From the Arctic to Enceladus: A Celebration of Unusual Ice
With the Arctic’s annual summer ice cover hovering at record lows; and a new record low in global sea ice coverage recorded earlier this year; and a large crack threatening the collapse of a large ice shelf in Antarctica, it can feel like the news about earth’s polar ice caps is all bad.
But for researchers who spend time in the frigid polar seas, ice is also a beautiful and unique phenomenon. Ever heard of frazil ice? How about pancake ice? Far from goofy names, these are key steps in the evolution of sea ice from water to a solid sheet. Oceanographer Ted Maksym shares his insights into the ice at earth’s poles.
Plus, how is Antarctica a good place for a painter of other planets? Astronomical artist Michael Carroll recounts how he explored Antarctica for hints about frozen moons like Europa and Enceladus. (See some of his art here.)
Finally, planetary scientist Rosaly Lopes takes Ira into the coldest reaches of our solar system, where there’s growing evidence of volcanoes powered not by magma under rock, but by frigid water bursting through icy crusts.
Ted Maksym is an associate scientist at the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts.
Michael Carroll is an astronomical artist based in Littleton, Colorado.
Rosaly Lopes is a senior research scientist and manager of planetary science at NASA’s Jet Propulsion Laboratory in Pasadena, California.
IRA FLATOW: This is Science Friday. I’m Ira Flatow. We’re going to be talking now about frazil, frazil ice, that is. That’s not ice that’s extremely stressed or harried. No, it’s just one of many kinds of ice you might find forming in the seas at our poles. There’s also pancake ice, shuga ice, ridge ice, grease ice. I could keep going on, but we’ll talk more about it.
Mariners and scientists that spend time in the sea ice, they have more than two dozen names for the types that they see. Since the Groundhog predicted another six weeks of winter for us, even as global ice cover hits a record low this January, we thought we’d celebrate a bit with a tour of the unique features of our polar ice. We’ll be touring all over our galaxy, so let’s talk about our polar ice, right here at home.
Ted Maxim is an associate scientist at Woods Hole Oceanographic Institute in Woods Hole, Massachusetts. Welcome to Science Friday.
TED MAXIM: Thanks for having me, Ira.
IRA FLATOW: I’m going to have to tighten up my mouth here a little bit. You’re packing for a trip to Antarctica, even as we speak where there’s a lot of ice?
TED MAXIM: Yes, I am. We’re going down to Antarctica this austral winter, so it’s sort of our summer. It’s actually April and May, and in trying to get us deep into the ice pack as we can to see what’s going on there.
IRA FLATOW: So that’s going to be an icebreaker then?
TED MAXIM: It’s going to be an ice breaker, yeah, and going through sea ice– so it’s not through big glaciers. That would be impossible. The sea ices down there is usually only a few feet thick, so you’ve got a strong enough ship, you can get through pretty well.
IRA FLATOW: So is it still dark down there? Is it going to be getting dark soon, I should say? It’s austral.
TED MAXIM: Right, so it’s the opposite of us. Right, so it’s quite light down there. By the time we get down there, which is going to be mid April, it’s going to be starting to get dark and we plan to get as far south as you possibly can at sea on this planet, which is about 78 degrees south. By the time we get there in mid May, it’s going to be 24 hours of darkness.
IRA FLATOW: And it’s not scary to be in the ocean surrounded by all that sea ice?
TED MAXIM: No, it’s not scary. You get used to work–
IRA FLATOW: In the dark?
TED MAXIM: Like an ice fisherman, you know he’s comfortable walking on ice in Minnesota. We get used to it. It’s not really that scary at all, but it’s certainly an eerie feeling. It’s sort of a very odd landscape, and in the darkness it adds an extra element to it.
IRA FLATOW: I’ll bet it does. Having been down there in the summertime, I can only imagine what wintering over must be like while in the dark. Let’s talk about some of the ice that’s down there. This thing I mentioned, frazil ice. What is that?
TED MAXIM: Yes, so frazil ice is really just a term for loose crystals of ice. It can be in the ocean or it could be in a river. It’s kind of a little bit like a snowflake in the water, I guess, and that forms because the water is turbulent. And you get lots of this in Antarctica because if you know your geography, in Antarctica, it’s surrounded by the stormiest ocean on the planet, more or less.
