1 00:00:01,102 --> 00:00:02,200 [narrator] Voyager, 2 00:00:02,202 --> 00:00:04,903 the most ambitious space mission in history. 3 00:00:05,806 --> 00:00:08,941 The two Voyager spacecraft are iconic. 4 00:00:09,043 --> 00:00:10,242 Iconic. 5 00:00:10,311 --> 00:00:12,077 Iconic. 6 00:00:12,079 --> 00:00:16,515 They're the first probes to truly explore half the planets in our solar system. 7 00:00:17,618 --> 00:00:20,019 Jupiter, Saturn, Uranus and Neptune. 8 00:00:20,021 --> 00:00:22,721 These went from dots of light in the sky, 9 00:00:22,723 --> 00:00:24,623 to real worlds. 10 00:00:24,625 --> 00:00:30,729 The Voyager missions have ventured far beyond where other probes have explored. 11 00:00:30,731 --> 00:00:34,900 They are the most distant emissary, representatives 12 00:00:34,902 --> 00:00:37,002 of the human species. 13 00:00:37,004 --> 00:00:40,639 They're the first spacecraft to taste interstellar space. 14 00:00:40,708 --> 00:00:45,344 [narrator] Exploring furthe than any humanmade spacecraf has gone before. 15 00:01:01,462 --> 00:01:05,664 [narrator] These are the logs of starships, Voyager 1 and 2. 16 00:01:05,766 --> 00:01:08,600 They have crossed the final frontier 17 00:01:08,602 --> 00:01:11,537 and are now in interstellar space. 18 00:01:12,706 --> 00:01:14,306 Almost a decade ago, 19 00:01:14,308 --> 00:01:17,042 Voyager 1 achieved something that had never been achieved before. 20 00:01:17,044 --> 00:01:18,944 It left our solar system. 21 00:01:18,946 --> 00:01:22,314 When Voyager crossed into interstellar space, 22 00:01:22,316 --> 00:01:25,517 humans became an interstellar species. 23 00:01:28,055 --> 00:01:30,556 [narrator] 14 billion miles from Earth, 24 00:01:30,624 --> 00:01:33,692 their radio signals travelin at the speed of light 25 00:01:33,694 --> 00:01:36,462 still take 21 hours to reach us. 26 00:01:39,033 --> 00:01:40,632 The Voyagers are so far t 27 00:01:40,634 --> 00:01:43,602 that when they look back towards the sun, it's just a pinprick of light. 28 00:01:43,604 --> 00:01:46,105 And they would need an exceptionally powerful telescope 29 00:01:46,107 --> 00:01:48,607 just to see the Earth. 30 00:01:48,609 --> 00:01:53,345 [narrator] Their original four-year mission has been extended to 44, 31 00:01:53,447 --> 00:01:54,947 and counting. 32 00:01:55,048 --> 00:01:57,850 From their current distant vantage point, 33 00:01:57,918 --> 00:02:01,120 they look back on strange new worlds 34 00:02:01,122 --> 00:02:04,022 and bold new science they've discovered. 35 00:02:06,694 --> 00:02:08,961 August 20th, 1977. 36 00:02:11,432 --> 00:02:13,298 [man] We have ignition, 37 00:02:13,300 --> 00:02:15,033 and we have liftoff. 38 00:02:15,069 --> 00:02:18,103 [narrator] The mission begin when Voyager 2 blasts of 39 00:02:19,940 --> 00:02:23,742 Followed two weeks later by its twin, Voyager 1, 40 00:02:23,844 --> 00:02:26,712 which will take a shorter and faster route. 41 00:02:27,948 --> 00:02:30,149 Their destination, Jupiter. 42 00:02:30,250 --> 00:02:32,518 And then, Saturn. 43 00:02:32,520 --> 00:02:38,357 When the time comes that that mission is actually ready to go to the launchpad, 44 00:02:38,425 --> 00:02:41,260 it's a funny mixture of joy 45 00:02:41,361 --> 00:02:43,395 and bittersweet loss. 46 00:02:43,397 --> 00:02:45,531 [woman] They become like your children. 47 00:02:45,533 --> 00:02:48,300 And that launch is like the birth of a baby. 48 00:02:48,302 --> 00:02:51,503 I was standing there, watching it climb up into the sky. 49 00:02:51,505 --> 00:02:53,739 We were cheering, we were so happy. 50 00:02:53,807 --> 00:02:55,707 Voyager was on its way. 51 00:02:57,945 --> 00:03:01,413 [narrator] Though funded to just explore the two gas giants, 52 00:03:01,415 --> 00:03:04,650 mission planners have a muc bigger journey in mind. 53 00:03:05,953 --> 00:03:08,420 To send the Voyager spacec 54 00:03:08,422 --> 00:03:10,822 on a grand tour of the solar system. 55 00:03:12,092 --> 00:03:13,425 To the outermost planets, 56 00:03:13,961 --> 00:03:16,395 Uranus and Neptune, 57 00:03:16,397 --> 00:03:19,031 worlds that have never been explored. 58 00:03:21,535 --> 00:03:22,801 To visit each planet, 59 00:03:22,803 --> 00:03:25,304 the probes must stick to a strict schedule, 60 00:03:25,306 --> 00:03:27,839 with only a quick flyby of each world. 61 00:03:29,710 --> 00:03:31,476 Once reaching Jupiter, 62 00:03:31,478 --> 00:03:35,013 they must use every second to complete close-up studie of the planet 63 00:03:35,015 --> 00:03:36,515 and its largest moons. 64 00:03:38,619 --> 00:03:41,954 One of the biggest challenges with flyby spacecraft is 65 00:03:41,956 --> 00:03:44,122 it may have taken years to get there, 66 00:03:44,124 --> 00:03:47,559 but the actual time that you're close to the planet 67 00:03:47,661 --> 00:03:49,161 is remarkably short. 68 00:03:49,229 --> 00:03:51,663 The Jupiter close-up data 69 00:03:51,732 --> 00:03:53,732 occurred during just three days. 70 00:03:54,935 --> 00:03:57,269 [narrator] February 1979, 71 00:03:57,271 --> 00:04:01,540 Voyager 1 begins beaming pictures back to Earth. 72 00:04:01,642 --> 00:04:02,941 It's an anxious wait. 73 00:04:03,811 --> 00:04:05,410 [Cooper] This is pre interne 74 00:04:05,412 --> 00:04:07,946 And so, when you look at the data coming in, 75 00:04:08,015 --> 00:04:11,116 it's coming in line by line, pixel by pixel. 76 00:04:11,118 --> 00:04:14,653 It was such an exciting time it was hard to know when to sleep. 77 00:04:14,755 --> 00:04:17,289 I brought my sleeping bag into my office 78 00:04:17,291 --> 00:04:20,626 so I wouldn't miss a single exciting picture. 79 00:04:22,630 --> 00:04:27,032 [narrator] Both Voyagers reveal an unbelievably dynamic world. 80 00:04:29,770 --> 00:04:33,305 Scientists were able to take a sequence of images of Jupiter 81 00:04:33,307 --> 00:04:36,942 that they could put together like a flipbook to get a sense of motion. 82 00:04:37,044 --> 00:04:38,944 And it was just astounding. 83 00:04:38,946 --> 00:04:43,115 Now we can see things moving within the atmospher of Jupiter 84 00:04:43,117 --> 00:04:45,751 in a way that we had no sense of before. 85 00:04:49,356 --> 00:04:54,559 [narrator] Together, the spacecraft take over 33,000 images of the gas giant. 86 00:04:56,063 --> 00:04:59,798 These pictures reshape our understanding of Jupiter 87 00:04:59,800 --> 00:05:01,933 Especially its largest moons 88 00:05:03,304 --> 00:05:04,236 Ganymede, 89 00:05:05,039 --> 00:05:06,038 Callisto, 90 00:05:07,174 --> 00:05:07,939 Europa, 91 00:05:09,710 --> 00:05:11,042 and Io. 92 00:05:12,946 --> 00:05:15,647 We saw all sorts of different kinds of landscapes on them 93 00:05:15,749 --> 00:05:19,117 and each one had its own individual type of personality. 94 00:05:20,954 --> 00:05:24,056 Of all the moons around Jupiter, and there are a lot, 95 00:05:24,058 --> 00:05:27,592 Io is the one that shocked everybody. 96 00:05:27,594 --> 00:05:30,228 [Linda] We got back this very unusual picture. 97 00:05:30,230 --> 00:05:34,433 We saw this bright feature on the dark limb of Io. 98 00:05:34,501 --> 00:05:36,301 We wondered, "What could it be?" 99 00:05:37,838 --> 00:05:41,440 At first, they thought that arc might be another moon behind Io. 100 00:05:41,541 --> 00:05:45,010 But the geometry was wrong. There were no moons there. 