 It's one o'clock on a Monday afternoon. Welcome. You're watching think tech Hawaii research in Manoa. I'm Pete McGinnis-Mark and today we're going to be exploring the solar system. We have a very special guest with us today, Dr. Ed Scott, who is an emeritus researcher at the Hawaii Institute of Geophysics and Planetology at UH Manoa. Welcome Ed, it's a pleasure to have you here. I've seen some of the slides and I'm sure the viewers are going to just find this a fascinating program today. You're going to be talking to us about a mixture of things. So you're going to talk about meteorites, asteroids and what that tells us about the early solar system. Is that correct? That's right. Yes. Okay. And some people have heard about meteorites. They've heard very things about what these asteroids are. Hopefully we're going to learn today something about the interconnected and the story which they can tell us about things happening in the solar system. How long ago are we going to go back in time? Well, we're starting four and a half billion years ago. Four and a half billion years. Which is the age we get from the meteorites. That is a long time. Tell us exactly when the solar system started. Oh, great. And it's amazing that in the kind of research you do, we can actually go back that far in time. Yes. And the age of the rock is crucial to understanding the story. Okay. Well, as I said, you've brought along some slides. So why don't we go to the first image and this will introduce us to the whole problem of what an asteroid looks like. Okay. Just describe to us what we're seeing here. So this is an asteroid called Itakawa, photographed by Japanese spacecraft. It's about 500 yards long. And that would be what about the size of diamond head craters? Diamond head craters, yes. Absolutely. And this was the first small asteroid that we had seen in such detail. And as you can see, it looks like a pile of rocks. Yes, it does. Which is exactly what we would hope in many ways. And you say this is a small asteroid. So the largest are a thousand kilometers across, and they go all the way down to a few meters in size. Okay. And Itakawa, that image which you showed us, there are a number of rocks, you say, on the surface. So the sun shining from which direction? The left. Looks like from the left hand side. Yes. Okay. And you've got quite a variety, some really big boulders like the one on the right hand side. Presumably that's your house size or something like that. Absolutely. Yes. And then there are smooth areas with dust on them. But basically, yes, a collection of rocks that have reassembled after an impact. Okay. And where is Itakawa? So we know is this near the earth? Should we worry about it? Or is it far out in space beyond Jupiter? Well, the asteroids go around the sun between Mars and Jupiter. Okay. So we don't have to worry about them. Occasionally, their orbits get changed, and a small piece hits the earth and we have a meter, right? Luckily. Or if you were a dinosaur, you would have to worry about it. Absolutely. Yes. 65 million years ago, there was a larger one about a kilometer, a few kilometers across which hit the earth. And so the rocks which we saw in that image, they sometimes jump off of the surface of the asteroid and come to earth? Or how does this work? Well, curiously enough, that picture of Itakawa is missing something. And that's that the impact craters, it's one of the few bodies in the solar system that isn't peppered with impact craters. They do form. There are lots of impacts. It's just that there's so much rubble that we don't see them. And in previous shows, we've learned that if there were impact craters, these holes in the ground, the more holes per unit area, the older the surface is. Absolutely. Yes. And this is a very old collection of rocks. But because of all these impacts in the solar system that we get fragments from asteroids, like Itakawa. All right. So we've got a whole series of rocks on the surface. Do we just study them on the surface of the asteroid? Or do we have samples? You brought some rocks in to show. I'm guessing that there must be a connection here between what we saw in the first session. Absolutely. Yes. We know from the work that was been done on the samples that were brought back from Itakawa that we do have meteorites that are very closely related to the rocks. And this is research which is being done at the University of Hawaii? Yes. Yes. We have a group of planetary scientists who study meteorites. Excellent. And so I'm privileged to be part of that group. Wonderful. Well, as we have some meteorites here, show the viewers some of these meteorites and tell us a little bit about some of them. So these are small samples, but nevertheless, you will get the idea that rocks come to the surface of the Earth because of impacts in space. And usually, they're small, a few pounds in size, a few kilograms. Sometimes, as we said, they're very large. This is a piece that weighs a few hundred grams. And you can see it's made up of metal, iron-nickel metal, and silicates. The silicates are perfectly ordinary silicates. And this white surface here, that's not the way that the meteorites fail to work. Absolutely, yes. The outside is, you can see it's rounded, brownish. And when it's cut and polished, then you can see the metal grains inside. Okay. And how do you know it's a meteorite? So, you won't find metal grains inside rocks from the Earth because conditions are so oxidizing. Okay. So, if you ever find a funny looking rock with metal grains in, it's almost certainly a meteorite. Okay. And presumably, you don't find them that common in Hawaii. Where do you know? You want somewhere dry, where a dry desert or Antarctica, certain areas where there's no precipitation. Okay. So, none of these rocks actually come from Hawaii? No, there are only two that have been seen to fall and recovered in Hawaii. Everything else that we studied is... This one here is a particularly pretty