1 00:00:01,107 --> 00:00:02,205 [narrator] Voyager, 2 00:00:02,207 --> 00:00:04,908 the most ambitious space mission in history. 3 00:00:05,811 --> 00:00:08,946 The two Voyager spacecraft are iconic. 4 00:00:09,048 --> 00:00:10,247 Iconic. 5 00:00:10,316 --> 00:00:12,082 Iconic. 6 00:00:12,084 --> 00:00:16,520 They're the first probes to truly explore half the planets in our solar system. 7 00:00:17,623 --> 00:00:20,024 Jupiter, Saturn, Uranus and Neptune. 8 00:00:20,026 --> 00:00:22,726 These went from dots of light in the sky, 9 00:00:22,728 --> 00:00:24,628 to real worlds. 10 00:00:24,630 --> 00:00:30,734 The Voyager missions have ventured far beyond where other probes have explored. 11 00:00:30,736 --> 00:00:34,905 They are the most distant emissary, representatives 12 00:00:34,907 --> 00:00:37,007 of the human species. 13 00:00:37,009 --> 00:00:40,644 They're the first spacecraft to taste interstellar space. 14 00:00:40,713 --> 00:00:45,349 [narrator] Exploring furthe than any humanmade spacecraf has gone before. 15 00:01:01,467 --> 00:01:05,669 [narrator] These are the logs of starships, Voyager 1 and 2. 16 00:01:05,771 --> 00:01:08,605 They have crossed the final frontier 17 00:01:08,607 --> 00:01:11,542 and are now in interstellar space. 18 00:01:12,711 --> 00:01:14,311 Almost a decade ago, 19 00:01:14,313 --> 00:01:17,047 Voyager 1 achieved something that had never been achieved before. 20 00:01:17,049 --> 00:01:18,949 It left our solar system. 21 00:01:18,951 --> 00:01:22,319 When Voyager crossed into interstellar space, 22 00:01:22,321 --> 00:01:25,522 humans became an interstellar species. 23 00:01:28,060 --> 00:01:30,561 [narrator] 14 billion miles from Earth, 24 00:01:30,629 --> 00:01:33,697 their radio signals travelin at the speed of light 25 00:01:33,699 --> 00:01:36,467 still take 21 hours to reach us. 26 00:01:39,038 --> 00:01:40,637 The Voyagers are so far t 27 00:01:40,639 --> 00:01:43,607 that when they look back towards the sun, it's just a pinprick of light. 28 00:01:43,609 --> 00:01:46,110 And they would need an exceptionally powerful telescope 29 00:01:46,112 --> 00:01:48,612 just to see the Earth. 30 00:01:48,614 --> 00:01:53,350 [narrator] Their original four-year mission has been extended to 44, 31 00:01:53,452 --> 00:01:54,952 and counting. 32 00:01:55,053 --> 00:01:57,855 From their current distant vantage point, 33 00:01:57,923 --> 00:02:01,125 they look back on strange new worlds 34 00:02:01,127 --> 00:02:04,027 and bold new science they've discovered. 35 00:02:06,699 --> 00:02:08,966 August 20th, 1977. 36 00:02:11,437 --> 00:02:13,303 [man] We have ignition, 37 00:02:13,305 --> 00:02:15,038 and we have liftoff. 38 00:02:15,074 --> 00:02:18,108 [narrator] The mission begin when Voyager 2 blasts of 39 00:02:19,945 --> 00:02:23,747 Followed two weeks later by its twin, Voyager 1, 40 00:02:23,849 --> 00:02:26,717 which will take a shorter and faster route. 41 00:02:27,953 --> 00:02:30,154 Their destination, Jupiter. 42 00:02:30,255 --> 00:02:32,523 And then, Saturn. 43 00:02:32,525 --> 00:02:38,362 When the time comes that that mission is actually ready to go to the launchpad, 44 00:02:38,430 --> 00:02:41,265 it's a funny mixture of joy 45 00:02:41,366 --> 00:02:43,400 and bittersweet loss. 46 00:02:43,402 --> 00:02:45,536 [woman] They become like your children. 47 00:02:45,538 --> 00:02:48,305 And that launch is like the birth of a baby. 48 00:02:48,307 --> 00:02:51,508 I was standing there, watching it climb up into the sky. 49 00:02:51,510 --> 00:02:53,744 We were cheering, we were so happy. 50 00:02:53,812 --> 00:02:55,712 Voyager was on its way. 51 00:02:57,950 --> 00:03:01,418 [narrator] Though funded to just explore the two gas giants, 52 00:03:01,420 --> 00:03:04,655 mission planners have a muc bigger journey in mind. 53 00:03:05,958 --> 00:03:08,425 To send the Voyager spacec 54 00:03:08,427 --> 00:03:10,827 on a grand tour of the solar system. 55 00:03:12,097 --> 00:03:13,430 To the outermost planets, 56 00:03:13,966 --> 00:03:16,400 Uranus and Neptune, 57 00:03:16,402 --> 00:03:19,036 worlds that have never been explored. 58 00:03:21,540 --> 00:03:22,806 To visit each planet, 59 00:03:22,808 --> 00:03:25,309 the probes must stick to a strict schedule, 60 00:03:25,311 --> 00:03:27,844 with only a quick flyby of each world. 61 00:03:29,715 --> 00:03:31,481 Once reaching Jupiter, 62 00:03:31,483 --> 00:03:35,018 they must use every second to complete close-up studie of the planet 63 00:03:35,020 --> 00:03:36,520 and its largest moons. 64 00:03:38,624 --> 00:03:41,959 One of the biggest challenges with flyby spacecraft is 65 00:03:41,961 --> 00:03:44,127 it may have taken years to get there, 66 00:03:44,129 --> 00:03:47,564 but the actual time that you're close to the planet 67 00:03:47,666 --> 00:03:49,166 is remarkably short. 68 00:03:49,234 --> 00:03:51,668 The Jupiter close-up data 69 00:03:51,737 --> 00:03:53,737 occurred during just three days. 70 00:03:54,940 --> 00:03:57,274 [narrator] February 1979, 71 00:03:57,276 --> 00:04:01,545 Voyager 1 begins beaming pictures back to Earth. 72 00:04:01,647 --> 00:04:02,946 It's an anxious wait. 73 00:04:03,816 --> 00:04:05,415 [Cooper] This is pre interne 74 00:04:05,417 --> 00:04:07,951 And so, when you look at the data coming in, 75 00:04:08,020 --> 00:04:11,121 it's coming in line by line, pixel by pixel. 76 00:04:11,123 --> 00:04:14,658 It was such an exciting time it was hard to know when to sleep. 77 00:04:14,760 --> 00:04:17,294 I brought my sleeping bag into my office 78 00:04:17,296 --> 00:04:20,631 so I wouldn't miss a single exciting picture. 79 00:04:22,635 --> 00:04:27,037 [narrator] Both Voyagers reveal an unbelievably dynamic world. 80 00:04:29,775 --> 00:04:33,310 Scientists were able to take a sequence of images of Jupiter 81 00:04:33,312 --> 00:04:36,947 that they could put together like a flipbook to get a sense of motion. 82 00:04:37,049 --> 00:04:38,949 And it was just astounding. 83 00:04:38,951 --> 00:04:43,120 Now we can see things moving within the atmospher of Jupiter 84 00:04:43,122 --> 00:04:45,756 in a way that we had no sense of before. 85 00:04:49,361 --> 00:04:54,564 [narrator] Together, the spacecraft take over 33,000 images of the gas giant. 86 00:04:56,068 --> 00:04:59,803 These pictures reshape our understanding of Jupiter 87 00:04:59,805 --> 00:05:01,938 Especially its largest moons 88 00:05:03,309 --> 00:05:04,241 Ganymede, 89 00:05:05,044 --> 00:05:06,043 Callisto, 90 00:05:07,179 --> 00:05:07,944 Europa, 91 00:05:09,715 --> 00:05:11,047 and Io. 92 00:05:12,951 --> 00:05:15,652 We saw all sorts of different kinds of landscapes on them 93 00:05:15,754 --> 00:05:19,122 and each one had its own individual type of personality. 94 00:05:20,959 --> 00:05:24,061 Of all the moons around Jupiter, and there are a lot, 95 00:05:24,063 --> 00:05:27,597 Io is the one that shocked everybody. 96 00:05:27,599 --> 00:05:30,233 [Linda] We got back this very unusual picture. 97 00:05:30,235 --> 00:05:34,438 We saw this bright feature on the dark limb of Io. 98 00:05:34,506 --> 00:05:36,306 We wondered, "What could it be?" 99 00:05:37,843 --> 00:05:41,445 At first, they thought that arc might be another moon behind Io. 100 00:05:41,546 --> 00:05:45,015 But the geometry was wrong. There were no moons there. 