATOR: Could an epic cyclonic storm 649 00:29:34,080 --> 00:29:36,360 be responsible for Saturn's hexagon? 650 00:29:36,520 --> 00:29:38,280 CYLITA GUY: But there's a problem. 651 00:29:38,440 --> 00:29:40,480 This hexagon isn't like Earth storms. 652 00:29:40,640 --> 00:29:43,840 NARRATOR: In 1981, the Voyager II space probe 653 00:29:44,000 --> 00:29:45,800 approaches Saturn, 654 00:29:45,960 --> 00:29:48,120 and this historic view from above 655 00:29:48,280 --> 00:29:51,840 reveals something shocking when it sees Saturn's north pole. 656 00:29:52,000 --> 00:29:54,800 GEORGE KOUROUNIS: And what did they find? A hexagon. 657 00:29:54,960 --> 00:29:56,960 CYLITA GUY: And since that first finding, 658 00:29:57,120 --> 00:29:59,360 when Saturn's tilted just right, 659 00:29:59,520 --> 00:30:01,800 we've even been able to spot it from Earth. 660 00:30:02,720 --> 00:30:04,640 - This strange shape has been sitting right here 661 00:30:04,800 --> 00:30:06,480 at Saturn's north pole for decades. 662 00:30:06,640 --> 00:30:08,880 PETER SOROYE: But how could a cyclone 663 00:30:09,040 --> 00:30:10,680 last for such a long time? 664 00:30:10,840 --> 00:30:12,520 - (dramatic music) 665 00:30:12,680 --> 00:30:15,840 NARRATOR: A clue lies over 600 million kilometres away, 666 00:30:16,000 --> 00:30:18,000 where a space landmark 667 00:30:18,160 --> 00:30:20,840 on another gas giant stands out... 668 00:30:21,000 --> 00:30:23,920 Jupiter's famous red spot. 669 00:30:24,080 --> 00:30:26,760 DAN RISKIN: The red spot on Jupiter is iconic. 670 00:30:26,920 --> 00:30:29,920 TORRI YATES-ORR: There have been records of a red spot on Jupiter 671 00:30:30,080 --> 00:30:31,960 since the 1600s. 672 00:30:32,120 --> 00:30:34,160 And while we can't be totally sure it's the same one, 673 00:30:34,320 --> 00:30:36,320 it sure looks similar. 674 00:30:36,480 --> 00:30:37,600 - From more modern records, 675 00:30:37,760 --> 00:30:39,440 we know that Jupiter's red spot 676 00:30:39,600 --> 00:30:41,600 is at least 150 years old. 677 00:30:41,760 --> 00:30:45,200 Now, if those 17th century images are of the same spot, 678 00:30:45,360 --> 00:30:48,680 it could be over 350 years old. 679 00:30:48,840 --> 00:30:51,120 TORRI YATES-ORR: So is there something about 680 00:30:51,280 --> 00:30:53,040 a gas-planet atmosphere that can make 681 00:30:53,200 --> 00:30:56,600 these enormous storms live for decades or even centuries? 682 00:30:56,760 --> 00:30:59,080 PETER SOROYE: Unlike Earth and other rocky planets, 683 00:30:59,240 --> 00:31:02,640 gas-planet atmospheres can stretch for thousands of kilometres 684 00:31:02,800 --> 00:31:04,560 before you reach the core. 685 00:31:04,720 --> 00:31:06,880 DAN RISKIN: Basically, gas giants just don't experience 686 00:31:07,040 --> 00:31:09,360 the same kinds of factors we have here on Earth 687 00:31:09,520 --> 00:31:13,440 that make our atmosphere so changeable from day to day. 688 00:31:13,600 --> 00:31:15,280 So if something gets going, 689 00:31:15,440 --> 00:31:17,360 chances are its gonna keep going. 690 00:31:17,520 --> 00:31:19,520 CYLITA GUY: It's an important clue. 691 00:31:19,680 --> 00:31:23,320 But is Saturn's hexagon a cyclonic storm like Jupiter's red spot 692 00:31:23,480 --> 00:31:25,440 or is there something more going on? 693 00:31:26,480 --> 00:31:28,920 NARRATOR: A closer look at Saturn's hexagon 694 00:31:29,080 --> 00:31:31,080 reveals something staggering. 695 00:31:31,240 --> 00:31:33,000 GEORGE KOUROUNIS: How crazy is this? 696 00:31:33,160 --> 00:31:35,160 The centre looks like a hurricane. 