Emory Mckenzie
Welcome to Longitude Sound Bytes, where we bring innovative insights from around the world directly to you.

As part of our new series focusing on expeditions and the roles of individuals who are advancing science through explorations in harsh environments, our conversations aim to shed light on fascinating projects that help us understand our planet and make life on earth better.

I am Emory Mckenzie, a graduate student at Rice University pursing my masters in Earth Science.

For this episode, I had an opportunity to speak with Dr. Ralph Harvey, principal investigator of the Antarctic Meteorite Search Program for over 30 years!

Ralph is a professor of planetary sciences in the Department of Earth, environment and Planetary Sciences at Case Western Reserve University in Cleveland, Ohio. He has been running the US Antarctic meteorite search program since the early 90s.

I’ve learned that going to Antarctica is no easy feat.  He speaks about the harsh conditions and small windows of opportunities each year for these meteorite searches. 

We begin our conversation with how and why the meteorite searches started, and how Dr. Harvey got involved in them while being a grad student. 

Ralph Harvey
Basically, way back in 1969, some Japanese glaciologist stumbled on the first concentration of Antarctic meteorites. They had been found before, kind of serendipitously by people exploring the continent. In fact, the first one was found in 1912 by some guys. They had dog sleds and woolen canvas clothing. They were Australians, and they were just kind of crossing a bit of ice and there was a meteorite laying there. They knew it had to have fallen from the sky. There wasn’t any terrestrial rocks around, it was just snow for 100 miles in every direction. But this Japanese group in 1969 stumbled across nine of them, stretched out over kind of about a kilometer or so. They weren’t 100% sure that anything interesting was going on but my PhD advisor, the late Bill Cassidy, had seen a talk about this find, and then later on, saw a talk where they described the rocks. There were five different kinds of rocks amongst those meteorites. Some of them were relatively rare types of meteorites. And he had one of those eureka moments. You know, he did the math in his head, and said, nine meteorites but a couple of them are kind of one and thousand kind of meteorites, there must be a boatload more of them out there. He ran up to the Japanese speakers and said, do you know what you’ve got? This is a treasure trove and it’s out there somewhere! And so, the Japanese researchers went right back. In the next year, they found like 40, in the next year, they found like 500, in the next year, they found like 1000. Meanwhile, Bill Cassidy had been trying to get the US Antarctic program to start a search, and the US Antarctic program said, there is no such thing, you’re dreaming, you know, but after a few years of watching the Japanese strike gold, so to speak, they turned around and they said, Okay, go look for some. That was the first year of our project in 1976. We have been going into field, basically continuously since then. And with the pandemic, the last couple of years, it is the third one we’ve missed in a row because of pandemic related stops. That’s where the project comes from. I was a graduate student of Bill Cassidy’s at the University of Pittsburgh in the late 80s. Got my PhD in 1990 and ended up essentially adopting the program or inheriting it might be a better word, started leading the field parties in 1991, and I’ve been the PI, the principal investigator, since. In fact, I’m going to step back from that leadership in just a few months. A guy named Jim Karner is going to take over the functional leadership.

Emory
So typically, how long are the field seasons?

Ralph
Well, we’re working in Antarctica and Antarctica has reverse seasons than the north hemisphere, right. It’s called the Austral summer that runs from kind of November through February. We are working high up on the East Antarctic Ice Sheet at altitudes the equivalent of… pressure altitude would be about 10,000 feet, the functional altitudes like 2500 meters, 2200 meters. So, we’re way up there. The winds are incredibly fierce. There’s nothing to stop the winds. And these are katabatic winds, they call them. They just scour the edges of the ice sheet and blow away all the snow and stuff. We try to get out there. When those katabatic winds are starting to die down. We can’t go out there just when the sun rises because that wind is howl. We’re talking periods of continuous 80 mile an hour wind for two weeks. I’m not talking gusts, I’m talking continuous, right? It’s pretty much like a hurricane that doesn’t pass through. It’s a hurricane that just keeps going for weeks and weeks and weeks.

