WEBVTT - The Burning Mountains of Io, Part 2 0:00:03.000 --> 0:00:06.760 Welcome to Stuff to Blow Your Mind production of iHeartRadio. 0:00:12.720 --> 0:00:15.160 Hey, welcome to Stuff to Blow Your Mind. My name 0:00:15.200 --> 0:00:16.520 is Robert Lamb and. 0:00:16.440 --> 0:00:18.919 I am Joe McCormick, and we're back with part two 0:00:19.079 --> 0:00:23.279 in our series on Jupiter's innermost moon, Io, the most 0:00:23.360 --> 0:00:27.080 volcanic body in our Solar system, and, as I argued 0:00:27.120 --> 0:00:29.560 in the last episode, one of the most fascinating and 0:00:29.680 --> 0:00:33.120 dramatic places we know of beyond Earth. So if you 0:00:33.120 --> 0:00:35.479 haven't heard part one, we would recommend going back to 0:00:35.520 --> 0:00:38.440 listen to that one first. But for a brief recap 0:00:38.479 --> 0:00:41.280 of what we talked about last time. We started off 0:00:41.320 --> 0:00:44.840 talking about how I got interested in revisiting Io because 0:00:44.840 --> 0:00:47.440 we did do a series of episodes on Jupiter's moons 0:00:47.479 --> 0:00:50.480 at large several years back, but I wanted to come 0:00:50.520 --> 0:00:53.120 back and do a closer pass on Io, in particular 0:00:53.400 --> 0:00:56.920 because I got visually obsessed with some images produced by 0:00:56.960 --> 0:00:59.800 the NASA Juno mission in the past year or so. 0:01:00.000 --> 0:01:02.280 Guess it's actually little bit over a year because some 0:01:02.360 --> 0:01:04.560 of the data that we were looking at was collected 0:01:04.560 --> 0:01:07.840 in late twenty twenty three. But we talked about several 0:01:07.880 --> 0:01:13.000 of these images in detail, about the strangely polychrome surface 0:01:13.040 --> 0:01:17.920 of the Moon and its truly fascinating surface features, including 0:01:18.000 --> 0:01:25.120 gigantic blade like mountains, vast sulfurous plains, hundreds of erupting volcanoes, 0:01:25.640 --> 0:01:30.240 enormous hellish lava lakes rippling with lava waves, and lava 0:01:30.280 --> 0:01:35.280 flows stretching hundreds of kilometers, all situated within a land 0:01:35.360 --> 0:01:38.800 that is at once burning hot and freezing cold. So 0:01:38.840 --> 0:01:41.400 it is, as Bart Simpson might say, a land of contrasts, 0:01:41.440 --> 0:01:46.119 but also just a place of enormous physical and sort 0:01:46.120 --> 0:01:49.640 of geological drama. We also talked a little bit about 0:01:49.680 --> 0:01:52.400 the history of the exploration of Io, at least going 0:01:52.400 --> 0:01:55.680 back to Carl Sagan's account of the discoveries made by 0:01:55.680 --> 0:02:00.480 the Voyager Probe in nineteen seventy nine. Around then talked 0:02:00.480 --> 0:02:04.840 about the extremely thin sulfur dioxide atmosphere of Io, which 0:02:04.880 --> 0:02:09.080 is generated initially by venting from the Moon's volcanoes and 0:02:09.120 --> 0:02:13.720 subsequently by the cyclical freezing and sublimation of sulfur dioxide 0:02:13.760 --> 0:02:16.600 frost on the surface, freezing when the Moon passes into 0:02:16.680 --> 0:02:20.440 Jupiter's shadow, then transitioning into gas again once back in 0:02:20.440 --> 0:02:23.480 the sunlight. We also talked a good bit about the 0:02:23.680 --> 0:02:27.840 Greek myth of the Moon's namesake, sort of the themes of 0:02:27.880 --> 0:02:32.280 the Io story, especially in Ovid's telling and other versions 0:02:32.280 --> 0:02:35.000 of the story, and the way the tale was said 0:02:35.080 --> 0:02:40.080 in ancient times to interlock with Egyptian religious figures such 0:02:40.080 --> 0:02:43.160 as the goddess Isis, Shepherd of the dead, and the 0:02:43.200 --> 0:02:46.400 Sacred Mother of Pharaoh's And we are back today to 0:02:46.480 --> 0:02:48.120 talk once again about Io. 0:02:48.440 --> 0:02:48.960 That's right. 