Newly Fallen Meteorites Offer Fresh Look At Mars
IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I'm Ira Flatow. Russia's Phobos-Grunt spacecraft splashed, crashed into the Pacific Ocean on Sunday. It was a failed mission. It was meant to travel to the Martian moon Phobos and bring back a soil sample, but it got stuck in Earth orbit instead. And they were - never made it out of there. But in lieu of shooting off another expensive sample return mission to Mars, there is a cheaper way, just wait for those Mars rocks to come to us.
It happens once about every 50 years, and we got lucky last July when a meteor shower spits some Martian samples, right here down to Earth. They fell way out on the Moroccan desert, but the samples have come back. Since then, scientists, including my next guest, have been snatching up those meteorites from meteorite dealers. Yeah, they exist. What do you do once you get your hands on them? Can you even touch one without contaminating it? Is there any hope those chunks might contain some trace of organic compounds or even traces of past or present life?
Joining me now to talk about it is Chris Herd. He's associate professor and meteorite expert at the University of Alberta in Edmonton. He joins us by phone. Welcome to SCIENCE FRIDAY, Dr. Herd.
CHRIS HERD: Thanks very much.
FLATOW: You are actually in actual possession of one of these chunks?
HERD: Yes, yes. I arranged to purchase a specimen of this amazing meteorite for the University of Alberta Meteorite Collection.
FLATOW: How do you buy one of these?
HERD: Well, you talk to a meteorite dealer, and you work out a good value, a good rate. And then, yeah, you come up with the money.
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FLATOW: I'm picturing the scene from "Casablanca" and that marketplace where people were selling all kinds of stuff. Is there an underground meteorite market with folks who come in and out of the desert picking the stuff up?
HERD: Well, in actual fact, in morocco there's a whole economy set up with people picking up meteorites from the desert. They know what they look like, and they bring them into the markets and sell them there.
FLATOW: What do they look like? What does the one that you have looked like?
HERD: Well, it's kind of unusual as meteorites go, because it is a rarer type being from Mars. But it has a black what's called a fusion crust, the outer crust that formed as it came screaming through the atmosphere that sort of burnt look to it. And in - on one side, it's broken, and you can see a bit of the interior. The interior is sort of a greenish-gray color.
FLATOW: So sort of glass-encrusted in its own little delivery vehicle?
HERD: Yeah. That's right. The outside heats up enough to actually melt the rock, and then, that forms a glass as it cools off after it comes into the atmosphere.
FLATOW: And how do you analyze it without contaminating it? You know, because I'm figuring you're handling it, but you're saying since it's sort of covered in glass, it's - the inside is, sort of, kept pristine from the way it was.
HERD: Yeah. Well, that's something that we want to - we definitely want to test. How do you keep it from getting contaminated? That's probably one of the best questions, because this is really an incredible opportunity - being such a recent delivery, such a recent fall - that we want to try to do everything that we can to keep it from getting contaminated, including with organic molecules. And we have those on our fingers, all, you know, and it's just the way we are. We have things like cholesterol and squalene, weird compound - sounding compounds like that that actually are in our finger crease.
And so one of the things that I did after we've received this - the sample was to actually just give a little bit of a rinse on the outside with a solvent that we're going to - and we're going to analyze that, hopefully, later this week or next week and see what we find. It's actually kind of a way of detecting whether anybody has touched it before it got sent to me.
FLATOW: And then, how do you crack it open and look inside?
HERD: Well, then, we'll - we're going do everything we can before. There's a lot of sort of nondestructive, as we call it, tests that we can do first. But then once we - once we're ready, we'll cut it open. We'll use a very thin blade saw, and we'll cut it open. And we'll look inside, and we'll make polished mounts that we can do various types of analysis on with microscopes and just try to get as much as we can - much information as we can out of it.
FLATOW: How old is it, and is it - does it come from a period on Mars where life might have existed?
HERD: That we don't know at this point. All we can say is that, based on the original work that was done by my colleagues, Tony Irving and Scott Kuehner at University of Washington in Seattle, we know that they - it has a texture that is the minerals that are - the way they're inter-grown is very similar to other types of Martian meteorites that we've looked at before. But we don't know anything about the age yet. Having said that, those other meteorites that this is similar to, are in the sort of 200- to 500-million-year-old range. That's geologically fairly young, and that's not from a time period that that where we think there was a lot of water around on Mars, but you never know.
FLATOW: Yeah. You know, there was that famous meteorite from Mars that's supposedly had signs of ancient life on it that created a lot of excitement, and then went away very quickly.
HERD: That's right. And that one was - that one is of around four billion years old. So that dates, really, from way back in Mars' history. As I say, we don't really know, because we only just started working on this, how old this particular meteorite is. But the potential is there because it's a fresh meteorite fall, you know, because it's been kept pretty clean, as far as we know, that once we get into the inside of it, we may be able to find - you know, what we find inside is more likely to be from Mars than from the Earth.
FLATOW: Let's go to the phones. Dale in Denver. Hi, Dale.
DALE: Yes. I'd just like to make a comment that - I mean, ever since I first heard of these meteorites that supposedly come from Mars they found on Earth, I've been incredibly skeptical. You know, beyond an asteroid, you know, a large meteorite slamming into Mars and knocking debris up, and then having that stuff make it all the way to Earth are incredibly astronomical. Until we can actually get something from Mars and compare it to these meteorites, you know, I think it's a little farfetched making the claim that we're actually examining bits of Mars.
