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These are the user uploaded subtitles that are being translated: 0 00:00:00,010 --> 00:00:07,777 SUB BY : DENI AUROR@ https://aurorarental.blogspot.com/ 1 00:00:03,069 --> 00:00:05,504 3.7 billion years ago, 2 00:00:05,506 --> 00:00:10,141 early life was on the brink of extinction. 3 00:00:10,143 --> 00:00:11,376 Colossal impacts... 4 00:00:15,982 --> 00:00:18,483 Ferocious climate change... 5 00:00:18,485 --> 00:00:23,788 And total atmospheric collapse have turned paradise into hell. 6 00:00:24,657 --> 00:00:26,391 But this isn't earth ... 7 00:00:26,393 --> 00:00:27,626 it's Mars ... 8 00:00:27,628 --> 00:00:30,129 and this is the violent history of perhaps 9 00:00:30,131 --> 00:00:33,632 the first life forms in our solar system. 10 00:00:33,634 --> 00:00:36,935 Could these martians still exist today? 11 00:00:36,937 --> 00:00:39,938 Could they even be living among us? 12 00:00:42,743 --> 00:00:45,744 Captions paid for by discovery communications 13 00:00:57,223 --> 00:01:03,295 Scientists suspect that life may once have thrived on Mars... 14 00:01:03,297 --> 00:01:05,363 That the barren world we see today 15 00:01:05,365 --> 00:01:08,634 swarmed with martians long ago. 16 00:01:08,636 --> 00:01:10,669 If I had to bet something incredibly valuable to me ... 17 00:01:10,671 --> 00:01:12,938 if I had to bet my car ... on whether or not 18 00:01:12,940 --> 00:01:15,073 there's life on Mars, 19 00:01:15,075 --> 00:01:17,409 or evidence of past life on Mars, 20 00:01:17,411 --> 00:01:19,511 I'd take that bet. 21 00:01:19,513 --> 00:01:20,712 The building blocks for life 22 00:01:20,714 --> 00:01:23,382 are widespread in the universe, 23 00:01:23,384 --> 00:01:26,218 and early Mars could have been the perfect place 24 00:01:26,220 --> 00:01:29,188 to pull these ingredients together. 25 00:01:29,190 --> 00:01:31,823 If you had a recipe book for everything you need for life, 26 00:01:31,825 --> 00:01:35,093 you'd have things like water, organic chemistry, 27 00:01:35,095 --> 00:01:36,929 a stable surface, a thick atmosphere ... 28 00:01:36,931 --> 00:01:39,231 well, Mars had all of those. 29 00:01:39,233 --> 00:01:41,799 Mars satisfies every specific requirement 30 00:01:41,801 --> 00:01:45,737 for letting life get started. 31 00:01:45,739 --> 00:01:46,738 Life on Mars 32 00:01:46,740 --> 00:01:48,407 may have been inevitable, 33 00:01:48,409 --> 00:01:52,077 and we've sent a robot army to hunt for signs of it. 34 00:01:52,079 --> 00:01:55,113 But so far, it's been elusive. 35 00:01:55,115 --> 00:01:57,449 Our rovers, landers, and satellites 36 00:01:57,451 --> 00:01:59,351 haven't found life yet, 37 00:01:59,353 --> 00:02:03,055 but they have found evidence of something extraordinary. 38 00:02:05,625 --> 00:02:08,793 Mars was the victim of a devastating series 39 00:02:08,795 --> 00:02:10,595 of extinction-level events 40 00:02:10,597 --> 00:02:14,766 that rocked the red planet to its core... 41 00:02:14,768 --> 00:02:16,368 Leading us to wonder, 42 00:02:16,370 --> 00:02:20,138 if life could have started over multiple times, 43 00:02:20,140 --> 00:02:22,841 with generation after generation of martians 44 00:02:22,843 --> 00:02:28,180 rising and falling through Mars' violent history. 45 00:02:30,383 --> 00:02:33,518 It seems likely that a first Genesis of life 46 00:02:33,520 --> 00:02:36,988 could have occurred very early on in Mars' history, 47 00:02:36,990 --> 00:02:39,458 just as soon as the crust was cool enough 48 00:02:39,460 --> 00:02:42,194 to give it a solid foothold. 49 00:02:42,196 --> 00:02:44,463 The secret to this early life would have been 50 00:02:44,465 --> 00:02:50,002 a crucial ingredient, one shared by the young earth. 51 00:02:50,004 --> 00:02:54,873 Dry, harsh Mars once had oceans. 52 00:02:54,875 --> 00:02:56,341 For life to get started, 53 00:02:56,343 --> 00:02:58,277 you need some carbon, an energy source, 54 00:02:58,279 --> 00:03:00,379 it needs nutrients like nitrogen... 55 00:03:00,381 --> 00:03:02,714 But those are likely to be present on Mars, 56 00:03:02,716 --> 00:03:04,883 they are present and widespread on earth. 57 00:03:04,885 --> 00:03:07,051 The essential requirement is really the liquid water. 58 00:03:09,822 --> 00:03:10,956 Picture Mars 59 00:03:10,958 --> 00:03:15,326 4.5 billion years ago. 60 00:03:15,328 --> 00:03:19,531 Molten rock has cooled to form a solid crust. 61 00:03:19,533 --> 00:03:25,370 Water collects on the surface, forming primitive oceans. 62 00:03:25,372 --> 00:03:26,671 Rain clouds sweep across 63 00:03:26,673 --> 00:03:29,374 the steaming, volcanic landscape, 64 00:03:29,376 --> 00:03:31,576 and in shallow pools of water, 65 00:03:31,578 --> 00:03:35,480 the martians begin to emerge. 66 00:03:35,482 --> 00:03:37,416 But these first aliens are simpler 67 00:03:37,418 --> 00:03:40,685 than Sci-Fi would have us believe. 68 00:03:40,687 --> 00:03:42,487 We're probably not talking about little green men 69 00:03:42,489 --> 00:03:43,922 or women, or whoever. 70 00:03:43,924 --> 00:03:46,591 Walking around on the surface of Mars, we ... 71 00:03:46,593 --> 00:03:47,859 we're talking about something probably 72 00:03:47,861 --> 00:03:49,294 much, much smaller and simpler, 73 00:03:49,296 --> 00:03:51,096 single-celled life. 74 00:03:51,098 --> 00:03:52,230 If would look familiar, 75 00:03:52,232 --> 00:03:53,898 it would look just like bacteria on earth. 76 00:03:53,900 --> 00:03:58,036 Little, tiny, round, rod-shaped organisms. 77 00:03:58,038 --> 00:03:59,504 If this generation 78 00:03:59,506 --> 00:04:02,507 of bacterial martian life really did exist, 79 00:04:02,509 --> 00:04:06,044 it was the first life to grace our solar system. 80 00:04:06,046 --> 00:04:09,147 Multiplying inside the rock pools of Mars 81 00:04:09,149 --> 00:04:12,784 long before life took hold on earth, 82 00:04:12,786 --> 00:04:16,255 Mars' small size would've given it a head start. 83 00:04:17,857 --> 00:04:19,457 Because Mars is smaller 84 00:04:19,459 --> 00:04:20,659 than the earth it would have cooled 85 00:04:20,661 --> 00:04:22,794 a little bit faster than we did. 86 00:04:22,796 --> 00:04:24,630 So early on in the life of the solar system, 87 00:04:24,632 --> 00:04:26,898 Mars may have been more like earth 88 00:04:26,900 --> 00:04:29,101 than earth was at the time. 89 00:04:31,371 --> 00:04:33,505 Let's go back 100 million years 90 00:04:33,507 --> 00:04:35,641 after the sun formed. 91 00:04:35,643 --> 00:04:39,211 The surface of the earth is still a molten lake. 92 00:04:39,213 --> 00:04:41,146 But martian life could be thriving 93 00:04:41,148 --> 00:04:46,184 on the smaller, cooler world. 94 00:04:46,186 --> 00:04:48,253 But these first martians won't have long 95 00:04:48,255 --> 00:04:50,855 to enjoy their time in the sun. 96 00:04:50,857 --> 00:04:56,228 Inescapable death is already on its way from space... 97 00:04:57,630 --> 00:04:59,998 A cosmic bomb so huge, 98 00:05:00,000 --> 00:05:03,301 it would completely alter the shape of the planet, 99 00:05:03,303 --> 00:05:04,703 leaving it lopsided, 100 00:05:04,705 --> 00:05:09,107 the northern hemisphere crushed. 