0:02:49.560 --> 0:02:53.079 So there's something we didn't really talk about at all 0:02:53.200 --> 0:02:56.880 last time, and that was the use of IO as 0:02:56.919 --> 0:03:00.600 a setting or plot device in science fiction, which, you know, 0:03:00.800 --> 0:03:03.880 despite all of its, at least to me, really apparent 0:03:03.960 --> 0:03:07.560 aesthetic virtues as a setting for a story, it doesn't 0:03:07.720 --> 0:03:10.200 really seem to be a favorite place within our solar 0:03:10.200 --> 0:03:12.720 system for sci fi writers. Or maybe I'm wrong about that. 0:03:12.760 --> 0:03:14.880 Maybe it's just not in a lot of stories I've read. 0:03:14.919 --> 0:03:18.720 But I was having trouble thinking of many examples in 0:03:18.760 --> 0:03:22.120 which it featured in stories I knew. I think it 0:03:22.240 --> 0:03:26.840 showed up at some point briefly in the Expanse, and 0:03:27.360 --> 0:03:29.679 I can't really think of many other examples. 0:03:29.600 --> 0:03:32.880 Yeah, even in the Expanse. And I'm a little foggy 0:03:32.960 --> 0:03:36.440 on where it shows up or doesn't show up if 0:03:36.480 --> 0:03:39.320 it's in the novels by James S. A. Corey, or 0:03:39.360 --> 0:03:41.960 if it's in the TV adaptation. I've only read the 0:03:42.000 --> 0:03:44.440 first book in the series, Leviathan Wiggs, but I watched 0:03:44.480 --> 0:03:48.000 the entire run of the show. But even then, I 0:03:48.040 --> 0:03:50.520 think maybe it only partially factored in there. And I 0:03:50.520 --> 0:03:54.840 think one of the possibilities here is that i Owe 0:03:55.000 --> 0:03:58.480 is a moon that we know to be rather extreme 0:03:58.520 --> 0:04:03.760 and hostile, for even our sci fi visions and fantasies 0:04:04.160 --> 0:04:07.000 tend to give it a little safe distance. 0:04:07.040 --> 0:04:10.320 You know, it doesn't seem like a top candidate for colonization. 0:04:11.000 --> 0:04:15.960 Yeah, yeah, in well, I don't want to spoil too 0:04:16.040 --> 0:04:18.800 much of the plot if people aren't familiar with the expanse, 0:04:18.839 --> 0:04:21.520 but I do remember it pops up as the location 0:04:21.680 --> 0:04:23.680 of a quite cursed laboratory. 0:04:24.520 --> 0:04:28.040 Yes, they're working on a particular molecule. Yes, yes. Now. 0:04:28.040 --> 0:04:31.159 One place you do see Io pop up as a 0:04:31.200 --> 0:04:35.080 setting is the nineteen eighty one gritty sci fi western Outland. 0:04:35.880 --> 0:04:39.279 This one starred Sean Connery and Peter Boyle, has some 0:04:39.320 --> 0:04:42.520 other fairly big names sprinkled throughout the cast as well. 0:04:42.560 --> 0:04:45.400 Directed by Peter Hyam's and I guess they chose Io 0:04:45.520 --> 0:04:48.040 as a setting here because it would be such a 0:04:48.080 --> 0:04:52.560 horrible place to work. It's the horrible working conditions and 0:04:52.760 --> 0:04:55.479 there's a lot of like labor dispute in this particular 0:04:55.560 --> 0:04:58.080 sci fi vision, you know, eighty one, that's not too 0:04:58.120 --> 0:05:01.680 long after Ridley Scott's a and it's a film that 0:05:01.720 --> 0:05:05.440 you could almost assume to be in the same universe, 0:05:05.520 --> 0:05:10.120 you know. It's that sort of very gritty, essentially near 0:05:10.240 --> 0:05:14.920 future vision of science fiction that is very much focused 0:05:14.960 --> 0:05:17.120 on like the working man in space. 0:05:17.560 --> 0:05:19.760 I have meant to see this for years and never 0:05:19.839 --> 0:05:22.920 have it. It's intrigued me ever since my days of 0:05:22.960 --> 0:05:26.359 like in high school flipping through you know, stacks of 0:05:26.440 --> 0:05:30.640 DVDs at the used bookstore in town because it really 0:05:30.680 --> 0:05:34.160 pops because it's Sean Connery holding a shotgun, dressed like 0:05:34.200 --> 0:05:38.240 a cop, except he's in space. So strange vibes from 0:05:38.279 --> 0:05:40.800 the get go. But I've read that if you didn't 0:05:40.800 --> 0:05:43.359 already say this, I've read that this one is supposed 0:05:43.400 --> 0:05:45.520 to be like a Western but in space. 