 It's one o'clock on a Monday afternoon, so you must be watching Think Tech Hawaii research in Manoa. I'm your host, Pete McGinnis-Mark. Now every Monday we bring you science updates from the University of Hawaii, primarily from the School of Ocean Earth Science and Technology, bringing you the latest news either in oceanography, atmospheric sciences, geology, or planetary sciences. And it's in planetary sciences today that our guest is going to be talking about. And our guest is Caroline Kaplan, who is a graduate student within the Hawaii Institute of Geophysics and Planetology. So welcome, Caroline. Thank you so much for having me. I understand we're going to be talking about ancient meteorites, or little small pieces of meteorites. That sounds a fascinating topic, can you tell us a little bit about that? Yeah, so it's really fascinating because it's a new area of research that a couple groups have been working on. And we're really excited to look at ancient meteorites because they're giving us a way to look at what types of meteorites were falling throughout Earth's history, as well as the relative abundances of each of these types of meteorites. And we can use this information to understand some solar system processes that might have been happening throughout Earth's evolution. And the great thing about studying these ancient meteorites is that the meteorites that most people are studying today, from the past hundreds, maybe a thousand years ago, so it's really only telling you what's been going on recently. And I'm sure our viewers already started thinking, how does Caroline find ancient meteorites? So can you tell us how old and where do you find them? Yeah, so we can actually find them preserved in limestone and different time periods all around the world. Me specifically, I'm looking at the Jurassic time period, which is about 160 million years ago. And currently, I'm working on samples from Spain, and I will be working on samples from Italy. And the Jurassic is when dinosaurs were spotted in the air, not necessarily in Hawaii because Hawaii wasn't there. And I think it's probably going to be really helpful for our viewers just to see the kind of meteorite. We're not looking at giant chunks of iron meteorites. No. They're little tiny grains. So the first slide should tell us, here we've got a nice image, I guess, we're looking at one of these grains on the left-hand side, that's the dark patch. So this is actually a cutout of a piece of limestone from a limestone quarry in Sweden. And the image right here on the left, a large black circle, is actually a preserved meteorite in limestone. It's about five centimeters long, and this is a whole meteorite that was found. So if you look, you see all those little circles and details in the meteorite. It's actually, those are called chondrels, little more details about certain types of meteorites. But you can see the texture of the original meteorite, which is amazing. Fantastic. And we've also got a nice section of some kind of fossil as well to show that this is not a whole object from outer space. So you would study that whole meteorite, or would you study individual grains within that piece of meteorite? So we can actually only study a specific grain called a chromite, this is a specific mineral. The whole, the meteorite as a whole is preserved in this limestone, it was at the bottom of the deep sea ocean floor. So it was actually weathered and altered based on the Earth's surroundings. So a lot of the original material of the meteorite has been turned into like clays and calcite and other minerals. So it doesn't contain any of its original characteristics. Is it important to go and search for these grains in limestone? Could you do it in other kinds of rocks or is a limestone much more easy to find? We prefer limestone because we can actually get to the grains pretty easily because we can dissolve it in acid, which we'll talk about in a minute. But it's also that the limestone really preserves the time stamp that the meteorites fell. All right. And the time, even though you say it's in the Jurassic, the timing presumably is really important because I think what you're trying to accomplish is to see if over say a few million years time period, the number of the grains is changing its relative proportion. Yes. Right. And you find these in limestone quarries, right? You don't go like we have limestone of the coral reefs here in Hawaii. So the second slide, I believe, will show us a little bit about this is a quarry in Sweden. Have you been there? Yes. I actually took this photo of a quarry in Sweden. These rocks are specifically from the Ordovician time period, which are much older than the Jurassic, but 460 million years ago. We have these great outcrops. What I'm showing here is about six feet tall. So it's a huge area that's being mined for actual use to make roads or decoration. And the dark patches are just where water, presumably, is just streaming down. So this is kind of like the limestone I put in my kitchen or bathroom. Yes, it can be. So it doesn't have to be special limestone. You just really want to know its age, correct? Yes. And with the limestone quarries, since it's used so often, and what actually happens is that if we're lucky enough to have a limestone quarry that's active, and it's for the time period that we want, they've actually been able to train the people working there and let them know and be like, see this weird thing? This is a meteorite. Can you