Generally, we get to our field sites kind of the first week of December and spend about six weeks. So, we usually have a resupply mission in the middle. We’ll have a plane drop in to bring us any extra fuel we need any snowmobile parts, whatever, whatever’s broke, they can bring us to replacement. But other than we’re self-sufficient. We get out there with everything we need and we’re just out there camping for about six weeks. We still have those winds. Generally, we count on losing about 40% of our field season to winds that are just too high for us. The snow starts moving. You can’t see the ground in front of you. You can’t see the meteorites. So we’re all kind of hiding in our tents. And some of those storms can be 7-10 days, they can be pretty brutal, but more often it’s two or three days. We count on, maybe in a given work week, we’re happy if we get four of those days are full workdays. Sometimes we get a month that’s gorgeous, it’s the weather, right? It’s not fully predictable. And we are very much subject to it, you know, we’re out there, more exposed probably than almost any other Antarctic field team.

Emory
So, what’s like the threshold? You wake up one morning and the winds are gusting but it’s not too bad. So, what makes it too bad?

Ralph
It’s the visibility, really. We measure the wind. We put out weather stations stuff. You get about the equivalent of about 20 knots, which could be like 22 miles an hour. It starts to get to the point where there’s enough moving snow that your visibility’s going down. By the time you hit about 25, it’s pretty much time to go home. And of course, it’s very uncomfortable too, right. Our primary tool for finding the meteorites is their eyeballs and being able to look around put your face in the direction of the wind, that’s pretty critical for us. So if people are like pulling their hoods over and trying to look out a little slot in the hood, that’s, we understand that it’s not just the visibility of the meteorites, it is how well a human can search in those conditions as well. Because the weather can change pretty quickly. It’s not unusual for us to kind of work a half day when the conditions are marginal.

Emory
How do you choose who goes into the field?

Ralph
The process by which we select people, I’m gonna give you a little history first. The Antarctic meteorite program, after the first finds came back, my predecessor Bill Cassidy, had plans to bring the rocks back to Pittsburgh. But he also realized that every other museum, every other school, anybody could write the same proposal and say, oh, I am a doctor now, let’s  go get some meteorites for ourselves. In that, it was going to become a disaster because the US Antarctic Program wasn’t going to fund all of them. They were going to find maybe one a year. The meteorites would be scattered all over the place. Each different college, each different museum having a couple of dozen and that’s it. So, it wasn’t going to really help science that much, it was going to help individuals. And he made a very clever, altruistic decision, which was, he got together with the best meteorite labs out there; the Smithsonian, and the Johnson Space Center’s lab that used to handle the moon rocks. Of course, the Apollo program had been done for about five years by then. And they made a deal. The basic deal became to be called “the three-agency agreement”. What it said was Bill Cassidy would lead the fieldwork to pick up the meteorites, they would then go to the Johnson Space Center where they do initial characterization, and then the Smithsonian would do long-term curation and help with the characterization. And in exchange for kind of having these guaranteed jobs, everybody would give up their rights to the samples. No archaeologist studying cities in the Amazon would say, Oh, look at this great city I just found, why don’t I invite everybody else to profit from it? Nobody would do that, right. But in the case of the meteorites, Bill Cassidy was brilliant. Because he had a sense that they were going to be not just 1000s, but 10s of 1000s of them. It would have been more toys than he could ever do anything with, that also helped the project survive to this day, because it meant that other people could make the initial important discoveries.