101 00:05:45,017 --> 00:05:48,819 Well, they figured out that these were volcanic plumes. 102 00:05:48,821 --> 00:05:51,421 And that bright feature on the dark limb 103 00:05:51,423 --> 00:05:54,758 was a volcano erupting on Io. 104 00:06:01,834 --> 00:06:04,868 [narrator] Voyager 1 record ash and lava 105 00:06:04,937 --> 00:06:08,038 blasting 190 miles into spac 106 00:06:09,408 --> 00:06:13,610 Eight times higher than the largest eruptions on Earth. 107 00:06:13,612 --> 00:06:17,514 This is the first time we'd ever seen another volcanically active world 108 00:06:17,516 --> 00:06:20,350 anywhere in the solar system, right? 109 00:06:20,419 --> 00:06:24,755 It really transformed our ideas, our concept of what a moon could be. 110 00:06:26,358 --> 00:06:28,458 [narrator] But astronomers were also baffled. 111 00:06:30,329 --> 00:06:32,796 When scientists first saw these images of Io, 112 00:06:32,798 --> 00:06:36,600 they had to ask the question, "How is this little moon still so hot?" 113 00:06:36,602 --> 00:06:40,704 On Earth, we know, you know, it's a big planet, it's volcanically active 114 00:06:40,706 --> 00:06:42,439 because of plate tectonics, and there's this, 115 00:06:42,541 --> 00:06:45,509 you know, ancient heat system inside the planet. 116 00:06:45,511 --> 00:06:47,511 When you look at a little mo like Io, 117 00:06:47,513 --> 00:06:49,646 you expect, "Ah, it's gonna be dead." RIght? 118 00:06:49,748 --> 00:06:53,950 But instead, it's the most volcanically active body in the solar system. 119 00:06:55,854 --> 00:07:00,056 [narrator] Io's volcanism is powered by tidal heating 120 00:07:00,158 --> 00:07:01,691 [Phil] As it orbits Jupiter 121 00:07:01,693 --> 00:07:04,928 it gets stretched and compressed by the gravity of Jupiter 122 00:07:04,930 --> 00:07:07,130 and the other moons as they all pass by it. 123 00:07:09,234 --> 00:07:12,135 [narrator] The compression and expansion generates heat 124 00:07:12,137 --> 00:07:13,937 melting Io's interior. 125 00:07:14,506 --> 00:07:15,939 A planetary process 126 00:07:16,508 --> 00:07:17,808 never before witnessed. 127 00:07:21,280 --> 00:07:25,315 At Jupiter, the Voyagers discover three new moons 128 00:07:25,317 --> 00:07:28,351 and a ring system invisible from Earth. 129 00:07:28,453 --> 00:07:29,619 Not to be outdone, 130 00:07:29,621 --> 00:07:32,522 the planet itself has a few surprises. 131 00:07:34,927 --> 00:07:38,528 The probes turn to the gas giant's most famous feature, 132 00:07:39,131 --> 00:07:40,630 the Great Red Spot. 133 00:07:42,935 --> 00:07:45,435 [Nina] Jupiter's red spot is a feature 134 00:07:45,437 --> 00:07:48,705 that has existed in its atmosphere since we began looking at Jupiter. 135 00:07:48,707 --> 00:07:50,040 It's incredible. 136 00:07:50,108 --> 00:07:52,642 What it turns out to be is a storm 137 00:07:52,744 --> 00:07:54,077 that has lasted centuries. 138 00:07:55,414 --> 00:07:59,516 [narrator] The Voyagers re a maelstrom of gas 139 00:07:59,518 --> 00:08:04,054 swirling counterclockwise between two bands of high speed winds. 140 00:08:05,057 --> 00:08:07,324 The red spot has been kept in a single place 141 00:08:07,326 --> 00:08:10,660 because it's kind of sandwiched between these two bands of atmosphere. 142 00:08:10,729 --> 00:08:13,163 [Phil] Like a whirlpool or an eddy in two currents 143 00:08:13,231 --> 00:08:14,631 that are moving next to each other. 144 00:08:14,633 --> 00:08:18,435 that may have helped promote its stability over all these centuries. 145 00:08:18,437 --> 00:08:21,004 [narrator] But Voyager's closeup shots show 146 00:08:21,006 --> 00:08:23,607 a far more complex structur than we expected. 147 00:08:25,511 --> 00:08:28,945 [Phil] It turns out, the Great Red Spot is not a single vortex. 148 00:08:28,947 --> 00:08:30,647 It's more complicated than that. 149 00:08:30,749 --> 00:08:34,518 What you might expect from a storm bigger than the Earth. 150 00:08:34,520 --> 00:08:38,421 Voyager actually took close up images of it and sa several smaller vortices 151 00:08:38,423 --> 00:08:40,624 spinning around inside of it 152 00:08:40,626 --> 00:08:46,530 [narrator] These small vortices are ten times large than any hurricane on Earth 153 00:08:46,532 --> 00:08:50,967 But the Voyagers can't detect how they interact with the spot. 154 00:08:50,969 --> 00:08:53,770 It will take a new generatio of space probes 155 00:08:53,838 --> 00:08:55,038 to solve that mystery. 156 00:08:56,141 --> 00:08:57,908 so, after Voyager had flew past, 157 00:08:57,910 --> 00:08:59,976 there were lots of questions that went unanswered. 158 00:08:59,978 --> 00:09:02,212 And Jupiter is a long way from the Earth. 159 00:09:02,214 --> 00:09:04,514 And really, the only way to answer some of them was to go back. 160 00:09:05,817 --> 00:09:09,052 [narrator] 37 years after the Voyager flybys, 161 00:09:09,121 --> 00:09:12,322 the Juno probe arrives at Jupiter. 162 00:09:12,324 --> 00:09:15,025 [Carly] The Juno space probe has a microwave radiometer. 163 00:09:15,027 --> 00:09:18,228 That instrument is able to detect microwave radiatio 164 00:09:18,230 --> 00:09:20,897 coming from very deep inside Jupiter. 165 00:09:20,899 --> 00:09:24,701 And from that we're able to determine things like it's deep composition, 166 00:09:24,703 --> 00:09:25,936 and its deep temperature. 167 00:09:27,239 --> 00:09:29,606 [narrator] Juno finds the Great Red Spot 168 00:09:29,608 --> 00:09:33,610 stretches at least 200 mile below the surface. 169 00:09:34,513 --> 00:09:36,012 And in 2021, 170 00:09:36,014 --> 00:09:38,515 a team combines Juno 171 00:09:38,517 --> 00:09:40,517 with Hubble and ground-based telescopes 172 00:09:40,519 --> 00:09:44,254 to finally discover what powers the gargantuan storm 173 00:09:46,258 --> 00:09:48,358 These small storms that are coming in 174 00:09:48,460 --> 00:09:50,327 are rotating very quickly. 175 00:09:50,329 --> 00:09:54,230 All of that feeds the Great Red Spot and keeps it spinning. 176 00:09:54,232 --> 00:09:56,633 Gives it that spinning energ that it used to survive. 177 00:09:58,637 --> 00:10:03,206 [narrator] The Voyager pro are ready for their next destination, Saturn. 178 00:10:03,208 --> 00:10:08,244 But to get there, they must first fly dangerously close to Jupiter. 179 00:10:18,457 --> 00:10:22,125 [narrator] The next stop on the Voyager probes' grand tour of the solar system 180 00:10:22,127 --> 00:10:23,826 is Saturn. 181 00:10:25,063 --> 00:10:30,133 But the ringed planet is ove 450 million miles away from Jupiter. 182 00:10:31,303 --> 00:10:32,569 To get there, 183 00:10:32,571 --> 00:10:35,538 the Voyagers will need to perform a maneuver 184 00:10:35,641 --> 00:10:38,041 known as a gravitational slingshot, 185 00:10:39,311 --> 00:10:42,946 which will catapult them from one planet to the next 186 00:10:46,351 --> 00:10:49,119 We allowed the large gravity of Jupiter 187 00:10:49,121 --> 00:10:51,154 to actually capture the spacecraft 188 00:10:51,256 --> 00:10:54,224 and start accelerating it towards that massive planet. 189 00:10:54,226 --> 00:10:56,326 But we did it at just the right angle. 190 00:10:56,328 --> 00:11:00,530 So we would move around it, and then continue away from the planet. 