please set this aside for us? And they were actually really great about it. And they've been doing that ever since this whole thing started. So Sweden is a good place to go and stop looking limestone quarries? Well, it's all started in Sweden. So it's definitely a great place to go. But we've been able to collect samples from all over the world, China, Russia, old limestone quarries. But with those, since they're old, we don't have anyone getting the limestone out for us. We have to go there with hammers and bags and collect them ourselves. I know later on in the show, we'll get to the point where you do the comparison between these areas. But just trying to collect samples, how big a sample do you actually need if you went to that quarry? So we usually try to get about 300 kilograms per time period to start out with, which is 300 pounds, right? Yes. And so we usually, for each batch that we go through, it's about 100 kilograms. And to get to that point, we take as large chunks as we possibly can. Either you can hold them in your hands or you have to use your whole arms. And we put them in bags, and we try to calculate and get as much as we can. And I think the next slides are going to show us a little bit about actually what kinds of preparation you have to do. All right, so here we've got two individual images. Tell me a little bit what this appears to be a plastic drum on the left-hand side. What does that do? Yeah, so on the left, we do have this giant plastic container. I think it's about three or four feet tall. And that's where we put our limestone in, because we had these giant amounts of rock. But how do we get our samples out of it? So we actually take this limestone, and we put it in an acid bath of hydrochloric acid for a couple days. And then it dissolves and turns into this smooth clay mixture. And you do this at UH, or elsewhere? No, there's actually a specialized lab in Sweden that was created by the person who heads this type of research. His name's Birger Schmitz. They made the specialized lab with all of the acid and the tools that they need. Because obviously hydrochloric acid isn't the sort of thing you want to have lying around your lab and that sort of thing. Yeah, I know. It's not particularly safe. And then on the right-hand side, if we can go back to that same image, I think what you're starting to show is that you take all this material, a few hundred pounds, and then all you get left is what you can see under a microscope. Yeah, so we have this giant amount of clay sludge that's like in the bottom of this barrel. And we have to sort it by size with what we call sieves. And then we get the small amount of material left that we put into these little petri dishes. And so in order to find the grains that we want, we actually have to look through this microscope and pick out the grains that we want individually. And these grains are so small that you work with them through a microscope. Yeah, so you definitely need a microscope. They're about the size of a grain of sand or smaller. You start off with 300 pounds or more of limestone, put it in this acid bath, and then actually everything, apart from these little grains, you throw away or it gets dissolved and that sort of thing. And then that's all we keep. And that's all you keep. But that's all we need. And then what do you do with the grains once you've recovered them from this sample? Yeah, so in Sweden, they recover them. They send me the individual grains and I mount them. And then I look at what types of elements are in them, like titanium, zinc, iron, chromium. And we also look at their oxygen isotopes. And those things combined can help tell us what type of meteorite they came from. And you're confident that these are indeed meteoritic in origin. They're not from some big volcano eruption elsewhere or anything like that. Yeah, that's the great thing about all of the meteorites that are being found today is that a lot of people have done studies on them and they all have specific amounts of certain elements and specific oxygen isotopes that are uniquely for their type. And we can use that information, compare our own unknown grains to them, and then figure out what type they came from. Now, we've had Hope Ishi on the show a couple of months ago. She was talking about cosmic dust. What you're searching for is the equivalent of the cosmic dust that Hope is collecting today, except you know from the age of the limestone that you're actually looking at something which fell tens, hundreds of millions of years ago, right? Is there any special environment, these limestones that you can study, do you need to sort of pick and choose around the globe, or is it just the age? Well, we mainly look for the age. That's the most important thing, because we want to be able to compare the different ages and see how the windows open up for the different time periods. But for the limestone, once we have the age, we need to make sure that the limestone is useful for our research. So what we want is a really low sedimentation rate, which means that material is very, very slowly added to the surface of the seafloor. So we specifically look at the seafloor because it's very calm, not a lot's going on, so the grains don't get shoved around or anything, so they keep their time stamp, which is what we really need in order to know when they fell. And in this hypothetical 300-pound chunk of limestone, how many grains do you find? Hopefully at least one, right? So that bin that