0:05:45.920 --> 0:05:48.360 Correct. Yeah, And I saw it many many years ago, 0:05:48.520 --> 0:05:51.680 but I'm a little foggy on the details. But it 0:05:51.760 --> 0:05:54.120 is gritty, it is very much a Western in space. 0:05:54.800 --> 0:05:59.200 A lot of it concerns explosive decompression, people's heads exploding 0:05:59.240 --> 0:06:04.920 inside a set of suits, and yeah, terrible labor conditions. Now, 0:06:04.920 --> 0:06:06.920 one thing about it that I wasn't familiar with until 0:06:06.960 --> 0:06:09.800 very recently is there was a comic book adaptation of 0:06:09.839 --> 0:06:14.839 it for heavy metal, I believe, by comics legend Jim Staranco, 0:06:15.480 --> 0:06:17.920 and I include a few stills from it here for you, Joe. 0:06:17.920 --> 0:06:21.240 I've seen people talk about this online almost in terms 0:06:21.240 --> 0:06:23.680 of like a lost classic, Like it's apparently hard to 0:06:23.680 --> 0:06:27.520 get your hands on, but it's got some very impressive 0:06:27.600 --> 0:06:31.920 line work and just some really beautiful imagery. I mean, 0:06:32.520 --> 0:06:34.960 like I say that the film itself has a very 0:06:35.320 --> 0:06:39.320 gritty air to it, and that flavor is still present 0:06:39.360 --> 0:06:41.800 in the comic book apparently, but it also has this 0:06:41.880 --> 0:06:44.960 like extra like wilder vibe going on. 0:06:45.520 --> 0:06:48.039 Oh yeah, it's one of those comic book art styles 0:06:48.080 --> 0:06:53.080 where even apparently static objects seem to radiate with energy. 0:06:53.240 --> 0:06:56.239 It's just I don't know what you call that style, 0:06:56.240 --> 0:07:00.479 but it's where everything looks dynamic, like the style of 0:07:00.600 --> 0:07:04.200 drawing is of a reality in which everything is about 0:07:04.240 --> 0:07:05.000 to explode. 0:07:05.440 --> 0:07:07.239 Yeah, I'd be very interested to hear from anyone who's 0:07:07.240 --> 0:07:09.280 read the comic book. There was also an Alan Deine 0:07:09.320 --> 0:07:12.360 Foster novelization, so it has that in common with Alien 0:07:12.920 --> 0:07:18.720 and Aliens and Alien three as well. But as far 0:07:18.800 --> 0:07:22.920 as the treatment of Io in the motion picture and 0:07:22.960 --> 0:07:26.520 in the comic book, basically it's a hell world where 0:07:26.560 --> 0:07:30.440 they just decided to put a mining colony of some 0:07:30.480 --> 0:07:35.800 sort and then prioritize profits over human safety. Yeah, so 0:07:35.840 --> 0:07:37.520 it's the perfect setting for that. Now I had to 0:07:37.600 --> 0:07:40.240 hunt around a little bit more defined examples of Io 0:07:40.560 --> 0:07:42.920 being used as a setting in other sci fi visions. 0:07:43.240 --> 0:07:46.280 There's a nineteen ninety four mini series titled Escape from 0:07:46.360 --> 0:07:50.720 Jupiter that concerns an escape from Io. Apparently it's an 0:07:50.760 --> 0:07:55.040 Australian kids adventure and it's also has Steve Bisley in it, 0:07:55.080 --> 0:07:56.840 who's in a number of I think it was in 0:07:56.880 --> 0:07:58.480 at least one of the Mad Max films. 0:07:58.800 --> 0:08:01.840 Oh, okay, I don't reckon him by name. Yeah, well 0:08:01.920 --> 0:08:04.480 maybe what if I saw him? Is this a screenshot 0:08:04.520 --> 0:08:06.080 you've got from it with the bright colors? 0:08:06.400 --> 0:08:09.760 Yes, it's one of the most nineteen nineties TV images 0:08:09.800 --> 0:08:11.600 you could possibly look up online. 0:08:11.760 --> 0:08:13.880 Yeah, what what was the name of it? Wasn't there 0:08:13.920 --> 0:08:17.480 like a Canadian kids sci fi show, sort of a 0:08:17.480 --> 0:08:21.240 Star Trek for kids that was on Nickelodeon in the nineties. 0:08:21.360 --> 0:08:23.560 It was like Space Cases or something. 0:08:24.440 --> 0:08:26.600 Maybe that's ringing a bell only. 0:08:26.480 --> 0:08:28.960 The foggiest memory, but this is reminding me of that, 0:08:29.000 --> 0:08:31.440 except I recall that had a darker look and this 0:08:31.560 --> 0:08:32.480 is very pastel. 