101 00:05:45,012 --> 00:05:48,814 Well, they figured out that these were volcanic plumes. 102 00:05:48,816 --> 00:05:51,416 And that bright feature on the dark limb 103 00:05:51,418 --> 00:05:54,753 was a volcano erupting on Io. 104 00:06:01,829 --> 00:06:04,863 [narrator] Voyager 1 record ash and lava 105 00:06:04,932 --> 00:06:08,033 blasting 190 miles into spac 106 00:06:09,403 --> 00:06:13,605 Eight times higher than the largest eruptions on Earth. 107 00:06:13,607 --> 00:06:17,509 This is the first time we'd ever seen another volcanically active world 108 00:06:17,511 --> 00:06:20,345 anywhere in the solar system, right? 109 00:06:20,414 --> 00:06:24,750 It really transformed our ideas, our concept of what a moon could be. 110 00:06:26,353 --> 00:06:28,453 [narrator] But astronomers were also baffled. 111 00:06:30,324 --> 00:06:32,791 When scientists first saw these images of Io, 112 00:06:32,793 --> 00:06:36,595 they had to ask the question, "How is this little moon still so hot?" 113 00:06:36,597 --> 00:06:40,699 On Earth, we know, you know, it's a big planet, it's volcanically active 114 00:06:40,701 --> 00:06:42,434 because of plate tectonics, and there's this, 115 00:06:42,536 --> 00:06:45,504 you know, ancient heat system inside the planet. 116 00:06:45,506 --> 00:06:47,506 When you look at a little mo like Io, 117 00:06:47,508 --> 00:06:49,641 you expect, "Ah, it's gonna be dead." RIght? 118 00:06:49,743 --> 00:06:53,945 But instead, it's the most volcanically active body in the solar system. 119 00:06:55,849 --> 00:07:00,051 [narrator] Io's volcanism is powered by tidal heating 120 00:07:00,153 --> 00:07:01,686 [Phil] As it orbits Jupiter 121 00:07:01,688 --> 00:07:04,923 it gets stretched and compressed by the gravity of Jupiter 122 00:07:04,925 --> 00:07:07,125 and the other moons as they all pass by it. 123 00:07:09,229 --> 00:07:12,130 [narrator] The compression and expansion generates heat 124 00:07:12,132 --> 00:07:13,932 melting Io's interior. 125 00:07:14,501 --> 00:07:15,934 A planetary process 126 00:07:16,503 --> 00:07:17,803 never before witnessed. 127 00:07:21,275 --> 00:07:25,310 At Jupiter, the Voyagers discover three new moons 128 00:07:25,312 --> 00:07:28,346 and a ring system invisible from Earth. 129 00:07:28,448 --> 00:07:29,614 Not to be outdone, 130 00:07:29,616 --> 00:07:32,517 the planet itself has a few surprises. 131 00:07:34,922 --> 00:07:38,523 The probes turn to the gas giant's most famous feature, 132 00:07:39,126 --> 00:07:40,625 the Great Red Spot. 133 00:07:42,930 --> 00:07:45,430 [Nina] Jupiter's red spot is a feature 134 00:07:45,432 --> 00:07:48,700 that has existed in its atmosphere since we began looking at Jupiter. 135 00:07:48,702 --> 00:07:50,035 It's incredible. 136 00:07:50,103 --> 00:07:52,637 What it turns out to be is a storm 137 00:07:52,739 --> 00:07:54,072 that has lasted centuries. 138 00:07:55,409 --> 00:07:59,511 [narrator] The Voyagers re a maelstrom of gas 139 00:07:59,513 --> 00:08:04,049 swirling counterclockwise between two bands of high speed winds. 140 00:08:05,052 --> 00:08:07,319 The red spot has been kept in a single place 141 00:08:07,321 --> 00:08:10,655 because it's kind of sandwiched between these two bands of atmosphere. 142 00:08:10,724 --> 00:08:13,158 [Phil] Like a whirlpool or an eddy in two currents 143 00:08:13,226 --> 00:08:14,626 that are moving next to each other. 144 00:08:14,628 --> 00:08:18,430 that may have helped promote its stability over all these centuries. 145 00:08:18,432 --> 00:08:20,999 [narrator] But Voyager's closeup shots show 146 00:08:21,001 --> 00:08:23,602 a far more complex structur than we expected. 147 00:08:25,506 --> 00:08:28,940 [Phil] It turns out, the Great Red Spot is not a single vortex. 148 00:08:28,942 --> 00:08:30,642 It's more complicated than that. 149 00:08:30,744 --> 00:08:34,513 What you might expect from a storm bigger than the Earth. 150 00:08:34,515 --> 00:08:38,416 Voyager actually took close up images of it and sa several smaller vortices 151 00:08:38,418 --> 00:08:40,619 spinning around inside of it 152 00:08:40,621 --> 00:08:46,525 [narrator] These small vortices are ten times large than any hurricane on Earth 153 00:08:46,527 --> 00:08:50,962 But the Voyagers can't detect how they interact with the spot. 154 00:08:50,964 --> 00:08:53,765 It will take a new generatio of space probes 155 00:08:53,833 --> 00:08:55,033 to solve that mystery. 156 00:08:56,136 --> 00:08:57,903 so, after Voyager had flew past, 157 00:08:57,905 --> 00:08:59,971 there were lots of questions that went unanswered. 158 00:08:59,973 --> 00:09:02,207 And Jupiter is a long way from the Earth. 159 00:09:02,209 --> 00:09:04,509 And really, the only way to answer some of them was to go back. 160 00:09:05,812 --> 00:09:09,047 [narrator] 37 years after the Voyager flybys, 161 00:09:09,116 --> 00:09:12,317 the Juno probe arrives at Jupiter. 162 00:09:12,319 --> 00:09:15,020 [Carly] The Juno space probe has a microwave radiometer. 163 00:09:15,022 --> 00:09:18,223 That instrument is able to detect microwave radiatio 164 00:09:18,225 --> 00:09:20,892 coming from very deep inside Jupiter. 165 00:09:20,894 --> 00:09:24,696 And from that we're able to determine things like it's deep composition, 166 00:09:24,698 --> 00:09:25,931 and its deep temperature. 167 00:09:27,234 --> 00:09:29,601 [narrator] Juno finds the Great Red Spot 168 00:09:29,603 --> 00:09:33,605 stretches at least 200 mile below the surface. 169 00:09:34,508 --> 00:09:36,007 And in 2021, 170 00:09:36,009 --> 00:09:38,510 a team combines Juno 171 00:09:38,512 --> 00:09:40,512 with Hubble and ground-based telescopes 172 00:09:40,514 --> 00:09:44,249 to finally discover what powers the gargantuan storm 173 00:09:46,253 --> 00:09:48,353 These small storms that are coming in 174 00:09:48,455 --> 00:09:50,322 are rotating very quickly. 175 00:09:50,324 --> 00:09:54,225 All of that feeds the Great Red Spot and keeps it spinning. 176 00:09:54,227 --> 00:09:56,628 Gives it that spinning energ that it used to survive. 177 00:09:58,632 --> 00:10:03,201 [narrator] The Voyager pro are ready for their next destination, Saturn. 178 00:10:03,203 --> 00:10:08,239 But to get there, they must first fly dangerously close to Jupiter. 179 00:10:18,452 --> 00:10:22,120 [narrator] The next stop on the Voyager probes' grand tour of the solar system 180 00:10:22,122 --> 00:10:23,821 is Saturn. 181 00:10:25,058 --> 00:10:30,128 But the ringed planet is ove 450 million miles away from Jupiter. 182 00:10:31,298 --> 00:10:32,564 To get there, 183 00:10:32,566 --> 00:10:35,533 the Voyagers will need to perform a maneuver 184 00:10:35,636 --> 00:10:38,036 known as a gravitational slingshot, 185 00:10:39,306 --> 00:10:42,941 which will catapult them from one planet to the next 186 00:10:46,346 --> 00:10:49,114 We allowed the large gravity of Jupiter 187 00:10:49,116 --> 00:10:51,149 to actually capture the spacecraft 188 00:10:51,251 --> 00:10:54,219 and start accelerating it towards that massive planet. 189 00:10:54,221 --> 00:10:56,321 But we did it at just the right angle. 190 00:10:56,323 --> 00:11:00,525 So we would move around it, and then continue away from the planet. 