697 00:31:35,320 --> 00:31:36,720 - (tense music) 698 00:31:36,880 --> 00:31:38,560 DAN RISKIN: This thing's huge. 699 00:31:38,720 --> 00:31:41,640 The eye of this thing is 2,000 kilometres across. 700 00:31:41,800 --> 00:31:44,400 That's 50 times bigger than the eye of a hurricane on Earth. 701 00:31:44,560 --> 00:31:47,040 NARRATOR: But this stunning whirlwind 702 00:31:47,200 --> 00:31:50,200 is only a small piece of the giant hexagon. 703 00:31:50,360 --> 00:31:54,160 What other hidden forces could be behind this colossal mystery? 704 00:31:54,320 --> 00:31:57,080 GEORGE KOUROUNIS: With a shape like this right at the centre, 705 00:31:57,240 --> 00:32:00,000 it sure seems like there's some potent convection 706 00:32:00,160 --> 00:32:01,840 happening in the atmosphere here. 707 00:32:02,000 --> 00:32:05,200 But could that have any connection to the whole hexagon? 708 00:32:07,480 --> 00:32:09,480 - (ominous music) 709 00:32:09,640 --> 00:32:12,080 NARRATOR: In 2020, Harvard scientists investigate, 710 00:32:12,240 --> 00:32:16,520 running a simulation on NASA supercomputers to test their theory. 711 00:32:16,680 --> 00:32:18,400 CYLITA GUY: One that focused on 712 00:32:18,560 --> 00:32:20,920 the sheer size of Saturn's atmosphere. 713 00:32:21,080 --> 00:32:23,720 DAN RISKIN: Their model imagined clouds and winds 714 00:32:23,880 --> 00:32:26,480 going down to 10% of the planet's radius... 715 00:32:26,640 --> 00:32:29,720 So like 6,000 kilometres deep. 716 00:32:29,880 --> 00:32:32,920 Then they started looking at the kinds of wind patterns that happen 717 00:32:33,080 --> 00:32:35,080 when you combine the planet's rotation 718 00:32:35,240 --> 00:32:37,680 and that really, really deep convection. 719 00:32:38,720 --> 00:32:40,400 - (optimistic music) 720 00:32:40,560 --> 00:32:42,240 CYLITA: Let's remember convection - 721 00:32:42,400 --> 00:32:44,240 hot goes up, cold goes down - 722 00:32:44,400 --> 00:32:47,240 is behind the hexagons in our salt flats on Earth 723 00:32:47,400 --> 00:32:49,080 and the power behind hurricanes. 724 00:32:50,000 --> 00:32:52,240 - Their 3D model showed something really amazing. 725 00:32:52,400 --> 00:32:54,400 The thermal convection spontaneously 726 00:32:54,560 --> 00:32:58,320 makes exactly the right kinds of patterns all over the planet, 727 00:32:58,480 --> 00:33:00,600 including at the pole. 728 00:33:01,880 --> 00:33:05,000 Deep under the surface there are these vortices, these cyclones, 729 00:33:05,160 --> 00:33:09,400 that kind of pinch the jet stream into that hexagon shape. 730 00:33:09,560 --> 00:33:12,960 Because those air movements are deep, they're stable. 731 00:33:13,120 --> 00:33:15,560 So the forms they make stick around for decades. 732 00:33:15,720 --> 00:33:17,480 GEORGE KOUROUNIS: But this is space 733 00:33:17,640 --> 00:33:20,120 we're talking about. We can't close the case just yet. 734 00:33:20,280 --> 00:33:22,040 DAN RISKIN: These are just computer models 735 00:33:22,200 --> 00:33:25,920 based on what we can see from Cassini and a whole lot of guessing. 736 00:33:26,080 --> 00:33:29,000 If we wanna learn more, we gotta send a probe right into the hexagon, 737 00:33:29,160 --> 00:33:31,760 and that's probably at least a few years away. 738 00:33:31,920 --> 00:33:35,480 Until we get to the ringed planet ourselves, 739 00:33:35,640 --> 00:33:37,840 Earth is gonna be the only laboratory we have 740 00:33:38,000 --> 00:33:40,240 to learn about how it all works. 