And so you get these big waves traveling through it. So it’s really hard to form a solid sheet of ice, as you can imagine. So it has to form loose crystals first. This forms a soupy mass of frazil crystals, and eventually they start to agglomerate together as it damps out the waves.
IRA FLATOW: And we have all kinds of ice. I mentioned there were a dozen. What is pancake ice?
TED MAXIM: So pancake is the next stage of ice. So as you get a lot of this frazil in the ocean, it looks kind of like a soupy mass of slush. Now what that does, it sort of damps down the waves a little bit, and as it does that, things can start freezing together. But the waves are really big there, so it’s hard to damp them down right away.
So these soupy masses sort of stick together and bang against each other, and so you get these tiny little pans– well, tiny, maybe three to 10 feet across– that are just banging into each other like a bunch of pucks on an air hockey table, if you will. And they form these round shapes that people thought looked like pancakes, but they got kind of rough edges because they’re always crashing into each other.
IRA FLATOW: We have photos of these ices on our website. They are amazing. They do look like– I was waiting for the maple syrup to come out. And then you have ridges, and nilas, and shuga. Tell us about these.
TED MAXIM: Right, so– yeah, kind of like Eskimos with all their words for snow. Because things take different forms, you want to be able to describe it in a concise way. So shuga is actually a kind of ice you don’t see very often. It’s when the frazil kind of glomps together, almost like snowballs floating around in the ocean. Nilas is sort of the opposite of frazil ice. It’s when you have fresh ice forming, and I think everybody who’s been in cold weather is familiar with this, you see it as a very thin veneer of ice on top of a lake.
On the ocean it looks a little bit different because that is a little bit salty, so it tends not to be as clear as it would on the lake. So that has to form– you can imagine you need really calm conditions for that. No waves. So that forms sort of in the interior of the pack. Once you’ve got pack ice, if you’ve got any cracks or openings, nilas can form in there, and that’s quite thin.
And then it starts to thicken because it’s Antarctica, it’s really cold, and as the ice continues to move around, that can sort of pile up as big plates of ice crashed together. We call them ice flows, crash together, and bits break off and sort of pile up into these big sort of walls of ice, if you will, that can be many feet thick. In the Arctic, because forces are so large there, you can get ice piled up to tens of feet thick.
IRA FLATOW: Wow. You know, I remember when I was in the Arctic, right on the shoreline, in McMurdo there. It was some of the most beautiful stuff I’d ever seen, was the sea ice piling up, changing shape, forming caves. It was just beautiful. I can imagine why’d you want to go–
TED MAXIM: Yeah, and that’s something when we go south on these icebreakers, we’re always getting off on the ice and doing our measurements, and we’re busy with her science. But to me, one of the most enjoyable things is just sitting on the bridge of the ship just watching for hours as you’re going through different types of ice, or different formations of ice. It’s always constantly changing. I don’t want to say it’s boring on a lake, but it’s pretty uniform on a lake, most of the time. The Great Lakes are a little bit more interesting, I suppose. But, somewhere like Antarctica or the Arctic, you have this constantly changing landscape. But it’s all ice.
IRA FLATOW: We’ve had people on Twitter asking us about the brinicles, icy fingers. There’s a wonderful YouTube video on this that looks just like a CGI. It’s so spooky looking, but have you ever seen one? Describe what’s going on there.
TED MAXIM: So this is an interesting thing about ice, or sea ice. It’s not like other types of ice in that it’s a composite material. Because the ocean is salt water, of course, but it’s hard to freeze that salt into the ice. So what it does is it traps ice in little– I mean, sorry– salt in little pockets of brine in the ice, and that really determines the properties of that ice.
Now, when you get the salt trapped in there, it doesn’t like staying in there. So it tries to drain out through this porous network within the ice. There’s all these little channels of brine, and so when you get ice thick enough, and the salt starts draining out, it sort of drains out kind of like in a little river going down vertically.
Now, in Antarctica sometimes, like you mentioned McMurdo Sound Area, you can get these sort of rivers of brine coming down into water that’s at the freezing point. But that brine is much colder. So as soon as it hits that water, it freezes. So it starts forming this kind of icicle going down into the ocean below, except it’s hollow. So it can have this brine coming out down through this tube. And some of these tubes can be many feet long, and in that video it’s kind of cool.