191 00:11:00,527 --> 00:11:03,428 Jupiter itself is barreling around the sun 192 00:11:03,430 --> 00:11:05,263 at very fast velocities. 193 00:11:05,365 --> 00:11:06,965 As you pull away from Jupite 194 00:11:07,000 --> 00:11:08,633 you keep some of that velocity with you. 195 00:11:11,304 --> 00:11:12,804 [narrator] If it's successfu 196 00:11:12,806 --> 00:11:16,341 the slingshot will knock yea off the Voyager's journe 197 00:11:16,409 --> 00:11:18,610 If things go wrong, it's game over. 198 00:11:20,080 --> 00:11:21,813 To do a gravitational slingshot, 199 00:11:21,815 --> 00:11:23,415 you need to do three things. 200 00:11:23,417 --> 00:11:25,717 You need to have really good calculations, 201 00:11:25,719 --> 00:11:28,053 excellent planning and perfect timing. 202 00:11:29,556 --> 00:11:32,490 [narrator] Mission controlle achieve all three. 203 00:11:32,492 --> 00:11:33,925 And the maneuver works. 204 00:11:35,729 --> 00:11:41,032 Voyagers 1 and 2 speed up by 225,000 miles an hour 205 00:11:41,134 --> 00:11:42,634 and race towards Saturn. 206 00:11:44,404 --> 00:11:46,838 1980, right on schedule, 207 00:11:46,907 --> 00:11:49,107 Voyager 1 arrives at the ringed planet. 208 00:11:50,610 --> 00:11:53,278 Its sensors probe Saturn's atmosphere 209 00:11:53,280 --> 00:11:56,915 and discover it's mainly hydrogen and helium. 210 00:11:58,452 --> 00:12:01,653 [Phil] Saturn has nearly 100 times the mass of the Earth. 211 00:12:01,655 --> 00:12:03,922 But it has so much more volu 212 00:12:03,924 --> 00:12:08,326 that when you look at its density, it's actually less dense than water. 213 00:12:08,328 --> 00:12:10,028 It's a very old joke in astronomy 214 00:12:10,030 --> 00:12:13,298 that if you put Saturn in a bathtub, it would float. 215 00:12:13,300 --> 00:12:14,866 But it would leave a ring. 216 00:12:17,037 --> 00:12:20,138 [narrator] The most striking discovery emerges from the data 217 00:12:20,240 --> 00:12:23,308 nine years after Voyagers' flybys. 218 00:12:23,310 --> 00:12:26,544 A bizarre cloud formation at the north pole. 219 00:12:28,148 --> 00:12:30,949 [Phil] A giant hexagon over the north pole 220 00:12:31,050 --> 00:12:33,618 with sides 9000 miles long 221 00:12:33,620 --> 00:12:36,121 and it's 18,000 miles across. 222 00:12:36,123 --> 00:12:38,123 Yeah, that's bizarre. 223 00:12:39,826 --> 00:12:43,128 [Carly] We don't often think about very stable geometric shapes 224 00:12:43,130 --> 00:12:46,798 like a hexagon. That feels like it shouldn't happen, right? 225 00:12:46,800 --> 00:12:50,635 You don't get hexagon shaped clouds on the Earth. 226 00:12:50,704 --> 00:12:53,705 [narrator] What could possib create a hexagon 227 00:12:53,707 --> 00:12:55,540 more than twice the size of Earth? 228 00:12:56,409 --> 00:12:58,243 Voyager discovered the hexagon. 229 00:12:58,311 --> 00:13:01,246 But we didn't have enough information to truly understand it. 230 00:13:03,416 --> 00:13:06,417 [narrator] Jump forward 24 years after Voyager, 231 00:13:06,419 --> 00:13:09,120 and another probe arrives at Saturn, 232 00:13:09,556 --> 00:13:11,456 Cassini. 233 00:13:11,525 --> 00:13:14,425 The main difference between the Cassini mission and the Voyager missions, 234 00:13:14,427 --> 00:13:17,462 besides Cassini having more cutting edge equipment on it, 235 00:13:17,531 --> 00:13:18,863 is that it was an orbiter. 236 00:13:18,932 --> 00:13:22,100 It orbited Saturn for 13 years. 237 00:13:22,102 --> 00:13:24,202 The Voyager missions just flew past it. 238 00:13:25,939 --> 00:13:29,107 [narrator] Cassini watches the pole for several years, 239 00:13:29,109 --> 00:13:31,943 capturing thousands of image of the hexagon. 240 00:13:34,748 --> 00:13:37,816 [Phil] The beauty of the Cassini mission is th it showed us what the hexago 241 00:13:37,818 --> 00:13:39,884 looked like years later after Voyager. 242 00:13:39,886 --> 00:13:43,655 Didn't necessarily solve the problem of why this thing exists, 243 00:13:43,723 --> 00:13:46,558 but it gave scientists a lot of ammunition to figure it out. 244 00:13:47,928 --> 00:13:49,727 [narrator] Finally in 2020, 245 00:13:49,729 --> 00:13:51,763 a team solves the mystery. 246 00:13:54,301 --> 00:13:58,937 Many cyclones surround a large jet stream of the planet's north pole. 247 00:13:59,906 --> 00:14:01,840 Where the two weather systems meet, 248 00:14:01,941 --> 00:14:03,608 a hexagon cloud forms. 249 00:14:05,212 --> 00:14:07,645 Something we don't see here on Earth. 250 00:14:09,316 --> 00:14:11,516 [Carly] The trouble with the Earth is it has a lot going on. 251 00:14:11,518 --> 00:14:13,618 We have oceans, we have mountains, 252 00:14:13,620 --> 00:14:16,621 all of that disrupts the atmosphere. 253 00:14:16,623 --> 00:14:19,157 On Saturn, there isn't any of that. 254 00:14:19,226 --> 00:14:23,061 So you're able to have thes very stable airflows 255 00:14:23,162 --> 00:14:25,129 that just wouldn't be possib on the Earth. 256 00:14:25,131 --> 00:14:27,432 [chuckles] Nature's pretty wonderful. 257 00:14:29,436 --> 00:14:33,538 [narrator] Next, the Voyagers turn their gaze to Saturn's rings 258 00:14:35,308 --> 00:14:39,611 Their images are gamechanger 259 00:14:39,613 --> 00:14:44,249 [Heidi] One of my colleague in my undergraduate planetary astronomy class 260 00:14:44,284 --> 00:14:45,683 was a computer whiz. 261 00:14:45,685 --> 00:14:49,520 And he managed to hack into the NASA feed that was going out. 262 00:14:49,522 --> 00:14:51,723 We all piled into his dorm room, 263 00:14:51,725 --> 00:14:53,458 the professors, the students 264 00:14:53,526 --> 00:14:57,829 seeing images coming from the Saturn flyby. 265 00:14:57,831 --> 00:15:03,301 [narrator] We thought that Saturn had just a handful of wide, flat rings. 266 00:15:03,303 --> 00:15:07,405 Voyager's images reveal thousands of separate rings 267 00:15:07,407 --> 00:15:08,806 orbiting the planet. 268 00:15:09,943 --> 00:15:12,143 But there's an even bigger surprise. 269 00:15:12,212 --> 00:15:13,511 An impossible ring. 270 00:15:15,015 --> 00:15:17,916 When the F-ring of Saturn 271 00:15:17,918 --> 00:15:21,152 close up image appeared on the screen, 272 00:15:21,220 --> 00:15:23,521 and instead of being sort o a single ring, 273 00:15:23,523 --> 00:15:27,258 it looked like multiple rings that were braided together. 274 00:15:28,061 --> 00:15:30,728 And my professor, Irwin Shapiro, 275 00:15:30,730 --> 00:15:33,331 famous planetary astronomer professor said, 276 00:15:34,334 --> 00:15:36,034 "That's not possible." 277 00:15:38,104 --> 00:15:40,305 [narrator] Scientists pour over the images 278 00:15:40,307 --> 00:15:42,840 to figure out what's causin the bizarre structure. 279 00:15:44,544 --> 00:15:47,712 Our basic understanding of rings back then, 280 00:15:47,714 --> 00:15:50,381 was that they were collections of little particles 281 00:15:50,383 --> 00:15:52,951 that were all just following the same orbit. 282 00:15:52,953 --> 00:15:55,553 [Dan] You'd expect that syst to have settled out into, 283 00:15:55,655 --> 00:15:59,023 you know, all the traffic on the highway, driving in the same direction, 284 00:15:59,025 --> 00:16:01,526 parallel lanes, all nice and neat. 285 00:16:01,528 --> 00:16:05,730 You don't expect these weird, dynamic interactions that are going on. 286 00:16:07,100 --> 00:16:10,034 [narrator] Then, scientists find two clues 287 00:16:10,103 --> 00:16:12,203 to explain the interactions 288 00:16:12,205 --> 00:16:15,206 And one of the things that was discovered was two satellites 289 00:16:15,208 --> 00:16:18,409 that orbit inside and outside of the F-ring. 290 00:16:18,411 --> 00:16:20,144 Prometheus and Pandora. 