Ep. 675: Exotic Forms of Ice

Ice is ice, right? You know, what you get when water freezes. Well, maybe here on Earth. But across the Universe, water can be squeezed together at different temperatures and pressures, leading to very different structures. Today we’ll talk about the different forms that ice can take.

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Show Notes | Transcript

Show Notes

Crystallinity of the Ice (UCLA)

How to Make Clear Ice Cubes for Your Cocktails (Liquor.com)

You’re Doing It Wrong: The Guide to Making Perfect Pasta (Smithsonian Magazine)

Iceland Has Got a sparkling Ice Diamond Beach on Breiðamerkursandu (Guide to Iceland)

Centaurs (Swinburne University)

Scientists discover a new type of amorphous ice (Cosmos Magazine)

Scientists created a weird new type of ice that is almost exactly as dense as water (Live Science)

Ganymede (NASA)

Europa (NASA)

Enceladus (NASA)

Kuiper Belt Objects (Swinburne University)

An orbital dance may help preserve oceans on icy worlds (Phys.org)

Why do astronomers call Uranus and Neptune ice giants? (Astronomy)

Europa’s heaving ice might make more heat than scientists thought (Brown University)

What color is an iceberg? (NOAA)

Cat’s Cradle by Kurt Vonnegut Jr. (Goodreads)

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(This is an automatically generated transcript)

Frasier Cain [00:01:43] Astronomy Cast episode 675 Exotic Forms of Ice. Welcome to Astronomy Cast, a weekly facts based journey through the cosmos where we help you understand not only what we know, but how we know what we know. I’m Fraser Cain, I’m the publisher of Universe Today. With me is Doctor Pamela Kane, a senior scientist for the Planetary Science Institute and the director of Cosmic Quest. Hey, panel, how you doing? 

Pamela Gay [00:02:04] I am doing well. It is, odd to be recording this episode on a beautiful spring day, but on the day that I added it to our, show line up, it was a nasty, cold, cold, horrible Midwestern day. And, it just I was inspired. 

Frasier Cain [00:02:23] Well, it’s snowed here. This morning’s so perfectly appropriate. Although you it my my wife described it as a snow cone fight like it was. It did not last long. Gloopy blobs of snow blasting around to. No was not, you know, nice light, fluffy snow drifts. But it was just like someone was pouring gloop down from the sky. It was this is this, this spring. Climate change. Ice is ice, right? You know what you get when water freezes? Well, maybe here on Earth, but across the universe, water could be squeezed together at different temperatures and pressures, leading to very different structures. Today we’ll talk about the different forms that ice can take. All right. So in preparing for this show, one of the things that I didn’t even realize is that the kind of ice that we’re familiar with is actually the minority in the universe. 

Pamela Gay [00:03:25] What? It’s it’s it’s one of these things where, like, growing up, you’re you’re taught over and over in school that ice is the one solid that is bigger than, in volume than the liquid that it forms from. And you’re told all these things. Right. And it turns out that what we’re learning is the special case in which liquid water is able to freeze at a rate that allows crystals to form. And as the oxygen molecules come together to form these six sided crystals with the hydrogen atoms oriented, however, they will the volume gets bigger because the the molecules have to space themselves out to form these crystals. And, and the thing is that very special circumstance of liquid to ice that allows crystals to form isn’t gonna happen everywhere in the universe. 

Frasier Cain [00:04:41] Right? So we’ve got a habitable world where you have liquid water under air pressure. 

Pamela Gay [00:04:49] Yeah. 

Frasier Cain [00:04:50] And as the temperature drops below freezing, then you get these crystals able to form inside the water, float to the top and continue growing to form sheets of, of ice. So. So what is that called? 

Pamela Gay [00:05:08] A crystal in ice. 

Frasier Cain [00:05:09] Crystals on ice. Okay. So yeah. So from when it whenever you like, if you’re going to serve someone to drink, you ask them, would you like some crystal and ice cubes in your drink. 

Pamela Gay [00:05:20] Right. 

Frasier Cain [00:05:21] Well, if you want to go skating at the crystal and ice skating rink. 