191 00:11:00,532 --> 00:11:03,433 Jupiter itself is barreling around the sun 192 00:11:03,435 --> 00:11:05,268 at very fast velocities. 193 00:11:05,370 --> 00:11:06,970 As you pull away from Jupite 194 00:11:07,005 --> 00:11:08,638 you keep some of that velocity with you. 195 00:11:11,309 --> 00:11:12,809 [narrator] If it's successfu 196 00:11:12,811 --> 00:11:16,346 the slingshot will knock yea off the Voyager's journe 197 00:11:16,414 --> 00:11:18,615 If things go wrong, it's game over. 198 00:11:20,085 --> 00:11:21,818 To do a gravitational slingshot, 199 00:11:21,820 --> 00:11:23,420 you need to do three things. 200 00:11:23,422 --> 00:11:25,722 You need to have really good calculations, 201 00:11:25,724 --> 00:11:28,058 excellent planning and perfect timing. 202 00:11:29,561 --> 00:11:32,495 [narrator] Mission controlle achieve all three. 203 00:11:32,497 --> 00:11:33,930 And the maneuver works. 204 00:11:35,734 --> 00:11:41,037 Voyagers 1 and 2 speed up by 225,000 miles an hour 205 00:11:41,139 --> 00:11:42,639 and race towards Saturn. 206 00:11:44,409 --> 00:11:46,843 1980, right on schedule, 207 00:11:46,912 --> 00:11:49,112 Voyager 1 arrives at the ringed planet. 208 00:11:50,615 --> 00:11:53,283 Its sensors probe Saturn's atmosphere 209 00:11:53,285 --> 00:11:56,920 and discover it's mainly hydrogen and helium. 210 00:11:58,457 --> 00:12:01,658 [Phil] Saturn has nearly 100 times the mass of the Earth. 211 00:12:01,660 --> 00:12:03,927 But it has so much more volu 212 00:12:03,929 --> 00:12:08,331 that when you look at its density, it's actually less dense than water. 213 00:12:08,333 --> 00:12:10,033 It's a very old joke in astronomy 214 00:12:10,035 --> 00:12:13,303 that if you put Saturn in a bathtub, it would float. 215 00:12:13,305 --> 00:12:14,871 But it would leave a ring. 216 00:12:17,042 --> 00:12:20,143 [narrator] The most striking discovery emerges from the data 217 00:12:20,245 --> 00:12:23,313 nine years after Voyagers' flybys. 218 00:12:23,315 --> 00:12:26,549 A bizarre cloud formation at the north pole. 219 00:12:28,153 --> 00:12:30,954 [Phil] A giant hexagon over the north pole 220 00:12:31,055 --> 00:12:33,623 with sides 9000 miles long 221 00:12:33,625 --> 00:12:36,126 and it's 18,000 miles across. 222 00:12:36,128 --> 00:12:38,128 Yeah, that's bizarre. 223 00:12:39,831 --> 00:12:43,133 [Carly] We don't often think about very stable geometric shapes 224 00:12:43,135 --> 00:12:46,803 like a hexagon. That feels like it shouldn't happen, right? 225 00:12:46,805 --> 00:12:50,640 You don't get hexagon shaped clouds on the Earth. 226 00:12:50,709 --> 00:12:53,710 [narrator] What could possib create a hexagon 227 00:12:53,712 --> 00:12:55,545 more than twice the size of Earth? 228 00:12:56,414 --> 00:12:58,248 Voyager discovered the hexagon. 229 00:12:58,316 --> 00:13:01,251 But we didn't have enough information to truly understand it. 230 00:13:03,421 --> 00:13:06,422 [narrator] Jump forward 24 years after Voyager, 231 00:13:06,424 --> 00:13:09,125 and another probe arrives at Saturn, 232 00:13:09,561 --> 00:13:11,461 Cassini. 233 00:13:11,530 --> 00:13:14,430 The main difference between the Cassini mission and the Voyager missions, 234 00:13:14,432 --> 00:13:17,467 besides Cassini having more cutting edge equipment on it, 235 00:13:17,536 --> 00:13:18,868 is that it was an orbiter. 236 00:13:18,937 --> 00:13:22,105 It orbited Saturn for 13 years. 237 00:13:22,107 --> 00:13:24,207 The Voyager missions just flew past it. 238 00:13:25,944 --> 00:13:29,112 [narrator] Cassini watches the pole for several years, 239 00:13:29,114 --> 00:13:31,948 capturing thousands of image of the hexagon. 240 00:13:34,753 --> 00:13:37,821 [Phil] The beauty of the Cassini mission is th it showed us what the hexago 241 00:13:37,823 --> 00:13:39,889 looked like years later after Voyager. 242 00:13:39,891 --> 00:13:43,660 Didn't necessarily solve the problem of why this thing exists, 243 00:13:43,728 --> 00:13:46,563 but it gave scientists a lot of ammunition to figure it out. 244 00:13:47,933 --> 00:13:49,732 [narrator] Finally in 2020, 245 00:13:49,734 --> 00:13:51,768 a team solves the mystery. 246 00:13:54,306 --> 00:13:58,942 Many cyclones surround a large jet stream of the planet's north pole. 247 00:13:59,911 --> 00:14:01,845 Where the two weather systems meet, 248 00:14:01,946 --> 00:14:03,613 a hexagon cloud forms. 249 00:14:05,217 --> 00:14:07,650 Something we don't see here on Earth. 250 00:14:09,321 --> 00:14:11,521 [Carly] The trouble with the Earth is it has a lot going on. 251 00:14:11,523 --> 00:14:13,623 We have oceans, we have mountains, 252 00:14:13,625 --> 00:14:16,626 all of that disrupts the atmosphere. 253 00:14:16,628 --> 00:14:19,162 On Saturn, there isn't any of that. 254 00:14:19,231 --> 00:14:23,066 So you're able to have thes very stable airflows 255 00:14:23,167 --> 00:14:25,134 that just wouldn't be possib on the Earth. 256 00:14:25,136 --> 00:14:27,437 [chuckles] Nature's pretty wonderful. 257 00:14:29,441 --> 00:14:33,543 [narrator] Next, the Voyagers turn their gaze to Saturn's rings 258 00:14:35,313 --> 00:14:39,616 Their images are gamechanger 259 00:14:39,618 --> 00:14:44,254 [Heidi] One of my colleague in my undergraduate planetary astronomy class 260 00:14:44,289 --> 00:14:45,688 was a computer whiz. 261 00:14:45,690 --> 00:14:49,525 And he managed to hack into the NASA feed that was going out. 262 00:14:49,527 --> 00:14:51,728 We all piled into his dorm room, 263 00:14:51,730 --> 00:14:53,463 the professors, the students 264 00:14:53,531 --> 00:14:57,834 seeing images coming from the Saturn flyby. 265 00:14:57,836 --> 00:15:03,306 [narrator] We thought that Saturn had just a handful of wide, flat rings. 266 00:15:03,308 --> 00:15:07,410 Voyager's images reveal thousands of separate rings 267 00:15:07,412 --> 00:15:08,811 orbiting the planet. 268 00:15:09,948 --> 00:15:12,148 But there's an even bigger surprise. 269 00:15:12,217 --> 00:15:13,516 An impossible ring. 270 00:15:15,020 --> 00:15:17,921 When the F-ring of Saturn 271 00:15:17,923 --> 00:15:21,157 close up image appeared on the screen, 272 00:15:21,225 --> 00:15:23,526 and instead of being sort o a single ring, 273 00:15:23,528 --> 00:15:27,263 it looked like multiple rings that were braided together. 274 00:15:28,066 --> 00:15:30,733 And my professor, Irwin Shapiro, 275 00:15:30,735 --> 00:15:33,336 famous planetary astronomer professor said, 276 00:15:34,339 --> 00:15:36,039 "That's not possible." 277 00:15:38,109 --> 00:15:40,310 [narrator] Scientists pour over the images 278 00:15:40,312 --> 00:15:42,845 to figure out what's causin the bizarre structure. 279 00:15:44,549 --> 00:15:47,717 Our basic understanding of rings back then, 280 00:15:47,719 --> 00:15:50,386 was that they were collections of little particles 281 00:15:50,388 --> 00:15:52,956 that were all just following the same orbit. 282 00:15:52,958 --> 00:15:55,558 [Dan] You'd expect that syst to have settled out into, 283 00:15:55,660 --> 00:15:59,028 you know, all the traffic on the highway, driving in the same direction, 284 00:15:59,030 --> 00:16:01,531 parallel lanes, all nice and neat. 285 00:16:01,533 --> 00:16:05,735 You don't expect these weird, dynamic interactions that are going on. 286 00:16:07,105 --> 00:16:10,039 [narrator] Then, scientists find two clues 287 00:16:10,108 --> 00:16:12,208 to explain the interactions 288 00:16:12,210 --> 00:16:15,211 And one of the things that was discovered was two satellites 289 00:16:15,213 --> 00:16:18,414 that orbit inside and outside of the F-ring. 290 00:16:18,416 --> 00:16:20,149 Prometheus and Pandora. 