741 00:33:40,400 --> 00:33:42,400 - (contemplative music) 742 00:33:47,400 --> 00:33:49,520 NARRATOR: Far above the Canadian landscape, 743 00:33:49,680 --> 00:33:51,680 satellites looking down from space 744 00:33:51,840 --> 00:33:53,600 spot something uncanny 745 00:33:53,760 --> 00:33:55,760 among the lakes of Northern Saskatchewan. 746 00:33:56,800 --> 00:33:58,600 PETER SOROYE: There are over 100,000 747 00:33:58,760 --> 00:34:00,640 lakes and rivers in Saskatchewan, 748 00:34:00,800 --> 00:34:03,760 mainly left behind by Ice Age glaciers. 749 00:34:03,920 --> 00:34:06,200 - When seen from the skies, one of these lakes 750 00:34:06,360 --> 00:34:08,120 really stands out. 751 00:34:08,280 --> 00:34:11,080 SHEILA HOFFMAN: There's a body of water that looks almost like an eye. 752 00:34:11,240 --> 00:34:14,240 It's almost perfectly round and has an island right in the centre. 753 00:34:14,400 --> 00:34:16,080 CYLITA GUY: Which kind of makes 754 00:34:16,240 --> 00:34:18,040 the whole thing look like a giant Cheerio. 755 00:34:18,200 --> 00:34:20,640 GUY WALTER: Now, the lake isn't huge. 756 00:34:20,800 --> 00:34:22,720 It's about four to five kilometres across 757 00:34:22,880 --> 00:34:25,400 and the island itself is about two kilometres long, 758 00:34:25,560 --> 00:34:27,600 but it doesn't look normal. 759 00:34:27,760 --> 00:34:29,800 CYLITA GUY: If you think about the depth of the lake 760 00:34:29,960 --> 00:34:31,720 along with its circular shape 761 00:34:31,880 --> 00:34:34,720 it almost looks like a crater that's filled with water. 762 00:34:34,880 --> 00:34:38,200 TORRI YATES-ORR: What could have created such a bizarre formation 763 00:34:38,360 --> 00:34:41,120 and why does it look so different from the surrounding lakes? 764 00:34:41,280 --> 00:34:42,960 PETER SOROYE: What forces are capable 765 00:34:43,120 --> 00:34:45,920 of creating huge circles on the Earth's surface? 766 00:34:46,080 --> 00:34:48,080 - (tense music) 767 00:34:48,240 --> 00:34:50,280 NARRATOR: A potential clue could be hidden 768 00:34:50,440 --> 00:34:52,440 around 6,000 kilometres away, 769 00:34:52,600 --> 00:34:54,680 in the English village of Hanbury. 770 00:34:54,840 --> 00:34:57,960 From above, among a patchwork of farm fields, 771 00:34:58,120 --> 00:35:02,120 lies an unexpected circular crater filled with trees 772 00:35:02,280 --> 00:35:04,600 concealing the heart of a disaster. 773 00:35:05,440 --> 00:35:07,880 GUY WALTERS: About 80 years ago, in 1944, 774 00:35:08,040 --> 00:35:10,920 the UK is in the home stretch of the Second World War. 775 00:35:11,080 --> 00:35:12,760 - (artillery fire) 776 00:35:12,920 --> 00:35:14,600 GUY WALTERS: That's the year that you have 777 00:35:14,760 --> 00:35:18,280 the D-Day landings in Normandy and the liberation of Paris. 778 00:35:18,440 --> 00:35:20,280 TORRI YATES-ORR: But in the rural countryside, 779 00:35:20,440 --> 00:35:22,600 hundreds of kilometres from the front lines, 780 00:35:22,760 --> 00:35:24,880 peace is about to be shattered. 781 00:35:25,040 --> 00:35:26,720 GUY WALTER: On November the 27th, 782 00:35:26,880 --> 00:35:29,720 at 11 o'clock in the morning, there's this sudden explosion 783 00:35:29,880 --> 00:35:32,560 that shakes the entire village of Hanbury. 784 00:35:32,720 --> 00:35:34,680 - (explosion) 785 00:35:34,840 --> 00:35:36,720 GUY WALTER: You've got this double blast 786 00:35:36,880 --> 00:35:39,600 shooting this mushroom cloud into the sky, 787 00:35:39,760 --> 00:35:43,240 and it flattens everything in a 13-hundred-metre radius. 788 00:35:43,400 --> 00:35:45,480 TORRI YATES-ORR: The blast leaves 789 00:35:45,640 --> 00:35:47,600 a huge circular crater on the landscape. 