Pamela Gay [00:05:27] What I love is there are pubs and bars around the world that have gone to great extremes to figure out how exactly you should freeze ice to get perfectly clear ice cubes, because the the goal is to get all the crystals aligned just so that you don’t have any defects. Just like a diamond, you judge it for its clarity. Well, a diamond is a crystal, an ice is a crystal. And apparently we sometimes judge our ice by its clarity. 

Frasier Cain [00:06:02] What’s the trick? How do you make ice clearer than cloudy eye? 

Pamela Gay [00:06:07] So it’s a combination of, how quickly you freeze it and, just making sure that it is pure water free of defects. And I think I remember reading that you start with hot water and then let that go. And I don’t know why that would be possible. 

Frasier Cain [00:06:29] And there’s something like you have to agitate it, I think. 

Pamela Gay [00:06:34] So you get the air bubbles out. 

Frasier Cain [00:06:36] To get the air bubbles out. Yeah. So you have to keep you have to keep slowly mixing it to get all the air bubbles out, because they’ll cause little blobs of cloud inside that will then make it not clear. Yeah. Yeah. 

Pamela Gay [00:06:47] And a quick side PSA. So I’ve gone through life not knowing why people said use, cold water to make pasta and things like that because it’s it’s not really going to make a big difference on how quickly things boil. And it’s because the cold water going through your pipes doesn’t pull the irregularities off the sides of the pipes, so you actually get softer water from the cold tap than from the hot tap. So if you don’t want as many kidney stones, use the cold water. Yeah, that totally blew my mind. I heard that a few weeks ago. That’s really, you know. 

Frasier Cain [00:07:24] Well, in in my in our new place, we’ve got a pretty big problem with, with hard water. So before, I never had hard water and now I have hard water. Now I’m learning these terrible lessons. As for cleaning the gunk off of faucets and things like that. But I had no idea. That’s really interesting. Okay. Yeah. Now, the the clearest ice that I’ve ever seen was in Iceland. There’s this. Oh, if you take a tour, there’s this. This lake where where glaciers are dropping blobs of ice into the lake, and then they go out into the ocean, and then the ocean wears them down a bit, and then barfs them back up onto the shoreline. And you walk along and they’re just these chunks of glass of diamond. It seems like they’re beautiful. And then you bring one back to the bar and they’ll mix them into your drinks if you want. So it’s, it’s a it’s an amazing experience. Like, like I think seeing geysers and waterfalls and all that was great. But seeing these, these shards of glass, of glass like ice. Yeah. On the shore. And I guess the, you know, something, I guess the enormous pressure of the glacier helped clear the the ice out. All right. So we’ve talked about crystalline ice. Boring. But so let’s talk about the other kind of ice. 

Pamela Gay [00:08:45] So I first learned about this, and I trying to understand the different theories on why objects like centaurs out around Jupiter’s orbit, between Jupiter and Saturn, are able to sometimes become active at that particular distance. A icy object shouldn’t be getting enough energy from the sun to be thermally excited. And so there’s ideas that in some cases, it’s landslides release energy that causes activity. But another idea is as objects move into the inner solar system, while things don’t get warm enough to melt crystalline ice, they do get warm enough to transition ice from what’s called amorphous ice to crystalline ice, which is a process that releases energy. 

Frasier Cain [00:09:42] To what is amorphous ice. 

Pamela Gay [00:09:44] It is ice that comes in many different kinds of density structures, where basically you have water molecules that are so cold that if you put them all in a cup, they wouldn’t form water, but they’re so cold that they can’t orient themselves to form crystals. So you end up with all these water molecules collecting together. The closest analogy I can think of is like dust gathering together. And as these molecules of ice come together without any orientation being dictated upon them, you get amorphous ice. So not crystalline is amorphous. 

Frasier Cain [00:10:34] Right? Right. And so if you were to like take a magnifying glass and look at crystalline ice, you would see all these molecules lined up perfectly, but with amorphous ice. 

Pamela Gay [00:10:46] All over the. 

Frasier Cain [00:10:46] Place. They’re all over the place. But it’s not a liquid. 