one. What is that? That's a mixture of the iron-nickel metal, roughly the same composition as the metal grains in the first one we looked at. But in addition, we have these large crystals of olivine, dunite. So, like green sand, same mineral. Okay. And so, it's an amazing meteorite that there's a mixture of these materials, which are very common in space, the iron-nickel metal and the silicate, which is just magnesium iron, silicon and oxygen. But presumably, this one wouldn't be just lying around the surface of that asteroid you showed us, would it? I mean, this is another one that's been cut and polished to show us the structure, yes. Okay. So, but going back to the first one we looked at, what makes this meteorite really unremarkable is it's composed of a whole collection of different materials. And if we look at the next image, we can see what is it. Wow, and what is this? So, it's a picture of a thin slice of a rock like this one. It's about an inch across in a microscope. Okay. And you can see it's just chock-a-block with little rounds, spherules we call chondrels. So, the rock is called a chondrite and the small millimetre-sized spherules are chondrels, which were once drops of molten magma in space. In space. So, you'd have, would that be a volcanic eruption or would that be when? That was one of the earliest ideas that it was, but we don't think it was a volcanic eruption. And the colors in that particular image, do they tell you something about the chemistry of the rock or how it cooled? Yes, I mean, each of those particles has a history to tell about how it formed, what its composition is, and how quickly it cooled. They cooled very quickly in minutes, hours. So, we're talking about droplets that were in space. We're not talking about droplets on the surface of an asteroid. They eventually came together and made an asteroid, but what we're looking at are particles that were freely floating around in this disc of material from which the planets were made. So, those particles are very old, presumably. Absolutely, yes. From the age of the solar systems. Absolutely, yes. Yes. Four and a half billion years old. Wow. So, that's the oldest rock that you'll ever touch. That's one right here, the oldest rock. Okay, yes. And I've been on Kilauea volcano. I've touched on the youngest one. Absolutely, yes. The whole age distribution of the solar system. Yes. It's mind boggling that you can... The rocks will tell us for half a billion years of history. How do you get the ages? So, are there radioactive clocks, what we called, decay of radioactive elements? We know the rate at which they decay, and if you can measure what's left and infer what was there originally, then you can... So, it's like radiocarbon dating, except much older than that. That's it, exactly the same principle, yes. Very good. And it's much more difficult, of course. I have to admit that an old rock could have been heated up by an impact, for example, so you can only date the really pristine meteorites. I see. Pristine means completely unaltered. Unaltered by heating and impact and other things that can happen in space. And we have two other samples here. We have a really heavy one, which I presume is just the iron. That's it. All right. Yes. So, there are some meteorites that are virtually all iron nickel. And then this one has a much lower density than this one, the one in this hand here, in my left hand. Yes. It's much lower density. It's about half the density of this. So, do these come from different parts of the same asteroid? Yes. If you have an asteroid like the first one we saw, which is a mixture of metal and silicate, and it gets heated up by radioactivity, then the metal is very dense and goes to the core of the asteroid. Okay. And we think that the iron meteorites are from the cores of asteroids that melted. So, the lighter, less dense rocks are from the mantle material. We don't have one here. So, we don't know if these all came from the same asteroid. We are quite confident they come from different ones. Physically, this really dense iron one will be in the middle. Absolutely. And then you'd have this lovely one between the core and the next layer. It, which you said was called the mantle. Yes. Okay. And then this one here would be... This is actually the starting material. That's the starting material. Yes, that's it. So, this has everything you need to make all the other meteorites. Okay. It's like a little detective story, isn't it? Oh, absolutely, yes. You find all these samples and presumably, how many meteorites do we have here on the Earth? It's something like 50,000 or 60,000 now, isn't it? So, and they must all tell basically the same story? Yes. I mean, the first job, if you get a meteorite, is to see which pile it belongs to. Okay. And we have samples, we think, from over a hundred different asteroids. And that categorization is what you do at the university, or do you look at them in thin section, or do you age date? What do you do? Yeah, we study them under the microscope. Okay. Starting out with an optical microscope and then using electron microscopes for more information. And then we collaborate with other people who make different types of chemical or isotopic measurements. Interesting. And what level of detail do you need? You know, if one of our viewers is watching and she actually is interested in doing this work, I mean, do you need better microscopes, or do you need? I mean, most, most meteorites that are found, I rather like this one. So, all you need is knock off the corner, make a thin section and study that. Okay. If it's the same type, then we probably wouldn't, we've got another 30,000 like this. Okay, so you put that one aside. That would be put aside. Just look for the really interesting ones. We look for the ones which are unusual, like very well preserved, or from a different. I think I would pick on this one first of all. I like those very much. They are spectacular. We have, these are