You have this drainage happen very rapidly, and when that brine hit the bottom of the ocean, that is what– it’s in a state we call supercooled. So it’s actually colder than the freezing point. As soon as it hits something where it can start nucleating ice, it starts to freeze, and you saw that spread along the ocean bottom. It’s really cool because you saw all these sea stars trying to run away from this thing, get trapped in the ice.
IRA FLATOW: It’s a great little video. It’s great to see that. You mentioned the Antarctic ocean. How are the oceans different? How is the ice in Antarctica different from the Arctic ice up north?
TED MAXIM: Right. Well, I should say that they used to be quite different. They’re getting more and more alike. In the Arctic, the ice– because the Arctic is sort of this enclosed basin, the ice doesn’t escape the Arctic Ocean very easily. So it can circulate there because ice drifts around. It can circulate there for many years and get thicker and thicker. So you have ice there that used to average maybe 10 feet thick, and it can get quite thick because the ocean doesn’t have– the deep ocean heat has trouble getting up to the ice and melting it.
In the Antarctic, things are very different. It’s wide open sea that it’s exposed to. So it’s always buffeted by the waves, and deep beneath the surface of the ocean there’s actually some really warm water that gets stirred up really easily, and that keeps ice very thin. So actually, most ice, unless it’s ridged, rarely gets more than a few feet thick in the Antarctic, which is convenient for those of us who want to drive our ice breaker through there. But it makes it for a very different environment.
The Arctic has this thick ice with big thick ridges. The Antarctic has thin ice with more pancake ice, and things are moving around much more rapidly. But that’s all sort of changing a little bit because we’ve seen, over the past decade, that in the summer in the Arctic almost half of the ice has been disappearing.
We’re getting about half of what we used to have, say back in the 1980s. So the Antarctic is sort of an interesting analog for what might expect to see in the Arctic. And actually, about a year and a half ago, we were up there and we saw this extensive field of frazil and pancake ice, that really haven’t been seen in the high Arctic before.
IRA FLATOW: Wow, things are changing. I want to add to the conversation, someone who has seen the poles with an artist’s eye. We were talking about how beautiful the ice is. Michael Carroll is an astronomical artist based in Littleton, Colorado. His work often tries to imagine the surface of distant worlds, and he has spent three weeks in December exploring Antarctica, looking for inspiration for the surface of the icy moons of Europa. Welcome to Science Friday.
MICHAEL CARROLL: Oh, Ira, I love your show and it’s great to be here, thanks.
IRA FLATOW: Well, thank you. We’re very happy to have you. Why is Antarctica such a good place to look for inspiration for a moon of Jupiter or Saturn?
MICHAEL CARROLL: Well, for some of the same things that your other guests have been talking about, it’s unique in so many ways, the way the ice behaves down their. Of course, in the outer solar system, a lot of these moons are ice worlds. Europa has an ocean probably 100 kilometers deep beneath an ice crust, and on that crust you see these pressure ridges and things that are somewhat similar to what we see down in Antarctica on the open sea ice, right there next to the Ross Ice Shelf. But more than that, there are some fairly specific analogs we’re looking at up on Mount Erebus on the big volcano down there.
IRA FLATOW: Really? Such a such as what?
MICHAEL CARROLL: So Erebus has these fumaroles, these volcanic vents, all over its slopes. So the hot air comes up through these things. It hits this frigid air up above and it forms columns of ice. And these towers of ice are just the most bizarre things. They are beautiful and inspiring. The blues, the textures in them, some of these things are five stories tall and they look like a nightmare from Salvador Dali’s diary. They’re the most bizarre things. But because you get this constant flow building these structures, we think that things similar to that may happen on for example, Saturn’s moon Enceladus.
IRA FLATOW: Wow. Ted, do you think that– let me first tell everybody that this is Science Friday from PRI, Public Radio International. Talking about the ice and onto poles, and now we’re moving out into space. Ted, could a place like Antarctica help scientists somehow plan for a mission to icy moons?