Pamela Gay [00:10:49] No. And this is where it’s. It’s so weird because I. There was there was this truly, truly delightful study. And and I’m always amazed at how researchers get permission to do it. And it’s not so much permission, but the creativity and and the funding to do certain things, or permission to use equipment to do certain things. I don’t really think this is a funding issue. Water’s kind of like comes out of the tap. Researchers took. Water froze it at at extreme pressures and extremely low temperatures in the vicinity of ball bearings, steel ball bearings, and essentially beat the tar out of it. And and it turns out that if you have ice and you beat the bejesus out of it, like literally take a container with ball bearings in it and shake it and shake it and shake it and shake it so that you don’t so much have a snow cone as you have snow, but then you put this under extreme pressure. What you have is all these disorganized ice crystals that are a powdery substance that can be considered as solid, but can behave more like a liquid. It’s right here. Weird. 

Frasier Cain [00:12:29] But I guess that’s what like on Earth, as we mentioned, you’ve got reasonable temperatures crossing the line between freezing and end and I guess not freezing. And then and then you got the air pressure. But in worlds like Europa and Enceladus, as you descend down into worlds like Jupiter, you’ve got varying both temperature and pressure, both vastly greater and vastly lower than what we have on Earth. So and these give us some of these weird forms of amorphous ice. All right. We’re gonna talk about that some more in a second, but it’s time for a break. 

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Frasier Cain [00:15:03] And we’re back to. So let’s talk about this and then give me some examples of amorphous ice here in the solar system in various places and how it might have formed and, and sort of just how behaves. 

Pamela Gay [00:15:18] So the most obvious one is what I mentioned. We have these objects that are not rocky asteroids are not comets because their orbit hasn’t carried them into the inner solar system yet. These are objects that formed out in the outer outer solar system. So out beyond 50 A.U. and where they formed was so cold that as ice crystals came together, they didn’t form crystals. And as gravity pulled all of these ice crystals together, it created greater and greater pressure. And so you have these objects that are made of amorphous ice. And as they migrate towards the inner solar system, they eventually get enough energy that the ice rearranges itself into crystalline ice. And we see these outbursts. Now that is kind of cool. It isn’t scary at all. And it’s like, Yeah, that totally makes sense. Yeah. Now, when you carry this research a little bit further. And start looking at worlds in the outer solar system and thinking about that ball bearing experiment. We have worlds like Ganymede that while you can’t really compare them to ice in a small container with ball bearings being beat up, they they do get struck by asteroids, which has a similar compression force. So what you can imagine is asteroid comes in or comet comes in, some source of force comes in, strikes the surface of the world. So Ganymede, one of these other icy worlds at the surface, some of that energy is going to lead to melting, but ultimately there’s going to be compression waves that move through the world and have the ability to transition ice from crystalline ice to amorphous ice. Now, over time, this pressure is going to get released through the world. It’s a tectonic force, just like pressure inside of of the place where two plates come together will eventually release as an earthquake. And. New research is theorizing that over time, the release of that pressure from ice going from crystalline to amorphous. When it goes back to crystalline. This can cause some of the massive cracks, some of the strange quakes and other formations that we’ve seen on the surfaces of these worlds, and previously couldn’t completely explain because they didn’t have tectonics like we have here on Earth. 

Frasier Cain [00:18:18] And so you’ve got I mean, when we think about Europa, like we know that the surface looks very icy and maybe it is crystalline ice at the at that point, but then you’ve got. Tens of kilometers of ice stacked on top of each other. So you can imagine the sorts of pressures that this ice is under, under 20, 30, 50km of pressure of all of this ice coming down on top of it. It must be. 

Pamela Gay [00:18:48] Extreme and well. 

Frasier Cain [00:18:50] And then there is that kind of in rippling back up and causing some of these, these cracks to make their way back up. 