FLATOW: All right. Thank...
DALE: We have no proof of that.
FLATOW: Well, let me get a reaction, Dale. Thanks for that comment.
HERD: Sure. I can definitely address that. And there was a really seminal series of studies that were done in the early 1980s on a particular Martian meteorite - a particular meteorite that belonged to this group that was found in the Antarctic. Prior to that - prior to the mid-1970s, early '80s, these meteorites were kind of lumped into a group on their own. We didn't really know where they came from. We just knew that they looked different front other meteorites.
In the - in 1976, we had the Viking landers, and the Viking landers had instruments onboard that could measure the composition of the Martian atmosphere, and they did that quite well. And in the early 1980s, this one meteorite was investigated and found to contain trapped gas inside of it. When that gas was analyzed, it was shown to be a match to what the Viking landers found in the Martian atmosphere. And further to that, it's been shown that the Martian atmosphere composition is unique in the solar system. There's no other planet or object or moon that has quite the same composition of atmosphere. So finding this trapped gas in the meteorite is a fingerprint that tells us that it comes from Mars.
FLATOW: What can you learn from this meteorite or other meteorites that land in Morocco or other places apart from what you can learn from the Antarctic ones that have already been discovered for many years?
HERD: Well, each one, they're all quite similar in some ways. They're all igneous rocks - that is rocks that started their lives as a magma somewhere in the interior of Mars and came up and erupted near the surface. But they all have slight differences to them, and there's - some of them are quite subtle. Some of them are even, you know, more subtle than what you see just by slicing it open and looking at the texture. And so these are the types of advance studies that we do to try to figure out what this new meteorite can tell us that we haven't found in other ones. Every single one tells us another piece of the puzzle of Mars geology as a whole.
One of the things that we can do is to actually peer back through the thing - the magma crystallizing into this rock. We can peer back and say something about the magma itself and the interior of Mars, that part of Mars that it came from. So in some ways, we can almost probe right into the inside of Mars through these kinds of studies.
FLATOW: Now, Dale is very - from Colorado is very skeptical about - I mean, how could a meteorite, a piece of Mars, get here?
HERD: Well, he was right that, you know, that the ideas that some large objects, some other meteorite slammed into Mars and launched rocks off the surface. Mars is a smaller planet than the Earth. It has lower gravity, about one-third the gravity of the Earth. And it has been shown through a modeling now that you can actually launch rocks off the surface of Mars. You don't even need a very large object hitting Mars in order to do it. The object - the minimum that you need is something like - something that would hit Mars and make a crater about three kilometers across, which, you know, sounds kind of large, but there's lots of craters that size or larger on Mars. You can get a rock sitting near the surface, accelerate it, you know, fast enough to leave Mars' gravity.
FLATOW: And maybe it could be floating around in the solar system for thousands of years until...
HERD: Thousands, or millions, at least.
FLATOW: Or millions. So something happens to nudge it in this direction, or it gets here?
HERD: Or just - yeah. It just happens across our orbit. And, in fact, you know, the - I mean, the point about it - this is that because we keep getting these - this is now the fifth fall of a Martian meteorite, plus we found a whole bunch of other ones, some other - 50-some other meteorites all over the world that have fallen in, you know, prehistoric times. We know that there's debris out there, Martian debris sort of floating around in the solar system, and it keeps landing on us.
FLATOW: So there could be a lot more stuff out there in the desert that...
HERD: Oh, almost certainly. Yes.
FLATOW: And are you going to be looking for more, or are people - is there a competition to own this?
HERD: Oh, there's a - I'm sure there is.
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HERD: There's always a competition. I'm sure there are groups out there looking right now. You know, the economy that exists around these things really drives people to, of course, go and look for more all the time.
FLATOW: What did you pay for this, if I might ask?
HERD: We paid $300 per gram.
FLATOW: And how many grams do you have?
FLATOW: I'm doing a quick - six...
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FLATOW: ...sixty times - it's $18,000, something like that?
HERD: Something like that, yeah.
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FLATOW: Something like that. Sounds pretty cheap to me, for something that comes from Mars.
HERD: It actually is on the low-end. I have to say it's on the low-end of what Martian and lunar meteorites tend to go for. They tend to be several hundred dollars per gram, on up.
FLATOW: And so, when do you - when can we see this? Will it be out exhibited, or can we...
HERD: Well, there are a number of - well, if any of your listeners get up to Edmonton in the next few years, we hope to have, you know, part of our piece that we purchased on display. But there are other groups making efforts to - other collections, meteorite collections purchasing other pieces. And the ones that are - I know for sure Arizona State and New Mexico. So hopefully they have plans to show us some specimens, as well.
FLATOW: And we have some photos on our website of this meteorite and other - for other raiders of the lost meteorites.
HERD: Yeah. That's right.
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FLATOW: Do you feel like Indiana Jones sometimes?
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FLATOW: Well, thank you very much. And we'll wait to see the publication of what you found there, the...
HERD: Oh, yes. It's just the beginning right now.
FLATOW: All right. Chris Herd is an associate professor and meteorite expert at the University of Alberta in Edmonton. Thank you for joining us today.
HERD: You're very welcome. My pleasure.
FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.
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