0:08:33.840 --> 0:08:38.640 Now. There's also a twenty nineteen film titled Io. This 0:08:38.760 --> 0:08:41.400 was apparently one that was put out on Netflix and 0:08:41.480 --> 0:08:44.720 I haven't seen it, but it concerns refugees of a 0:08:44.760 --> 0:08:48.440 destroyed Earth living on a space station near Io. It 0:08:48.520 --> 0:08:52.520 stars Margaret Qualley of the Substance fame, Anthony Mackie, and 0:08:52.640 --> 0:08:54.960 Danny Houston. Again, I haven't seen this one, but apparently 0:08:54.960 --> 0:08:58.559 it's one. It was released on Netflix. I have to say, 0:08:58.600 --> 0:09:00.680 in the one still I found from or a production 0:09:01.160 --> 0:09:05.040 image promotionary image, doesn't look very pizza in the background. 0:09:05.480 --> 0:09:08.880 No looks this is very gray. One of those shows 0:09:08.880 --> 0:09:11.520 where all the colors washed out. To be fair, this 0:09:11.600 --> 0:09:13.560 is just a still. I don't know the show, but 0:09:14.320 --> 0:09:17.280 marketing department is not selling me on it with this 0:09:17.800 --> 0:09:18.640 color here. 0:09:20.200 --> 0:09:23.480 All right. Now, In terms of written sci fi, there 0:09:23.480 --> 0:09:25.800 are at least there at least two examples to call out. 0:09:26.000 --> 0:09:29.920 There's The Mad Moon by Stanley Jen g Weinbaum. This 0:09:29.960 --> 0:09:34.400 is from nineteen thirty five, same individual who wrote a 0:09:34.400 --> 0:09:38.440 Martian Odyssey, and it features two different alien species that 0:09:38.480 --> 0:09:40.760 are supposed to be native to Io and there's a 0:09:40.800 --> 0:09:43.640 human colony. I haven't read that one, but I did 0:09:43.720 --> 0:09:46.320 read a story he wrote titled The Planet of Doubt, 0:09:46.760 --> 0:09:48.959 which I did a Monster Fact episode back in twenty 0:09:49.000 --> 0:09:51.440 twenty three, So I'm going to make sure that I 0:09:51.520 --> 0:09:55.040 re air that one either this week or the following 0:09:55.080 --> 0:09:57.040 week so you don't have to go look it up again. 0:09:57.080 --> 0:09:59.959 But it's a pretty fun one. This guy had a real, 0:10:00.000 --> 0:10:04.440 real creative mind for dreaming up alien creatures that you know, 0:10:04.520 --> 0:10:09.280 often reflected some of the stranger biological examples we have 0:10:09.320 --> 0:10:11.720 on our own planet, but with you know, a nineteen 0:10:11.800 --> 0:10:14.840 thirties or slightly later sci fi spin. 0:10:15.400 --> 0:10:18.760 But now nineteen thirties, so that's long before Voyager. I'm 0:10:18.800 --> 0:10:21.720 wondering what did we actually know about Io at that 0:10:21.800 --> 0:10:25.320 point to inform a vision of the biology that would 0:10:25.320 --> 0:10:26.000 arise there. 0:10:26.640 --> 0:10:29.200 Well, that may maybe not enough to know that two 0:10:29.240 --> 0:10:34.000 indigenous species of any human colony were not maybe that likely. 0:10:34.880 --> 0:10:37.880 We have some caveats on the whole life on IO thing. Well, 0:10:37.920 --> 0:10:41.000 we'll come back to it though. Another one that came 0:10:41.000 --> 0:10:44.079 out though is The Very Pulse of the Machine by 0:10:44.160 --> 0:10:48.000 Michael Swanwick. This is from nineteen ninety eight and it 0:10:48.080 --> 0:10:52.920 concerns a possibly sentient IO. It was adapted into an 0:10:52.920 --> 0:10:56.720 episode of Love, Death and Robots on Netflix again, Netflix 0:10:56.760 --> 0:11:00.679 loves Io with the main character voice by McKinsey Davis, 0:11:01.400 --> 0:11:03.319 who's been in things like Halden Catch Fire and I 0:11:03.360 --> 0:11:05.200 believe the more recent Blade Runner of film. 0:11:05.559 --> 0:11:08.319 So when you say sentient io, you're talking about the 0:11:08.920 --> 0:11:12.960 moon itself, the planetary body being a sentient organism or 0:11:13.080 --> 0:11:14.240 sentient in some way. 0:11:14.600 --> 0:11:17.440 Yes, I believe so, And I haven't read the story, 0:11:17.520 --> 0:11:21.480 but I have seen this episode of Love, Death and Robots, 0:11:22.080 --> 0:11:24.240 