I showed you before, where we put all the rock in, that's about 100 kilograms of rock that we put in there, and for my study, I get about 30 grains out of that. 30 grains, all right? And we'll ask you later on, how long does it take you to analyze the 30 grains? We've got time for just one more slide before the break, but let's see what we have here, and I guess this is what you're actually looking at, right? Yes. Here we're seeing, with the 200-micron scale at the bottom, right, this is four grains, the black pieces, is that correct? Yes, so the very large grain comparatively that's on the right, that's what actually is standard. So it's a chromite grain from Earth, and we need a standard in our analyses to make sure that we're getting the right kind of data. So we compare that, and we make corrections as necessary because instruments in the environment can affect things. Because you're part of an international team from the sound of it, and so you're having to compare your own results to what other people's on, maybe they're finding grains in different types of areas or different limestones or whatever. So that's why you need a calibration point. Yes. Okay, great, well this is really interesting stuff, and this is your PhD thesis, correct? So how long have you been doing this kind of thing? I've been working on this for about three or four years, and I've been doing a lot of other projects with it. Right now I'm working on, I just finished working on samples from Spain, and in the spring I'm gonna start working on samples from Italy in the same time period. Okay, and as a PhD student, when do you expect to graduate? When are you defending? I'm about a year left, so I'm gonna wrap up my Italian grains in the next year, and then I'm gonna get to figure out what it all means. Go somewhere else, and just before the break, you've been to Italy for Sweden to look at some of these grains yourself, so it must be fun being a planetary scientist who actually gets to do fieldwork, right? Yeah, it's very exciting. Terrific. Well, we're just about getting towards the break, so let me just remind the viewers you are watching Think Tech Hawaii research in Manila. I'm your host, Pete McGinnis-Mark, and my guest today is Caroline Kaplan, who is a graduate student within the Hawaii Institute of Geophysics and Planetology, and we'll be back in about a minute. We'll see you then. This is Think Tech Hawaii, Raising Public Awareness. Aloha, I'm Kaui Lucas, host of Hawaii is My Mainland. Think Tech is important to our community because instead of the usual 30-second soundbite, we have enough time to have the discussions to come up with real solutions. And for the first time, Think Tech Hawaii is participating in an online web-based fundraising campaign to raise $40,000. Give thanks to Think Tech will run only during the month of November, and you can help. Please donate what you can so that Think Tech Hawaii can continue to raise public awareness and promote civic engagement through free programming like mine. I've already made my donation and look forward to yours. Please send in your tax-deductible contribution by going to this website. Thanks for thinktech.causevox.com. On behalf of the community enriched by Think Tech Hawaii's 30-plus weekly shows, mahalo. And welcome back to Think Tech Hawaii Research in Manoa. I'm your host, Pete McGinnis-Mark, and my guest today is Caroline Kaplan, who is a graduate student within the Hawaii Institute of Geophysics and Planetology, and we're learning all about ancient meteorite grains. So Caroline, the first question I'm sure a lot of the viewers are asking is, what's the big deal? Why are you trying to find old meteorites? What's the underlying science behind your research? Well, like I said before, the exciting thing about looking at ancient meteorites is that it's a time that no one's been able to look at before. Like right now all the meteorites that we're studying are from a couple hundred years ago, but being able to look at these meteorites in limestone gives us a whole new view about what's going on out there. So if we're able to open up these windows, we might be able to understand what collisions might have been going on, how like impacts might have affected evolution over time. So it's really exciting. So I think what we should tell the viewers, in part, is that not all meteorites are the same, are they? No. And while they come from the asteroid belt, they might be from completely different places in the solar system, correct? And so, am I correct in thinking what you're trying to do is almost a detective story? Yes. Do we get meteorites from the same part of the asteroid belt today as the time periods you're studying? Yeah, so that's something I'll talk about comparing different work from other people with their own time periods, but we're finding that things are a little different depending on what time period you're looking at. Okay, well, let's get more into the science and then take a look at the next image. And before we start talking about some of the results, this gizmo here, this looks really impressive. This is one of the machines you do use for your research? Yes, it is. This is a... What is this? It's a kamika instrument that we actually use to understand and figure out the oxygen isotopes that are in our samples. So the oxygen isotopes can help tell us if the sample is from Earth or not and what type of meteorite it came from. Okay, and that is all one piece of equipment for the entire