101 00:05:09,109 --> 00:05:10,442 Most planets are round, 102 00:05:10,444 --> 00:05:11,843 and that's just something you don't really 103 00:05:11,845 --> 00:05:13,477 give much thought to, 104 00:05:13,479 --> 00:05:16,681 but it turns out Mars isn't as round as it could be. 105 00:05:16,683 --> 00:05:20,152 The Southern hemisphere, on average, 106 00:05:20,154 --> 00:05:23,455 has a higher elevation than the northern hemisphere. 107 00:05:23,457 --> 00:05:25,990 So, in other words, if you were to start on the north pole 108 00:05:25,992 --> 00:05:28,593 and walk all the way around to the south pole, 109 00:05:28,595 --> 00:05:32,397 you'd be walking uphill, essentially, the whole time. 110 00:05:36,936 --> 00:05:38,704 So, we call this difference between the northern 111 00:05:38,706 --> 00:05:39,938 and the Southern hemisphere, 112 00:05:39,940 --> 00:05:41,973 we call this the crustal dichotomy on Mars, 113 00:05:41,975 --> 00:05:44,509 and it's been one of the biggest mysteries of the planet, 114 00:05:44,511 --> 00:05:46,445 you know, it's the first thing that you see about it, 115 00:05:46,447 --> 00:05:48,680 and you say, well, how could this possibly have happened? 116 00:05:51,751 --> 00:05:53,652 In 2008, scientists mapping 117 00:05:53,654 --> 00:05:57,322 the surface of Mars came up with an explanation 118 00:05:57,324 --> 00:06:01,793 for the massive dent in the planet, shown in blue. 119 00:06:01,795 --> 00:06:04,162 This basin, the biggest in the solar system, 120 00:06:04,164 --> 00:06:07,699 had to be the result of a massive impact. 121 00:06:07,701 --> 00:06:09,734 Called the borealis impact, 122 00:06:09,736 --> 00:06:15,406 it blasted out a crater 6500 miles wide and five miles deep, 123 00:06:15,408 --> 00:06:18,610 big enough to swallow the entire United States 124 00:06:18,612 --> 00:06:20,512 with room to spare. 125 00:06:20,514 --> 00:06:22,613 Something really big happened. 126 00:06:22,615 --> 00:06:24,516 In fact, the entire top half of the planet 127 00:06:24,518 --> 00:06:26,651 seems to have practically been blown off. 128 00:06:26,653 --> 00:06:29,687 The only thing that could do that is a huge collision, 129 00:06:29,689 --> 00:06:31,122 and we're talking a collision 130 00:06:31,124 --> 00:06:33,091 with something the size of pluto, perhaps. 131 00:06:35,962 --> 00:06:38,029 You're talking about an impact 132 00:06:38,031 --> 00:06:39,931 that makes the dinosaur killer impact 133 00:06:39,933 --> 00:06:43,301 65 million years ago look pretty much like a wet firecracker. 134 00:06:46,405 --> 00:06:48,407 4.5 billion years ago, 135 00:06:48,409 --> 00:06:50,141 the early solar system is filled 136 00:06:50,143 --> 00:06:54,045 with planetesimals and protoplanets ... 137 00:06:54,047 --> 00:06:57,115 asteroid-like leftovers from a planet building process 138 00:06:57,117 --> 00:07:00,651 that created Mars and the earth. 139 00:07:00,653 --> 00:07:02,620 One of these asteroids is huge, 140 00:07:02,622 --> 00:07:06,758 and it's on a direct collision course with Mars. 141 00:07:06,760 --> 00:07:10,595 Any microscopic martians have just seconds to live. 142 00:07:12,899 --> 00:07:14,899 If this impact was happening today 143 00:07:14,901 --> 00:07:18,670 and we were so unlucky as to be there to witness it, 144 00:07:18,672 --> 00:07:21,940 what you first would have seen is another moon in the sky... 145 00:07:24,143 --> 00:07:25,744 And then you would've looked back and seen, 146 00:07:25,746 --> 00:07:28,179 oh, it's getting bigger. 147 00:07:31,384 --> 00:07:34,152 As it came down it would have filled the entire sky, 148 00:07:34,154 --> 00:07:35,953 from horizon to horizon, 149 00:07:35,955 --> 00:07:38,256 and as it struck, 150 00:07:38,258 --> 00:07:41,293 the top would have still been well out into space. 151 00:07:43,729 --> 00:07:44,729 The impactor 152 00:07:44,731 --> 00:07:46,898 is 1200 miles across, 153 00:07:46,900 --> 00:07:48,666 the size of pluto, 154 00:07:48,668 --> 00:07:51,302 and as it hits, the energy of the impact 155 00:07:51,304 --> 00:07:54,105 shakes Mars to its core. 156 00:07:54,107 --> 00:07:58,209 The entire planet wobbles like jell-o. 157 00:07:58,211 --> 00:07:59,478 As it came down, 158 00:07:59,480 --> 00:08:02,680 it would have been hitting into the surface of Mars 159 00:08:02,682 --> 00:08:05,850 as fast as a bullet out of a gun, 160 00:08:05,852 --> 00:08:08,286 and it would have slammed into the surface 161 00:08:08,288 --> 00:08:10,154 and sent a shockwave out 162 00:08:10,156 --> 00:08:12,591 that would've been bigger than any earthquake ever recorded. 163 00:08:14,661 --> 00:08:16,261 It would have been like a Tsunami of rock 164 00:08:16,263 --> 00:08:19,597 coming out and tossing us out of the way. 165 00:08:22,435 --> 00:08:25,036 The impact is catastrophic. 166 00:08:26,707 --> 00:08:30,375 It blows nearly half the planet's surface into space 167 00:08:30,377 --> 00:08:35,313 and turns what crust remains into a boiling lake of lava. 168 00:08:36,849 --> 00:08:39,016 You can't have an impact of that scale 169 00:08:39,018 --> 00:08:42,020 without almost melting the planet. 170 00:08:42,022 --> 00:08:43,989 It's not literally a planet breaking event, 171 00:08:43,991 --> 00:08:45,757 but it's a planet melting event, 172 00:08:45,759 --> 00:08:47,792 and it is, it is the sterilization 173 00:08:47,794 --> 00:08:48,527 of the planet at that point. 174 00:08:53,799 --> 00:08:56,834 The surface of Mars was molten, 175 00:08:56,836 --> 00:09:00,004 its atmosphere blown into space, 176 00:09:00,006 --> 00:09:02,807 the oceans boiled away. 177 00:09:02,809 --> 00:09:05,110 If Mars was home to the first generation of life 178 00:09:05,112 --> 00:09:07,144 in our solar system, 179 00:09:07,146 --> 00:09:10,115 that life didn't stand a chance. 180 00:09:10,117 --> 00:09:13,618 It would take the surface of Mars 50 million years 181 00:09:13,620 --> 00:09:15,720 to recover from the impact. 182 00:09:19,392 --> 00:09:23,028 But what sort of planet will rise from the ashes? 183 00:09:23,030 --> 00:09:26,798 Compelling new evidence suggests that the conditions for life 184 00:09:26,800 --> 00:09:29,568 may have returned to Mars, 185 00:09:29,570 --> 00:09:34,139 but did life itself make a comeback? 186 00:09:34,141 --> 00:09:36,807 This impact was only a blip in time, 187 00:09:36,809 --> 00:09:39,176 and there was possibilities for life 188 00:09:39,178 --> 00:09:40,678 and the planet to recover. 189 00:10:02,134 --> 00:10:04,335 4.5 billion years ago 190 00:10:04,337 --> 00:10:06,738 an asteroid the size of pluto 191 00:10:06,740 --> 00:10:12,277 slammed into the surface of infant Mars. 192 00:10:12,279 --> 00:10:14,446 It melted the surface of the planet, 193 00:10:14,448 --> 00:10:17,282 it blew the atmosphere into space, 194 00:10:17,284 --> 00:10:20,085 and it boiled away the oceans. 195 00:10:20,087 --> 00:10:22,954 If life had gotten a foothold on the planet, 196 00:10:22,956 --> 00:10:27,225 that life would have been completely exterminated. 197 00:10:27,227 --> 00:10:29,527 But some scientists believe this extinction 198 00:10:29,529 --> 00:10:31,029 could have been brief, 199 00:10:31,031 --> 00:10:35,833 and that life could have started again from scratch. 