called palisites. And we have about 30 different ones. And 25 of them come from the same asteroid. Okay. And then there are another group that comes from a second asteroid. And then there are a few more that come from a third one. We're getting close to a break, but I'm hoping you'll be able to tell us a bit more about, you know, what the diversity of these asteroids really are as we sort of look out from earth throughout the rest of the solar system. That presumably they, meteorites come from different asteroids, which are looking at different distances away from the sun, have different geological histories, or maybe they're involved in different chemical processes. So I think when we come back after the break, we'll look forward to hearing a bit more about some of the diversity. Just to remind you, you are watching Think Tech Hawaii research in Manoa. I'm Pete McGinnis-Mark. And my guest today is Dr. Ed Scott, who is an emeritus researcher at the Hawaii Institute of Geophysics and Planetology at UH Manoa. And we'll be right back. Hi, I'm Nicole Alexandrinos, and I was born three weeks ago. Congratulations on being there for me for some of the few weeks of my life. I'm starting a new show, The Millennial Mind, every Wednesday at 2 p.m. for the month of April, where we'll go over some of the reasons why millennials are some of the most anxious and frustrated people at the moment. Aloha. My name is John Waihei, and I used to be a part of all the things that you might be angry at. I served in government here and may have made decisions that affect you. So I want to invite you in. I want to invite you in to talk story with me and some very special guests every other Monday here at Talk Story with John Waihei. Come on in, join us, express your opinion, learn more about your state, and then do something about it. Aloha. And welcome back. You're watching Think Tech Hawaii Research in Manoa. I'm Pete McGinnis-Mark, and my guest today is Dr. Ed Scott, who is an emeritus professor at the Hawaii Institute of Geophysics and Planetology at UH Manoa. Now, Ed, just before the break, you were talking to us about some molten rock, okay, in some of these meteorites. How do you get molten rock? Do we see any examples of an asteroid that might have been molten? Okay, certainly, yes. Let's go to the next picture. And this is a picture of an asteroid called Vesta. It's about 500 kilometers across, and we 500 kilometers would be like the distance between Honolulu and Hilo or something like that. Yes, that's good. And you can see this is just covered with craters like the moon, which means it's old, is that correct? Yes. And what's interesting about Vesta, apart from this gorgeous image which you brought for us? So we think this is made up of the surface, is made up of basalts. It's an asteroid that melted. The metal went to the center to make the metallic core. Okay. And what we're looking at is a basaltic surface, and we think we have meteorites from this asteroid so we can connect up the dots. And Vesta is where? So Vesta is in the main asteroid belt between Mars and Jupiter. Okay. And how do we get that spectacular image then? Is that a telescopic image? So this is the dawn spacecraft that orbited Vesta for several years. All right. And Vesta, it almost looks spherical, not quite, but it was much rounder. Most of the asteroids that shaped it, do we have any diversity in the type of objects which we can see? So if they're round, then if they're very large, they tend to be round. Gravity will make them round, but if they're small, like it a cover, gravity is not strong enough to make them round. Okay. And you've got some other examples. This is Ijikawa again. Yes. Okay. Here's the... All right. Now here's a dog bone. Isn't that amazing? Yes. What is this that we're looking at? So it's a radar image. It's not an optical image. A radar image. Taken from Earth. From Earth? Yes. And it's an asteroid that we think is rich in iron, nickel, metal. And that's probably why it's this very unusual shape, because it's probably all made of iron, nickel, and metal. And it's about 200 kilometers along. Does it perform in this shape? We could guess this might be part of a metallic core of an asteroid, or it got reassembled from fragments of a core of an asteroid. Okay. And perhaps coated with some of the rock fragments too. But I'm amazed that you can actually obtain a radar picture of some things so far away, millions of miles away, correct? Yes. And as we go further through some of the other images, I think you've got some other really useful examples. And this one, is that... Is true shape, or what do we see in this one? Yes, very deep shadows, but you can see that it's it's a funny-looking shape, a flat-ish on top. This one's about 50 kilometers across, and this one's actually a very dark asteroid. They've enhanced the... A bit smaller than the Oahu thing, correct? Yes, that's it. Okay. About half the asteroids are dark like this one. And interestingly enough, we think that we do have some meteorites from this, which we call carbonaceous chondrites, because we think that this asteroid is also rich in carbon. And we used to think they formed in the asteroid belt, but now it's possible they're actually forming further away between the giant planets. So delving more into why bother studying meteorites and asteroids, what does it tell a scientist like yourself? What are you trying to tease out of all of these samples? I mean, we have these incredible collection of rocks, and they all contain clues about what was going on when the planets were forming, and that's what makes it so exciting. And you say when the planets were forming, that's soon after our sun started to... Yeah, so imagine the sun is creating out of this great cloud of gas and dust, and because it's rotating somewhat, as it creeds, we land up with this disk of dust and gas around the sun, the young sun, and we form from this tiny residue of material, and the sun takes up the