TED MAXIM: Yeah, definitely, and there are scientists doing specifically that. One of the interesting things in sea ice, like I said, there’s liquid Brine in the ice. What that has in it is these organisms that can tolerate extreme cold, and so people are interested in looking at sea ice as an analog for what kind of habitats you might possibly have on a moon like Europa.
But Antarctica is also a really nice proving ground for vehicles that you might design to explore a moon like Europa. And so there are a couple of groups that are trying to develop vehicles, sort of prototype vehicles that might go up to Europa, and putting them under these ice shelf to see how you can technologically achieve getting down through many kilometers of ice, down to some unknown ocean.
IRA FLATOW: Michael Carroll, when you look at a place on earth like this, how do you account for how a moon or another planet might look differently?
MICHAEL CARROLL: Well, the main difference is, of course, air. We’ve got lots of nice air to breathe here on earth. Although, up on Mount Erebus there isn’t that much. But when you’re dealing with a vacuum, these powers that build may take on some different textures and forms because on Antarctica they’re sculpted by wind. But nevertheless, we do think that there are some fascinating structures out there, and for an astronomical artist, we try to learn from nature to inform us for those guesses that we’re making in terms of the geology on other worlds.
IRA FLATOW: Because you have such a good eye as an artist, do the scientists come to you and say, hey, have you seen anything that we have missed, perhaps?
MICHAEL CARROLL: Well, you know, it’s always a wonderful collaboration. My colleague that I traveled to Antarctica with, Rosalie Lopez, who has been on your show, by the way. She is often talking to me about how things would look because she doesn’t think in those terms, and so she’ll give me some numbers, and I take those and translate them into something visual that the non-scientists can understand and relate to.
IRA FLATOW: Now, we’re going to have Rosalie join us right after the break. We have to say goodbye to both of you because we are running out of time. Fascinating. Ted Maxim is associate scientist at the Woods Hole Oceanographic Institute in Woods Hole. Michael Carroll is an astronomical artist based in Littleton, Colorado. And we have, actually up on our website, some of your artwork at sciencefriday.com/spaceart. So it’s really interesting stuff that you’re doing, and thank you both for taking time to be with us today. Have a great weekend.
MICHAEL CARROLL: Hey, thanks Ira.
TED MAXIM: Thank you.
IRA FLATOW: You’re welcome. As I said, we’re going to take a break. When we come back, one last chilly adventure, the icy cryovolcanoes. Cryo, you know what that– cryo, volcanoes, put them together and where are they? That’s right, they’re outside in our solar system. Go to the head of the class. We’ll be right back after this break. Stay with us.
This is Science Friday. I’m Ira Flatow. If you just joined us, we were just marveling at the ice at the earth’s poles, and it certainly is beautiful, and it is interesting. But we’re not quite done with ice yet because it’s certainly not as unusual as the icy phenomenon at work in the far reaches of our solar system, and I’m talking about the cryo volcano. It is like a volcano, but instead of hot magma, you have this rigid slush bursting through an icy crust.
Cryo volcanoes have been suspected on the icy moons of Saturn and Jupiter, like Enceladus and Titan, and even dwarf planet Pluto may have some. My guest, Rosalie Lopez, a vulcanologist and Manager of Planetary Sciences at NASA’s Jet Propulsion Laboratory in Pasadena, California knows a lot about this. Hi, welcome to Science Friday.
ROSALIE LOPEZ: Oh, Hello. Hello, it’s nice to be back.
IRA FLATOW: Nice to have you back. How are ice volcanoes possible? What’s going on inside there?
ROSALIE LOPEZ: Well, they’re very weird. We didn’t even think they were possible until we actually saw evidence because there is nothing like them on earth. But when the Voyager spacecraft flew by Neptune in 1989, it actually saw some eight kilometer high plumes, and also some very smooth regions that people figured out had to be caused by volcanoes. But not rock vulcanism, or magma vulcanism like we see on Earth, but a very special kind of volcanism that we call cryo volcanism.
IRA FLATOW: Does the science of these ordinary volcanoes translate easily to cryo volcanoes? Or are they just different in how they behave?