200 00:10:35,835 --> 00:10:37,235 One of the wonderful things 201 00:10:37,237 --> 00:10:38,670 to imagine is that there probably wasn't 202 00:10:38,672 --> 00:10:40,338 a single origin of life. 203 00:10:40,340 --> 00:10:41,739 It's not like it happened once 204 00:10:41,741 --> 00:10:43,875 and then everything just went from there. 205 00:10:43,877 --> 00:10:45,810 Maybe there were multiple times that life got started 206 00:10:45,812 --> 00:10:49,280 and went extinct. 207 00:10:49,282 --> 00:10:50,281 Ten million years 208 00:10:50,283 --> 00:10:51,482 after the borealis impact 209 00:10:51,484 --> 00:10:54,019 crushed the planet's northern hemisphere, 210 00:10:54,021 --> 00:10:56,354 Mars has cooled enough for its surface 211 00:10:56,356 --> 00:10:59,590 to become solid once more. 212 00:10:59,592 --> 00:11:02,127 The planet has some of the ingredients for life ... 213 00:11:02,129 --> 00:11:04,262 the right molecules, a stable surface, 214 00:11:04,264 --> 00:11:06,464 and an energy source. 215 00:11:06,466 --> 00:11:08,866 But something's missing. 216 00:11:08,868 --> 00:11:13,805 4.49 billion years ago the surface of Mars was dry, 217 00:11:13,807 --> 00:11:16,074 and without water, life can't start over 218 00:11:16,076 --> 00:11:20,912 and a second generation of martian can never arise. 219 00:11:20,914 --> 00:11:22,347 As far as we know life, 220 00:11:22,349 --> 00:11:25,349 water is absolutely, fundamentally important to life. 221 00:11:28,687 --> 00:11:31,956 2004 ... NASA's opportunity rover 222 00:11:31,958 --> 00:11:33,792 lands on Mars. 223 00:11:33,794 --> 00:11:36,060 Part of its mission is to search for evidence 224 00:11:36,062 --> 00:11:41,933 that water returned to Mars after the borealis impact. 225 00:11:41,935 --> 00:11:43,301 It's not long before opportunity 226 00:11:43,303 --> 00:11:46,437 stumbles across something strange on the surface 227 00:11:46,439 --> 00:11:49,640 of a fossilized sand dune... 228 00:11:49,642 --> 00:11:55,012 Bizarre, round, metallic rocks. 229 00:11:55,014 --> 00:11:56,781 These rocks are called blueberries, 230 00:11:56,783 --> 00:11:59,350 and they're an important find for planetary geologists, 231 00:11:59,352 --> 00:12:01,686 like jani radebaugh, 232 00:12:01,688 --> 00:12:05,857 because fossilized sand dunes also exist on earth. 233 00:12:05,859 --> 00:12:07,892 And Utah's petrified dunes 234 00:12:07,894 --> 00:12:11,562 are also littered with blueberries. 235 00:12:11,564 --> 00:12:12,764 This is really exciting 236 00:12:12,766 --> 00:12:16,968 because we've seen the exact same thing on Mars. 237 00:12:16,970 --> 00:12:18,769 Finding blueberries on Mars 238 00:12:18,771 --> 00:12:21,239 is significant, because the borealis impact 239 00:12:21,241 --> 00:12:22,673 melted the planet, 240 00:12:22,675 --> 00:12:25,209 so anything found on Mars today 241 00:12:25,211 --> 00:12:28,680 must have formed after the impact. 242 00:12:28,682 --> 00:12:31,882 But crucially, these nodules of iron oxide 243 00:12:31,884 --> 00:12:36,354 formed deep underground and in the presence of water. 244 00:12:36,356 --> 00:12:38,489 In order to form one of these little blueberries, 245 00:12:38,491 --> 00:12:40,625 there needs to be huge amounts of water 246 00:12:40,627 --> 00:12:43,762 flushing down through the fossil sand dunes, 247 00:12:43,764 --> 00:12:45,263 and as it does that, 248 00:12:45,265 --> 00:12:47,364 it carries with it all of the iron oxides 249 00:12:47,366 --> 00:12:49,167 around each sand grain. 250 00:12:49,169 --> 00:12:51,369 And just one tiny, little one like this ... 251 00:12:51,371 --> 00:12:52,637 now, this is maybe about 252 00:12:52,639 --> 00:12:54,339 an ounce of iron, maybe a little bit more ... 253 00:12:54,341 --> 00:12:56,608 and in order to get an ounce of iron 254 00:12:56,610 --> 00:12:58,442 to concentrate into this blueberry, 255 00:12:58,444 --> 00:13:02,480 you need to have a thousand gallons of water. 256 00:13:02,482 --> 00:13:03,614 Blueberries form 257 00:13:03,616 --> 00:13:06,650 deep inside sandstone. 258 00:13:06,652 --> 00:13:08,118 But over thousands of years, 259 00:13:08,120 --> 00:13:10,888 wind erosion blows away the softer rock, 260 00:13:10,890 --> 00:13:14,725 leaving just the blueberries behind. 261 00:13:16,261 --> 00:13:18,596 If we walk to the edge of this 262 00:13:18,598 --> 00:13:20,198 pile of blueberries, 263 00:13:20,200 --> 00:13:22,166 we could see the process by which 264 00:13:22,168 --> 00:13:23,768 they're actually eroding out of the rock. 265 00:13:23,770 --> 00:13:26,337 The blueberries right here contain 266 00:13:26,339 --> 00:13:29,607 within this fossil sandstone layer. 267 00:13:29,609 --> 00:13:31,909 The winds are blowing in this direction, 268 00:13:31,911 --> 00:13:33,477 down the layers, 269 00:13:33,479 --> 00:13:36,547 and they're actually eroding out the soft sandstones right here 270 00:13:36,549 --> 00:13:40,618 and leaving behind very dense iron nodules, 271 00:13:40,620 --> 00:13:42,086 and as they pluck themselves out of the rock, 272 00:13:42,088 --> 00:13:44,655 they roll down the hill and they collect... 273 00:13:44,657 --> 00:13:48,659 Right here, in between layers. 274 00:13:48,661 --> 00:13:50,862 We know we found conditions just like this on Mars. 275 00:13:50,864 --> 00:13:52,930 We have fossil sand dune layers, 276 00:13:52,932 --> 00:13:56,266 we also have blueberries all over the surface, 277 00:13:56,268 --> 00:13:57,802 so we know the same kinds of things 278 00:13:57,804 --> 00:14:00,204 had to have happened on Mars that have happened here. 279 00:14:00,206 --> 00:14:02,140 There has to be water flowing through the rock, 280 00:14:02,142 --> 00:14:03,407 gathering iron, 281 00:14:03,409 --> 00:14:05,643 and then there has to be a huge amount of wind 282 00:14:05,645 --> 00:14:10,047 to strip away the fossil sand dunes. 283 00:14:10,049 --> 00:14:11,115 For blueberries to exist 284 00:14:11,117 --> 00:14:13,851 on the surface of Mars today, 285 00:14:13,853 --> 00:14:15,786 the red planet must have gotten its water 286 00:14:15,788 --> 00:14:20,825 and its atmosphere back after the catastrophic impact. 287 00:14:20,827 --> 00:14:22,460 With liquid water on the surface, 288 00:14:22,462 --> 00:14:25,630 the ingredients of life might have combined, once again, 289 00:14:25,632 --> 00:14:30,434 to create a second generation of martians. 290 00:14:30,436 --> 00:14:33,371 But where did this water come from? 291 00:14:33,373 --> 00:14:36,307 The answer is surprising. 292 00:14:36,309 --> 00:14:38,610 It could have been in the planet itself ... 293 00:14:38,612 --> 00:14:40,210 water is incredibly abundant. 294 00:14:40,212 --> 00:14:42,013 We know that there's water deep, 295 00:14:42,015 --> 00:14:44,515 deep, deep in the earth's mantle, 296 00:14:44,517 --> 00:14:47,218 and so it's entirely possible that on Mars 297 00:14:47,220 --> 00:14:48,853 there was water so deep in the planet 298 00:14:48,855 --> 00:14:53,457 that even after this catastrophe, it came back up. 299 00:14:53,459 --> 00:14:54,692 On the earth, scientists 300 00:14:54,694 --> 00:14:57,628 diffuse the seismic waves of earthquakes 301 00:14:57,630 --> 00:15:00,231 to detect an ocean's worth of water 302 00:15:00,233 --> 00:15:04,335 chemically embedded in minerals deep underground. 