Pamela Gay [00:18:57] Europa and Enceladus are their own kind of special case. They they have more heat inside of them than, Ganymede does. And this additional heat allows ocean currents. Especially with Europa, it’s looking like to actually affect, to create drag forces, to build up torque forces on the ice above that is generating a lot of these structures we see. And the ice, it’s it’s still being debated whether it is consistently tens of kilometers thick or in some places, just a few kilometers thick, with, water being able to seep out. Now, with Ganymede, you’re looking at a world that doesn’t have the same tremendous amount of heat built up in the core. While it may have subsurface oceans, it is going to have significantly thicker ice on the surface. And it’s in these cases with the significantly thicker ice, such as with with Kuiper belt objects in particular, that we’re going to be looking at having this amorphous ice potentially getting formed during collision events where there was once crystalline ice, and then that flipped back from amorphous to crystalline again, that releases energy. 

Frasier Cain [00:20:19] So what about some of the like, the most massive places in the solar system? When you think about as you descend down through the cloud tops of the of the giant planets of Jupiter, Saturn, Uranus, Neptune, I mean, they’re called ice worlds. Yeah, because they have ice like Neptune and Uranus. Like if you brought them to Earth and just sort of spread them out, they would be made of ice. They’d be made of the kinds of material that forms ice, different kinds of ice. So, yeah, what can those planets get up to as you descend down into them? 

Pamela Gay [00:20:59] So this this is yet another form of amorphous ice where the different structures are defined by the, the density of the ice. And, essentially the chaos of how the molecules aren’t aligned with one another. And. They they’ve been doing wild things like using lasers to smash things together, to try and get an understanding of what kinds of ices are existing at these pressures and temperatures, where the temperatures are. It’s a gas body with a lot of gravity compressing inwards. It’s higher temperatures here. So here you have high pressures creating the ice because of pressure. And then. The temperature is above what we’re used to thinking of for freezing. So here again we’re looking at something that think of the molecules more as dust grains that are confined together to form ices in a situation that just doesn’t exist on our planet. And what is really amazing me, is the creativity. And I’m just going to say this over and over, the creativity of the researchers to understand this stuff, where they they are like, okay, so we see this thing, how do we get water on our planet? That is that one atmosphere and that human survivable temperatures. How do we make the water molecules suffer the way they suffer? Right. And how do we explain the colors? One of the weirdest new releases I’ve seen is researchers have really been struggling to try and understand how Europa has the colors that we see. And just like you can get different gem colors by having the crystalline structure include different impurities, whether it be lead or zinc or whatever impurities makes your different colored gems. Well, it turns out that if you have water molecules where you have different ratios of the H2O combined with salts, the ratio of the number of water molecules to salt molecules that are together forming a different kind of crystal. These different kinds of crystals can produce different colors. So while it’s crystal in ice on Europa, it’s now starting to be thought that when we’re seeing these, these gorgeous, brightly colored lines where there’s cracks, that is extremely salty water that has frozen into a crystalline structure, that is a combination of salt molecules and water molecules forming their own structure that just happens to scatter red light. 

Frasier Cain [00:24:15] And like I know that the thinking for like Europa was that this might be some kind of or the hope, whether this is some kind of organic molecule that is being mixed in, that you’ve got some kind of long chain carbon molecules that are mixed in with the ice, and maybe this is evidence of life, but what you’re saying was hope. Yeah. But maybe I mean, who knows. But the but the but it seems like in fact, it’s just salt mixed with water. And it’s forming crystals that are taking on these, these strange shapes. And I think what’s really interesting about a place like Europa is that when you reach the surface, whatever you created is going to last because it’s so far away from the sun, so it’s not going to sublimate. Yeah, you’re you’re far enough away from Jupiter that the tidal interactions, all of the heating that’s coming from that, that’s happening down inside the world. But the stuff that’s reaching the surface is hard as rock, literally. And now it’s being exposed to space, micrometeorites, other debris and stuff that could be raining down on it. But it’s not like it’s going to be sublimating in the same way that that you would get if you moved Europa close to the sun. 

Pamela Gay [00:25:33] And it’s just amazing to to realize that just like carbon, we’re all familiar with how it’s able to be like regular everyday pencil lead versus, forming complex structures with buckyballs versus forming, diamonds of various colors based on what pollutants are in the crystals. Well, water really does the exact same thing where we have the amorphous structure. That’s a lot like your pencil lead. We have the crystalline pure structure that you sometimes see in pubs. That’s crystal clear. We have the salt crystals that are a whole variety of different colors, depending on the ratio of salts to water molecules, which are forming our different color crystals. It it’s all the same chemistry, but occurring at different pressures and temperatures with different molecules or atoms in the case of carbon. 