291 00:16:22,220 --> 00:16:26,856 It pointed to the idea that the moons and the rings were constantly interacting, 292 00:16:26,924 --> 00:16:29,625 but it didn't really tell us how. 293 00:16:29,627 --> 00:16:33,463 [narrator] Voyagers' discove of the moons doesn't solve the mystery 294 00:16:33,564 --> 00:16:35,231 of the braided F-ring. 295 00:16:35,233 --> 00:16:37,734 But it does tell the Cassini probe, 296 00:16:37,736 --> 00:16:40,236 25 years later, where to loo 297 00:16:41,439 --> 00:16:43,806 Cassini watches the tiny moo 298 00:16:43,808 --> 00:16:46,409 looping and twisting around each other 299 00:16:46,411 --> 00:16:47,876 as they orbit the planet. 300 00:16:49,214 --> 00:16:52,815 When you have two little moons, sort of co-orbiting with the ring, 301 00:16:52,817 --> 00:16:57,220 there's a complex gravitational dance that happens 302 00:16:57,222 --> 00:16:59,989 with the inner moon wanting to speed up particle 303 00:16:59,991 --> 00:17:02,558 the outer moon wanting to slow them down. 304 00:17:02,660 --> 00:17:05,428 And that interesting gravitational dance 305 00:17:05,430 --> 00:17:08,031 is what actually helps confine the ring into 306 00:17:08,033 --> 00:17:09,932 the narrow structure that we actually see. 307 00:17:12,137 --> 00:17:14,504 [Carly] By seeing these moons either side, 308 00:17:14,506 --> 00:17:17,540 there was an idea that they could be shepherding, 309 00:17:17,642 --> 00:17:19,409 they could be holding the ring in place. 310 00:17:21,446 --> 00:17:24,247 [narrator] Saturn's many moo and complicated rings 311 00:17:24,315 --> 00:17:25,848 are like a mini solar system 312 00:17:29,020 --> 00:17:32,388 Now, the two Voyager spacecraft separate 313 00:17:32,390 --> 00:17:35,224 to carry out two individual missions. 314 00:17:35,226 --> 00:17:39,729 Voyager 1 heads off to explo the edge of the solar system 315 00:17:39,731 --> 00:17:43,733 and Voyager 2 flies int the freezing cold 316 00:17:43,735 --> 00:17:45,535 of Saturn's shadow. 317 00:17:48,807 --> 00:17:50,406 For over two hours, 318 00:17:50,408 --> 00:17:54,043 the giant planet blocks all contact with the space probe. 319 00:17:57,348 --> 00:17:58,714 After a tense wait, 320 00:17:58,716 --> 00:18:00,416 Voyager 2 emerges. 321 00:18:02,253 --> 00:18:04,420 But something's wrong with the spacecraft. 322 00:18:05,523 --> 00:18:08,624 [Linda] Picture after pictur of dark sky came back. 323 00:18:08,626 --> 00:18:11,260 And we realized, something had either happened to the cameras, 324 00:18:11,329 --> 00:18:13,663 or something had happened to the scan platform. 325 00:18:14,933 --> 00:18:16,432 [narrator] The scan platform 326 00:18:16,434 --> 00:18:20,269 the vital rotating joint tha points the probe's instrumen 327 00:18:20,338 --> 00:18:21,704 isn't working. 328 00:18:21,706 --> 00:18:24,440 But how can scientists fix a probe 329 00:18:24,509 --> 00:18:26,042 2 billion miles from Earth? 330 00:18:34,519 --> 00:18:36,419 [narrator] August, 1981. 331 00:18:37,822 --> 00:18:41,457 Pioneering space probe, Voyager 2 , is in trouble. 332 00:18:42,460 --> 00:18:43,960 Passing behind Saturn, 333 00:18:43,962 --> 00:18:48,965 one of its key components, the scan platform, jams. 334 00:18:49,066 --> 00:18:51,968 [Linda] The scan platform is kind of like your head and neck. 335 00:18:51,970 --> 00:18:54,103 Imagine the cameras as your eyes. 336 00:18:54,105 --> 00:18:57,039 And if you want to turn to look at something, you'd turn your head. 337 00:18:57,041 --> 00:18:59,442 And your neck has to move. 338 00:18:59,511 --> 00:19:02,211 [narrator] When Voyager 2 passed behind Saturn, 339 00:19:02,213 --> 00:19:06,315 it ploughed through the ring at 29,000 miles an hour. 340 00:19:06,317 --> 00:19:09,452 Maybe a chunk of ice damaged the platform. 341 00:19:09,521 --> 00:19:13,823 Or maybe the maneuver gave the probe whiplash. 342 00:19:13,825 --> 00:19:18,928 We had been so ambitious in looking at the moons and the rings and Saturn, 343 00:19:18,930 --> 00:19:21,631 that we had literally squeezed the lubricant 344 00:19:21,633 --> 00:19:23,799 out of the bearings of the scan platform. 345 00:19:23,801 --> 00:19:25,133 And it got stuck. 346 00:19:26,037 --> 00:19:28,604 [narrator] The broken scan platform could be fata 347 00:19:28,606 --> 00:19:30,706 for the rest of the mission 348 00:19:30,708 --> 00:19:32,742 [Linda] And so, we worried, "Could we fix it?" 349 00:19:32,843 --> 00:19:35,811 We had Uranus and Neptune ahead of us with Voyager 2. 350 00:19:35,813 --> 00:19:38,247 We wanted to be able to fix the scan platform. 351 00:19:39,317 --> 00:19:40,549 [narrator] To fix it, 352 00:19:40,551 --> 00:19:45,021 the engineers employ some space physiotherapy. 353 00:19:45,023 --> 00:19:49,325 We slowly commanded it from Earth and got it to move a little bit at a time, 354 00:19:49,327 --> 00:19:53,829 until finally we could get those beautiful outbound pictures of Saturn 355 00:19:53,831 --> 00:19:54,897 that you see. 356 00:19:54,966 --> 00:19:57,233 [narrator] With Voyager operational again, 357 00:19:57,235 --> 00:20:01,270 NASA agreed to fund the next stage of the missio 358 00:20:01,306 --> 00:20:04,941 [Heidi] I'm eternally gratef that NASA did decide to 359 00:20:04,943 --> 00:20:06,943 complete the grand tour. 360 00:20:07,044 --> 00:20:10,947 It was tremendous relief to know we had a healthy spacecraft, 361 00:20:10,949 --> 00:20:12,315 Voyager 2, 362 00:20:12,317 --> 00:20:13,950 to go on to Uranus and Neptune. 363 00:20:16,020 --> 00:20:17,954 [narrator] 1986, 364 00:20:17,956 --> 00:20:20,623 boosted by a slingshot from Saturn, 365 00:20:20,625 --> 00:20:23,559 Voyager 2 arrives at Uranus 366 00:20:25,096 --> 00:20:27,263 After nine years in space, 367 00:20:27,332 --> 00:20:30,132 the probe is now in uncharted territory. 368 00:20:32,437 --> 00:20:34,370 [Carly] Ahead of Voyager's encounter, 369 00:20:34,405 --> 00:20:37,039 Uranus was really difficult to know much about 370 00:20:37,041 --> 00:20:38,908 We knew what its color was, 371 00:20:38,910 --> 00:20:41,777 but it didn't have any obvious features from the Earth. 372 00:20:41,779 --> 00:20:45,414 It looked sort of like a generic green blob. 373 00:20:45,416 --> 00:20:46,816 [narrator] We did know a couple things. 374 00:20:46,818 --> 00:20:48,718 Uranus has rings 375 00:20:48,720 --> 00:20:50,152 and sits on its side. 376 00:20:51,422 --> 00:20:53,155 [Dan] Unlike most of the other planets, 377 00:20:53,157 --> 00:20:58,427 whose spin axis are oriented more or less perpendicular to their orbital plane, 378 00:20:58,429 --> 00:21:01,264 Uranus is tipped over on its side, 379 00:21:01,332 --> 00:21:03,833 it rolls around the sun like a barrel at times. 380 00:21:03,835 --> 00:21:07,403 There are other times when the sun is shining right dow the equator. 381 00:21:07,405 --> 00:21:09,705 It's very unusual. 382 00:21:09,707 --> 00:21:12,608 [narrator] In a flyby lastin just five and a half hours, 383 00:21:12,610 --> 00:21:15,945 Voyager 2 discovers 11 new moons, 384 00:21:15,947 --> 00:21:19,115 and two more ghostly rings circling Uranus. 