and I just the only thing I remember about it 0:11:24.280 --> 0:11:27.320 is that it looked beautiful and it concerned bad things 0:11:27.360 --> 0:11:29.480 happening in space on the Moon. 0:11:31.400 --> 0:11:34.480 That sounds kind of like silarious, But having not seen it, 0:11:34.520 --> 0:11:37.360 I don't want to be overly broad about that. 0:11:37.600 --> 0:11:41.720 But there's a fair amount of variety in Love, Death 0:11:41.760 --> 0:11:44.640 and Robots. It's a really fun series, but there are 0:11:44.679 --> 0:11:47.120 a number of episodes I think that you can describe 0:11:47.160 --> 0:11:50.600 as bad things happen to people in space. So maybe 0:11:50.640 --> 0:11:52.520 some of those bleed together in my memory. 0:11:52.840 --> 0:11:54.920 I'm going to write some sci fi where only good 0:11:54.960 --> 0:11:56.400 things happen to people in space. 0:11:56.679 --> 0:11:58.160 There you go, That's what we need, you know, we 0:11:58.160 --> 0:12:01.560 need a dash of the more of the Star Trek 0:12:01.600 --> 0:12:02.920 optimism these days. 0:12:03.400 --> 0:12:06.600 Like page three hundred, people just wake up, Oh splendid 0:12:06.679 --> 0:12:10.440 day once again, smooth sailing. 0:12:11.160 --> 0:12:12.840 So that's what I've got. Now, there may be some 0:12:12.920 --> 0:12:17.720 other fantastic examples or just even marginally interesting examples of 0:12:17.760 --> 0:12:20.680 IO in science fiction. So if you have any of those, 0:12:21.000 --> 0:12:24.040 do write in. We'd love to share them with everyone 0:12:24.040 --> 0:12:25.880 else on a future listener mail episode. 0:12:26.080 --> 0:12:28.720 Yeah, especially if it's something that takes the real physical 0:12:28.800 --> 0:12:32.600 characteristics of IO seriously as either a source of creating 0:12:32.640 --> 0:12:35.360 alien biology or something people on the planet would have 0:12:35.600 --> 0:12:37.760 on the moon would have to live with. Yeah, right 0:12:37.840 --> 0:12:40.320 in contact at stuff to Blow your mind dot com. 0:12:40.679 --> 0:12:43.240 Yeah again. One of the challenges though, is we've been 0:12:43.240 --> 0:12:45.600 discussing it and will continue to discuss It's just it's 0:12:45.600 --> 0:12:49.160 a very extreme place. There are there are I'm not 0:12:49.200 --> 0:12:51.880 going to say there are more interesting Jovian moons, But 0:12:51.960 --> 0:12:54.840 there are other Jovian moons that are better candidates for 0:12:54.960 --> 0:12:58.880 things like some sort of life form being present there potentially, 0:12:59.120 --> 0:13:04.600 or there being some possibility for human colonization or outpost efforts, 0:13:04.600 --> 0:13:05.040 and so. 0:13:04.960 --> 0:13:17.000 Forth, bridging to the next thing I wanted to talk about. 0:13:17.040 --> 0:13:20.080 Even though Io, and as you said, we'll get into 0:13:20.080 --> 0:13:22.440 this a bit more later, might not be the best 0:13:22.520 --> 0:13:26.520 place to search for alien life, might not be the 0:13:26.559 --> 0:13:29.600 best place for humans to colonize, that doesn't mean it 0:13:29.640 --> 0:13:32.880 is a place without mysteries of its own. There can 0:13:32.920 --> 0:13:35.920 be mysteries of a quite inorganic nature that I still 0:13:35.960 --> 0:13:39.520 think are pretty compelling, and I wanted to bring up 0:13:39.520 --> 0:13:44.320 one of those, the mystery dunes of Io. So Rob 0:13:44.400 --> 0:13:46.640 to start off with, I'm gonna have you look at 0:13:46.640 --> 0:13:49.080 two images side by side in our outline here, and 0:13:49.120 --> 0:13:51.360 folks at home, we will describe them for you so 0:13:51.679 --> 0:13:54.480 you understand what we're looking at. On the right, we 0:13:54.600 --> 0:13:58.839 have a satellite image. This is taken from above the 0:13:59.200 --> 0:14:03.120 Namib Desert, which is on the west facing Atlantic coast 0:14:03.200 --> 0:14:06.679 of Southern Africa, and that desert covers parts of the 0:14:06.920 --> 0:14:12.400 coastal region of Angola, South Africa, and primarily Namibia. Now, 0:14:12.440 --> 0:14:16.040 looking down at this desert from an orbital perspective, we 0:14:16.160 --> 0:14:21.200 can see a beautiful, almost hypnotic pattern repeating across the 0:14:21.240 --> 0:14:27.400 sandy expanse. Those are dunes, and sand dunes are characteristic 0:14:27.480 --> 0:14:30.920 of many, but certainly not all, desert environments on Earth. 