291 00:16:22,215 --> 00:16:26,851 It pointed to the idea that the moons and the rings were constantly interacting, 292 00:16:26,919 --> 00:16:29,620 but it didn't really tell us how. 293 00:16:29,622 --> 00:16:33,458 [narrator] Voyagers' discove of the moons doesn't solve the mystery 294 00:16:33,559 --> 00:16:35,226 of the braided F-ring. 295 00:16:35,228 --> 00:16:37,729 But it does tell the Cassini probe, 296 00:16:37,731 --> 00:16:40,231 25 years later, where to loo 297 00:16:41,434 --> 00:16:43,801 Cassini watches the tiny moo 298 00:16:43,803 --> 00:16:46,404 looping and twisting around each other 299 00:16:46,406 --> 00:16:47,871 as they orbit the planet. 300 00:16:49,209 --> 00:16:52,810 When you have two little moons, sort of co-orbiting with the ring, 301 00:16:52,812 --> 00:16:57,215 there's a complex gravitational dance that happens 302 00:16:57,217 --> 00:16:59,984 with the inner moon wanting to speed up particle 303 00:16:59,986 --> 00:17:02,553 the outer moon wanting to slow them down. 304 00:17:02,655 --> 00:17:05,423 And that interesting gravitational dance 305 00:17:05,425 --> 00:17:08,026 is what actually helps confine the ring into 306 00:17:08,028 --> 00:17:09,927 the narrow structure that we actually see. 307 00:17:12,132 --> 00:17:14,499 [Carly] By seeing these moons either side, 308 00:17:14,501 --> 00:17:17,535 there was an idea that they could be shepherding, 309 00:17:17,637 --> 00:17:19,404 they could be holding the ring in place. 310 00:17:21,441 --> 00:17:24,242 [narrator] Saturn's many moo and complicated rings 311 00:17:24,310 --> 00:17:25,843 are like a mini solar system 312 00:17:29,015 --> 00:17:32,383 Now, the two Voyager spacecraft separate 313 00:17:32,385 --> 00:17:35,219 to carry out two individual missions. 314 00:17:35,221 --> 00:17:39,724 Voyager 1 heads off to explo the edge of the solar system 315 00:17:39,726 --> 00:17:43,728 and Voyager 2 flies int the freezing cold 316 00:17:43,730 --> 00:17:45,530 of Saturn's shadow. 317 00:17:48,802 --> 00:17:50,401 For over two hours, 318 00:17:50,403 --> 00:17:54,038 the giant planet blocks all contact with the space probe. 319 00:17:57,343 --> 00:17:58,709 After a tense wait, 320 00:17:58,711 --> 00:18:00,411 Voyager 2 emerges. 321 00:18:02,248 --> 00:18:04,415 But something's wrong with the spacecraft. 322 00:18:05,518 --> 00:18:08,619 [Linda] Picture after pictur of dark sky came back. 323 00:18:08,621 --> 00:18:11,255 And we realized, something had either happened to the cameras, 324 00:18:11,324 --> 00:18:13,658 or something had happened to the scan platform. 325 00:18:14,928 --> 00:18:16,427 [narrator] The scan platform 326 00:18:16,429 --> 00:18:20,264 the vital rotating joint tha points the probe's instrumen 327 00:18:20,333 --> 00:18:21,699 isn't working. 328 00:18:21,701 --> 00:18:24,435 But how can scientists fix a probe 329 00:18:24,504 --> 00:18:26,037 2 billion miles from Earth? 330 00:18:34,514 --> 00:18:36,414 [narrator] August, 1981. 331 00:18:37,817 --> 00:18:41,452 Pioneering space probe, Voyager 2 , is in trouble. 332 00:18:42,455 --> 00:18:43,955 Passing behind Saturn, 333 00:18:43,957 --> 00:18:48,960 one of its key components, the scan platform, jams. 334 00:18:49,061 --> 00:18:51,963 [Linda] The scan platform is kind of like your head and neck. 335 00:18:51,965 --> 00:18:54,098 Imagine the cameras as your eyes. 336 00:18:54,100 --> 00:18:57,034 And if you want to turn to look at something, you'd turn your head. 337 00:18:57,036 --> 00:18:59,437 And your neck has to move. 338 00:18:59,506 --> 00:19:02,206 [narrator] When Voyager 2 passed behind Saturn, 339 00:19:02,208 --> 00:19:06,310 it ploughed through the ring at 29,000 miles an hour. 340 00:19:06,312 --> 00:19:09,447 Maybe a chunk of ice damaged the platform. 341 00:19:09,516 --> 00:19:13,818 Or maybe the maneuver gave the probe whiplash. 342 00:19:13,820 --> 00:19:18,923 We had been so ambitious in looking at the moons and the rings and Saturn, 343 00:19:18,925 --> 00:19:21,626 that we had literally squeezed the lubricant 344 00:19:21,628 --> 00:19:23,794 out of the bearings of the scan platform. 345 00:19:23,796 --> 00:19:25,128 And it got stuck. 346 00:19:26,032 --> 00:19:28,599 [narrator] The broken scan platform could be fata 347 00:19:28,601 --> 00:19:30,701 for the rest of the mission 348 00:19:30,703 --> 00:19:32,737 [Linda] And so, we worried, "Could we fix it?" 349 00:19:32,838 --> 00:19:35,806 We had Uranus and Neptune ahead of us with Voyager 2. 350 00:19:35,808 --> 00:19:38,242 We wanted to be able to fix the scan platform. 351 00:19:39,312 --> 00:19:40,544 [narrator] To fix it, 352 00:19:40,546 --> 00:19:45,016 the engineers employ some space physiotherapy. 353 00:19:45,018 --> 00:19:49,320 We slowly commanded it from Earth and got it to move a little bit at a time, 354 00:19:49,322 --> 00:19:53,824 until finally we could get those beautiful outbound pictures of Saturn 355 00:19:53,826 --> 00:19:54,892 that you see. 356 00:19:54,961 --> 00:19:57,228 [narrator] With Voyager operational again, 357 00:19:57,230 --> 00:20:01,265 NASA agreed to fund the next stage of the missio 358 00:20:01,301 --> 00:20:04,936 [Heidi] I'm eternally gratef that NASA did decide to 359 00:20:04,938 --> 00:20:06,938 complete the grand tour. 360 00:20:07,039 --> 00:20:10,942 It was tremendous relief to know we had a healthy spacecraft, 361 00:20:10,944 --> 00:20:12,310 Voyager 2, 362 00:20:12,312 --> 00:20:13,945 to go on to Uranus and Neptune. 363 00:20:16,015 --> 00:20:17,949 [narrator] 1986, 364 00:20:17,951 --> 00:20:20,618 boosted by a slingshot from Saturn, 365 00:20:20,620 --> 00:20:23,554 Voyager 2 arrives at Uranus 366 00:20:25,091 --> 00:20:27,258 After nine years in space, 367 00:20:27,327 --> 00:20:30,127 the probe is now in uncharted territory. 368 00:20:32,432 --> 00:20:34,365 [Carly] Ahead of Voyager's encounter, 369 00:20:34,400 --> 00:20:37,034 Uranus was really difficult to know much about 370 00:20:37,036 --> 00:20:38,903 We knew what its color was, 371 00:20:38,905 --> 00:20:41,772 but it didn't have any obvious features from the Earth. 372 00:20:41,774 --> 00:20:45,409 It looked sort of like a generic green blob. 373 00:20:45,411 --> 00:20:46,811 [narrator] We did know a couple things. 374 00:20:46,813 --> 00:20:48,713 Uranus has rings 375 00:20:48,715 --> 00:20:50,147 and sits on its side. 376 00:20:51,417 --> 00:20:53,150 [Dan] Unlike most of the other planets, 377 00:20:53,152 --> 00:20:58,422 whose spin axis are oriented more or less perpendicular to their orbital plane, 378 00:20:58,424 --> 00:21:01,259 Uranus is tipped over on its side, 379 00:21:01,327 --> 00:21:03,828 it rolls around the sun like a barrel at times. 380 00:21:03,830 --> 00:21:07,398 There are other times when the sun is shining right dow the equator. 381 00:21:07,400 --> 00:21:09,700 It's very unusual. 382 00:21:09,702 --> 00:21:12,603 [narrator] In a flyby lastin just five and a half hours, 383 00:21:12,605 --> 00:21:15,940 Voyager 2 discovers 11 new moons, 384 00:21:15,942 --> 00:21:19,110 and two more ghostly rings circling Uranus. 