385 00:21:20,451 --> 00:21:23,319 But Voyager 2's strangest discovery 386 00:21:23,321 --> 00:21:26,522 is the planet's freakish magnetic field. 387 00:21:27,725 --> 00:21:30,326 Voyager carried a magnetic boom that told us about 388 00:21:30,328 --> 00:21:31,827 the magnetic field of the planet. 389 00:21:31,829 --> 00:21:35,298 And that turned out to be really interesting. 390 00:21:35,300 --> 00:21:39,201 [narrator] The strength and direction of Uranus' magnetic field 391 00:21:39,203 --> 00:21:41,637 turns out to be unlike any other planet. 392 00:21:42,540 --> 00:21:44,407 [Phil] The Earth has a magnetic field 393 00:21:44,409 --> 00:21:46,208 and it's pretty complicated how it behaves. 394 00:21:46,210 --> 00:21:50,846 But you can think of it as if there's a giant bar magnet inside the planet. 395 00:21:50,915 --> 00:21:53,716 There's a north magnetic pol and a south magnetic pole, 396 00:21:53,718 --> 00:21:56,819 and magnetic field lines around them. 397 00:21:56,821 --> 00:22:02,158 [narrator] On Earth, the bar magnet lines up clos to our planet's spin axis. 398 00:22:02,226 --> 00:22:06,062 The Voyager probes foun the same in Saturn and Jupiter. 399 00:22:07,031 --> 00:22:10,733 But Uranus' magnetosphere is different. 400 00:22:10,735 --> 00:22:13,836 The north and south axis of the magnetic field is tilted 401 00:22:13,838 --> 00:22:15,638 by almost 60 degrees, 402 00:22:15,707 --> 00:22:18,507 relative to the spin axis of Uranus. 403 00:22:18,509 --> 00:22:20,309 That's strange. 404 00:22:20,311 --> 00:22:23,746 [Dan] If you imagine transforming the Earth's magnetic field to be like 405 00:22:23,814 --> 00:22:25,180 the Uranus one, 406 00:22:25,182 --> 00:22:28,284 you'd have the magnetic north pole near Miami someplace. 407 00:22:28,286 --> 00:22:30,820 It's way out there in left field. 408 00:22:30,822 --> 00:22:34,623 [narrator] And the magnetic field isn't just tilted. 409 00:22:34,625 --> 00:22:37,360 [Dan] It's off center! The center of the magnetic field, 410 00:22:37,461 --> 00:22:39,028 you think would be at the center of the planet, 411 00:22:39,030 --> 00:22:42,164 it's actually offset by 5000 miles, 412 00:22:42,266 --> 00:22:43,566 which is a lot. 413 00:22:43,634 --> 00:22:46,769 We think it may be generated in the mantle of Uranus, 414 00:22:46,804 --> 00:22:50,740 where there is molten water, not molten iron. 415 00:22:50,808 --> 00:22:54,410 [narrator] Extreme heat and pressure breaks water molecules apart 416 00:22:54,412 --> 00:22:58,714 and rearranges them into a molten crystal structure, 417 00:22:58,716 --> 00:23:01,717 an exotic state called superionic ice. 418 00:23:03,421 --> 00:23:04,720 When we talk about ice, 419 00:23:04,722 --> 00:23:07,823 like, superionic ice inside a giant planet, 420 00:23:07,825 --> 00:23:10,126 we're not talking about ice cubes. [chuckles] 421 00:23:10,128 --> 00:23:12,661 Water has lots of different ways of being. 422 00:23:12,730 --> 00:23:14,764 And some of them are really strange. 423 00:23:16,367 --> 00:23:18,634 [narrator] The half liquid, half solid ice 424 00:23:18,636 --> 00:23:21,804 swirls around in the outer layer of the planet, 425 00:23:21,806 --> 00:23:24,140 moving like liquid metal. 426 00:23:24,208 --> 00:23:26,142 Because the ice conducts electricity, 427 00:23:26,210 --> 00:23:30,112 this produces the offset magnetic field around Uranus 428 00:23:32,216 --> 00:23:37,486 Voyager 2 also uncovered a gigantic magnetic glitch 429 00:23:37,488 --> 00:23:39,555 but it remained hidden in the data 430 00:23:39,657 --> 00:23:42,825 until scientists discovered in 2020. 431 00:23:43,828 --> 00:23:45,961 [Phil] What they found was a blip, 432 00:23:45,963 --> 00:23:48,130 a strengthening of the magnetic field, 433 00:23:48,132 --> 00:23:51,066 and it was about a million miles behind Uranus. 434 00:23:51,068 --> 00:23:54,370 And whatever was causing this was quite large. 435 00:23:54,438 --> 00:23:57,139 [narrator] It's a giant magnetic bubble, 436 00:23:57,241 --> 00:23:59,308 250,000 miles across, 437 00:24:00,011 --> 00:24:01,911 floating in space. 438 00:24:01,913 --> 00:24:04,713 [Phil] This type of magnetic bubble is called a plasmoid, 439 00:24:04,715 --> 00:24:07,416 and it happens when the magnetic field lines ge pinched off 440 00:24:07,418 --> 00:24:10,453 and it can create, sort of a self-contained shell. 441 00:24:10,521 --> 00:24:13,222 This means that the magnetic field around Uranus 442 00:24:13,224 --> 00:24:15,090 is dynamic 443 00:24:15,092 --> 00:24:19,228 and can fracture and interact with the solar win in very interesting ways. 444 00:24:19,230 --> 00:24:22,231 This can also have some of the atmosphere of Uranus in it. 445 00:24:22,233 --> 00:24:25,534 So, it's literally leaking gas into space. 446 00:24:25,536 --> 00:24:27,970 Uranus is belching. 447 00:24:28,038 --> 00:24:30,406 [narrator] It will take another mission to Uranus 448 00:24:30,408 --> 00:24:34,043 to truly understand this strange world. 449 00:24:34,045 --> 00:24:38,614 For now, Voyager 2 is the only spacecraft to ever visit. 450 00:24:39,317 --> 00:24:41,617 And what awaits the probe ne 451 00:24:41,619 --> 00:24:44,653 could be Voyager's greatest discovery yet. 452 00:24:54,232 --> 00:24:59,034 [narrator] 1989, Voyager 2 makes one last flyby. 453 00:24:59,036 --> 00:25:02,738 Neptune is the final stop on the planet hopping tour 454 00:25:02,840 --> 00:25:04,607 of the outer solar system. 455 00:25:04,609 --> 00:25:06,909 It's once in a lifetime opportunity 456 00:25:06,911 --> 00:25:11,080 to study the blue ice giant up close. 457 00:25:11,082 --> 00:25:13,916 [Heidi] We had these hints from our ground-based telescopes 458 00:25:13,918 --> 00:25:17,119 that there was activity in the atmosphere. 459 00:25:17,955 --> 00:25:20,256 But what its nature was, 460 00:25:20,825 --> 00:25:22,324 what was it like? 461 00:25:22,326 --> 00:25:26,695 There absolutely was nothing we had to prepare us 462 00:25:26,697 --> 00:25:28,764 for what we were going to see. 463 00:25:30,735 --> 00:25:35,704 [narrator] Voyager 2 spots four new rings and six more moons. 464 00:25:35,706 --> 00:25:41,143 It detects hydrogen, helium and methane in Neptune's atmosphere. 465 00:25:41,245 --> 00:25:45,314 And it records the fastest winds in the solar system, 466 00:25:45,316 --> 00:25:48,150 pushing white clouds across the planet 467 00:25:48,219 --> 00:25:50,619 at up to 1500 miles an hour 468 00:25:51,155 --> 00:25:53,622 And at their center, 469 00:25:53,624 --> 00:25:55,824 a colossal dark storm. 470 00:25:57,728 --> 00:25:59,028 [Heidi] There was a dark spo 471 00:25:59,030 --> 00:26:04,066 A big, dark spot on the disc of Neptune. 472 00:26:04,068 --> 00:26:07,036 We hadn't seen anything like that from the ground. [laughing] 473 00:26:07,038 --> 00:26:09,438 It was like, "What is that? 474 00:26:09,540 --> 00:26:12,741 Uh, we called it "The Great Dark Spot" because... 475 00:26:12,810 --> 00:26:14,143 that's all we could think of at the time. 476 00:26:15,179 --> 00:26:17,112 [narrator] Five years later 477 00:26:17,114 --> 00:26:21,016 when astronomers looked for the Great Dark Spot wit the Hubble Space telescope, 478 00:26:21,018 --> 00:26:22,384 they get a surprise. 