303 00:15:04,337 --> 00:15:06,537 A similar water source could have been hidden 304 00:15:06,539 --> 00:15:10,441 hundreds of miles below post-impact Mars, 305 00:15:10,443 --> 00:15:15,212 and volcanoes could have brought that water back to the surface. 306 00:15:15,214 --> 00:15:16,780 One way for water to get from 307 00:15:16,782 --> 00:15:19,516 deep underneath the surface to the surface of the planet 308 00:15:19,518 --> 00:15:21,585 would be through geologic activities ... 309 00:15:21,587 --> 00:15:23,220 volcanoes, for example. 310 00:15:23,222 --> 00:15:25,823 We know that volcanoes spew out a lot of gasses on earth, 311 00:15:25,825 --> 00:15:27,191 including water vapor, 312 00:15:27,193 --> 00:15:29,660 and we see volcanoes on Mars. 313 00:15:32,965 --> 00:15:34,332 Mars is home to the largest 314 00:15:34,334 --> 00:15:36,834 volcanoes in the solar system. 315 00:15:36,836 --> 00:15:39,203 The biggest of all, Olympus mons, 316 00:15:39,205 --> 00:15:42,340 is over three times taller than mount Everest. 317 00:15:45,177 --> 00:15:50,448 4.49 billion years ago volcanoes spew lava spiked with water 318 00:15:50,450 --> 00:15:54,085 into the atmosphere and create ferocious rainstorms 319 00:15:54,087 --> 00:15:57,588 that flood the surface of Mars. 320 00:16:04,129 --> 00:16:06,197 Over tens of thousands of years 321 00:16:06,199 --> 00:16:09,434 Mars becomes a watery world once again 322 00:16:09,436 --> 00:16:12,303 with the perfect conditions for a second generation 323 00:16:12,305 --> 00:16:16,207 of martians to rise up. 324 00:16:16,209 --> 00:16:17,274 It would seem that 325 00:16:17,276 --> 00:16:19,009 when you have a massive collision, 326 00:16:19,011 --> 00:16:20,211 like what happened to Mars, 327 00:16:20,213 --> 00:16:22,213 it would be game over for life. 328 00:16:22,215 --> 00:16:24,782 But there's something more complicated going on. 329 00:16:24,784 --> 00:16:26,417 Maybe that asteroid impact kicked off 330 00:16:26,419 --> 00:16:30,722 an entirely new cycle of life on Mars. 331 00:16:30,724 --> 00:16:31,856 In theory, 332 00:16:31,858 --> 00:16:33,524 four billion years ago, 333 00:16:33,526 --> 00:16:36,627 a second generation of single-cell bacterial life 334 00:16:36,629 --> 00:16:38,863 arose on Mars, 335 00:16:38,865 --> 00:16:41,265 and for the very first time there was life 336 00:16:41,267 --> 00:16:45,036 on two planets in the solar system. 337 00:16:45,038 --> 00:16:50,008 140 million miles away, life on earth had just begun, 338 00:16:50,010 --> 00:16:52,343 and thanks to earth's stable climate, 339 00:16:52,345 --> 00:16:55,946 it would one day evolve into us. 340 00:16:59,084 --> 00:17:02,387 But the outlook for Mars was very different. 341 00:17:02,389 --> 00:17:04,989 Evidence from the Mars reconnaissance orbiter 342 00:17:04,991 --> 00:17:10,461 suggests an icy apocalypse was about to strike. 343 00:17:10,463 --> 00:17:15,400 For Mars' second generation, winter was coming. 344 00:17:40,259 --> 00:17:41,459 Four billion years ago, 345 00:17:41,461 --> 00:17:44,261 the first life has arisen on earth, 346 00:17:44,263 --> 00:17:49,967 but on Mars, life may be starting out for a second time. 347 00:17:49,969 --> 00:17:51,102 It's possible that Mars 348 00:17:51,104 --> 00:17:53,804 had life before earth did ... it got wiped out ... 349 00:17:53,806 --> 00:17:59,877 and then got started again by rehydrating the planet. 350 00:17:59,879 --> 00:18:01,278 A planetary collision 351 00:18:01,280 --> 00:18:04,148 has blown away Mars' atmosphere and oceans, 352 00:18:04,150 --> 00:18:06,284 along with any life, 353 00:18:06,286 --> 00:18:09,754 but giant volcanoes have brought water back to the surface 354 00:18:09,756 --> 00:18:11,756 from deep within the planet. 355 00:18:11,758 --> 00:18:12,957 This could have allowed 356 00:18:12,959 --> 00:18:15,893 for a second generation of life to rise up. 357 00:18:15,895 --> 00:18:18,996 But these martians are about to be tested to their limits 358 00:18:18,998 --> 00:18:22,199 by catastrophic climate change. 359 00:18:30,676 --> 00:18:33,978 2008 ... NASA's Mars reconnaissance orbiter 360 00:18:33,980 --> 00:18:40,017 flies high over the surface of Mars. 361 00:18:40,019 --> 00:18:41,552 Its ground-penetrating instruments 362 00:18:41,554 --> 00:18:43,521 peer deep below the surface, 363 00:18:43,523 --> 00:18:47,791 aiming to unlock Mars' geological secrets. 364 00:18:47,793 --> 00:18:49,927 As it scans near Mars' equator, 365 00:18:49,929 --> 00:18:53,598 the orbiter spots something that has no right to be there ... 366 00:18:53,600 --> 00:18:57,869 a vast, underground glacier. 367 00:18:57,871 --> 00:19:01,839 One mile thick and three times the size of Los Angeles, 368 00:19:01,841 --> 00:19:06,810 ice on this scale should only form at the frigid poles. 369 00:19:06,812 --> 00:19:08,546 The only explanation ... 370 00:19:08,548 --> 00:19:10,881 Mars must have been tipped over 371 00:19:10,883 --> 00:19:15,485 with its equator tilted away from the sun. 372 00:19:15,487 --> 00:19:16,753 The tilt on Mars' axis 373 00:19:16,755 --> 00:19:19,190 has actually changed significantly over time, 374 00:19:19,192 --> 00:19:21,359 and in non-systematic ways, 375 00:19:21,361 --> 00:19:23,761 it just happens randomly that it will start moving, 376 00:19:23,763 --> 00:19:25,997 and so there are some models that suggest 377 00:19:25,999 --> 00:19:29,133 that Mars has actually been almost tipped over on its end. 378 00:19:32,337 --> 00:19:33,537 Most planets wobble, 379 00:19:33,539 --> 00:19:36,207 and from time to time, they wobble so much 380 00:19:36,209 --> 00:19:41,145 they can tip over, leading to super winters. 381 00:19:41,147 --> 00:19:42,379 If that had happened here on earth, 382 00:19:42,381 --> 00:19:45,482 Los Angeles could become the arctic. 383 00:19:45,484 --> 00:19:47,851 Well, you can imagine something similar would happen on Mars, 384 00:19:47,853 --> 00:19:51,555 how drastic the change would be. 385 00:19:51,557 --> 00:19:53,357 You're used to seeing the sun overhead, 386 00:19:53,359 --> 00:19:55,359 it's very warm, there's probably liquid water, 387 00:19:55,361 --> 00:19:58,262 and as the planet starts going this way, 388 00:19:58,264 --> 00:20:01,332 the sun is not gonna rise as high in the sky. 389 00:20:01,334 --> 00:20:04,735 Eventually you may not see sunrise for half a year, 390 00:20:04,737 --> 00:20:10,307 and any water that's there is gonna be frozen solid. 391 00:20:10,309 --> 00:20:12,143 3.9 billion years ago, 392 00:20:12,145 --> 00:20:15,980 Mars is tilting by as much as 80 degrees. 393 00:20:15,982 --> 00:20:21,452 Winter temperatures drop below minus 125 degrees fahrenheit. 394 00:20:23,221 --> 00:20:26,424 As the polar ice sheet spreads quickly toward the equator, 395 00:20:26,426 --> 00:20:28,626 liquid water is frozen solid, 396 00:20:28,628 --> 00:20:32,296 along with any potential martians. 397 00:20:32,298 --> 00:20:34,498 The water that drives the biochemistry of life 398 00:20:34,500 --> 00:20:38,869 freezes inside the tiny bacteria. 399 00:20:38,871 --> 00:20:42,439 Ice crystals form and puncture the martian's cell walls 400 00:20:42,441 --> 00:20:48,112 until eventually, they die. 401 00:20:48,114 --> 00:20:52,383 Every 120,000 years the tilt of Mars changes, 402 00:20:52,385 --> 00:20:55,185 as again and again the planet's chaotic wobble 403 00:20:55,187 --> 00:21:00,391 flips the martians in and out of the deep freeze. 