slide. Yeah, so it makes a little upside down U-shape or like an N-shape with the user in the front and it uses magnets to help differentiate the different types of isotopes. And it's really fascinating, you can get... You can look at really big samples relatively about an inch in size or you can look at really, really small grains like what I look at. Right, and the isotopic composition at the first order will tell you a little bit about whether the sample comes from Earth or it comes from the moon or elsewhere in the solar system, great. But it must be great to be able to work on some piece of equipment like that. Offline, you told me also that with Hopi-shi on this transmission electron microscope, cutting edge kinds of equipment for our graduate students that must be really exciting stuff. Yeah, it's really exciting because you as a graduate student when you first start out, you don't really know what's gonna happen or what you're gonna work on, but every turn of your research, you find all of these new types of technology that you can use for your research. And it's great that we have all of these instruments at the university. Yeah, but how did you get interested? I mean, you couldn't have been a college or high school, I'm thinking. I really wanna go and put a chunk of limestone in acid to find out how did this happen? What's your background? So my undergraduate degree is an astronomy. So I did, was really interested in outer space and everything that goes on with that, but I was particularly interested in meteorites. But we didn't do a lot of that research in my undergrad. So I decided, well, meteorite's the type of rock. Why don't I just look into geology programs? And I was lucky enough that Gary Huss does research that I'm really interested in. And Gary's your advisor? Yes, my advisor. And so when I first started, I didn't really know what I wanted to work on. So I talked to Gary about the different types of research he's working on, and he gave me a paper that kind of reviewed this type of research and I immediately fell in love with it. It's geology, it's outer space. It's a combination of all these different types of sciences, which I fell in love with. So you get to do field work in Sweden or Italy, right? Yes, I get to travel, which is amazing. And there aren't that many people doing this kind of research, so you're going to become one of the world leaders. Yeah, we'll see, hopefully. But yeah, there are maybe a dozen or less people working on different time periods right now. And are you basically, say, a geologist, or a mathematician, or a geochemist, or what kind of skill set would someone have to have to follow in your career path? So the title of what we do is Cosmochemistry. So a background in astronomy is helpful, geology is also helpful, but it's also what you really learn as you're working. So that's what I love about grad school, is you're always learning things that doesn't stop with the classes that you take. So you could really come from any type of similar background and be able to get into this work. And presumably the ability to use a power drill to take some of the samples would be good as well. Oh, if only we had a power drill. They only give us hammers. Oh, we do, we do. Well, let's get back to the science and let's take a look at the next slide. This is presumably one of the grains, right? Yes, this is one of my grains. This is actually a picture taken in a scanning electron microscope, which is what we use to take images of our samples. So we can have an idea of what they look like once they're mounted and polished down. And we need to take pictures of these samples because sometimes there's cracks that we want to avoid because cracks can greatly ruin the data that we collect. The viewers may not be able to recognize this is 800 times magnification. So we've got the scale above 20 microns. So it's really about the human hair width or something like that. Yes, it's very small. It's very small. And so you then get that amazing piece of equipment we saw in the previous slide set up just to analyze isotopic composition of this green. Yes. Here's the equipment again. And all of that would be focused on just that one grain. And that grain would tell you what the isotopic composition is. Yes. Okay, and then do you just look at one grain or do you look at as many grains as available? We look at as many grains as we can get. Okay. So like I said before, in the 100 kilograms, we get about 30 grains. And in each session, I can do about 40 grains maybe. Okay. Probably less than that. But we can get a decent amount of grains. And when we're on that instrument, we usually take a week of time because it's very sensitive. It takes a while to set it up. So once you're on it, you just like go for as long as you can. Last three. Now we've talked a little bit about isotopes. I think the next diagram will actually show something where isotopes become really important. So if you can go to the next slide, we're just looking at oxygen isotopes on this, all right? And that apparently is one of the important diagnostics. Yes. Explain to the viewers what it is we're looking here. We're looking at two different isotopes of oxygen, is that correct? Yes. So on the x-axis, we have delta-18 oxygen. And on the y-axis, we have delta-17 oxygen. And so the delta notation is basically that we have the different isotopes. We have 16, 17, and 18. And 16 is the most common, so we want to compare the other two isotopes to 16. So it's