479 00:26:24,121 --> 00:26:27,056 [Heidi] I was gonna look at how it changed with time 480 00:26:27,157 --> 00:26:30,259 and, you know, where it was located, things like that. 481 00:26:30,361 --> 00:26:34,163 And I remember, I got my first images back from Hubble. 482 00:26:34,264 --> 00:26:36,532 No Great Dark Spot. 483 00:26:36,534 --> 00:26:38,033 It was gone. 484 00:26:38,035 --> 00:26:39,835 It simply wasn't there. 485 00:26:39,837 --> 00:26:42,705 [laughs] I'm like, "What happened?" 486 00:26:42,707 --> 00:26:44,406 How is this even possible? 487 00:26:44,408 --> 00:26:48,711 The great Red Spot on Jupiter's lasted for hundreds of years. 488 00:26:48,713 --> 00:26:51,747 This is only five years, and this huge feature 489 00:26:52,216 --> 00:26:54,350 was simply gone. 490 00:26:56,454 --> 00:26:57,953 [narrator] Since Voyager, 491 00:26:57,955 --> 00:27:01,957 we've seen seven different dark spots on Neptune's surface. 492 00:27:02,860 --> 00:27:04,827 None lasting more than a few years. 493 00:27:06,030 --> 00:27:09,765 As to why that is and what's driving that, 494 00:27:09,833 --> 00:27:13,736 um, those are still mysteries that we haven't fully solved. 495 00:27:15,539 --> 00:27:17,606 [narrator] Before leaving the Neptune system, 496 00:27:17,608 --> 00:27:22,044 Voyager 2 turns its gaze to Neptune's largest moon, 497 00:27:22,046 --> 00:27:23,244 Triton. 498 00:27:24,315 --> 00:27:27,116 It was sort of a bit like, Voyager's last hurrah, 499 00:27:27,118 --> 00:27:31,053 sort of one of the last things that it showed us, and it was just phenomenal. 500 00:27:32,723 --> 00:27:36,659 [narrator] Voyager 2's instruments reveal a frozen world. 501 00:27:37,328 --> 00:27:40,129 At 391 degrees below zero, 502 00:27:40,131 --> 00:27:44,233 Triton is one of the coldes objects in the solar system 503 00:27:45,770 --> 00:27:47,870 [Linda] Here was a very intriguing world. 504 00:27:47,938 --> 00:27:50,439 We saw these dark streaks on the surface 505 00:27:50,508 --> 00:27:54,309 and realized that they were actually sticking up above the surface. 506 00:27:54,311 --> 00:27:58,747 What they were seeing was an active cryo volcano 507 00:27:58,816 --> 00:28:02,051 jetting a jet of black material, 508 00:28:02,086 --> 00:28:07,122 something like eight miles up above the surface of Triton. 509 00:28:07,124 --> 00:28:13,429 And then, the atmosphere of Triton was sheering it ou into a large cloud pattern. 510 00:28:13,431 --> 00:28:14,863 That was one of our first indications 511 00:28:14,932 --> 00:28:17,433 of geyser-like activity on a planet other than the Earth. 512 00:28:18,636 --> 00:28:20,335 It was almost pandemonium 513 00:28:20,337 --> 00:28:23,205 trying to figure out how do you generate this kind of activity 514 00:28:23,207 --> 00:28:26,508 on a moon that should be cryogenically frozen solid. 515 00:28:26,510 --> 00:28:28,310 Where is the energy source for this? 516 00:28:28,946 --> 00:28:30,446 [narrator] In 2019, 517 00:28:30,514 --> 00:28:32,648 scientists finally identify 518 00:28:32,750 --> 00:28:37,619 frozen nitrogen and carbon monoxide in the streaks. 519 00:28:37,621 --> 00:28:41,623 We think now what actually is going on there is it's the action of sunlight 520 00:28:41,625 --> 00:28:46,161 shining in some of the darker deposits on the surface of the moon. 521 00:28:46,263 --> 00:28:48,397 Just a little bit of a temperature change 522 00:28:48,399 --> 00:28:51,734 can take the nitrogen and liberate it off the surface. 523 00:28:55,506 --> 00:28:57,706 [narrator] In their grand to of the solar system, 524 00:28:57,708 --> 00:29:02,211 the Voyager probes produ an astounding number of discoveries. 525 00:29:04,315 --> 00:29:07,349 [Dan] Volcanoes on Io, geysers on Triton, 526 00:29:07,451 --> 00:29:10,319 and little weavy features on the Rings of Saturn, 527 00:29:10,321 --> 00:29:14,056 it all turned out to be far, far more interesting and alive 528 00:29:14,158 --> 00:29:16,325 and dynamic than we ever imagined. 529 00:29:17,962 --> 00:29:21,396 [narrator] While Voyager 2 leaves the planets behind, 530 00:29:21,398 --> 00:29:27,436 its twin, Voyager 1, heads to the edge of the solar system. 531 00:29:27,438 --> 00:29:30,639 But not before taking one last snapshot of home. 532 00:29:31,408 --> 00:29:33,742 A family portrait. 533 00:29:33,811 --> 00:29:36,545 [Phil] This idea by Carl Sag to take this family portrai 534 00:29:36,614 --> 00:29:38,413 is just magnificent. 535 00:29:38,415 --> 00:29:41,316 And the scientific need for it may be limited 536 00:29:41,318 --> 00:29:44,753 but the appeal to our sense of beauty, 537 00:29:45,589 --> 00:29:47,356 is staggering. 538 00:29:47,424 --> 00:29:51,260 [narrator] This shot isn't in pursuit of a new discover 539 00:29:51,361 --> 00:29:53,328 It's about finding a new perspective. 540 00:29:54,965 --> 00:29:57,900 [Phil] This family portrait is a series of 60 images 541 00:29:57,902 --> 00:29:59,535 put together into a mosaic. 542 00:29:59,537 --> 00:30:02,738 And in it you can see the sun and six planets, 543 00:30:02,840 --> 00:30:06,608 Venus, Earth, Jupiter, Satur Uranus and Neptune. 544 00:30:06,610 --> 00:30:10,412 As we're sending the images, we noticed along one of these sunbeams, 545 00:30:10,414 --> 00:30:11,814 there was the Earth. 546 00:30:12,449 --> 00:30:14,783 That pale blue dot, 547 00:30:14,785 --> 00:30:17,219 which contains every single person. 548 00:30:17,221 --> 00:30:21,623 We realized just how tiny our planet is. 549 00:30:21,625 --> 00:30:23,425 And how very special. 550 00:30:23,427 --> 00:30:27,629 It's one of the most amazing and beautiful things I've ever seen. 551 00:30:29,333 --> 00:30:31,200 [narrator] February 1990, 552 00:30:31,202 --> 00:30:34,469 the cameras power down for the last time. 553 00:30:34,505 --> 00:30:36,538 But this mission isn't over 554 00:30:36,640 --> 00:30:42,144 The Voyager probes are about to reach the edge of the solar system, 555 00:30:42,246 --> 00:30:45,814 a region no spacecraft has been to before. 556 00:30:53,524 --> 00:30:54,823 [narrator] Far from the sun 557 00:30:54,825 --> 00:30:57,326 at the very edge of the solar system, 558 00:30:57,328 --> 00:30:59,528 lies a vast expanse 559 00:30:59,530 --> 00:31:03,332 where no human-made object has ever entered. 560 00:31:04,101 --> 00:31:05,734 Until the Voyagers. 561 00:31:06,937 --> 00:31:10,305 This is like early explorers leaving sight of land. 562 00:31:10,307 --> 00:31:14,309 They are just surrounded by a vast ocean of night. 563 00:31:14,311 --> 00:31:16,645 They are all alone. 564 00:31:16,747 --> 00:31:20,816 It's sort of like the boat going from the bay, out into the open ocean. 565 00:31:20,818 --> 00:31:23,452 It's a whole different environment. 566 00:31:25,222 --> 00:31:28,724 [narrator] The Voyager pro are about to leave the calm of the solar system 567 00:31:28,726 --> 00:31:32,127 and enter the stormy waters of the galaxy. 568 00:31:33,831 --> 00:31:35,831 They start to exit the heliosphere, 569 00:31:35,833 --> 00:31:38,867 a protective bubble around the whole solar system 570 00:31:38,936 --> 00:31:41,270 and cross into a combat zon 571 00:31:41,338 --> 00:31:46,341 that hosts a cosmic battle between the sun and interstellar space. 