404 00:21:00,393 --> 00:21:03,995 Any second generation of life on Mars... 405 00:21:03,997 --> 00:21:05,763 Is left in tatters. 406 00:21:14,172 --> 00:21:19,843 Meanwhile, on earth, our ancient ancestors have it easy. 407 00:21:19,845 --> 00:21:23,948 The earth's wobble, and its seasons, stay relatively stable, 408 00:21:23,950 --> 00:21:27,018 and it's all thanks to our secret weapon ... 409 00:21:27,020 --> 00:21:31,622 our oversized moon. 410 00:21:31,624 --> 00:21:33,858 The interaction of our planet and the moon 411 00:21:33,860 --> 00:21:37,227 means that the axis of our rotation is very, very stable. 412 00:21:37,229 --> 00:21:41,298 The seasons return year after year, century after century, 413 00:21:41,300 --> 00:21:45,235 for billions of years. 414 00:21:45,237 --> 00:21:46,570 Our moon's enormous mass 415 00:21:46,572 --> 00:21:49,940 exerts a huge gravitational pull on the earth, 416 00:21:49,942 --> 00:21:52,242 stabilizing the wobble of our planet 417 00:21:52,244 --> 00:21:55,979 and keeping our climate in check. 418 00:21:55,981 --> 00:21:57,714 Without the moon, the early earth 419 00:21:57,716 --> 00:22:00,718 would have wobbled just as wildly as Mars, 420 00:22:00,720 --> 00:22:04,054 and our ancestors could have faced the same icy fate 421 00:22:04,056 --> 00:22:08,058 as the early martians. 422 00:22:08,060 --> 00:22:09,460 Mars doesn't have a big moon, 423 00:22:09,462 --> 00:22:10,328 it has two, little, tiny moons 424 00:22:10,330 --> 00:22:14,065 that don't really affect it much. 425 00:22:14,067 --> 00:22:15,699 So if the martians were killed 426 00:22:15,701 --> 00:22:17,434 the first time by a giant impact, 427 00:22:17,436 --> 00:22:18,902 they may have been killed a second time 428 00:22:18,904 --> 00:22:22,572 by Mars itself not being stable and flipping over 429 00:22:22,574 --> 00:22:27,244 and having catastrophic super winters and super summers, 430 00:22:27,246 --> 00:22:33,284 basically, mega catastrophic climate change. 431 00:22:33,286 --> 00:22:34,752 On Mars, the outlook for life 432 00:22:34,754 --> 00:22:37,455 seems bleak. 433 00:22:37,457 --> 00:22:40,256 But the brutal conditions that drive martian life 434 00:22:40,258 --> 00:22:43,026 to the edge of extinction may also have pushed it 435 00:22:43,028 --> 00:22:46,497 to adapt and evolve. 436 00:22:46,499 --> 00:22:50,468 We know this because on earth organisms known as extremophiles 437 00:22:50,470 --> 00:22:54,004 have evolved to live in the most severe of circumstances, 438 00:22:54,006 --> 00:22:58,075 from boiling, hydro-thermal vents... 439 00:22:58,077 --> 00:23:01,011 To the deep freeze of glacial ice. 440 00:23:01,013 --> 00:23:06,549 When the going gets tough, life seems to get tougher. 441 00:23:06,551 --> 00:23:08,251 Maybe the martian super winters 442 00:23:08,253 --> 00:23:11,355 gave rise to a third generation of life ... 443 00:23:11,357 --> 00:23:14,692 a super tough army of bugs able to survive 444 00:23:14,694 --> 00:23:18,195 the harshest of climate swings. 445 00:23:19,598 --> 00:23:21,732 What we see on earth is that life evolves 446 00:23:21,734 --> 00:23:24,969 to occupy whatever niche it lives in, 447 00:23:24,971 --> 00:23:27,705 and that evolution takes time. 448 00:23:27,707 --> 00:23:31,442 So as the environment changes, life changes with it. 449 00:23:31,444 --> 00:23:32,877 If there are sudden changes, 450 00:23:32,879 --> 00:23:36,580 then life forms can't cope with it and many die away. 451 00:23:36,582 --> 00:23:41,252 Those that survive, they continue on. 452 00:23:41,254 --> 00:23:43,187 3.8 billion years ago 453 00:23:43,189 --> 00:23:45,556 a third generation of life could have thrived 454 00:23:45,558 --> 00:23:48,391 on the surface of Mars. 455 00:23:48,393 --> 00:23:50,795 Evolved from a handful of its predecessors 456 00:23:50,797 --> 00:23:53,597 to make it through Mars' super winters, 457 00:23:53,599 --> 00:23:57,600 it's the toughest martian life yet. 458 00:23:57,602 --> 00:23:59,503 But, as the super winters end, 459 00:23:59,505 --> 00:24:03,407 the challenges for life on Mars are set to get worse. 460 00:24:03,409 --> 00:24:07,077 Another extinction-level event is on the way. 461 00:24:07,079 --> 00:24:12,583 Mars' atmosphere is being ripped away molecule by molecule. 462 00:24:12,585 --> 00:24:14,218 Could this be the killer punch 463 00:24:14,220 --> 00:24:16,253 that wipes out the martians for good? 464 00:24:35,273 --> 00:24:36,473 Imagine Mars 465 00:24:36,475 --> 00:24:40,443 3.8 billion years ago. 466 00:24:40,445 --> 00:24:42,513 It's a warm, wet world, 467 00:24:42,515 --> 00:24:46,950 and super tough bacterial life is thriving. 468 00:24:46,952 --> 00:24:51,589 But these martians are not the planet's first inhabitants. 469 00:24:54,727 --> 00:24:56,861 The first generation of martian is vaporized 470 00:24:56,863 --> 00:25:02,099 by the huge borealis impact. 471 00:25:02,101 --> 00:25:04,034 Perhaps life starts over from scratch, 472 00:25:04,036 --> 00:25:07,738 but endures a series of extreme climate swings. 473 00:25:07,740 --> 00:25:11,441 Only the toughest martians make it through. 474 00:25:17,182 --> 00:25:19,683 But another disaster is about to strike, 475 00:25:19,685 --> 00:25:26,323 and this catastrophe will test even the strongest martians. 476 00:25:26,325 --> 00:25:30,861 They're about to lose the most basic ingredient of life ... 477 00:25:30,863 --> 00:25:32,530 liquid water. 478 00:25:32,532 --> 00:25:34,832 You really have to appreciate how difficult it is 479 00:25:34,834 --> 00:25:37,834 to have liquid water on the surface of a planet. 480 00:25:37,836 --> 00:25:39,736 We know that life works so well 481 00:25:39,738 --> 00:25:41,538 when there's liquid water around. 482 00:25:41,540 --> 00:25:43,540 But you need just the right balance 483 00:25:43,542 --> 00:25:47,044 of air pressure and temperature. 484 00:25:47,046 --> 00:25:48,045 Without air pressure 485 00:25:48,047 --> 00:25:49,546 weighing down on it, 486 00:25:49,548 --> 00:25:52,949 liquid water will evaporate from the surface of a planet, 487 00:25:52,951 --> 00:25:55,553 whatever the temperature. 488 00:25:55,555 --> 00:25:57,121 That air pressure is generated 489 00:25:57,123 --> 00:26:00,624 by the presence of an atmosphere. 490 00:26:00,626 --> 00:26:01,625 In a lot of ways that atmosphere 491 00:26:01,627 --> 00:26:03,093 serves as a kind of a lid 492 00:26:03,095 --> 00:26:05,062 stopping down the water from escaping into space. 493 00:26:05,064 --> 00:26:09,700 It's very important to have that atmosphere. 494 00:26:09,702 --> 00:26:11,735 3.7 billion years ago, 495 00:26:11,737 --> 00:26:16,607 life on earth enjoys warm oceans and a thick atmosphere. 496 00:26:16,609 --> 00:26:19,609 But on Mars, a third extinction-level event 497 00:26:19,611 --> 00:26:21,412 is gaining momentum. 498 00:26:25,984 --> 00:26:29,286 The atmosphere is slowly being stripped away, 499 00:26:29,288 --> 00:26:35,925 and Mars' great oceans are starting to evaporate. 