385 00:21:20,446 --> 00:21:23,314 But Voyager 2's strangest discovery 386 00:21:23,316 --> 00:21:26,517 is the planet's freakish magnetic field. 387 00:21:27,720 --> 00:21:30,321 Voyager carried a magnetic boom that told us about 388 00:21:30,323 --> 00:21:31,822 the magnetic field of the planet. 389 00:21:31,824 --> 00:21:35,293 And that turned out to be really interesting. 390 00:21:35,295 --> 00:21:39,196 [narrator] The strength and direction of Uranus' magnetic field 391 00:21:39,198 --> 00:21:41,632 turns out to be unlike any other planet. 392 00:21:42,535 --> 00:21:44,402 [Phil] The Earth has a magnetic field 393 00:21:44,404 --> 00:21:46,203 and it's pretty complicated how it behaves. 394 00:21:46,205 --> 00:21:50,841 But you can think of it as if there's a giant bar magnet inside the planet. 395 00:21:50,910 --> 00:21:53,711 There's a north magnetic pol and a south magnetic pole, 396 00:21:53,713 --> 00:21:56,814 and magnetic field lines around them. 397 00:21:56,816 --> 00:22:02,153 [narrator] On Earth, the bar magnet lines up clos to our planet's spin axis. 398 00:22:02,221 --> 00:22:06,057 The Voyager probes foun the same in Saturn and Jupiter. 399 00:22:07,026 --> 00:22:10,728 But Uranus' magnetosphere is different. 400 00:22:10,730 --> 00:22:13,831 The north and south axis of the magnetic field is tilted 401 00:22:13,833 --> 00:22:15,633 by almost 60 degrees, 402 00:22:15,702 --> 00:22:18,502 relative to the spin axis of Uranus. 403 00:22:18,504 --> 00:22:20,304 That's strange. 404 00:22:20,306 --> 00:22:23,741 [Dan] If you imagine transforming the Earth's magnetic field to be like 405 00:22:23,809 --> 00:22:25,175 the Uranus one, 406 00:22:25,177 --> 00:22:28,279 you'd have the magnetic north pole near Miami someplace. 407 00:22:28,281 --> 00:22:30,815 It's way out there in left field. 408 00:22:30,817 --> 00:22:34,618 [narrator] And the magnetic field isn't just tilted. 409 00:22:34,620 --> 00:22:37,355 [Dan] It's off center! The center of the magnetic field, 410 00:22:37,456 --> 00:22:39,023 you think would be at the center of the planet, 411 00:22:39,025 --> 00:22:42,159 it's actually offset by 5000 miles, 412 00:22:42,261 --> 00:22:43,561 which is a lot. 413 00:22:43,629 --> 00:22:46,764 We think it may be generated in the mantle of Uranus, 414 00:22:46,799 --> 00:22:50,735 where there is molten water, not molten iron. 415 00:22:50,803 --> 00:22:54,405 [narrator] Extreme heat and pressure breaks water molecules apart 416 00:22:54,407 --> 00:22:58,709 and rearranges them into a molten crystal structure, 417 00:22:58,711 --> 00:23:01,712 an exotic state called superionic ice. 418 00:23:03,416 --> 00:23:04,715 When we talk about ice, 419 00:23:04,717 --> 00:23:07,818 like, superionic ice inside a giant planet, 420 00:23:07,820 --> 00:23:10,121 we're not talking about ice cubes. [chuckles] 421 00:23:10,123 --> 00:23:12,656 Water has lots of different ways of being. 422 00:23:12,725 --> 00:23:14,759 And some of them are really strange. 423 00:23:16,362 --> 00:23:18,629 [narrator] The half liquid, half solid ice 424 00:23:18,631 --> 00:23:21,799 swirls around in the outer layer of the planet, 425 00:23:21,801 --> 00:23:24,135 moving like liquid metal. 426 00:23:24,203 --> 00:23:26,137 Because the ice conducts electricity, 427 00:23:26,205 --> 00:23:30,107 this produces the offset magnetic field around Uranus 428 00:23:32,211 --> 00:23:37,481 Voyager 2 also uncovered a gigantic magnetic glitch 429 00:23:37,483 --> 00:23:39,550 but it remained hidden in the data 430 00:23:39,652 --> 00:23:42,820 until scientists discovered in 2020. 431 00:23:43,823 --> 00:23:45,956 [Phil] What they found was a blip, 432 00:23:45,958 --> 00:23:48,125 a strengthening of the magnetic field, 433 00:23:48,127 --> 00:23:51,061 and it was about a million miles behind Uranus. 434 00:23:51,063 --> 00:23:54,365 And whatever was causing this was quite large. 435 00:23:54,433 --> 00:23:57,134 [narrator] It's a giant magnetic bubble, 436 00:23:57,236 --> 00:23:59,303 250,000 miles across, 437 00:24:00,006 --> 00:24:01,906 floating in space. 438 00:24:01,908 --> 00:24:04,708 [Phil] This type of magnetic bubble is called a plasmoid, 439 00:24:04,710 --> 00:24:07,411 and it happens when the magnetic field lines ge pinched off 440 00:24:07,413 --> 00:24:10,448 and it can create, sort of a self-contained shell. 441 00:24:10,516 --> 00:24:13,217 This means that the magnetic field around Uranus 442 00:24:13,219 --> 00:24:15,085 is dynamic 443 00:24:15,087 --> 00:24:19,223 and can fracture and interact with the solar win in very interesting ways. 444 00:24:19,225 --> 00:24:22,226 This can also have some of the atmosphere of Uranus in it. 445 00:24:22,228 --> 00:24:25,529 So, it's literally leaking gas into space. 446 00:24:25,531 --> 00:24:27,965 Uranus is belching. 447 00:24:28,033 --> 00:24:30,401 [narrator] It will take another mission to Uranus 448 00:24:30,403 --> 00:24:34,038 to truly understand this strange world. 449 00:24:34,040 --> 00:24:38,609 For now, Voyager 2 is the only spacecraft to ever visit. 450 00:24:39,312 --> 00:24:41,612 And what awaits the probe ne 451 00:24:41,614 --> 00:24:44,648 could be Voyager's greatest discovery yet. 452 00:24:54,227 --> 00:24:59,029 [narrator] 1989, Voyager 2 makes one last flyby. 453 00:24:59,031 --> 00:25:02,733 Neptune is the final stop on the planet hopping tour 454 00:25:02,835 --> 00:25:04,602 of the outer solar system. 455 00:25:04,604 --> 00:25:06,904 It's once in a lifetime opportunity 456 00:25:06,906 --> 00:25:11,075 to study the blue ice giant up close. 457 00:25:11,077 --> 00:25:13,911 [Heidi] We had these hints from our ground-based telescopes 458 00:25:13,913 --> 00:25:17,114 that there was activity in the atmosphere. 459 00:25:17,950 --> 00:25:20,251 But what its nature was, 460 00:25:20,820 --> 00:25:22,319 what was it like? 461 00:25:22,321 --> 00:25:26,690 There absolutely was nothing we had to prepare us 462 00:25:26,692 --> 00:25:28,759 for what we were going to see. 463 00:25:30,730 --> 00:25:35,699 [narrator] Voyager 2 spots four new rings and six more moons. 464 00:25:35,701 --> 00:25:41,138 It detects hydrogen, helium and methane in Neptune's atmosphere. 465 00:25:41,240 --> 00:25:45,309 And it records the fastest winds in the solar system, 466 00:25:45,311 --> 00:25:48,145 pushing white clouds across the planet 467 00:25:48,214 --> 00:25:50,614 at up to 1500 miles an hour 468 00:25:51,150 --> 00:25:53,617 And at their center, 469 00:25:53,619 --> 00:25:55,819 a colossal dark storm. 470 00:25:57,723 --> 00:25:59,023 [Heidi] There was a dark spo 471 00:25:59,025 --> 00:26:04,061 A big, dark spot on the disc of Neptune. 472 00:26:04,063 --> 00:26:07,031 We hadn't seen anything like that from the ground. [laughing] 473 00:26:07,033 --> 00:26:09,433 It was like, "What is that? 474 00:26:09,535 --> 00:26:12,736 Uh, we called it "The Great Dark Spot" because... 475 00:26:12,805 --> 00:26:14,138 that's all we could think of at the time. 476 00:26:15,174 --> 00:26:17,107 [narrator] Five years later 477 00:26:17,109 --> 00:26:21,011 when astronomers looked for the Great Dark Spot wit the Hubble Space telescope, 478 00:26:21,013 --> 00:26:22,379 they get a surprise. 