572 00:31:48,412 --> 00:31:50,012 Inside the heliosphere, 573 00:31:50,014 --> 00:31:52,547 waves of particles from the sun, 574 00:31:52,616 --> 00:31:55,617 called the solar wind, push outward. 575 00:31:55,619 --> 00:31:59,054 Outside, an ocean of gas and particles 576 00:31:59,056 --> 00:32:00,222 pushes back. 577 00:32:01,525 --> 00:32:04,126 As the solar wind is expanding away from the sun, 578 00:32:04,128 --> 00:32:07,229 it's pushing against this thin stuff between the stars 579 00:32:07,231 --> 00:32:08,830 the interstellar medium. 580 00:32:08,832 --> 00:32:12,634 [Paul] That's the last influence that the sun has 581 00:32:12,636 --> 00:32:14,703 in the bubble surrounding it. 582 00:32:14,705 --> 00:32:18,707 Once you cross that, you are in interstellar space. 583 00:32:20,611 --> 00:32:23,345 [narrator] The heliosphere' frontline protects us 584 00:32:23,414 --> 00:32:26,248 from one of the galaxy's deadliest weapons, 585 00:32:26,317 --> 00:32:29,551 high energy particles called cosmic rays. 586 00:32:30,854 --> 00:32:33,221 Cosmic rays are like tiny bullets 587 00:32:33,223 --> 00:32:35,657 and they travel at close to the speed of light. 588 00:32:36,327 --> 00:32:38,727 [narrator] December 2004, 589 00:32:38,729 --> 00:32:43,031 Voyager 1 detects a sudden drop in the solar wind, 590 00:32:43,033 --> 00:32:47,536 evidence that the space prob is nearing the heart of the battlefield, 591 00:32:47,538 --> 00:32:50,439 a region known as the Termination Shock. 592 00:32:52,543 --> 00:32:55,711 [Paul] The Termination Shoc is the region 593 00:32:55,713 --> 00:32:59,114 where the solar wind starts to meet resistance, 594 00:32:59,116 --> 00:33:00,615 starts to run into something. 595 00:33:00,617 --> 00:33:02,951 And that causes it to slow down. 596 00:33:04,455 --> 00:33:08,123 [narrator] Voyager 1 picks u surges from both opposing forces, 597 00:33:08,759 --> 00:33:10,759 blasts of cosmic rays, 598 00:33:10,861 --> 00:33:14,796 followed by waves of the solar wind. 599 00:33:14,798 --> 00:33:18,800 The instruments onboard Voyager didn't just suddenly change from 600 00:33:18,802 --> 00:33:21,603 sun space to galaxy space. 601 00:33:21,605 --> 00:33:24,206 It actually kind of went back and forth several times 602 00:33:24,208 --> 00:33:27,509 as it was measuring the energies of the particle at that region. 603 00:33:29,346 --> 00:33:32,214 [narrator] This suggests tha the edge of the heliosphere 604 00:33:32,216 --> 00:33:34,116 is not a single battlefront 605 00:33:34,118 --> 00:33:38,020 but rather, a complex regio of skirmishes. 606 00:33:38,022 --> 00:33:41,523 A sea of gigantic, magnetic bubbles 607 00:33:41,525 --> 00:33:43,625 created by the sun's magnetic fields. 608 00:33:44,962 --> 00:33:48,330 The sun's magnetic field rotates with the sun, physically. 609 00:33:48,332 --> 00:33:51,400 But this far out, billions of miles from the sun, 610 00:33:51,402 --> 00:33:54,136 those magnetic field lines get dragged by particles 611 00:33:54,138 --> 00:33:55,437 and there's a lot of different effects on them. 612 00:33:55,506 --> 00:33:57,839 And they can get tangled up and loose. 613 00:33:57,908 --> 00:33:59,474 This creates bubbles, 614 00:33:59,476 --> 00:34:03,311 and some of these bubbles are a hundred million miles across. 615 00:34:03,313 --> 00:34:06,648 [narrator] The magnetic bubb boundary is not watertight. 616 00:34:06,717 --> 00:34:09,951 Some cosmic rays blast through. 617 00:34:09,953 --> 00:34:14,156 [Paul] This heliosphere is much more foamy than we had thought. 618 00:34:14,257 --> 00:34:16,124 There are gaps in our defens 619 00:34:16,126 --> 00:34:19,528 where deadly cosmic rays can find their way through 620 00:34:19,530 --> 00:34:22,064 into the inner solar system 621 00:34:22,165 --> 00:34:26,735 [narrator] The foamy defensi line blocks 90 percent of cosmic rays 622 00:34:26,737 --> 00:34:28,537 but allows 10 percent throug 623 00:34:30,507 --> 00:34:32,841 As Voyager 1 passes throu the battlefield, 624 00:34:32,943 --> 00:34:36,311 it detects fewer and fewer solar particles. 625 00:34:36,313 --> 00:34:39,347 Eventually, there are only cosmic rays 626 00:34:39,416 --> 00:34:40,949 and interstellar space. 627 00:34:42,219 --> 00:34:46,521 In 2012, the probe becomes humankind's first object 628 00:34:46,523 --> 00:34:48,824 to leave the solar system, 629 00:34:48,826 --> 00:34:52,828 followed in 2018 by Voyager. 630 00:34:53,864 --> 00:34:57,299 It's been 50 years since the first satellite 631 00:34:57,301 --> 00:35:00,535 poked their way out of the Earth's atmosphere. 632 00:35:00,537 --> 00:35:02,938 And now, both Voyager spacecraft 633 00:35:02,940 --> 00:35:06,241 have poked their heads out of the sun's atmosphere, 634 00:35:06,343 --> 00:35:08,043 are outside the solar system 635 00:35:08,045 --> 00:35:09,811 and exploring the galaxy. 636 00:35:12,216 --> 00:35:15,517 [narrator] The Voyagers cr the final frontier 637 00:35:15,519 --> 00:35:18,653 and sail the ocean between the stars. 638 00:35:18,755 --> 00:35:21,056 They don't see their first discovery, 639 00:35:21,458 --> 00:35:22,524 they hear it. 640 00:35:24,261 --> 00:35:26,328 In space, no one can hear you scream. 641 00:35:26,330 --> 00:35:29,831 There is no actual soundwaves moving around. 642 00:35:29,833 --> 00:35:32,367 But there are waves of plasma. 643 00:35:32,469 --> 00:35:34,069 Of electrons. 644 00:35:34,104 --> 00:35:37,639 [Phil] So, as Voyager pas through this, we can transla 645 00:35:37,708 --> 00:35:40,308 these changes in the plasma density to soundwaves. 646 00:35:40,310 --> 00:35:42,711 [deep space sounds] 647 00:35:42,713 --> 00:35:46,214 [narrator] This is the soun of interstellar space. 648 00:35:48,652 --> 00:35:52,821 Poetically, I kind of like to think of it as the song the galaxy is singing, 649 00:35:52,823 --> 00:35:56,057 welcoming Voyager to interstellar space. 650 00:35:56,059 --> 00:36:00,629 [Paul] Some of the sounds may even come from distant supernovas. 651 00:36:00,631 --> 00:36:03,431 Think about that, a star dyi 652 00:36:03,433 --> 00:36:05,800 tens of thousands of lightyears away 653 00:36:05,802 --> 00:36:08,069 and here's an echo of it, here. 654 00:36:12,109 --> 00:36:17,445 [narrator] The sounds of deep space tell us more abou our part of the galaxy. 655 00:36:17,514 --> 00:36:20,615 [Paul] As Voyager travel through the interstellar medium, 656 00:36:21,852 --> 00:36:26,054 we can use these sounds to map out its local environment. 657 00:36:26,056 --> 00:36:30,725 And since 2017, we've been mapping how these sounds get higher, 658 00:36:30,727 --> 00:36:33,528 and lower and higher, louder and softer, 659 00:36:33,530 --> 00:36:38,333 and it's telling us that the interstellar medium is not uniform at all. 660 00:36:38,335 --> 00:36:41,069 [narrator] Built to last five years, 661 00:36:41,138 --> 00:36:45,207 Voyager 1 and 2 are now more than 40 years old. 662 00:36:45,209 --> 00:36:47,943 Only one final mission remains, 663 00:36:48,044 --> 00:36:50,612 perhaps the most important mission. 664 00:36:50,614 --> 00:36:53,715 To let the rest of the galax know we're here. 665 00:37:03,327 --> 00:37:07,529 [narrator] The Voyager spacecraft are now outside the solar system. 666 00:37:07,531 --> 00:37:11,233 Our sun is just the brightest star among man 667 00:37:11,235 --> 00:37:14,669 How much longer can the prob keep going? 