790 00:35:47,760 --> 00:35:51,120 It's around 250 metres across and about 30 metres deep. 791 00:35:52,280 --> 00:35:55,400 NARRATOR: But what explosive power is behind this destruction? 792 00:35:56,440 --> 00:35:59,000 Could the answer be concealed below the surface? 793 00:35:59,920 --> 00:36:01,880 GUY WALTER: What you've got here is a highly secret 794 00:36:02,040 --> 00:36:04,280 British bomb storage site, 795 00:36:04,440 --> 00:36:06,320 known as RAF Fauld. 796 00:36:06,480 --> 00:36:08,880 And this place stored absolutely huge amounts 797 00:36:09,040 --> 00:36:11,200 of various explosive munitions. 798 00:36:11,360 --> 00:36:13,920 I mean, this place was packed to the rafters. 799 00:36:15,160 --> 00:36:18,080 TORRI YATES-ORR: That's a lot of power in one place, 800 00:36:18,240 --> 00:36:21,280 and if anyone found out about it that would be a major target. 801 00:36:21,440 --> 00:36:23,880 So did spies discover it and plan its destruction? 802 00:36:24,040 --> 00:36:25,720 Was it sabotaged? 803 00:36:26,640 --> 00:36:28,320 GUY WALTER: This is a part of England 804 00:36:28,480 --> 00:36:31,480 that has long been targeted by Axis air raids, 805 00:36:31,640 --> 00:36:33,320 and the Nazis very quickly claim 806 00:36:33,480 --> 00:36:37,920 that it's one of their V-2 rockets that has caused this devastation. 807 00:36:38,080 --> 00:36:39,520 - (explosion) 808 00:36:39,680 --> 00:36:41,520 SHEILA HOFFMAN: But this time, it isn't the Germans. 809 00:36:41,680 --> 00:36:44,520 The investigation revealed something shocking and tragic. 810 00:36:44,680 --> 00:36:46,560 In the pressure of wartime, 811 00:36:46,720 --> 00:36:48,440 a fatal mistake was made. 812 00:36:48,600 --> 00:36:50,680 GUY WALTER: It's very likely that someone 813 00:36:50,840 --> 00:36:52,840 mishandled a live bomb. 814 00:36:53,000 --> 00:36:57,120 Now, the thick walls of the mine prevent an even worse catastrophe, 815 00:36:57,280 --> 00:36:59,560 but what happened was bad enough. 816 00:36:59,720 --> 00:37:03,080 TORRI YATES-ORR: About four million kilograms of explosives, 817 00:37:03,240 --> 00:37:07,960 including a whopping 500 million rounds of rifle ammunition, blew up. 818 00:37:08,120 --> 00:37:09,800 - (explosion) 819 00:37:09,960 --> 00:37:12,840 TORRI YATES-ORR: It was one of the largest explosions ever in the UK. 820 00:37:14,000 --> 00:37:16,160 SHEILA HOFFMAN: When you see it from above today, 821 00:37:16,320 --> 00:37:18,200 the crater is filled with trees and plants 822 00:37:18,360 --> 00:37:20,040 and looks quite peaceful and safe. 823 00:37:20,200 --> 00:37:23,200 GUY WALTER: But the hole in the earth remains, 824 00:37:23,360 --> 00:37:27,360 along with a number of explosives still buried in those tunnels below. 825 00:37:27,520 --> 00:37:30,920 NARRATOR: Could the strange-shaped lake in Saskatchewan 826 00:37:31,080 --> 00:37:34,120 be the result of a World War II era weapon? 827 00:37:34,280 --> 00:37:35,720 GUY WALTER: While Japan lobbed shells 828 00:37:35,880 --> 00:37:38,520 at a British Columbia lighthouse in 1942 829 00:37:38,680 --> 00:37:40,800 and Axis forces hit the St Lawrence River 830 00:37:40,960 --> 00:37:42,800 during the Battle of the Atlantic, 831 00:37:42,960 --> 00:37:44,960 Saskatchewan was well out of reach. 832 00:37:45,120 --> 00:37:47,800 TORRI YATES-ORR: So if this weird doughnut-shaped lake 833 00:37:47,960 --> 00:37:50,840 isn't a sign of some kind of human-made explosion, 834 00:37:51,000 --> 00:37:52,760 what else could be going on? 835 00:37:52,920 --> 00:37:54,600 SHEILA HOFFMAN: What other forces can make 836 00:37:54,760 --> 00:37:56,720 this kind of unique shape on the landscape? 