479 00:26:24,116 --> 00:26:27,051 [Heidi] I was gonna look at how it changed with time 480 00:26:27,152 --> 00:26:30,254 and, you know, where it was located, things like that. 481 00:26:30,356 --> 00:26:34,158 And I remember, I got my first images back from Hubble. 482 00:26:34,259 --> 00:26:36,527 No Great Dark Spot. 483 00:26:36,529 --> 00:26:38,028 It was gone. 484 00:26:38,030 --> 00:26:39,830 It simply wasn't there. 485 00:26:39,832 --> 00:26:42,700 [laughs] I'm like, "What happened?" 486 00:26:42,702 --> 00:26:44,401 How is this even possible? 487 00:26:44,403 --> 00:26:48,706 The great Red Spot on Jupiter's lasted for hundreds of years. 488 00:26:48,708 --> 00:26:51,742 This is only five years, and this huge feature 489 00:26:52,211 --> 00:26:54,345 was simply gone. 490 00:26:56,449 --> 00:26:57,948 [narrator] Since Voyager, 491 00:26:57,950 --> 00:27:01,952 we've seen seven different dark spots on Neptune's surface. 492 00:27:02,855 --> 00:27:04,822 None lasting more than a few years. 493 00:27:06,025 --> 00:27:09,760 As to why that is and what's driving that, 494 00:27:09,828 --> 00:27:13,731 um, those are still mysteries that we haven't fully solved. 495 00:27:15,534 --> 00:27:17,601 [narrator] Before leaving the Neptune system, 496 00:27:17,603 --> 00:27:22,039 Voyager 2 turns its gaze to Neptune's largest moon, 497 00:27:22,041 --> 00:27:23,239 Triton. 498 00:27:24,310 --> 00:27:27,111 It was sort of a bit like, Voyager's last hurrah, 499 00:27:27,113 --> 00:27:31,048 sort of one of the last things that it showed us, and it was just phenomenal. 500 00:27:32,718 --> 00:27:36,654 [narrator] Voyager 2's instruments reveal a frozen world. 501 00:27:37,323 --> 00:27:40,124 At 391 degrees below zero, 502 00:27:40,126 --> 00:27:44,228 Triton is one of the coldes objects in the solar system 503 00:27:45,765 --> 00:27:47,865 [Linda] Here was a very intriguing world. 504 00:27:47,933 --> 00:27:50,434 We saw these dark streaks on the surface 505 00:27:50,503 --> 00:27:54,304 and realized that they were actually sticking up above the surface. 506 00:27:54,306 --> 00:27:58,742 What they were seeing was an active cryo volcano 507 00:27:58,811 --> 00:28:02,046 jetting a jet of black material, 508 00:28:02,081 --> 00:28:07,117 something like eight miles up above the surface of Triton. 509 00:28:07,119 --> 00:28:13,424 And then, the atmosphere of Triton was sheering it ou into a large cloud pattern. 510 00:28:13,426 --> 00:28:14,858 That was one of our first indications 511 00:28:14,927 --> 00:28:17,428 of geyser-like activity on a planet other than the Earth. 512 00:28:18,631 --> 00:28:20,330 It was almost pandemonium 513 00:28:20,332 --> 00:28:23,200 trying to figure out how do you generate this kind of activity 514 00:28:23,202 --> 00:28:26,503 on a moon that should be cryogenically frozen solid. 515 00:28:26,505 --> 00:28:28,305 Where is the energy source for this? 516 00:28:28,941 --> 00:28:30,441 [narrator] In 2019, 517 00:28:30,509 --> 00:28:32,643 scientists finally identify 518 00:28:32,745 --> 00:28:37,614 frozen nitrogen and carbon monoxide in the streaks. 519 00:28:37,616 --> 00:28:41,618 We think now what actually is going on there is it's the action of sunlight 520 00:28:41,620 --> 00:28:46,156 shining in some of the darker deposits on the surface of the moon. 521 00:28:46,258 --> 00:28:48,392 Just a little bit of a temperature change 522 00:28:48,394 --> 00:28:51,729 can take the nitrogen and liberate it off the surface. 523 00:28:55,501 --> 00:28:57,701 [narrator] In their grand to of the solar system, 524 00:28:57,703 --> 00:29:02,206 the Voyager probes produ an astounding number of discoveries. 525 00:29:04,310 --> 00:29:07,344 [Dan] Volcanoes on Io, geysers on Triton, 526 00:29:07,446 --> 00:29:10,314 and little weavy features on the Rings of Saturn, 527 00:29:10,316 --> 00:29:14,051 it all turned out to be far, far more interesting and alive 528 00:29:14,153 --> 00:29:16,320 and dynamic than we ever imagined. 529 00:29:17,957 --> 00:29:21,391 [narrator] While Voyager 2 leaves the planets behind, 530 00:29:21,393 --> 00:29:27,431 its twin, Voyager 1, heads to the edge of the solar system. 531 00:29:27,433 --> 00:29:30,634 But not before taking one last snapshot of home. 532 00:29:31,403 --> 00:29:33,737 A family portrait. 533 00:29:33,806 --> 00:29:36,540 [Phil] This idea by Carl Sag to take this family portrai 534 00:29:36,609 --> 00:29:38,408 is just magnificent. 535 00:29:38,410 --> 00:29:41,311 And the scientific need for it may be limited 536 00:29:41,313 --> 00:29:44,748 but the appeal to our sense of beauty, 537 00:29:45,584 --> 00:29:47,351 is staggering. 538 00:29:47,419 --> 00:29:51,255 [narrator] This shot isn't in pursuit of a new discover 539 00:29:51,356 --> 00:29:53,323 It's about finding a new perspective. 540 00:29:54,960 --> 00:29:57,895 [Phil] This family portrait is a series of 60 images 541 00:29:57,897 --> 00:29:59,530 put together into a mosaic. 542 00:29:59,532 --> 00:30:02,733 And in it you can see the sun and six planets, 543 00:30:02,835 --> 00:30:06,603 Venus, Earth, Jupiter, Satur Uranus and Neptune. 544 00:30:06,605 --> 00:30:10,407 As we're sending the images, we noticed along one of these sunbeams, 545 00:30:10,409 --> 00:30:11,809 there was the Earth. 546 00:30:12,444 --> 00:30:14,778 That pale blue dot, 547 00:30:14,780 --> 00:30:17,214 which contains every single person. 548 00:30:17,216 --> 00:30:21,618 We realized just how tiny our planet is. 549 00:30:21,620 --> 00:30:23,420 And how very special. 550 00:30:23,422 --> 00:30:27,624 It's one of the most amazing and beautiful things I've ever seen. 551 00:30:29,328 --> 00:30:31,195 [narrator] February 1990, 552 00:30:31,197 --> 00:30:34,464 the cameras power down for the last time. 553 00:30:34,500 --> 00:30:36,533 But this mission isn't over 554 00:30:36,635 --> 00:30:42,139 The Voyager probes are about to reach the edge of the solar system, 555 00:30:42,241 --> 00:30:45,809 a region no spacecraft has been to before. 556 00:30:53,519 --> 00:30:54,818 [narrator] Far from the sun 557 00:30:54,820 --> 00:30:57,321 at the very edge of the solar system, 558 00:30:57,323 --> 00:30:59,523 lies a vast expanse 559 00:30:59,525 --> 00:31:03,327 where no human-made object has ever entered. 560 00:31:04,096 --> 00:31:05,729 Until the Voyagers. 561 00:31:06,932 --> 00:31:10,300 This is like early explorers leaving sight of land. 562 00:31:10,302 --> 00:31:14,304 They are just surrounded by a vast ocean of night. 563 00:31:14,306 --> 00:31:16,640 They are all alone. 564 00:31:16,742 --> 00:31:20,811 It's sort of like the boat going from the bay, out into the open ocean. 565 00:31:20,813 --> 00:31:23,447 It's a whole different environment. 566 00:31:25,217 --> 00:31:28,719 [narrator] The Voyager pro are about to leave the calm of the solar system 567 00:31:28,721 --> 00:31:32,122 and enter the stormy waters of the galaxy. 568 00:31:33,826 --> 00:31:35,826 They start to exit the heliosphere, 569 00:31:35,828 --> 00:31:38,862 a protective bubble around the whole solar system 570 00:31:38,931 --> 00:31:41,265 and cross into a combat zon 571 00:31:41,333 --> 00:31:46,336 that hosts a cosmic battle between the sun and interstellar space. 