668 00:37:14,738 --> 00:37:18,840 [Linda] A limiting factor on the mission has turned out to be power. 669 00:37:18,909 --> 00:37:22,310 And every year there are four watts less power 670 00:37:22,312 --> 00:37:24,713 to run each of the Voyager spacecraft. 671 00:37:24,715 --> 00:37:27,449 There are no service stations out there, no way to, 672 00:37:27,550 --> 00:37:29,618 you know, repair things that go wrong. 673 00:37:29,620 --> 00:37:32,053 And it's really remarkable, the fact that they're still out there, 674 00:37:32,122 --> 00:37:33,622 in the cryogenic cold, 675 00:37:33,624 --> 00:37:35,624 you know, operating, they're still working. 676 00:37:35,626 --> 00:37:37,292 They're still alive. 677 00:37:37,294 --> 00:37:40,328 [narrator] In just five year there may be too little powe 678 00:37:40,330 --> 00:37:42,130 to transmit signals to Earth 679 00:37:42,833 --> 00:37:44,833 After a final message home, 680 00:37:44,835 --> 00:37:48,570 the Voyagers will fall silent forever. 681 00:37:48,638 --> 00:37:50,705 This part of the Voyager mission, 682 00:37:50,707 --> 00:37:52,340 flying in interstellar space, 683 00:37:52,409 --> 00:37:53,942 is the long goodbye. 684 00:37:57,014 --> 00:38:00,348 [Dan] They're gonna become our messages in a bottle. 685 00:38:00,417 --> 00:38:02,317 Little bit of humanity, 686 00:38:02,319 --> 00:38:05,420 you know, representing us when we're long gone. 687 00:38:05,422 --> 00:38:08,757 [narrator] The two probes could survive for billions of years. 688 00:38:09,993 --> 00:38:12,627 They could be not only, you know, interstellar voyagers, 689 00:38:12,629 --> 00:38:14,763 they could turn into intergalactic voyagers, ultimately. 690 00:38:17,067 --> 00:38:20,368 [narrator] Maybe the Voyages won't just drift forever. 691 00:38:21,538 --> 00:38:23,405 Maybe they'll be found. 692 00:38:25,208 --> 00:38:28,310 [Michelle] It was kind of a wonderful little jaunt of imagination. 693 00:38:28,312 --> 00:38:32,447 that maybe some alien civilization with incredibly powerful telescopes 694 00:38:32,549 --> 00:38:34,516 might notice that there's a little artificial object 695 00:38:34,518 --> 00:38:36,551 flying through space and be curious about it. 696 00:38:38,121 --> 00:38:41,523 [narrator] Strapped to each Voyager is an aluminum case 697 00:38:41,525 --> 00:38:44,926 On the outer side, is a map of how to find Eart 698 00:38:44,928 --> 00:38:47,329 with directions from different pulsars. 699 00:38:49,232 --> 00:38:52,834 [Michelle] So why use pulsars to direct the aliens to our location? 700 00:38:52,836 --> 00:38:56,504 These are the dead cores of stars after a supernova explosion. 701 00:38:56,506 --> 00:39:00,709 Well, amazingly, pulsars all spin at slightly different rates 702 00:39:00,711 --> 00:39:03,378 So, if you can actually triangulate your location, 703 00:39:03,380 --> 00:39:06,448 based on the rates of different pulsars in the sky, 704 00:39:06,516 --> 00:39:09,617 you can actually have sort of a galactic GPS system. 705 00:39:09,619 --> 00:39:12,620 You can show the aliens where we are with incredible accuracy. 706 00:39:13,523 --> 00:39:15,724 [narrator] Inside each case 707 00:39:15,726 --> 00:39:17,826 a gold plated copper disc. 708 00:39:18,595 --> 00:39:19,828 [Michelle] Looking back on i 709 00:39:19,830 --> 00:39:22,130 it's really kind of this wonderful part of humanity. 710 00:39:22,132 --> 00:39:23,665 We sent aliens out there, 711 00:39:23,700 --> 00:39:26,835 unimaginably, technologically advanced aliens, 712 00:39:26,837 --> 00:39:29,704 we sent them, basically, a vinyl record. 713 00:39:29,706 --> 00:39:32,807 [Paul] Yeah, the golden disc are literally discs. 714 00:39:32,809 --> 00:39:35,243 They actually are records with grooves. 715 00:39:35,312 --> 00:39:37,512 You can play them. You can jam out to them. 716 00:39:37,514 --> 00:39:39,948 It's got a soundtrack of our species. 717 00:39:39,950 --> 00:39:43,852 [Beethoven's 'Fifth Symphony' plays] 718 00:39:43,953 --> 00:39:46,421 [narrator] The records have tracks by Beethoven, 719 00:39:46,423 --> 00:39:49,624 Blind Willie Nelson and Chuck Berry, 720 00:39:49,626 --> 00:39:53,528 the sound of surf, of thunde of birdsong, 721 00:39:53,530 --> 00:39:55,129 and a human heartbeat. 722 00:39:56,299 --> 00:40:01,102 So, will aliens ever find the records and give them a spin? 723 00:40:01,104 --> 00:40:03,838 [Phil] The Golden Record is a lovely idea. 724 00:40:03,907 --> 00:40:07,108 Especially to energize and excite the public about this. 725 00:40:07,110 --> 00:40:09,144 Will it ever be found? 726 00:40:09,212 --> 00:40:11,613 There's a reason we call it space. 727 00:40:14,317 --> 00:40:16,818 [narrator] A tiny, cold spacecraft 728 00:40:16,820 --> 00:40:19,053 is a difficult target to fin 729 00:40:19,122 --> 00:40:21,823 Any species capable of detecting them, 730 00:40:21,825 --> 00:40:25,360 would have a better chance of spotting our planet. 731 00:40:25,428 --> 00:40:29,164 But the Voyagers will long outlive Earth. 732 00:40:29,232 --> 00:40:31,766 [Michelle] It's possible tha they will find it millions, 733 00:40:31,868 --> 00:40:33,168 or even billions of years in the future. 734 00:40:33,236 --> 00:40:34,803 Long after we are gone. 735 00:40:34,805 --> 00:40:37,305 When there really aren't humans anymore. 736 00:40:37,307 --> 00:40:40,708 Or is there even a possibility that when we start traveling to the stars 737 00:40:40,710 --> 00:40:42,243 in the far future, we'll find them. 738 00:40:43,814 --> 00:40:45,346 [narrator] Awaiting discover 739 00:40:45,382 --> 00:40:47,849 or doomed to drift alone, 740 00:40:47,918 --> 00:40:51,352 the Voyager probes have already inspired one civilization, 741 00:40:51,955 --> 00:40:53,721 ours. 742 00:40:53,723 --> 00:40:56,958 Calling these " Voyager "... [kisses] ...it's perfect. 743 00:40:56,960 --> 00:40:58,259 Because that's what they are doing. 744 00:40:58,261 --> 00:41:01,863 They are voyaging out to the outer solar system and beyond 745 00:41:01,931 --> 00:41:06,134 and showing that there is no end to our desire to explore. 746 00:41:08,238 --> 00:41:11,606 [narrator] They've shown us countless wonders of the solar system 747 00:41:11,608 --> 00:41:14,108 and a glimpse of what lies beyond. 748 00:41:15,045 --> 00:41:16,845 [Heidi] We, as a species, 749 00:41:17,314 --> 00:41:19,414 can build ships 750 00:41:19,416 --> 00:41:22,116 that not only sail the oceans of our Earth, 751 00:41:22,118 --> 00:41:24,452 but that can sail outwards, 752 00:41:24,521 --> 00:41:27,355 to the other planets in our system 753 00:41:27,424 --> 00:41:29,924 and reveal new worlds. 754 00:41:29,926 --> 00:41:33,027 [narrator] They are the greatest space mission ever 755 00:41:33,029 --> 00:41:36,564 [Paul] The legacy of Voyagr is our remnant. 756 00:41:36,633 --> 00:41:37,732 It is our memory. 757 00:41:37,734 --> 00:41:41,769 It is a sampling of humanity 758 00:41:41,838 --> 00:41:45,139 that is out there now among the stars. 759 00:41:45,208 --> 00:41:48,209 [narrator] And if they last until the death of the Universe, 760 00:41:48,211 --> 00:41:50,411 as the final stars fade, 761 00:41:50,413 --> 00:41:52,847 and everything goes dark, 762 00:41:52,916 --> 00:41:55,617 they will be humanity's final statement, 763 00:41:56,653 --> 00:41:57,819 "We were here."