500 00:26:35,927 --> 00:26:37,728 The fate of life on both planets 501 00:26:37,730 --> 00:26:42,566 now rests on the strength of their magnetic cores. 502 00:26:42,568 --> 00:26:44,234 It turns out that the existence 503 00:26:44,236 --> 00:26:48,305 of an atmosphere on earth may rely on the magnetic field, 504 00:26:48,307 --> 00:26:50,174 because what our magnetic field does 505 00:26:50,176 --> 00:26:53,510 is it protects us from the onslaught of this wind, 506 00:26:53,512 --> 00:26:54,778 of subatomic particles 507 00:26:54,780 --> 00:26:57,848 that the sun is blowing out all the time. 508 00:26:57,850 --> 00:26:59,650 We call this the solar wind. 509 00:27:03,387 --> 00:27:04,521 And if we didn't have a magnetic field 510 00:27:04,523 --> 00:27:08,224 to basically catch and deflect those particles gently, 511 00:27:08,226 --> 00:27:12,463 they would directly slam into the earth's atmosphere. 512 00:27:12,465 --> 00:27:14,230 If you think of the magnetic field 513 00:27:14,232 --> 00:27:16,266 as a windbreaker from the solar winds, 514 00:27:16,268 --> 00:27:17,801 once we lose that protection, 515 00:27:17,803 --> 00:27:22,806 that planet becomes very vulnerable. 516 00:27:22,808 --> 00:27:24,040 The earth's magnetic core 517 00:27:24,042 --> 00:27:27,477 has stayed strong for 3.45 billion years 518 00:27:27,479 --> 00:27:31,248 as super hot molten iron churns over and over 519 00:27:31,250 --> 00:27:35,585 within the planet like a lava lamp. 520 00:27:35,587 --> 00:27:37,721 Churning iron creates electricity, 521 00:27:37,723 --> 00:27:40,290 which in turn generates a magnetic field 522 00:27:40,292 --> 00:27:44,861 that rises up around the earth, acting like a magnetic shield, 523 00:27:44,863 --> 00:27:49,466 protecting our atmosphere from the ravages of the solar wind. 524 00:27:49,468 --> 00:27:50,934 3.8 billion years ago 525 00:27:50,936 --> 00:27:54,438 Mars had a molten core and a magnetic field. 526 00:27:54,440 --> 00:27:58,142 But something caused its shield to drop. 527 00:27:58,144 --> 00:28:02,713 Did Mars' small molten core simply get too cold to function? 528 00:28:02,715 --> 00:28:04,081 Or did something else kickstart 529 00:28:04,083 --> 00:28:07,751 this third great extinction of martian life? 530 00:28:07,753 --> 00:28:10,787 A new and controversial theory points the finger 531 00:28:10,789 --> 00:28:14,525 partly at the ancient borealis impact. 532 00:28:17,496 --> 00:28:19,096 A giant impact of this scale 533 00:28:19,098 --> 00:28:21,398 can affect a range of temperatures, 534 00:28:21,400 --> 00:28:25,735 from the hot inner core to the cooler outer mantle. 535 00:28:25,737 --> 00:28:27,404 4.5 billion years ago 536 00:28:27,406 --> 00:28:29,339 the impact that vaporizes 537 00:28:29,341 --> 00:28:31,675 the first generation of martian life 538 00:28:31,677 --> 00:28:35,011 also drives heat into the planet, 539 00:28:35,013 --> 00:28:38,515 increasing the temperatures in the outer mantle. 540 00:28:38,517 --> 00:28:41,251 The heat inside the planet evens out, 541 00:28:41,253 --> 00:28:44,855 and the metals slowly stop churning. 542 00:28:44,857 --> 00:28:46,724 But there's less of a temperature gradient ... 543 00:28:46,726 --> 00:28:49,526 that makes it harder for this dyno process to, 544 00:28:49,528 --> 00:28:52,796 to drive a strong magnetic field. 545 00:28:52,798 --> 00:28:53,930 Over hundreds of millions 546 00:28:53,932 --> 00:29:00,270 of years, Mars' magnetic field shuts down. 547 00:29:00,272 --> 00:29:01,605 When Mars lost its magnetic 548 00:29:01,607 --> 00:29:03,073 field all of a sudden 549 00:29:03,075 --> 00:29:05,509 it was completely vulnerable to the solar wind. 550 00:29:05,511 --> 00:29:07,076 The solar wind could break apart 551 00:29:07,078 --> 00:29:09,346 and carry away the martian atmosphere. 552 00:29:17,489 --> 00:29:19,422 3.7 billion years ago 553 00:29:19,424 --> 00:29:24,094 super tough martian life faces annihilation. 554 00:29:24,096 --> 00:29:28,899 Bit by bits, the atmosphere is being swept into space. 555 00:29:28,901 --> 00:29:31,735 The air pressure is dropping across the planet 556 00:29:31,737 --> 00:29:35,605 and most of Mars' water has already boiled away. 557 00:29:38,910 --> 00:29:40,344 The chances of survival 558 00:29:40,346 --> 00:29:43,814 without this precious liquid are remote. 559 00:29:43,816 --> 00:29:47,584 But, for the martians, there's an even more immediate danger. 560 00:29:47,586 --> 00:29:51,355 With no magnetic field and no thick atmosphere, 561 00:29:51,357 --> 00:29:54,324 the surface of Mars feels the full force 562 00:29:54,326 --> 00:29:57,394 of the sun's radiation. 563 00:30:03,835 --> 00:30:05,002 If you're a microbe 564 00:30:05,004 --> 00:30:06,269 on the surface, 565 00:30:06,271 --> 00:30:07,371 you would have to make do 566 00:30:07,373 --> 00:30:09,706 with very little atmosphere, no water, 567 00:30:09,708 --> 00:30:11,642 this flood of ultraviolet light from the sun, 568 00:30:11,644 --> 00:30:14,511 and these particles which are slamming into you all the time. 569 00:30:17,615 --> 00:30:18,982 The martians are bombarded 570 00:30:18,984 --> 00:30:21,618 by radiation from the solar wind. 571 00:30:21,620 --> 00:30:25,622 It rips their DNA apart. 572 00:30:25,624 --> 00:30:27,023 Without an atmosphere, 573 00:30:27,025 --> 00:30:30,627 the surface of the planet is sterilized. 574 00:30:30,629 --> 00:30:35,031 But is this really the end for martian life? 575 00:30:35,033 --> 00:30:36,567 Life is so tenacious, 576 00:30:36,569 --> 00:30:40,470 it can survive even those incredible catastrophic changes, 577 00:30:40,472 --> 00:30:43,507 and it may still be there today. 578 00:30:43,509 --> 00:30:45,175 To survive the radiation, 579 00:30:45,177 --> 00:30:49,646 martian life would have had to have moved deep underground. 580 00:30:51,749 --> 00:30:54,217 In this protected subterranean environment 581 00:30:54,219 --> 00:30:57,720 it may also have found a source of liquid water, 582 00:30:57,722 --> 00:30:59,122 and if that happened, 583 00:30:59,124 --> 00:31:02,292 could the martians still be there today, 584 00:31:02,294 --> 00:31:06,897 waiting for us to drop in and say hello? 585 00:31:25,249 --> 00:31:26,683 Since the 1960s 586 00:31:26,685 --> 00:31:28,585 robotic probes and landers 587 00:31:28,587 --> 00:31:34,090 have been searching the surface of Mars for signs of life. 588 00:31:34,092 --> 00:31:37,427 But have they been looking in the right places? 589 00:31:37,429 --> 00:31:39,630 The surface of Mars is a waterless desert 590 00:31:39,632 --> 00:31:43,700 that's bombarded by harmful radiation. 591 00:31:43,702 --> 00:31:47,637 If a fourth incarnation of martian life is alive today, 592 00:31:47,639 --> 00:31:53,042 many scientists think it'll have to be deep underground. 593 00:31:53,044 --> 00:31:54,177 Underneath the surface of Mars 594 00:31:54,179 --> 00:31:56,446 you may have all the conditions you need for life. 595 00:31:56,448 --> 00:31:58,281 There may be some liquid water down there, 596 00:31:58,283 --> 00:32:00,984 and you're also protected from the intense radiation 597 00:32:00,986 --> 00:32:02,386 that you find on the surface. 