a ratio, and then the delta notation comes in because we compare it to standard mean ocean water. Kind of that it's all related back to something so that everything can compare. And then we've got a number of things labeled here. We've got the dashed line labeled as Earth. Yes. So pretty much any point that falls on the Earth line is from Earth, usually. There are some cases where we have some extra triangles. And yet Mars and the Moon, which are also arrowed on this diagram, fall on the same line as the Earth. Yes. So the Moon falls very close to the line because it came from... It falls from the Earth. Yeah, yeah. So it formed from the Earth, so it makes sense that it has the same similar values. Mars is pretty close. And then we also have different types of meteorites. What we're labeled here, ordinary chondrites and carbonations chondrites. They're all types of meteorites. Yes, they are. So where would your data fall on a plot like this? My data actually falls all over the place. All over the place. Yes, which is really exciting. We have a whole bunch of data points that are in the ordinary chondrite region and then a whole bunch of data points that are below this Earth line. So does that mean that they come from different places? Yes, so they come from different meteorites, different meteorite types formed in different areas of the solar system. So yeah, they formed all over the place and they somehow made it Earth. All right, so you sort of hinted that the difference in oxygen isotopes might tell us a little bit about where the meteorites came from. You know, sort of not specific asteroids, but say beyond the orbit of Mars or beyond the orbit of Saturn or something like that or... So they definitely formed in different areas of the solar system, but right now we can't tell exactly where they formed. And that's what you're searching for, huh? That's what everyone's kind of searching for. So look for clusters. Mm-hmm. So you've got these samples. You're studying a time period 140, 160 million years ago, the Jurassic in terms of the Sweden. How do these samples compare? I think you brought along another diagram to show us, so I think we can go to the last diagram. All right, and this must be the really exciting part, right? Yes. So the project is this area of research is just starting out right now, so we don't have a lot to compare to at the moment. But here, this is a histogram with the cluster on the left showing the abundances of ordinary chondrites. And on the right, we have the other types of meteorites, which are, there are so many of them. And the colors basically represent... Different time periods. Different time periods. Great. So we have, first, we have pre-467 million years ago, which relates to the second one, which is the breakup of the alchondrate parent body. And then this was actually the big discovery that started it all, where I was talking about that image of the fossilized meteorite, that was from the Ordovician time period. And it turns out pretty much every type of sample that they found during the Ordovician... During this time period was all the same type of meteorite. So it was extremely, extremely unusual. So it was a huge research group went out and discovered from different places to find that the same type of meteorite fell to Earth at the same time. So this is very unique in Earth's history. So al-type chondrites, basically, they don't fall at the present time? They do fall at the present time. There were just a lot of them at the specific time because that's when the breakup of its asteroid occurred. And the influence then is that they originated from the destruction of a single asteroid, as opposed to the gravity field of Jupiter hurling more projectiles towards Earth at some unspecified time. Well, this is really interesting. And presumably, is the community trying to look at other time periods to see if we've had similar events or we get spikes in different types of meteorite? Yeah, so it's starting out that different groups are looking at different time periods. Like on that histogram I showed you, someone looked at the 466 million years ago, someone looked right before it and found that it was a little different. So kind of the background flux of different types of meteorites. I'm looking at the Jurassic and then we have the comparison today, of course. Right, and how far back in time might one theoretically be able to study? Oh gosh, millions and millions of years. As long as there's limestone first to look at, we have a chance. Okay, so I've gone to Arizona, I see Kaibab limestone, for example. In theory at least there might be meteorite grains stuck in that limestone as well. And obviously this is the sort of thing that graduate students can do when they become postdocs, right? Oh, yes, of course. There's plenty of time periods out there that still need to be worked on. So a whole detective story, wonderful. Well, Caroline, it's been really fascinating talk to you. I'm afraid we're running towards the end of the show. So let me thank you for appearing on the show and also to remind the viewers, you have been watching ThinkTech Hawaii Research in Manau. I've been your host, Pete McGinnis-Mark and my guest today has been Caroline Kaplan, who is a graduate student in the Hawaii Institute of Geophysics and Planetology admin at UH Manau. So thanks again for watching and come back again next Monday at one o'clock for another episode of ThinkTech Hawaii Research in Manau. See you then, bye.