Date: March 3, 2011
Title: Meteorites in Antarctica
Podcaster: The Ordinary Guy from the Brains Matter podcast
Organization: Brains Matter – http://www.brainsmatter.com
Description: We hear a bit about astronomers and their interest in obtaining meteorites from our polar regions. What makes Antarctica, in particular, attractive for meteorite hunters? How easy is it to find a meteorite? The Ordinary Guy from the Brains Matter podcast talks to Professor Ray Jayawardene from the University of Toronto, who recently came back from a trip to Antarctica, these exact conundrums.
Bio: The Brains Matter podcast has been producing and communicating science stories and interviews since September 2006. The show is based out of Melbourne, Australia, and takes an everyday person’s perspective of science in easy-to-understand language.
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Transcript:
Hello everyone, and welcome to today’s episode of 365 Days of Astronomy. I’m the Ordinary Guy from the Brains Matter podcast – you can find Brains Matter episodes at www.brainsmatter.com
In today’s show, I’m going to talk to Professor Ray Jayawardene from the University of Toronto about why astronomers like going to Antarctica:
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OG: Everyone has heard that Antarctica is pristine, is this the reason why astronomers like going to Antarctica?
RJ: Well, there are a number of reasons. One being because the amount of weathering in Antarctica tends to be less, it’s mainly wind and then flows of ice, for example. So the meteorites seem to last longer, and to be able to, you know – they’re easier to find against the blue ice, for example. And in some parts of the ice, there’s not a whole lot of other rocks, so we looked at some of those regions, we also looked in the moraines with thousands and thousands of Earth rocks as well. But you can still identify the meteorites.
OG: Do they visually look very different from the rocks around it?
RJ: They do once you get used to them for, you know, a few hours or a day all of sudden you can spot them, very, very well. And it’s surprising because it’s not easy to explain in words exactly exactly why. I mean the most obvious thing would be they have; they mostly tend to have what we call a ‘fusion crust’, which is basically this, you know, somewhat shiny crust which forms because..
OG: Because of the heat
RJ: The heat, exactly, when the meteorite enters the Earth’s atmosphere the skin basically heats up and it develops this shiny skin we call a fusion crust. So that’s probably the most obvious, general feature to look for. But basically they look different from Earth rocks in – I’m not by no means an expert on meteorites and yet it was very; it was pretty quick and easy to pick up, you know, what to look for. And they tend not to have very sharp angles – though there are exceptions – so they are not very angular usually, they tend to be rounded a bit. There’s carbonaceous chondrites, which look rather different, there was, you know, iron meteorites that look a bit different. Many of them tend to be magnetic, so there are a number of different characteristics you could look for. But it was a wonderful experience – mostly we were riding around on snow mobiles and systematically searching large blue ice fields, and sometimes we would do foot searches in the moraines because there were lots of other rocks we had to, you know, walk around and look for them.
OG: So is there, because of the location, is there a more likelihood of a meteorite landing in the poles, or is it just purely because of the fact of the lack of weathering that …
RJ: Well, it’s the lack of weathering and there’s some ideas that – some suggestions that at least meteorites may concentrate in some parts because of the motion of the, you know, they get carried around with the ice flows. And when there’s a barrier to the flow of ice, for example, in a mountain range, or something like that, then meteorites can kind of pile up, over tens of thousands of, or even hundreds of thousands of years. So I think that we’re seeing possibly that kind of concentration due to ice flows. As well as simply the fact that we’re not just picking up meteorites that fell, you know, within the last hundred years, we’re picking up meteorites that; some of them which may have been on ice for thousands or tends of thousands of years so it’s also kind of adding up over time, that there’s a build up of a meteorite concentration. It’s a really – it’s a very extreme environment in other ways, we were camping on ice for 37 days in a remote camp. So it was an interesting experience from, you know, shared with a small team out on the ice and in twenty-four hour sunlight and all of that. So it was a very interesting, unusual experience.
OG: It almost sounds a bit like gold prospecting back in the 1800s where there’s a whole concentration of something you’re looking for in one spot and that’s where you go to get it because in other places it’s already been eroded, plundered, civilisation’s been built on it and so on…
RJ: Yeah, in some ways, yeah, except we don’t’ sell our meteorites. All of them are on their way to the NASA Johnson Space Centre in Houston for curation and then they’ll be sent … samples will be sent to the Smithsonian, where they classify them, and then researchers from around the world can request samples of these meteorites for their studies. It’s really very much a kind of, you know, a kind of gathering of all these valuable scientific material that can provide us clues to everything from, you know, the birth of the solar system to, you know, what Moon and Mars are made of. Pretty much the only samples we have of planet Mars to date are meteorites that came from there.
OG: How do we know where a particular meteorite came from? How do we know if it’s from Mars or from, you know, the Asteroid Belt, or you know, something like that?
RJ: So this is where the classification and processing of the materials comes in. So the experts do that work and then, for example, one example of telling if something is from Mars, you know, some of the trapped gasses in the meteorite, you know, does it have the same kind of composition as the atmosphere of Mars? So that would be one kind of tell-tale signature… you know, does it have the same isotope ratios as a particular body … so there are a number of different ways of tying them together to what their parent body might have been. And there are a number of confirmed Lunar meteorites, there are a number of confirmed Martian meteorites and then lots and lots of meteorites trace back to particular asteroids or asteroid families. It’s really kind of – you’re looking at the leftover material and looking at, possibly, little visitors from other plants in our neighbourhood.
OG: Well Professor Ray Jayawardene, I’d like to thank you very much for appearing on the show today.
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Well that’s it for today’s show – come over to www.brainsmatter.com to enjoy more great science stories. Bye for now!
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365 Days of Astronomy
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