837 00:37:56,880 --> 00:37:59,240 Is a powerful natural force at play here? 838 00:37:59,400 --> 00:38:02,320 CYLITA GUY: There's another out-of-this world possibility. 839 00:38:03,760 --> 00:38:05,760 - (meteor cracks) 840 00:38:07,080 --> 00:38:10,000 PETER SOROYE: There are a few known impact craters around Canada, 841 00:38:10,160 --> 00:38:12,440 so it makes sense to think this could be among them. 842 00:38:14,640 --> 00:38:16,560 NARRATOR: But when researchers venture 843 00:38:16,720 --> 00:38:18,680 into the wilds of Saskatchewan to investigate, 844 00:38:18,840 --> 00:38:20,680 they uncover something revealing. 845 00:38:20,840 --> 00:38:23,440 TORRI YATES-ORR: When they examine the rock of the centre island, 846 00:38:23,600 --> 00:38:26,120 they realise something strange is going on. 847 00:38:27,160 --> 00:38:30,600 NARRATOR: This isn't like any impact crater they've ever seen on Earth. 848 00:38:30,760 --> 00:38:32,440 CYLITA GUY: On Earth, you expect 849 00:38:32,600 --> 00:38:34,320 two main kinds of impact craters. 850 00:38:34,480 --> 00:38:36,600 Smaller impacts make simple craters, 851 00:38:36,760 --> 00:38:39,720 which are basically just these bowl-shaped holes. 852 00:38:39,880 --> 00:38:43,280 Bigger impacts make something called complex craters. 853 00:38:43,440 --> 00:38:46,040 PETER SOROYE: When these bigger meteors hit the ground, 854 00:38:46,200 --> 00:38:49,040 it's so big and powerful, has so much energy, 855 00:38:49,200 --> 00:38:51,800 that solid earth starts to act like a fluid 856 00:38:51,960 --> 00:38:55,240 and rebounds or splashes up in the middle of the impact hole, 857 00:38:55,400 --> 00:38:57,480 like when a stone is thrown into the water. 858 00:38:57,640 --> 00:38:59,920 When that rebound of solid earth drops back down, 859 00:39:00,080 --> 00:39:02,000 you're left with a central peak. 860 00:39:02,160 --> 00:39:04,640 GEORGE KOUROUNIS: If you look at the shape of this lake doughnut, 861 00:39:04,800 --> 00:39:07,880 it looks just like a complex crater filled with water. 862 00:39:08,040 --> 00:39:10,480 That's what the researchers expected to find. 863 00:39:10,640 --> 00:39:12,320 - (dramatic music) 864 00:39:12,480 --> 00:39:14,680 NARRATOR: But what they uncover is out of this world. 865 00:39:16,120 --> 00:39:19,120 CYLITA GUY: Basically, the rock here is the wrong kind of rock. 866 00:39:19,280 --> 00:39:21,320 Whatever this central island is, 867 00:39:21,480 --> 00:39:25,120 it wasn't made by the rebound you see of a complex crater. 868 00:39:25,280 --> 00:39:27,840 DAN RISKIN: But it can't be a simple crater either 869 00:39:28,000 --> 00:39:30,640 because the floor and the walls are too full of debris. 870 00:39:30,800 --> 00:39:32,480 CYLITA GUY: The researchers realised 871 00:39:32,640 --> 00:39:34,360 they'd seen something like this before 872 00:39:34,520 --> 00:39:36,520 but not on Earth. 873 00:39:36,680 --> 00:39:38,760 NARRATOR: The final clue to solve this mystery 874 00:39:38,920 --> 00:39:41,200 can be found by looking down from above 875 00:39:41,360 --> 00:39:43,520 at our planet's nearest neighbour... 876 00:39:43,680 --> 00:39:45,520 the moon. 877 00:39:45,680 --> 00:39:47,560 PETER SOROYE: Earth's moon is pockmarked 878 00:39:47,720 --> 00:39:49,920 by countless thousands of craters 879 00:39:50,080 --> 00:39:53,440 from the giant 25-hundred-kilometre South Pole-Aitken basin 880 00:39:53,600 --> 00:39:58,040 to the microscopic dents found in moon rocks from the Apollo missions. 