572 00:31:48,407 --> 00:31:50,007 Inside the heliosphere, 573 00:31:50,009 --> 00:31:52,542 waves of particles from the sun, 574 00:31:52,611 --> 00:31:55,612 called the solar wind, push outward. 575 00:31:55,614 --> 00:31:59,049 Outside, an ocean of gas and particles 576 00:31:59,051 --> 00:32:00,217 pushes back. 577 00:32:01,520 --> 00:32:04,121 As the solar wind is expanding away from the sun, 578 00:32:04,123 --> 00:32:07,224 it's pushing against this thin stuff between the stars 579 00:32:07,226 --> 00:32:08,825 the interstellar medium. 580 00:32:08,827 --> 00:32:12,629 [Paul] That's the last influence that the sun has 581 00:32:12,631 --> 00:32:14,698 in the bubble surrounding it. 582 00:32:14,700 --> 00:32:18,702 Once you cross that, you are in interstellar space. 583 00:32:20,606 --> 00:32:23,340 [narrator] The heliosphere' frontline protects us 584 00:32:23,409 --> 00:32:26,243 from one of the galaxy's deadliest weapons, 585 00:32:26,312 --> 00:32:29,546 high energy particles called cosmic rays. 586 00:32:30,849 --> 00:32:33,216 Cosmic rays are like tiny bullets 587 00:32:33,218 --> 00:32:35,652 and they travel at close to the speed of light. 588 00:32:36,322 --> 00:32:38,722 [narrator] December 2004, 589 00:32:38,724 --> 00:32:43,026 Voyager 1 detects a sudden drop in the solar wind, 590 00:32:43,028 --> 00:32:47,531 evidence that the space prob is nearing the heart of the battlefield, 591 00:32:47,533 --> 00:32:50,434 a region known as the Termination Shock. 592 00:32:52,538 --> 00:32:55,706 [Paul] The Termination Shoc is the region 593 00:32:55,708 --> 00:32:59,109 where the solar wind starts to meet resistance, 594 00:32:59,111 --> 00:33:00,610 starts to run into something. 595 00:33:00,612 --> 00:33:02,946 And that causes it to slow down. 596 00:33:04,450 --> 00:33:08,118 [narrator] Voyager 1 picks u surges from both opposing forces, 597 00:33:08,754 --> 00:33:10,754 blasts of cosmic rays, 598 00:33:10,856 --> 00:33:14,791 followed by waves of the solar wind. 599 00:33:14,793 --> 00:33:18,795 The instruments onboard Voyager didn't just suddenly change from 600 00:33:18,797 --> 00:33:21,598 sun space to galaxy space. 601 00:33:21,600 --> 00:33:24,201 It actually kind of went back and forth several times 602 00:33:24,203 --> 00:33:27,504 as it was measuring the energies of the particle at that region. 603 00:33:29,341 --> 00:33:32,209 [narrator] This suggests tha the edge of the heliosphere 604 00:33:32,211 --> 00:33:34,111 is not a single battlefront 605 00:33:34,113 --> 00:33:38,015 but rather, a complex regio of skirmishes. 606 00:33:38,017 --> 00:33:41,518 A sea of gigantic, magnetic bubbles 607 00:33:41,520 --> 00:33:43,620 created by the sun's magnetic fields. 608 00:33:44,957 --> 00:33:48,325 The sun's magnetic field rotates with the sun, physically. 609 00:33:48,327 --> 00:33:51,395 But this far out, billions of miles from the sun, 610 00:33:51,397 --> 00:33:54,131 those magnetic field lines get dragged by particles 611 00:33:54,133 --> 00:33:55,432 and there's a lot of different effects on them. 612 00:33:55,501 --> 00:33:57,834 And they can get tangled up and loose. 613 00:33:57,903 --> 00:33:59,469 This creates bubbles, 614 00:33:59,471 --> 00:34:03,306 and some of these bubbles are a hundred million miles across. 615 00:34:03,308 --> 00:34:06,643 [narrator] The magnetic bubb boundary is not watertight. 616 00:34:06,712 --> 00:34:09,946 Some cosmic rays blast through. 617 00:34:09,948 --> 00:34:14,151 [Paul] This heliosphere is much more foamy than we had thought. 618 00:34:14,252 --> 00:34:16,119 There are gaps in our defens 619 00:34:16,121 --> 00:34:19,523 where deadly cosmic rays can find their way through 620 00:34:19,525 --> 00:34:22,059 into the inner solar system 621 00:34:22,160 --> 00:34:26,730 [narrator] The foamy defensi line blocks 90 percent of cosmic rays 622 00:34:26,732 --> 00:34:28,532 but allows 10 percent throug 623 00:34:30,502 --> 00:34:32,836 As Voyager 1 passes throu the battlefield, 624 00:34:32,938 --> 00:34:36,306 it detects fewer and fewer solar particles. 625 00:34:36,308 --> 00:34:39,342 Eventually, there are only cosmic rays 626 00:34:39,411 --> 00:34:40,944 and interstellar space. 627 00:34:42,214 --> 00:34:46,516 In 2012, the probe becomes humankind's first object 628 00:34:46,518 --> 00:34:48,819 to leave the solar system, 629 00:34:48,821 --> 00:34:52,823 followed in 2018 by Voyager. 630 00:34:53,859 --> 00:34:57,294 It's been 50 years since the first satellite 631 00:34:57,296 --> 00:35:00,530 poked their way out of the Earth's atmosphere. 632 00:35:00,532 --> 00:35:02,933 And now, both Voyager spacecraft 633 00:35:02,935 --> 00:35:06,236 have poked their heads out of the sun's atmosphere, 634 00:35:06,338 --> 00:35:08,038 are outside the solar system 635 00:35:08,040 --> 00:35:09,806 and exploring the galaxy. 636 00:35:12,211 --> 00:35:15,512 [narrator] The Voyagers cr the final frontier 637 00:35:15,514 --> 00:35:18,648 and sail the ocean between the stars. 638 00:35:18,750 --> 00:35:21,051 They don't see their first discovery, 639 00:35:21,453 --> 00:35:22,519 they hear it. 640 00:35:24,256 --> 00:35:26,323 In space, no one can hear you scream. 641 00:35:26,325 --> 00:35:29,826 There is no actual soundwaves moving around. 642 00:35:29,828 --> 00:35:32,362 But there are waves of plasma. 643 00:35:32,464 --> 00:35:34,064 Of electrons. 644 00:35:34,099 --> 00:35:37,634 [Phil] So, as Voyager pas through this, we can transla 645 00:35:37,703 --> 00:35:40,303 these changes in the plasma density to soundwaves. 646 00:35:40,305 --> 00:35:42,706 [deep space sounds] 647 00:35:42,708 --> 00:35:46,209 [narrator] This is the soun of interstellar space. 648 00:35:48,647 --> 00:35:52,816 Poetically, I kind of like to think of it as the song the galaxy is singing, 649 00:35:52,818 --> 00:35:56,052 welcoming Voyager to interstellar space. 650 00:35:56,054 --> 00:36:00,624 [Paul] Some of the sounds may even come from distant supernovas. 651 00:36:00,626 --> 00:36:03,426 Think about that, a star dyi 652 00:36:03,428 --> 00:36:05,795 tens of thousands of lightyears away 653 00:36:05,797 --> 00:36:08,064 and here's an echo of it, here. 654 00:36:12,104 --> 00:36:17,440 [narrator] The sounds of deep space tell us more abou our part of the galaxy. 655 00:36:17,509 --> 00:36:20,610 [Paul] As Voyager travel through the interstellar medium, 656 00:36:21,847 --> 00:36:26,049 we can use these sounds to map out its local environment. 657 00:36:26,051 --> 00:36:30,720 And since 2017, we've been mapping how these sounds get higher, 658 00:36:30,722 --> 00:36:33,523 and lower and higher, louder and softer, 659 00:36:33,525 --> 00:36:38,328 and it's telling us that the interstellar medium is not uniform at all. 660 00:36:38,330 --> 00:36:41,064 [narrator] Built to last five years, 661 00:36:41,133 --> 00:36:45,202 Voyager 1 and 2 are now more than 40 years old. 662 00:36:45,204 --> 00:36:47,938 Only one final mission remains, 663 00:36:48,039 --> 00:36:50,607 perhaps the most important mission. 664 00:36:50,609 --> 00:36:53,710 To let the rest of the galax know we're here. 665 00:37:03,322 --> 00:37:07,524 [narrator] The Voyager spacecraft are now outside the solar system. 666 00:37:07,526 --> 00:37:11,228 Our sun is just the brightest star among man 667 00:37:11,230 --> 00:37:14,664 How much longer can the prob keep going? 