0:14:30.960 --> 0:14:34.520 Some desert environments are very rocky, others are very cold, 0:14:34.800 --> 0:14:38.520 places you might find ice fields, and then other desert 0:14:38.600 --> 0:14:41.520 environments are the places you would find vast expanses of 0:14:41.640 --> 0:14:47.480 sand dunes. Sand Dunes on Earth are formed primarily by 0:14:47.520 --> 0:14:51.840 what are called Eolian forces, meaning they're created by the 0:14:51.920 --> 0:14:56.080 action of wind, and actually the influence of wind comes 0:14:56.120 --> 0:14:58.880 in at multiple stages because if you go way back 0:14:58.920 --> 0:15:03.440 to the point of of the sand, wind along with water, 0:15:03.880 --> 0:15:08.280 plays a role in the weathering and the transportation of rocks. 0:15:08.440 --> 0:15:11.040 So you start off with rocks. You might have rocks 0:15:11.080 --> 0:15:13.640 in the mountains or something, and they are broken up 0:15:13.680 --> 0:15:16.320 by weathering, they get rained on, or they get the 0:15:16.600 --> 0:15:20.640 wind blows on them, and various forces break those rocks 0:15:20.720 --> 0:15:25.240 up into smaller pieces which can then be transported by 0:15:25.520 --> 0:15:29.520 water and by wind downhill into places where they collect, 0:15:29.800 --> 0:15:32.600 and over time those pieces of rock are continually broken 0:15:32.680 --> 0:15:36.600 down into smaller and smaller pieces by further weathering and 0:15:36.680 --> 0:15:41.240 erosion and transport, and the smallest sizes of mineral grains. 0:15:41.240 --> 0:15:43.080 You might remember this if you listen to our series 0:15:43.120 --> 0:15:47.080 on dust, are known as from larger to smaller are 0:15:47.080 --> 0:15:51.680 known as sand, silt, and then clay. Sand Dunes are 0:15:51.720 --> 0:15:55.680 created in areas where sand collects, So after the rocks 0:15:56.280 --> 0:15:59.040 are weathered and eroded and then the sand is broken 0:15:59.080 --> 0:16:02.280 down in transport, it'll sort of end up in some 0:16:02.400 --> 0:16:07.480 kind of catching place, a depression, usually a lower lying area, 0:16:07.840 --> 0:16:11.280 And when the wind blows it can move sand particles 0:16:11.360 --> 0:16:14.440 along with it, And this is something yet again we 0:16:14.480 --> 0:16:17.600 talked about in our series on dust. The term for 0:16:17.800 --> 0:16:21.000 the process by which sand is moved around by the 0:16:21.040 --> 0:16:25.760 wind is known as saltation. So you can get different 0:16:25.960 --> 0:16:30.800 ways that the wind interacts with sediments and rock pieces 0:16:30.800 --> 0:16:33.640 of different sizes. So you know, a larger rock, the 0:16:33.680 --> 0:16:36.720 wind blows against it, it's not going anywhere. Maybe a 0:16:36.760 --> 0:16:38.920 pebble the wind blows against it, it might kind of 0:16:38.960 --> 0:16:40.680 move it a little bit, or a pebble might get 0:16:40.720 --> 0:16:43.120 blown off another a pile of other pebbles and kind 0:16:43.120 --> 0:16:44.880 of tumble a little bit, but it doesn't really go 0:16:45.000 --> 0:16:48.400 much of anywhere unless you get really high winds. And 0:16:48.480 --> 0:16:50.680 then meanwhile, if you go all the way down to 0:16:50.760 --> 0:16:54.000 the sort of the dust size of grains of sediment, 0:16:54.440 --> 0:16:56.480 the wind can pick it up and carry it up 0:16:56.520 --> 0:16:58.840 into the atmosphere and then the dust just you know, 0:16:59.120 --> 0:17:01.320 it is borne a lot for a long long time. 0:17:01.320 --> 0:17:03.840 It can travel anywhere. It can travel across the land, 0:17:03.840 --> 