Frasier Cain [00:26:37] So the thing that I recommend is, is do a search for that. I guess ball bearing ice. Yeah. Experimentally. Yeah. Yeah. And you can really see that the, the lab setup that they had, it’s, it’s quite amazing to see these fairly large ball bearing. Mashing ice to produce the strange shape. And as he said, write the creativity. Do you like how do we replicate an environment that is completely alien to Earth here on Earth? 

Pamela Gay [00:27:06] We’re going to super freeze water and beat the bejesus out. 

Frasier Cain [00:27:10] And punish it with a steal until I guess. Did you ever. Was it Cat’s cradle theory that Kurt Vonnegut told story? 

Pamela Gay [00:27:18] And I didn’t read? 

Frasier Cain [00:27:19] Yeah. And there was this thing called ice nine in that, that that scientists had made this material called ice nine. And the thing that it did was anything it had touched turned into more ice nine and so turned the entire planet into ice nine and then proceeded to attempt to turn the entire universe into ice nine at the at the speed of light. And so, yeah, I don’t think. 

Pamela Gay [00:27:42] That ice doesn’t do that. Just, you know. 

Frasier Cain [00:27:45] Just because it’s a science fiction story doesn’t mean it’s true. Now, if you make strange matter now or now, we’re talking about, you know, not ice, you can’t get that version of ice. 

Pamela Gay [00:27:55] And it’s important to note that if you take a regular ice crystal and you super freeze it slowly, it’s just going to sit there going, hi, I’m ice. You have to do something to it to break the crystal structure, to get the amorphous ice, or have it freeze super fast so the crystal structure doesn’t have a chance to form. So that idea of contagious ice structure is not a concern. 

Frasier Cain [00:28:23] Right? All right. Well, thanks, Pamela. 

Pamela Gay [00:28:26] Thank you, Fraser. And as always, thank you so much to all of our patrons out there through Patreon.com slash astronomy Cast. You allow us to pay the folks behind the scenes Allie Beth Rich who make this show possible. This week I would like to thank a selection of our patrons, planetary Andrew Stevenson, cameras, Ian, Paul Hayden, James Roger, Alex Rain, Gabriel Galvin, Sean Mattes, Glenn McDavid, Arctic fox, Karthik Vaca, trauma and Stephen coffee, Brian Kilby, Dean Kurien, dump truck, Lu Zealand, Bart Flaherty, the air major. John Drake, Benjamin Davies, Nate that Wyler, Benjamin Carrier, the lonely sand person knew la Sam Brooks and his mom Jason cards. Lucas, Robert. Handle, Kim. Barron, Paula. Esposito, Bob. Zach ski, Gordon. Turner, Ron. Thorsen. Arts. Lots. Hall. Arthur. Lots. Hall, Mark H. Whittock, Hal McKinney, Bruno Latz, Reuben McCarthy, time Lord, IRA, Daniel. Donaldson, Frank. Stewart, Wil. Hamilton, Ian. Abdullah, Jeff and Jeff MacDonald. And if you would like to listen to this show with no ads, go join our Patreon and get your own special access feed. 

Frasier Cain [00:29:50] Thanks everyone and we’ll see you next week. 
Pamela Gay [00:29:52] Goodbye. Astronomy cast is a joint product of Universe Today and the Planetary Science Institute. Astronomy cast is released under a Creative Commons Attribution license. So love it, share it, and remix it, but please credit it to our hosts, Fraser Cain and Doctor Pamela Gay. You can get more information on today’s show topic on our website. Astronomy. Cars.com. This episode was brought to you. Thanks to our generous patrons on Patreon. If you want to help keep the show going, please consider joining our community at Patreon.com Slash Astronomy Cast. Not only do you help us pay our producers a fair wage, you will also get special access to content right in your inbox and invites to online events. We are so grateful to all of you who have joined our Patreon community already. Anyways, keep looking up. This has been Astronomy Cast.