668 00:37:14,733 --> 00:37:18,835 [Linda] A limiting factor on the mission has turned out to be power. 669 00:37:18,904 --> 00:37:22,305 And every year there are four watts less power 670 00:37:22,307 --> 00:37:24,708 to run each of the Voyager spacecraft. 671 00:37:24,710 --> 00:37:27,444 There are no service stations out there, no way to, 672 00:37:27,545 --> 00:37:29,613 you know, repair things that go wrong. 673 00:37:29,615 --> 00:37:32,048 And it's really remarkable, the fact that they're still out there, 674 00:37:32,117 --> 00:37:33,617 in the cryogenic cold, 675 00:37:33,619 --> 00:37:35,619 you know, operating, they're still working. 676 00:37:35,621 --> 00:37:37,287 They're still alive. 677 00:37:37,289 --> 00:37:40,323 [narrator] In just five year there may be too little powe 678 00:37:40,325 --> 00:37:42,125 to transmit signals to Earth 679 00:37:42,828 --> 00:37:44,828 After a final message home, 680 00:37:44,830 --> 00:37:48,565 the Voyagers will fall silent forever. 681 00:37:48,633 --> 00:37:50,700 This part of the Voyager mission, 682 00:37:50,702 --> 00:37:52,335 flying in interstellar space, 683 00:37:52,404 --> 00:37:53,937 is the long goodbye. 684 00:37:57,009 --> 00:38:00,343 [Dan] They're gonna become our messages in a bottle. 685 00:38:00,412 --> 00:38:02,312 Little bit of humanity, 686 00:38:02,314 --> 00:38:05,415 you know, representing us when we're long gone. 687 00:38:05,417 --> 00:38:08,752 [narrator] The two probes could survive for billions of years. 688 00:38:09,988 --> 00:38:12,622 They could be not only, you know, interstellar voyagers, 689 00:38:12,624 --> 00:38:14,758 they could turn into intergalactic voyagers, ultimately. 690 00:38:17,062 --> 00:38:20,363 [narrator] Maybe the Voyages won't just drift forever. 691 00:38:21,533 --> 00:38:23,400 Maybe they'll be found. 692 00:38:25,203 --> 00:38:28,305 [Michelle] It was kind of a wonderful little jaunt of imagination. 693 00:38:28,307 --> 00:38:32,442 that maybe some alien civilization with incredibly powerful telescopes 694 00:38:32,544 --> 00:38:34,511 might notice that there's a little artificial object 695 00:38:34,513 --> 00:38:36,546 flying through space and be curious about it. 696 00:38:38,116 --> 00:38:41,518 [narrator] Strapped to each Voyager is an aluminum case 697 00:38:41,520 --> 00:38:44,921 On the outer side, is a map of how to find Eart 698 00:38:44,923 --> 00:38:47,324 with directions from different pulsars. 699 00:38:49,227 --> 00:38:52,829 [Michelle] So why use pulsars to direct the aliens to our location? 700 00:38:52,831 --> 00:38:56,499 These are the dead cores of stars after a supernova explosion. 701 00:38:56,501 --> 00:39:00,704 Well, amazingly, pulsars all spin at slightly different rates 702 00:39:00,706 --> 00:39:03,373 So, if you can actually triangulate your location, 703 00:39:03,375 --> 00:39:06,443 based on the rates of different pulsars in the sky, 704 00:39:06,511 --> 00:39:09,612 you can actually have sort of a galactic GPS system. 705 00:39:09,614 --> 00:39:12,615 You can show the aliens where we are with incredible accuracy. 706 00:39:13,518 --> 00:39:15,719 [narrator] Inside each case 707 00:39:15,721 --> 00:39:17,821 a gold plated copper disc. 708 00:39:18,590 --> 00:39:19,823 [Michelle] Looking back on i 709 00:39:19,825 --> 00:39:22,125 it's really kind of this wonderful part of humanity. 710 00:39:22,127 --> 00:39:23,660 We sent aliens out there, 711 00:39:23,695 --> 00:39:26,830 unimaginably, technologically advanced aliens, 712 00:39:26,832 --> 00:39:29,699 we sent them, basically, a vinyl record. 713 00:39:29,701 --> 00:39:32,802 [Paul] Yeah, the golden disc are literally discs. 714 00:39:32,804 --> 00:39:35,238 They actually are records with grooves. 715 00:39:35,307 --> 00:39:37,507 You can play them. You can jam out to them. 716 00:39:37,509 --> 00:39:39,943 It's got a soundtrack of our species. 717 00:39:39,945 --> 00:39:43,847 [Beethoven's 'Fifth Symphony' plays] 718 00:39:43,948 --> 00:39:46,416 [narrator] The records have tracks by Beethoven, 719 00:39:46,418 --> 00:39:49,619 Blind Willie Nelson and Chuck Berry, 720 00:39:49,621 --> 00:39:53,523 the sound of surf, of thunde of birdsong, 721 00:39:53,525 --> 00:39:55,124 and a human heartbeat. 722 00:39:56,294 --> 00:40:01,097 So, will aliens ever find the records and give them a spin? 723 00:40:01,099 --> 00:40:03,833 [Phil] The Golden Record is a lovely idea. 724 00:40:03,902 --> 00:40:07,103 Especially to energize and excite the public about this. 725 00:40:07,105 --> 00:40:09,139 Will it ever be found? 726 00:40:09,207 --> 00:40:11,608 There's a reason we call it space. 727 00:40:14,312 --> 00:40:16,813 [narrator] A tiny, cold spacecraft 728 00:40:16,815 --> 00:40:19,048 is a difficult target to fin 729 00:40:19,117 --> 00:40:21,818 Any species capable of detecting them, 730 00:40:21,820 --> 00:40:25,355 would have a better chance of spotting our planet. 731 00:40:25,423 --> 00:40:29,159 But the Voyagers will long outlive Earth. 732 00:40:29,227 --> 00:40:31,761 [Michelle] It's possible tha they will find it millions, 733 00:40:31,863 --> 00:40:33,163 or even billions of years in the future. 734 00:40:33,231 --> 00:40:34,798 Long after we are gone. 735 00:40:34,800 --> 00:40:37,300 When there really aren't humans anymore. 736 00:40:37,302 --> 00:40:40,703 Or is there even a possibility that when we start traveling to the stars 737 00:40:40,705 --> 00:40:42,238 in the far future, we'll find them. 738 00:40:43,809 --> 00:40:45,341 [narrator] Awaiting discover 739 00:40:45,377 --> 00:40:47,844 or doomed to drift alone, 740 00:40:47,913 --> 00:40:51,347 the Voyager probes have already inspired one civilization, 741 00:40:51,950 --> 00:40:53,716 ours. 742 00:40:53,718 --> 00:40:56,953 Calling these " Voyager "... [kisses] ...it's perfect. 743 00:40:56,955 --> 00:40:58,254 Because that's what they are doing. 744 00:40:58,256 --> 00:41:01,858 They are voyaging out to the outer solar system and beyond 745 00:41:01,926 --> 00:41:06,129 and showing that there is no end to our desire to explore. 746 00:41:08,233 --> 00:41:11,601 [narrator] They've shown us countless wonders of the solar system 747 00:41:11,603 --> 00:41:14,103 and a glimpse of what lies beyond. 748 00:41:15,040 --> 00:41:16,840 [Heidi] We, as a species, 749 00:41:17,309 --> 00:41:19,409 can build ships 750 00:41:19,411 --> 00:41:22,111 that not only sail the oceans of our Earth, 751 00:41:22,113 --> 00:41:24,447 but that can sail outwards, 752 00:41:24,516 --> 00:41:27,350 to the other planets in our system 753 00:41:27,419 --> 00:41:29,919 and reveal new worlds. 754 00:41:29,921 --> 00:41:33,022 [narrator] They are the greatest space mission ever 755 00:41:33,024 --> 00:41:36,559 [Paul] The legacy of Voyagr is our remnant. 756 00:41:36,628 --> 00:41:37,727 It is our memory. 757 00:41:37,729 --> 00:41:41,764 It is a sampling of humanity 758 00:41:41,833 --> 00:41:45,134 that is out there now among the stars. 759 00:41:45,203 --> 00:41:48,204 [narrator] And if they last until the death of the Universe, 760 00:41:48,206 --> 00:41:50,406 as the final stars fade, 761 00:41:50,408 --> 00:41:52,842 and everything goes dark, 762 00:41:52,911 --> 00:41:55,612 they will be humanity's final statement, 763 00:41:56,648 --> 00:41:57,814 "We were here."