0:17:07.560 across the ocean, end up in different places. But sand 0:17:07.640 --> 0:17:11.000 is in this middle zone where it's subject primarily to 0:17:11.160 --> 0:17:14.560 the forces known as saltation. When wind blows on sand, 0:17:15.000 --> 0:17:17.679 the sand will be blown along the surface of the ground, 0:17:17.760 --> 0:17:21.040 or will follow the surface of whatever sort of the 0:17:21.320 --> 0:17:24.840 base layer of the earth is, and it will will 0:17:24.880 --> 0:17:27.680 be kicked up, and it'll kind of jump and bounce 0:17:27.760 --> 0:17:30.640 and then come back down and hit the sand, and 0:17:30.720 --> 0:17:33.320 that will cause other pieces of sand to kind of 0:17:33.359 --> 0:17:36.520 get knocked out of place when the initial piece of 0:17:36.560 --> 0:17:41.240 sand lands, So it creates this kind of bouncing, jumping, 0:17:41.480 --> 0:17:45.080 hopping motion as sand is blown along by the wind, 0:17:45.880 --> 0:17:48.440 As sand gets blown along by the wind, as saltation 0:17:48.640 --> 0:17:52.119 is going on. At some point the flow of wind 0:17:52.200 --> 0:17:57.359 driven sand can become obstructed. Maybe it gets caught on 0:17:57.560 --> 0:18:01.240 an obstacle like there's a bush, or maybe it falls 0:18:01.280 --> 0:18:04.520 behind an obstacle like a bush or piece of vegetation, 0:18:04.880 --> 0:18:07.439 and then the wind cannot exert as much of a 0:18:07.480 --> 0:18:10.000 force on it anymore, so it just kind of like 0:18:10.080 --> 0:18:12.960 sits there and grains can pile up, or maybe it 0:18:13.000 --> 0:18:17.080 gets blown against the side of a slightly elevated pile 0:18:17.240 --> 0:18:20.440 of other grains of sand and it gets stuck there 0:18:20.560 --> 0:18:24.800 instead of moving on and from here, these places where 0:18:24.960 --> 0:18:29.680 sand starts to collect can be a self reinforcing process, 0:18:30.080 --> 0:18:32.800 where a mound of sand just gets bigger and bigger 0:18:33.320 --> 0:18:37.359 as the wind forces blowing sand particles against it cause 0:18:37.480 --> 0:18:41.120 the particles to collect around this mound in one way 0:18:41.200 --> 0:18:44.760 or another. So a common format of sand dune that 0:18:44.800 --> 0:18:48.080 you will get in places, especially where the dominant winds 0:18:48.119 --> 0:18:52.960 are blowing primarily in one direction, is that the side 0:18:53.000 --> 0:18:58.120 of the sand dune facing the wind will be a smoother, slower, 0:18:58.200 --> 0:19:00.880 more gradual slope, and then the side of the sand 0:19:00.960 --> 0:19:03.480 dune facing away from the dominant winds will be a 0:19:03.560 --> 0:19:07.119 much steeper, sharper slope. And what's usually happening is the 0:19:07.119 --> 0:19:11.400 wind is blowing sand along and it's eroding sand from 0:19:11.480 --> 0:19:15.000 the middle of the rising slope on the windward side, 0:19:15.320 --> 0:19:18.200 and then trying to deposit it right at the crest, 0:19:18.320 --> 0:19:22.720 right at the peak of the dune. And in this way, 0:19:22.760 --> 0:19:25.840 over years and years, more and more sand accumulates. But 0:19:26.160 --> 0:19:30.320 sand dunes don't just grow higher and higher forever. Eventually 0:19:30.440 --> 0:19:35.920 a sand dune will collapse, not totally disappearing, but losing height. 0:19:36.040 --> 0:19:39.160 And this happens when one side of the dune becomes 0:19:39.359 --> 0:19:45.440 too steep, exceeding what is called the angle of repose. Now, 0:19:45.480 --> 0:19:48.040 this is a kind of cool physics principle. I think 0:19:48.080 --> 0:19:50.000 we may have talked about this on the show before, 0:19:50.040 --> 0:19:54.639 but the angle of repose is the steepest angle that 0:19:54.800 --> 0:20:00.199 a pile of sediment or whatever other granular substance can 0:20:00.320 --> 0:20:04.120 attain before it collapses under its own weight. In fact, 0:20:04.160 --> 0:20:06.359 I wonder if we talked about the angle of repose 0:20:06.880 --> 0:20:09.960 in when we were talking about the ant lion, because 0:20:10.000 --> 0:20:12.399 I believe that is a factor in the construction of 0:20:12.400 --> 0:20:16.159 their conical traps. That you know, they make them so 0:20:16.960 --> 0:20:19.920 just so that they're sort of right on the edge, 0:20:19.960 --> 0:20:22.679 and it's easy for the sides to start collapsing and 0:20:22.760 --> 0:20:24.640 pull an ant down if they fall in. 0:20:25.359 --> 0:20:27.680 That may be a place where it's come up before. Yeah. 0:20:27.800 --> 0:20:31.879 Yeah, Now, the angle of repose is not a universal constant. 