rest. So do meteorites condense, if that's the right term, before the planets formed or at the same time? Well, we used to say these are the oldest meteorites that formed, they're building blocks for making planets, but actually it's more interesting than that, because we think we've got different generations of planets have some of the smallest objects that make the planets. How do you know that? Well, because of the radiometric dating, and also logic, because the earlier the body formed, the more likely it was to melt, because the clock, the aluminum 26 is the heat source, every 700,000 years there's less, 50% less, so any body that it creates in the first one and a half million years will melt if it's more than 20 kilometers across. And so really early on in solar system history must have been really chaotic, right? Was it all the same as you went away from the sun? No, things took longer, further away, but we, as I say, we think we have meteorites that formed among the giant planets or what were they, the proto-planets we would call them, the starting materials for the giant planets, and we have not only the chondrites, but we also have some of these rocks, meteorites from asteroids that melted. Some of them were in the asteroid belt, some of them were between the giant planets and conceivably somewhere in a solar system right there where the earth was formed. And I've heard that there's some debate among scientists like yourself that even the giant planets Jupiter and Saturn may not have been at the same place, distance from the sun. Yes, that's one of the exciting things we've learned by looking at other solar systems, other planetary systems that giant planets migrate, and it's conceivable that the asteroid belt is so small the total mass is less than a thousandth of the earth's mass because Jupiter migrated. Fortunately for us Saturn came along behind and pulled it back, otherwise we wouldn't be here. Alas, I won't digress today into exoplanets and other star systems, but I'm hoping in a future show we'll actually have a discussion on that. But in terms of our solar system, you've got all these rocking meteorites and asteroids. Was there anything different as you went further away? I think you brought along another image of something which may not be a rocking asteroid, is that correct? Yes, let's look at the next slide Alas, this one is... Ah, good heavens, this is the same shape as that radar image, but what is it? This is a very different type of object, this is the nucleus of a comet, it's about seven kilometers across, but it's very porous, it would float in water if you put it, because we know that it's made up of dust grains, ice grains, and a lot of holes, it's very porous. And again, it's just incredible that you have an image of the nucleus of a comet. Absolutely, and I believe you can even see there appears to be some white stuff coming out of the thin part, is that the comet's tail? So as the comet heats up, the ice is evaporate, the molecules come off the surface and they bring some of the dust off, and we have dust particles that have been collected by high-flying aeroplanes, and I think that's the last image which you brought along, right? One more, that's it. What is this, is this from that comet? No, but it is a dust particle that was recovered by one of these planes that fly in the upper atmosphere, so it's just a few microns across, so less than the width of your hair, it's a small particle in an electron microscope, and we believe you can see it, it's very porous, very made up of lots of different constituents, and we think this is probably coming from a comet, don't know for sure, but almost certainly. What is more informative to you and your colleagues, having material like that IDP into planetary dust particle from a comet, or having a wonderful meteorite like this, you're biased I'm sure. No, the amazing thing is we've got everything, we've got so many different types of material which seem to come from right across the solar system, we have meteorites that may be resembling what Mercury was forming, what the Earth was forming from, and then we've got dust particles that are coming from bodies that formed outside the giant planets. So you've got all this information, but what's the Holy Grail? You're an emeritus professor, right, but you're still doing active research, so what do you hope to see in say the next five years in terms of, I guess you would call this early solar system geology or cosmochemistry or something. What do you hope to do? Yes, what we hope to do is to fit together the information that we get from the meteorites into the models that astronomers have to explain how the planets form. Astronomers have models. Yeah, astrophysicists who start from scratch thinking about discs of dust and gash, how the dust could have creeped together into larger bodies, and now we have various different mechanisms that may well tell us how these planet astronauts were forming. Okay, and I guess that's where the connection is between the kind of research that you do and our colleagues at the Institute for Astronomy, IFA, where they can actually go and take a look at other star systems. That's right, they can image discs around young stars and get clues as to how planets formed, and that's where the excitement comes. So that's what motivates you in retirement to come in and work every day and still working on some of these meteorites. This is fascinating stuff, thank you very much for coming on. Thank you, Pete. Just to remind our viewers, today we've been hearing from Dr. Ed Scott, who is an emeritus researcher at the Hawaii Institute of Geophysics and Planetology at UH Manoa, and you've been watching Think Tech Hawaii, and may I at least remind you to come back every Monday at one o'clock, Hawaii standard time, where I hope to introduce another of our research faculty here at the University of Hawaii. So until that time, thank you very much for watching the show. Goodbye.