The way this interacts with the field party selection, is that by the time I came on board, we realized that sharing not just the samples, but sharing the field experience could do the same thing for us in the long term. And so I set a policy where we would accept volunteers. It’s not a democracy. It’s not first come first serve. We have our priorities, right. But the idea was that we would accept volunteers, anybody that said they could deal with it could write me a letter. Now, it would go to Jim Karner at Utah, and explain to us what they would get from it. We gave the highest priority, we still do, we give the highest priority to people that are actually doing research on Antarctic meteorites. But that’s not a very deep list. You know, next priority would come to people that are in related fields, like planetary geology, or mineralogy, or whatever, that also have maybe field experience that we need. But we don’t throw any letter away. We would take one from someone who’s interpretive dancer, if they can compel to us the value of their participation. Not just for us, but for the community as a whole. We, in fact, had some writers go with us, which was good. We’ve had astronauts go with us. That would be part of their training for extreme environments. We’ve also been very, very careful to try and make it as diverse as we could, taking people from all around the world. I don’t know how many countries are represented right now but I think it’s about 45, there is a lot of countries. Gender, race, all of that we try to have that as balanced as we can. But anyway, so it’s not a democracy, we look at these letters every year.

The letters have to be on paper. That’s turned out to be an awesome, big hurdle for most people in the modern era, right? Anybody can shoot off an email or a tweet or a text and say, oh, yeah, man, this is what I’ve always wanted to do. But most of the time you make him sit down and put it on paper and write and find an envelope with a stamp. A lot of people who stop right there and say, you know, wait a minute, this seems a wee bit like I’m being official, I’m not just expressing my curiosity anymore. I’m saying I’ll do it, if you invite me. We get about 100 letters a year. Opportunities are very limited, you know, our typical field size is eight. We want half of those people to be veterans. Now that would involve one or two of us, a mountaineer, and one of the leadership team. Sometimes two mountaineers, and then the rest, if at all possible, we fill with newbies. In recent years that means one, two or three people a year, which isn’t that much in real terms but it’s phenomenal by this stage. There’s probably, I think we’re over 200 Different people across the scientific community that have been with us in Antarctica, had this experience and it is generally described as a life changing experience.

Patience is the key. So, if you yourself want to write a letter, you write the letter. What’s really smart, though, is to make sure that you don’t say, I could go any time, or I want to go right now. I love it. Love it, love it. Now, what do you want to do is say, I’m a grad student, I’m gonna finish in 2024. 2025 sounds pretty good to me and here’s my skills, and this is why I want to do it. We look at all those letters every year. Again, not first come first serve, not a democracy. We construct a field team that we think is going to be positive, that is going to be able to deal with the isolation, and the physical hardships, and is going to be so jazzed about the meteorites themselves, that getting out to work every day or doing nasty stuff when it’s super cold, they’re never going to say not today. They’re always going to say, please, I’ll do more.

Emory
What is like the operating procedure for sampling? So how do you move around on the ice sheets? How are you choosing positions for sampling?

Ralph
The meteorite concentrations that have been found so far, are on very old surfaces, what we call blue ice. It is blue, it is deep glacial ice that is in places where the ice sheet is eroding because of these fierce winds because very, very dry air. The ice sheet is eroding down into ice several 100 meters down where you’re seeing bubble free blue ice. Just like deep, deep, clear water. All around the edges of these Antarctic ice sheet there are places like this, where that flow is then hindered by the presence of submerged mountains or emergent mountains. Basically, the equivalent of ice cul-de-sacs where the ice flows in and either has to throw out so slowly, that loss mechanisms like the fierce winds like a one sunny, warm day, where those loss mechanisms succeed any input from ice flow or falling snow or whatever. And when you have a surface like that, what you have is effectively, we call it an ablation surface because it’s losing material. If that surface is stable for 10s, of 1000s of years, hundreds of 1000 years, even millions of years, the meteorites that are falling from the sky just tend to build up there. And that’s probably most of what’s happening. They don’t get buried on these sites because there’s not much precipitation. You can get a lot of meteorites built up on every square kilometer. And given that there are hundreds of these kinds of sites, and some of them are quite extensive, finding the ones that have been this way, and that stable, is a big part of our job.

In the early days, they just flew around with an airplane and looked around. Satellite imagery really changed all that for us. Now we can look all across the continent in very high resolution, and kind of see these blue ice areas. And then we look at the setting of the blue ice areas. It’s got to be high enough, where the average temperature is really, really cold, like minus 15 minus 20 degrees Celsius. If it gets too much warmer than that meteorites can heat up and kind of thermally tunneled down into the ice. We’re not going to dig in for meteorites, when there’s other places where they’re, they’re piled out.