0:20:32.000 --> 0:20:35.479 It instead depends on a number of variables about the 0:20:35.520 --> 0:20:39.760 material you're piling up. So you know, different types of sand, 0:20:39.800 --> 0:20:43.959 different grain sizes of sand, like the amount of friction 0:20:44.119 --> 0:20:47.439 between the particles, how big the particles are on average, 0:20:47.440 --> 0:20:49.960 stuff like that will all affect what the angle of 0:20:50.000 --> 0:20:53.359 repose is for a pile of this stuff. But I 0:20:53.400 --> 0:20:56.439 was reading that. I was reading on an information page 0:20:56.440 --> 0:20:59.480 by the USGS. This was a page about Sand Dune's 0:20:59.560 --> 0:21:02.879 National Park in Colorado. The angle of repose for sand 0:21:02.960 --> 0:21:06.879 is usually between thirty and thirty four degrees, so once 0:21:07.080 --> 0:21:11.200 it gets steeper than that, the dune will collapse. And this, 0:21:11.280 --> 0:21:14.080 in part explains why when you're looking at pictures of 0:21:14.160 --> 0:21:16.720 sand dunes in the desert, you will, as I said, 0:21:16.840 --> 0:21:19.840 often see them with this one smooth side, kind of 0:21:20.080 --> 0:21:23.479 a gentler slope on one side ascending at a shallower angle, 0:21:23.800 --> 0:21:25.919 and then the other side will fall off at a 0:21:25.920 --> 0:21:29.120 steeper angle with an almost kind of sheared off texture. 0:21:29.560 --> 0:21:32.400 Yeah, looking like someone is sliced into it to get 0:21:33.160 --> 0:21:36.160 a little bit of the dessert. That's sort of a look. 0:21:36.320 --> 0:21:39.520 Yes, exactly. So generally the smoother side is facing the 0:21:39.520 --> 0:21:44.040 dominant winds, where the sediment continues to be eroded from 0:21:44.160 --> 0:21:46.840 the slope going up and then tries, and then the 0:21:46.880 --> 0:21:49.600 wind deposits more and more of it at the crest, 0:21:50.560 --> 0:21:53.399 and then it gets steeper and steeper on the downwind 0:21:53.480 --> 0:21:56.520 side until it collapses. And of course there's also going 0:21:56.600 --> 0:22:00.040 to be some sand grains falling over the top of 0:21:59.840 --> 0:22:02.720 the dune and then ending up down sort of in 0:22:02.760 --> 0:22:06.560 the shelter from the wind on the leeward side. And 0:22:06.720 --> 0:22:09.560 sand dunes are really interesting, you know, you can if 0:22:09.600 --> 0:22:13.120 you watch them over long periods of time, they can 0:22:13.600 --> 0:22:17.600 start to seem less like the geological formations we're used to. 0:22:17.600 --> 0:22:19.840 I mean, we know that mountains move over time, but 0:22:20.680 --> 0:22:23.720 you know, it's really hard to imagine how mountains move. 0:22:23.760 --> 0:22:26.000 You really have to just sort of think outside of 0:22:26.000 --> 0:22:30.080 the human timescale. Dunes are kind of somewhere in between 0:22:30.480 --> 0:22:34.239 mountains and the waves in the ocean. Over periods of 0:22:34.400 --> 0:22:37.640 you know, months or years, dunes will will creep across 0:22:37.680 --> 0:22:40.760 the surface of the Earth. So that's dunes on Earth. However, 0:22:40.880 --> 0:22:42.600 Rob I want to come back and have you look 0:22:42.640 --> 0:22:44.920 at the photos we started with, So the one we 0:22:44.920 --> 0:22:48.719 were looking at first is sand dunes on Earth. But 0:22:48.760 --> 0:22:51.280 then the photo I've got for you here on the 0:22:51.359 --> 0:22:55.399