598 00:32:06,524 --> 00:32:08,091 Scientists are split 599 00:32:08,093 --> 00:32:13,630 on the best underground places to search for martian life. 600 00:32:13,632 --> 00:32:15,432 But if jani radebaugh were on Mars, 601 00:32:15,434 --> 00:32:19,703 she would head to the nearest sand dune and start digging. 602 00:32:22,240 --> 00:32:23,340 Here you can see 603 00:32:23,342 --> 00:32:25,542 this is wet sand just below the surface. 604 00:32:25,544 --> 00:32:30,046 This is the perfect environment to be able to house life. 605 00:32:30,048 --> 00:32:32,282 Even in the very driest deserts on earth, 606 00:32:32,284 --> 00:32:34,651 in between the sand dunes, in the inter-dunes, 607 00:32:34,653 --> 00:32:37,554 you can find water percolating up from Springs 608 00:32:37,556 --> 00:32:39,556 that come up from deep under the ground, 609 00:32:39,558 --> 00:32:41,425 perfect for life to form and grow. 610 00:32:41,427 --> 00:32:43,493 And if you just keep on digging... 611 00:32:43,495 --> 00:32:46,029 Down into the bottom of the inter-dune, 612 00:32:46,031 --> 00:32:48,332 maybe you would reach the water table. 613 00:32:48,334 --> 00:32:50,434 And if you reach the water table on Mars, 614 00:32:50,436 --> 00:32:53,770 now you have all the conditions just right for life. 615 00:32:53,772 --> 00:32:55,839 This is my bet, this is where I'd go, 616 00:32:55,841 --> 00:32:59,175 right between the dunes. 617 00:32:59,177 --> 00:33:00,577 Digging for martian life 618 00:33:00,579 --> 00:33:02,612 in the desert is one option. 619 00:33:02,614 --> 00:33:05,849 But some scientists have very different ideas, 620 00:33:05,851 --> 00:33:08,184 and planetary scientist Nina lanza 621 00:33:08,186 --> 00:33:12,722 would need to pack a rope and a flashlight for her search. 622 00:33:12,724 --> 00:33:14,457 So if were to go to Mars to find life, 623 00:33:14,459 --> 00:33:15,959 I would go to a lava tube. 624 00:33:18,229 --> 00:33:19,096 Lava tubes are made 625 00:33:19,098 --> 00:33:21,297 by ancient volcanoes, 626 00:33:21,299 --> 00:33:25,335 the empty leftovers from underground lava flows. 627 00:33:25,337 --> 00:33:27,437 Today, they form deep tunnels, 628 00:33:27,439 --> 00:33:29,473 shielded from radiation and shut off 629 00:33:29,475 --> 00:33:32,475 from the harsh martian climate. 630 00:33:32,477 --> 00:33:33,477 We've never been 631 00:33:33,479 --> 00:33:35,145 in a lava tube on Mars, 632 00:33:35,147 --> 00:33:40,283 but it is absolutely possible that there's liquid water. 633 00:33:40,285 --> 00:33:43,353 So, that's an environment where you could have some moisture, 634 00:33:43,355 --> 00:33:46,189 you could have a little warmth, you're protected from radiation. 635 00:33:46,191 --> 00:33:50,093 I think that a martian microbe would be very happy there. 636 00:33:54,266 --> 00:33:55,432 Finding life on Mars 637 00:33:55,434 --> 00:33:58,435 would be a monumental human accomplishment. 638 00:33:58,437 --> 00:34:00,070 But there is a danger. 639 00:34:00,072 --> 00:34:03,607 By exposing martian life to life from earth, 640 00:34:03,609 --> 00:34:07,911 could we unwittingly set off yet another extinction event? 641 00:34:07,913 --> 00:34:09,312 Humans have been 642 00:34:09,314 --> 00:34:12,315 one of the most effective extinction mechanisms 643 00:34:12,317 --> 00:34:14,450 of life on earth. 644 00:34:14,452 --> 00:34:16,285 The interesting question will be, 645 00:34:16,287 --> 00:34:19,689 will we produce a similar calamity on Mars? 646 00:34:19,691 --> 00:34:21,424 If humans someday go to Mars, 647 00:34:21,426 --> 00:34:23,560 then we will be an invasive species, 648 00:34:23,562 --> 00:34:25,228 and if there is some martian life 649 00:34:25,230 --> 00:34:27,097 that's hanging on in some niche, 650 00:34:27,099 --> 00:34:29,466 we could be their ultimate destroyers. 651 00:34:29,468 --> 00:34:31,868 So we have an ethical responsibility 652 00:34:31,870 --> 00:34:36,807 to preserve whatever life may be on Mars. 653 00:34:36,809 --> 00:34:38,608 The problem isn't us, 654 00:34:38,610 --> 00:34:42,345 it's the bugs in and on our bodies. 655 00:34:42,347 --> 00:34:43,413 The average human has 656 00:34:43,415 --> 00:34:47,650 ten to 20 trillion bacterial hitchhikers. 657 00:34:47,652 --> 00:34:48,918 If we go to Mars, 658 00:34:48,920 --> 00:34:51,888 we'll be taking our tiny companions along for the ride, 659 00:34:51,890 --> 00:34:55,024 and any one of those bugs could turn out to be 660 00:34:55,026 --> 00:34:58,161 a deadly competitor for martian life. 661 00:35:01,332 --> 00:35:03,333 It's NASA engineer moogega Cooper's 662 00:35:03,335 --> 00:35:07,403 job to keep Mars rovers bug-free. 663 00:35:07,405 --> 00:35:11,974 But keeping astronauts clean, that's a whole different matter. 664 00:35:11,976 --> 00:35:13,743 We bake our spacecraft hardware 665 00:35:13,745 --> 00:35:17,147 at 110 degrees celsius for at least 50 hours 666 00:35:17,149 --> 00:35:19,882 to prevent the contamination of Mars. 667 00:35:19,884 --> 00:35:23,386 But unlike spacecraft, we cannot bake humans out. 668 00:35:23,388 --> 00:35:25,856 We will not survive those temperatures. 669 00:35:30,862 --> 00:35:31,928 Unless we find a way 670 00:35:31,930 --> 00:35:34,297 to keep astronauts bug-free, 671 00:35:34,299 --> 00:35:37,166 exploring Mars with robots is our best option 672 00:35:37,168 --> 00:35:41,838 for keeping the martians safe from harm. 673 00:35:41,840 --> 00:35:43,707 But what will happen when our robots 674 00:35:43,709 --> 00:35:47,644 finally find that life and we look deep into the workings 675 00:35:47,646 --> 00:35:50,680 of our extraterrestrial neighbors? 676 00:35:52,550 --> 00:35:56,719 What will the martians turn out to be like? 677 00:35:56,721 --> 00:35:59,689 Our example where DNA is the organic molecule 678 00:35:59,691 --> 00:36:00,957 that carries the information of life ... 679 00:36:00,959 --> 00:36:02,291 we don't even know 680 00:36:02,293 --> 00:36:05,628 if that's gonna be the rulebook in other places. 681 00:36:05,630 --> 00:36:07,631 Finding any evidence whatsoever on Mars 682 00:36:07,633 --> 00:36:11,768 would help us better understand what else is possible. 683 00:36:14,171 --> 00:36:15,171 Will the martians 684 00:36:15,173 --> 00:36:17,007 be different than us? 685 00:36:17,009 --> 00:36:19,042 Made from different materials 686 00:36:19,044 --> 00:36:22,145 and with a different biochemistry? 687 00:36:22,147 --> 00:36:26,149 Or will they seem shockingly familiar? 688 00:36:26,151 --> 00:36:29,452 Some scientists think that the very first martian life 689 00:36:29,454 --> 00:36:32,322 may not have stayed on Mars. 690 00:36:32,324 --> 00:36:34,991 It may have come here. 691 00:36:34,993 --> 00:36:36,492 It's not that farfetched to think 692 00:36:36,494 --> 00:36:38,928 that life could have jumped from Mars 693 00:36:38,930 --> 00:36:41,798 or been a back and forth from Mars to earth. 694 00:36:41,800 --> 00:36:43,733 If the martians came to earth, 695 00:36:43,735 --> 00:36:46,536 could they have seeded life on our planet? 696 00:36:46,538 --> 00:36:48,938 Maybe the martians aren't dead. 697 00:36:48,940 --> 00:36:51,007 Maybe I'm a martian, maybe you're a martian. 698 00:37:12,630 --> 00:37:15,798 We've sent a robot army to Mars, 699 00:37:15,800 --> 00:37:18,368 and what it's found is astonishing. 