The first job for us as a research project, is to kind of locate these places, and prioritize them. The second job is to put boots on the ice and go look at the rocks that are on the ice and see if they’re really meteorites. In ideal circumstances, there are no terrestrial rocks there, you know, it’s a place where all the terrestrial stuff is downhill and downwind. Those are awesome, right? Any meteorite, any rock, you see sitting on the ice had to fall from the sky. So, it’s almost certainly a meteorite. Those areas where the gold mines of the first 20 years of the project. At the time I was in a leadership role, we were finding more and more of them in places that were like downwind traps and other things like that. And so nowadays, that’s a more likely place where we would spend significant parts of a field season. Places where the meteorites sat on the ice, but then they got blown downwind by these fierce winds and all of that.

So, a very big part of our job is, is learning to tell terrestrial rocks from meteorites. Turns out that the human brain is really pretty good at that. Rocks falling from space have a burnt outer crust, so they look different in terms of their exterior texture and color. And once your brain is kind of memorized with the rocks around, the normal terrestrial rocks around are like, your brain is really good at kind of just ruling those out. And we found that even people that are really not rock people can learn to tell terrestrial rock from a meteorite with about a day or two a training, it really doesn’t take a lot. And we really trust that because what we found is, when we use metal detectors or something else that’s a little more sophisticated, people tend to get a little bit of tunnel vision. The human eye-brain system is so evolved to notice things that are a little different, than when you focus on like the signal from a metal detector. Or you focus on a needle on a dial, you lose a lot of that you become one dimensional, and we don’t want to do that, because a lot of the best meteorites to be found look a whole lot like a terrestrial rock but there’s just some little difference, you know.

Emory
Would you describe the burnt outer crust of the meteorites?

Ralph
It looks a lot like a charcoal briquette. You know, what’s happening is the meteorites are sitting out in space at like 17 degrees Kelvin, I mean, it’s incredibly cold. And when they hit the Earth’s atmosphere, they’re going brutally fast. We are talking 1000s of miles per hour. The result is that all that kinetic energy, by the time it hits the atmosphere, even the tenuous little molecules in the outer atmosphere, they’re hitting like little grenades. Rocks don’t transmit heat very well. They don’t conduct heat basically at all. So the friction that develops becomes fireballs we see at night. The inside of the rock is still 17 degrees Kelvin. The result is that these rocks when they do finally get to the surface of the Earth, almost inevitably have this thin coating, a millimeter or two, basically bubbly blasts. It’s usually black simply because it’s got all the elements that are in the meteorite kind of mixed together and dust. And, it’s black. It can be matte or it can be really pretty glossy glass depending on what melted. But the point is, it’s this black outer coating. Meanwhile, the inside can be very different. It can be bright white, colored gray or green or whatever. So when we see a rock, that’s like, rounded corners like a charcoal briquette, black, and kind of matte on the outside, and particularly if we see corners knocked off, and the inside is a completely different color. Bingo. It’s probably a meteorite. That said, some of these have been sitting on Earth for 200,000 years, and the fierce winds and everything can knock that fusion crust off. Sometimes all you see is the inside. Sometimes they almost kind of look terrestrial. That’s another reason we like to have veterans on the program, right? Because the newbies figure out the fuse compressing really pretty quick. But there are other types rarer types of meteorites that we don’t want to miss that, we hope the newbie says, This doesn’t look right. It doesn’t look like a meteorite to me but it does have some of those features. And you call over a veteran, they say, Holy cow, you found a piece of the moon! So that fusion crust is the number one thing kind of we’re looking for. There are other ways to tell something is a meteorite, right? The most common ones to fall have metal in them. So, a metal detector could do that. But the fancy ones that we really care about, like a rock from Mars, they don’t have any metal in them. They look like a volcanic rock, which Antarctic is covered with so we don’t want to miss those. And again, we stick with the trust of the human eye brain system, totally intuitive but they know it’s there.

