Studying Rocks Found On Earth For Clues About Space

Transcript

IRA FLATOW, HOST:

For the rest of the hour, we're going to talk about meteorites. They are more than just a chunk of rock. They can be a time capsule, or ancient secrets of our solar system may be locked up in its core. And it turns out - I didn't know this - that one of the largest meteorite collections, the largest one, the largest collection held by any university is just up the road from us in Tempe. And joining us now to talk about the collection is Meenakshi Wadhwa.

She is director of the Center for Meteorite Studies and a professor in the School of Earth and Space Exploration at ASU. Meenakshi, welcome to SCIENCE FRIDAY.

DR. MEENAKSHI WADHWA: Thanks, Ira.

FLATOW: Let's talk about your collection. How did you get a collection?

WADHWA: So, this is actually part of a great story too. There's a really famous collector, an Arizonan, Harvey Nininger, who had this wonderful collection. He is probably the person who I would say was responsible for bringing up the science of meteorites to the United States. And he had this great passion for meteorites. Actually, in the natural world in general but a great passion for collecting these space rocks. And he did this in the 1930s and '40s, and he had this wonderful collection, probably the best in the world.

And towards the late 1950s, he actually sold - he was basically deciding what to do with it and wanted it to have a life beyond his at some point and he sold half of it to the British Museum.

FLATOW: Wow.

WADHWA: And so Arizona State, actually, very forward looking at the time - this was an era when, you know, Sputnik happened, 1959 - and they were thinking, well, you know, space, this is the new frontier. This is where we ought to go. And they had the vision to actually buy the rest of his collection, and that's where the core of our collection comes from.

FLATOW: Is there a great black market in meteorites?

WADHWA: Oh, gosh. There is a great community of collectors and people that like to collect and buy meteorites.

FLATOW: Is that a euphemism for a black market?

(LAUGHTER)

WADHWA: Well, it's an interesting question. I'm sure there are people that collect meteorites in places that aren't - where the laws don't actually allow them to collect these things. I'm sure that happens. But basically, we, you know, we as a community of scientists would not have some of the most interesting samples to study if there was not a community of people interested in collecting these things in places that are hard to get to and so...

FLATOW: Is the big catch now the one that blew up over Russia? Are people looking for pieces? Have they found the pieces?

WADHWA: Yes, they have, actually. Yeah, they're...

FLATOW: Are they...

WADHWA: You know, within hours of the news, there were people converging on Chelyabinsk.

FLATOW: So what do you have to do to get one of those pieces?

WADHWA: Well, I've actually - we don't have a piece of that meteorite in our collection yet...

FLATOW: Not yet.

WADHWA: But again, you know, it would be governed by laws of Russia and whether they would be able to export those materials legally. And so I think, you know, we would obviously be concerned about all of that, but...

FLATOW: Would do they go to auction, something like that...?

WADHWA: Possibly.

FLATOW: And what would something like that fetch on...

WADHWA: Oh, gosh.

FLATOW: Just to ballpark it.

(LAUGHTER)

WADHWA: Any known observed fall, anything that's of historic interest, naturally just by the news-making aspect of it, has more value to it than what it would otherwise be.

FLATOW: Right.

WADHWA: I believe it's what's called an ordinary chondrite. It's one of the more common types of meteorites. So just in and of itself, it's probably not one of the rare kinds of meteorites that's out there. But yeah, I would be hard put to put a figure...

FLATOW: Millions.

WADHWA: Well...

FLATOW: Not millions?

WADHWA: Well, it depends on the piece. But I would say certainly, you know, hundreds or thousands of dollars per gram, possibly. But I, you know, I...

FLATOW: Per gram.

WADHWA: Yes. But I don't - as a scientist that studies meteorites, you know, it's kind of blasphemy to actually put a value on - dollar value on these...

FLATOW: No one's listening.

(LAUGHTER)

FLATOW: They're all priceless, right?

WADHWA: They're priceless.

FLATOW: They're all priceless.

WADHWA: Exactly.

FLATOW: Tell us about the priceless ones in your collection. How many do you have in your collection?

WADHWA: We have about - in excess of 1,800 different meteorites. If you consider...

FLATOW: Wow.

WADHWA: ...all the different individual pieces, we've got tens of thousands of pieces, but basically, 1,800 or more than 1,800 different distinct meteorites. And we have some of the - there's all different kinds of meteorites. I know this is radio, but I actually did bring some samples in with me for the studio audience at least. So if anybody afterwards wants to come by and take a look at these...

FLATOW: You'll count them on the way out.

WADHWA: I will count them on the way out.

(LAUGHTER)

WADHWA: Absolutely. But we have in our collection - all of these are important classes of meteorites. We have some that come from Mars. We have some that come from the moon. Most of them come from asteroids.

FLATOW: Can you tell immediately by looking at a rock that it's a meteorite or not?