700 00:37:18,370 --> 00:37:21,838 The possibility that life could have arisen there, 701 00:37:21,840 --> 00:37:24,541 perhaps more than once, 702 00:37:24,543 --> 00:37:28,210 with different generations of martians emerging from the ashes 703 00:37:28,212 --> 00:37:31,248 of catastrophic extinction events. 704 00:37:33,451 --> 00:37:36,052 Life could still be sheltering 705 00:37:36,054 --> 00:37:40,523 below the surface of Mars right now. 706 00:37:42,993 --> 00:37:46,562 But there's another possibility that's truly astounding ... 707 00:37:46,564 --> 00:37:50,299 that martians aren't just hiding out on Mars, 708 00:37:50,301 --> 00:37:53,770 they're thriving, right here on earth. 709 00:37:57,341 --> 00:37:58,408 I might be a martian, 710 00:37:58,410 --> 00:38:00,777 you might be a martian. 711 00:38:00,779 --> 00:38:03,012 We might be from another planet. 712 00:38:03,014 --> 00:38:07,083 We might have already travelled and lived on two planets 713 00:38:07,085 --> 00:38:09,786 as life forms ... not as a species, certainly, 714 00:38:09,788 --> 00:38:13,256 but our ancestors may have come from another planet, 715 00:38:13,258 --> 00:38:16,893 and that is mind blowing. 716 00:38:16,895 --> 00:38:18,728 The idea that our ancestors 717 00:38:18,730 --> 00:38:21,564 could be martians is a new take on an old theory 718 00:38:21,566 --> 00:38:24,901 called panspermia. 719 00:38:24,903 --> 00:38:25,835 According to the theory, 720 00:38:25,837 --> 00:38:28,237 life on earth began when a space rock 721 00:38:28,239 --> 00:38:31,341 filled with alien bacteria landed on the earth 722 00:38:31,343 --> 00:38:34,778 and every living thing we see today, including us, 723 00:38:34,780 --> 00:38:39,515 evolved from those cosmic hitchhikers. 724 00:38:39,517 --> 00:38:42,518 The idea of panspermia has been around for centuries, 725 00:38:42,520 --> 00:38:44,620 but had a resurgence when scientists 726 00:38:44,622 --> 00:38:48,858 determined that life on earth may go back four billion years, 727 00:38:48,860 --> 00:38:51,961 to the end of a sustained attack of asteroid showers 728 00:38:51,963 --> 00:38:56,366 known as the late heavy bombardment. 729 00:38:56,368 --> 00:38:59,001 There are a lot of objects from the outer solar system ... 730 00:38:59,003 --> 00:39:00,603 comets and asteroids, all kinds of things ... 731 00:39:00,605 --> 00:39:02,338 coming into the inner solar system 732 00:39:02,340 --> 00:39:05,374 and slamming into the planets. 733 00:39:05,376 --> 00:39:06,676 Conventional wisdom 734 00:39:06,678 --> 00:39:09,612 suggests the objects hitting the earth at the time 735 00:39:09,614 --> 00:39:11,347 were leftover debris 736 00:39:11,349 --> 00:39:14,250 from the formation of the solar system. 737 00:39:14,252 --> 00:39:16,553 But a very controversial idea 738 00:39:16,555 --> 00:39:22,959 suggests these space rocks were actually all pieces of Mars, 739 00:39:22,961 --> 00:39:26,262 thrown off in the borealis space impact 740 00:39:26,264 --> 00:39:30,500 when a huge object blasted into Mars. 741 00:39:30,502 --> 00:39:36,406 The timing links up really well for the borealis space impact. 742 00:39:36,408 --> 00:39:39,008 If you calculate how much debris 743 00:39:39,010 --> 00:39:40,844 that would have been thrown out into space 744 00:39:40,846 --> 00:39:43,579 and when it would have had to have happened, 745 00:39:43,581 --> 00:39:45,748 according to the martian geologic record, 746 00:39:45,750 --> 00:39:49,118 it coincides with the late heavy bombardment... 747 00:39:53,792 --> 00:39:56,359 It's possible that the debris 748 00:39:56,361 --> 00:39:57,994 from the borealis space in forming impact 749 00:39:57,996 --> 00:40:00,997 might have come to earth and rained down on us 750 00:40:00,999 --> 00:40:02,665 and made the late heavy bombardment, 751 00:40:02,667 --> 00:40:06,202 seeding the earth with bacterial spores from Mars. 752 00:40:06,204 --> 00:40:08,905 Now, this is just a hypothesis, we don't know this for certain, 753 00:40:08,907 --> 00:40:10,306 we don't have evidence. 754 00:40:10,308 --> 00:40:13,443 But it is physically possible for that to have happened. 755 00:40:15,647 --> 00:40:16,980 Was the earth seeded 756 00:40:16,982 --> 00:40:18,481 by microscopic martians 757 00:40:18,483 --> 00:40:23,853 blown into space by the borealis impact? 758 00:40:23,855 --> 00:40:27,890 It sounds crazy, but the science stacks up. 759 00:40:27,892 --> 00:40:30,026 We know that simple life is tough, 760 00:40:30,028 --> 00:40:33,830 able to survive in the cold vacuum of space, 761 00:40:33,832 --> 00:40:35,898 and the timing of the borealis impact 762 00:40:35,900 --> 00:40:41,704 works out well for the rise of the first organisms on earth. 763 00:40:42,873 --> 00:40:46,175 Crucially, we know that rocks ejected from Mars 764 00:40:46,177 --> 00:40:48,377 can make it all the way to earth 765 00:40:48,379 --> 00:40:53,182 because they're still crash landing here, even today. 766 00:40:53,184 --> 00:40:55,285 One of the coolest things I've done as a scientist 767 00:40:55,287 --> 00:40:57,187 is held a piece of Mars in my hands. 768 00:40:57,189 --> 00:41:00,490 Now, we never had a mission that returned a sample from Mars, 769 00:41:00,492 --> 00:41:02,358 we had to come about it a different way. 770 00:41:02,360 --> 00:41:03,960 And it turns out we have meteorites 771 00:41:03,962 --> 00:41:07,664 that we are 100% sure are bits of Mars. 772 00:41:07,666 --> 00:41:10,233 They were actually exploded out during huge collisions, 773 00:41:10,235 --> 00:41:12,235 and eventually they fell on the earth. 774 00:41:18,176 --> 00:41:19,675 Four different generations 775 00:41:19,677 --> 00:41:21,677 of martians, each of them facing 776 00:41:21,679 --> 00:41:25,548 a different planetary catastrophe. 777 00:41:25,550 --> 00:41:27,116 But despite enormous odds, 778 00:41:27,118 --> 00:41:29,786 martians could still be alive today, 779 00:41:29,788 --> 00:41:32,856 buried deep under the surface of Mars, 780 00:41:32,858 --> 00:41:37,393 or maybe even thriving on earth. 781 00:41:37,395 --> 00:41:39,362 If life is really that tenacious 782 00:41:39,364 --> 00:41:41,764 that it can come back and keep coming back 783 00:41:41,766 --> 00:41:42,965 and keep coming back, 784 00:41:42,967 --> 00:41:45,634 that gives me a lot of hope for life in the universe. 785 00:41:45,636 --> 00:41:48,637 That tells me that life is maybe tough, 786 00:41:48,639 --> 00:41:53,409 maybe individuals are fragile, but maybe life itself is tough. 787 00:41:53,411 --> 00:41:54,544 For now, 788 00:41:54,546 --> 00:41:56,813 all we can do is speculate 789 00:41:56,815 --> 00:41:59,649 until future generations develop the technology 790 00:41:59,651 --> 00:42:01,984 to visit the red planet 791 00:42:01,986 --> 00:42:07,190 and grab our first sample of extraterrestrial life. 792 00:42:07,192 --> 00:42:09,158 That's going to change everything. 793 00:42:09,160 --> 00:42:10,360 We're going to have another example 794 00:42:10,362 --> 00:42:12,628 of how life started and how life works. 795 00:42:12,630 --> 00:42:14,663 And even if it's something that's dead, 796 00:42:14,665 --> 00:42:15,798 we knew it was there. 797 00:42:15,800 --> 00:42:18,167 The universe will never be the same again. 62071

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