Emory
Intuition is probably, not even probably, it is my favorite thing about geology. Sometimes you look at things, what you are looking at what you have that this is different from this, and that means something.

Ralph
Yeah, and just to stretch that a little further, we’re getting off in Arctic meteorites, but I’ve been teaching for a long time. A corollary to that is geology isn’t math. And it’s not physics. You can have two rocks that look exactly alike, and they have completely different origins, right? Different history, a different, you know, how did they get that way? Well, this one, sat in the Appalachians for 500,000 years and got rounded in a stream. This other one over here is four and a half billion years old. Geology is not an exact science. And it’s not two plus two always equals four. For us, four can happen a lot of different ways. And so you’re right. And it’s a reason that most of the geologists that make kind of geology changing discoveries, they’re the ones that have seen so many rocks, so many outcrops and everything, that they understand just how complex it will be, and they’re willing to let their intuition guide them toward the best solution out of 100 that are possible.

Emory
So you mentioned rare meteorites, what question are you trying to answer when you’re looking at these meteorites, and what would make a meteorite rare?

Ralph
About 90 to 92% of our type of meteorite we call ordinary chondrites. They seem to represent material that goes all the way back to the origins of the solar system, when there was this nebula of gas and dust, it started spinning together and under gravity forming the sun. And during that process, little grains of dust became bigger dust bunnies, became little bits of gravel, etc. And eventually, in some cases built up to be planets and the sun itself. And most ordinary chondrites have a composition very similar to the Sun itself. And so we argue that they represent this very earliest stage in the history of the solar system. That’s most of the meteorites that fall, they’re still really important, even if they’re not super rare. That said, most of those ordinary chondrites probably come from the asteroids in the asteroid belt, but some of them get knocked off bigger bodies, things that were almost planets, and some of them like we’ve described comes off full blown planets. We’ve got pieces of Mars, the Moon, and maybe technically not a planet, but it’s big enough.

Emory
What are the size of those samples, like, how big are those samples?

Ralph
Any of those that have undergone, let’s call it planetary processing, they are telling us about how planets evolved. They’re they’re giving us samples with different starting conditions, different sized planet, different amount of heat, different, maybe even different starting composition, right. So, these only make up 5% of what seemed to fall. But for those geologists that are really into the look for life on Mars, a Martian meteorite is awesome, that’s, it’s the best you’re going to do in terms of working on a real sample, right? There’s something on the order of about 100, Mars meteorites that are known now.

And then, on top of that, for some specimens, the rarest of the rare, they not only tell us about the formation of the rock, the lithology we’re looking at, but they may have secondary minerals on them. That original lithology may have interacted with the environment of its parent body, whether it’s Mars or an asteroid or whatever later on. And so suddenly, we begin to learn about the environmental conditions that were extant in the surface of that planet. You can dish out a lot of information from samples, and that’s one of the drivers for us to continue to do this recovery of the specimens in Antarctica. It is a place where, on average, we can bring back four or 500 specimens every year that are new to science. And while 90% of them may be stuff, very similar to what’s been found before, the only way we’re going to find stuff new is to keep doing it. That alone makes it worth it to the scientific community.

Emory
Are you able to take any samples for yourself?

Ralph
No, in fact, in fact, that’s part of the deal I was talking about this kind of altruistic deal that Bill Cassidy set up. It actually goes further than that, you know. I don’t dare be seen having a meteorite collection myself. That goes so counter to the spirit of what this project is supposed to be about. I love meteorites, but it’s the sacrifice that had to be made for me to be able to run this program for so long. It’s so fundamental to our purpose, right? That what we are doing is recovering these specimens for other people to make discoveries. Not for us, and certainly not for us to put on the mantle above the fireplace, like a trophy.

[music]

Emory
We hope you enjoyed our episode. Please visit Longitude [dot] site for the episode transcript.

This spring our podcast episodes are accompanied by an exhibit of photographs from the Antarctica expeditions at the Rice University library. Our exhibit will be available for display at other university libraries upon request.

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