881 00:39:59,000 --> 00:40:01,560 - Because of the lack of atmosphere and plate tectonics, 882 00:40:01,720 --> 00:40:03,520 the moon's craters aren't subject to 883 00:40:03,680 --> 00:40:05,360 the same changes we see here on Earth. 884 00:40:05,520 --> 00:40:09,240 For example, they don't get hidden over time by things like water. 885 00:40:09,400 --> 00:40:11,520 As a result, these craters can tell us 886 00:40:11,680 --> 00:40:15,240 a lot about the history of the meteoroid strikes that form them. 887 00:40:16,200 --> 00:40:18,200 NARRATOR: And one type of moon crater 888 00:40:18,360 --> 00:40:20,520 could solve the mystery in Saskatchewan. 889 00:40:21,360 --> 00:40:24,640 DAN RISKIN: When you look at sort of medium-size craters on the moon 890 00:40:24,800 --> 00:40:27,400 from like 15 to 42 kilometres in diameter, 891 00:40:27,560 --> 00:40:29,640 you see something pretty special. 892 00:40:29,800 --> 00:40:32,600 PETER SOROYE: These aren't bowl-shaped, like simple craters, 893 00:40:32,760 --> 00:40:35,760 but they don't have the central peak of complex craters either. 894 00:40:35,920 --> 00:40:39,160 DAN RISKIN: Instead, they're kind of like this in-between stage 895 00:40:39,320 --> 00:40:41,840 where they have some of the traits of each type of crater. 896 00:40:42,000 --> 00:40:44,120 These are called transitional craters. 897 00:40:44,280 --> 00:40:45,960 They have flat floors, 898 00:40:46,120 --> 00:40:48,120 one or more terraces or rock slides, 899 00:40:48,280 --> 00:40:50,080 like you'd see in a complex crater, 900 00:40:50,240 --> 00:40:52,120 but with no central peak. 901 00:40:52,280 --> 00:40:53,960 NARRATOR: But can this happen on Earth? 902 00:40:54,120 --> 00:40:57,640 CYLITA GUY: Transitional craters form so easily on the moon 903 00:40:57,800 --> 00:41:00,600 because of its lack of atmosphere and low gravity. 904 00:41:00,760 --> 00:41:03,520 So it's easier for larger objects to hit more gently. 905 00:41:03,680 --> 00:41:06,640 DAN RISKIN: But with Earth's atmosphere and gravity, 906 00:41:06,800 --> 00:41:09,640 we don't expect quite so much of that middle ground. 907 00:41:09,800 --> 00:41:11,960 Anything that would make a medium hit on the moon 908 00:41:12,120 --> 00:41:14,440 would accelerate way more in Earth's gravity, 909 00:41:14,600 --> 00:41:16,840 so it would end up being a big punch, not a medium one. 910 00:41:17,000 --> 00:41:18,680 - (meteor hisses) 911 00:41:18,840 --> 00:41:21,240 CYLITA: Science basically thought that finding that middle ground 912 00:41:21,400 --> 00:41:24,000 here on Earth was essentially impossible. 913 00:41:24,160 --> 00:41:27,080 But this discovery changes everything. 914 00:41:27,240 --> 00:41:28,920 DAN RISKIN: To find something 915 00:41:29,080 --> 00:41:32,200 that we can confirm is a transitional impact crater 916 00:41:32,360 --> 00:41:34,160 and to see that it's in such good shape, 917 00:41:34,320 --> 00:41:36,400 this is groundbreaking. 918 00:41:36,560 --> 00:41:38,360 PETER SOROYE: But then you've got to ask... 919 00:41:38,520 --> 00:41:40,200 how did the central island form 920 00:41:40,360 --> 00:41:42,200 if not through the initial space rock impact? 921 00:41:42,360 --> 00:41:44,040 - (dramatic music) 922 00:41:44,200 --> 00:41:46,440 DAN RISKIN: The crater is about 200 million years old. 923 00:41:46,600 --> 00:41:48,880 So it happened when the Earth looked very different 924 00:41:49,040 --> 00:41:50,720 from the way it looks today. 925 00:41:50,880 --> 00:41:52,560 CYLITA GUY: So it's hard to say for sure 926 00:41:52,720 --> 00:41:54,400 what factors created the island. 