WADHWA: Most times, but I actually...

FLATOW: Really?

WADHWA: Yeah. I actually just spent two months in Antarctica - two months ago, actually. I came back from there. And we were collecting meteorites out on the ice.

FLATOW: They're just sitting out there, aren't they?

WADHWA: They're sitting out there. In some places there's nothing but ice and the only dark rock that you see, that's a meteorite. But in other places, you actually go to these moraines where there's lots of terrestrial rocks mixed in. A lot of them look dark and heavy, and it takes your eye a little bit to get trained to seeing what meteorites look like. But when you're trained - when you're trained to look for these things, you can actually identify them fairly regularly and reliably.

FLATOW: This is SCIENCE FRIDAY from NPR.

Talking with Meenakshi Wadhwa about her collection of meteorites. And which one is your most favorite of all in the collection?

WADHWA: Yeah. It's like asking about your favorite child.

(LAUGHTER)

FLATOW: About your children. I'm going to ask it anyhow, so.

WADHWA: Actually, I will say my favorite one right now is this Mars meteorite, which we got just in the last couple of months. It's one that fell in Morocco last year, and it is only one of five known Martian meteorite falls. And so it's the most recent one that's happened. There's not been one in 50 years. And so, you know, if you want to understand something about Mars as a planet and you want to find something fresh and that's not been sitting around on Earth for very long and not contaminated by terrestrial things, this is the rock to look at.

FLATOW: How does that - how does it get from Mars to here?

WADHWA: So as Eric - we heard earlier in the show, there's probably large impacts that are hitting Mars even today, and certainly in the past. And so there was a large impact on Mars sometime in the past and it ejected these pieces from Mars and eventually it's made its way to the Earth.

FLATOW: Could there be pieces from other planets?

WADHWA: Absolutely. So there's pieces of the moon that are meteorites that have landed on the Earth. Theoretical calculations show that, in fact, there could be swapping of material between planets quite readily. And so absolutely, there's probably Earth meteorites on the moon, for example. And that's kind of a fascinating story in itself. You might actually find ancient Earth rocks somewhere lying around on the moon.

FLATOW: Wow. Location, location, location.

WADHWA: Yes.

FLATOW: It's very important. Well, but if a meteorite comes in and it gets - it's sitting here for a while, it gets contaminated by everything that's on Earth, what can you then learn from it about where it came from, or why is it important to look at it?

WADHWA: Yes. So some things do get compromised when they've been sitting around on the Earth, but there are other mineral components as well as, in some cases, organic materials in some of these meteorites that you can look at, that you can differentiate from Earth materials.

So even though there are contaminations or contaminants that can affect the meteorite, there is definitely a lot of information that you can learn about these. In fact, you know, a lot of times people wonder, you know, meteoritics is such a small sort of niche of very specialized science. But everything that we understand about the beginnings of the Earth, everything that we understand about beginnings of the solar system, what we're made of, what the planet's made of, the age of the Earth, all of that comes from studying meteorites. And, you know, we can learn a lot from that.

FLATOW: Would that be a good topic for a novel, do you think?

WADHWA: Absolutely. There are actually quite a few novels that have been written about meteorite impacts and, you know, microbes being carried over here from other places. And yes, there are science fiction books that I've certainly read very avidly about that, but, yes...

FLATOW: So what is the holy grail of a meteorite collector? What do you really wish for some day?

WADHWA: Oh, boy, a piece of Mercury maybe.

(LAUGHTER)

FLATOW: Got a little in my pocket. It's a little silvery liquid...

WADHWA: And, you know, it could very well happen. That's the great thing.

FLATOW: Is that right?

WADHWA: Yeah. There was actually at this last Lunar and Planetary Science Conference, there was a talk about a possible Mercurian meteorite.

FLATOW: Would you know it if you found it?

WADHWA: That's the good question. I mean in the case of the Mars meteorites and the moon meteorites, there's actually - we have pieces of evidence from other sciences that can relate to that. And we know that these things are fairly solid. But in the case of a Mercurian meteorite, that would be a little bit harder to do, but it wouldn't be impossible. Hopefully there might be a sample returned sometime in the future.

FLATOW: So there could be around us now and we wouldn't know it.

WADHWA: Yes. Absolutely. Same thing. You know, piece of Venus, we might have something...

FLATOW: And I wouldn't even know how to look at the rocks in my backyard to tell if they were.

WADHWA: Exactly.

FLATOW: We should all bring everything we have over here.

WADHWA: No. Let's not do that.

(LAUGHTER)

FLATOW: I want to thank you very much for taking time to talk with us today. Meenakshi Wadhwa is director of the Center for Meteorite Studies, professor in the School in Earth and Space Exploration at ASU. We'll be watching for that meteorite that you got there. Thank you, thank you for taking time.

WADHWA: Thanks you very much. Transcript provided by NPR, Copyright NPR.