ROSALIE LOPEZ: Not easily, no, and we’re still figuring that out. No, essentially on a volcano, it happens when you have an icy crust like on Jupiter’s moon, Europa or Saturn’s moon, Enceladus or Titan. And underneath that icy crust, you have an ocean of liquid water. Maybe liquid water with things like methane or ammonia.
And so vulcanists– we actually had to redefine what volcanism is because volcanism used to be defined as the process that brings molten rock from the interior of a bulge to the surface. But now we had to redefine it and say it brings magma, whatever the magma is for that specific body. So if the magma is water or slushy ice, that’s what that volcanism is on that bulge will bring up.
IRA FLATOW: So you’ve actually had to also redefine what magma is.
ROSALIE LOPEZ: Yes, exactly. Magma on an icy moon or on Pluto, it’s different. It’s not molten rock like on Earth, or on Venus, or on Mars. And when we studied volcanoes on Mars, for example, which I have done, we can use Earth analogs quite easily. You can go to [? Habai ?] or Iceland, places for example, that have chilled volcanoes. But when you’re studying cryo volcanism, there are no cryo volcanoes on Earth. So that’s what makes figuring out the process difficult.
IRA FLATOW: As you say, on Earth it’s this hot magma that comes shooting up. We can imagine why it would that. It’s hot, it’s coming out underneath the ground. What is driving the slushy water up through a volcano?
ROSALIE LOPEZ: Well, that’s what is difficult to figure out because if you think about just having a glass of water and ice cubes on top, ice cubes float. So the difficulty is how do we get around that density difference that the ice will want to be on top of the water? So how do you actually get the water up to erupt? And there are various theoretical explanations. You could get maybe part of that ice shelf melting because of tidal heating, and then they could make closed reservoirs of magma closer to the surface. You might get fractures like giant crevasses opening up, and maybe that cryo magma has a lot of bubbles that would make it easier to come up. Maybe even that ice shell is not completely ice, but it might have some silicates in it. There are a lot of things that we don’t know yet.
IRA FLATOW: I have a tweet coming in from [INAUDIBLE] says, could a solar refrigerator suck in salt water during– could you send somebody there to the space mission and investigate, and should you? Should that be part of any mission to these moons of Jupiter or Saturn?
ROSALIE LOPEZ: Oh, I think it’s very important to investigate cryo volcanism because if you have heat and you have water, those are two of the conditions that you need for life. So if you’re going to look for life in these icy moons of the outer solar system, the presence or absence of cryo volcanism is very important. And if I somehow landed on one of these worlds, I would definitely want to land near a cryo volcano. And NASA just released a report on a study of a land of Jupiter’s moons, Europa. So maybe we’re going to get there with a lander. So yes, we need more missions.
IRA FLATOW: Would this tell you– do these volcanoes speak anything about the possibility of any forms of life on any of these moons?
ROSALIE LOPEZ: Yes, because you need, as I said, heat and you need water. Those are not the only two things that you need for life, of course, and astrobiologists are still going about what all the conditions that you need, but you certainly need those two. So the places maybe near the surface where you actually have pockets of this molten ice water would be good places to sample to see if we actually have any kind of microbes there. And in fact, many Antarctica studies– some astrobiologists are going to Antarctica to actually study what kind of microorganisms we find there.
IRA FLATOW: I have to ask you a question akin to asking which child do you like best. You study both hot and cold volcanoes. Do you have–
ROSALIE LOPEZ: Yes, yes.
IRA FLATOW: Do you have a favorite? Just between you and me.
ROSALIE LOPEZ: OK, I actually like– maybe I like hot volcanoes better, because I can actually go to them on Earth.
IRA FLATOW: Good point. Good point, and then you can go home again, as they say.
ROSALIE LOPEZ: That’s right, yes. But I did go to Erebus, which is not a cryo volcano, but it was very, very cold. Michael Carroll and I went to Erebus in December, which was a fantastic trip.
IRA FLATOW: Yeah, I was there over 30 years ago myself. It really was a fantastic experience. Dr. Lopez, thank you very much for taking the time to be with us today.
ROSALIE LOPEZ: Oh, thank you so much.
IRA FLATOW: And we’ll have you back when you tell us more about these volcanoes. Rosalie Lopez is a vulcanologist and Manager of Planetary Sciences at NASA’s JPL in Pasadena, California.