927 00:41:54,560 --> 00:41:58,000 DAN RISKIN: But the thinking is that, over millions of years, 928 00:41:58,160 --> 00:42:00,160 wind and rain would have worn down 929 00:42:00,320 --> 00:42:02,840 the edges of the crater until it was almost flat, 930 00:42:03,000 --> 00:42:05,720 and that central dip would have filled with sediment. 931 00:42:05,880 --> 00:42:07,880 CYLITA GUY: Then, experts think that 932 00:42:08,040 --> 00:42:11,080 the movement of glaciers over the land during the last ice age 933 00:42:11,240 --> 00:42:13,080 could have carved up the landscape, 934 00:42:13,240 --> 00:42:15,080 including in this ancient crater. 935 00:42:15,240 --> 00:42:17,240 DAN RISKIN: Thanks to the melting glaciers, 936 00:42:17,400 --> 00:42:19,800 water would have filled these new scars in the landscape, 937 00:42:19,960 --> 00:42:23,840 which merged with the crater to form the lake as we see it today. 938 00:42:24,800 --> 00:42:28,080 NARRATOR: This astonishing discovery isn't just unprecedented. 939 00:42:28,240 --> 00:42:29,920 CYLITA GUY: It's the chance to study 940 00:42:30,080 --> 00:42:32,880 a phenomena we observe on the moon right here on Earth. 941 00:42:33,040 --> 00:42:35,960 This is what makes this discovery even more exciting. 942 00:42:36,840 --> 00:42:39,760 NARRATOR: Another Canadian impact crater in Labrador 943 00:42:39,920 --> 00:42:42,560 is already hosting cutting-edge lunar research. 944 00:42:42,720 --> 00:42:45,760 PETER SOROYE: The meteorite that made the Mistastin Lake crater 945 00:42:45,920 --> 00:42:48,240 left behind rocks that are almost identical 946 00:42:48,400 --> 00:42:50,920 to ones found all over the moon. 947 00:42:51,080 --> 00:42:54,240 CYLITA GUY: So today NASA uses the site to train astronauts 948 00:42:54,400 --> 00:42:56,640 for their new moon mission - Artemis. 949 00:42:56,800 --> 00:42:58,840 DAN RISKIN: And this lake may hold 950 00:42:59,000 --> 00:43:01,080 just as many lunar-style secrets. 951 00:43:01,240 --> 00:43:03,040 CYLITA GUY: It's amazing to me 952 00:43:03,200 --> 00:43:06,120 how much we can learn about our solar system and beyond 953 00:43:06,280 --> 00:43:08,880 from studying features right here on Earth. 954 00:43:09,800 --> 00:43:11,680 DAN RISKIN: I think this is cool because we use the moon 955 00:43:11,840 --> 00:43:13,360 to solve this mystery here on Earth. 956 00:43:13,520 --> 00:43:15,400 But as we do the research on the ground, 957 00:43:15,560 --> 00:43:18,000 we uncover these secrets that are gonna help us understand the moon. 958 00:43:18,160 --> 00:43:19,920 - (wind whistles) 959 00:43:20,080 --> 00:43:21,800 - (dramatic music) 960 00:43:21,960 --> 00:43:24,240 NARRATOR: From signs of ice on Mars 961 00:43:24,400 --> 00:43:26,320 and stunning shapes on Saturn 962 00:43:26,480 --> 00:43:30,600 to hidden impact craters and mysterious milky seas on Earth... 963 00:43:30,760 --> 00:43:33,920 some of the grandest mysteries are discovered from space. 964 00:43:34,880 --> 00:43:37,960 And with the latest technology looking down from above, 965 00:43:38,120 --> 00:43:40,720 Earth's secrets can reveal the truth about space 966 00:43:40,880 --> 00:43:43,720 and resolve longstanding riddles back home. 967 00:43:43,880 --> 00:43:45,880 - (uplifting music) 968 00:43:47,200 --> 00:43:49,880 - I love the fact that we're learning more and more 969 00:43:50,040 --> 00:43:53,400 about our own backyard here in the vastness of space. 970 00:43:54,520 --> 00:43:57,560 - And you just know that the next find is right around the corner. 971 00:44:03,120 --> 00:44:06,080 Subtitles by Sky Access Services