Interview with Guy Consolmagno

September 22, 2005


CI:      Your background is really diverse and interesting. How did you first become interested in astronomy and science?

GC:    Well, I was a Sputnik kid like everybody else in my generation. My dad was a navigator in WWII in the Air Corps, so he taught me astronomy when I was growing up. I wound up at the Jesuit high school in Detroit and studied classics, so I had an odd split interest between classics and astronomy which wasn’t resolved until my sophomore year.

CI:      Growing up in the city, did you get to do any naked eye observing?

GC:    I wouldn’t have, except that we had a summer cottage, and in the summertime we got a lot of naked-eye sky. I even got my first telescope with training steps, so that really initiated me into small telescope life.  

CI:      How did you decide between astronomy and classics? Did your college curriculum force you to tilt your hand in one direction or the other?

GC:    The decision happened in a funny way. At the time I was at Boston College, leaning towards classics. But my best friend went to MIT, and MIT had weekend movies, pinball machines, tunnels, and the world’s biggest science fiction collection. It just seemed like a whole lot more fun of a place.

CI:      Like nerd heaven.

GC:    Nerd heaven, exactly. And Boston College was not a place for nerds—it was a place for guys that wanted to have a good time. My idea of a good time means being a nerd. So I transferred to MIT and chose astronomy. Except that they didn’t have an astronomy department—they had an Earth and Planetary Sciences department. I signed up for that, thinking it was astronomy. In fact, I discovered that it was geology, with the geology of the planets as a subtopic. So basically it was by accident that I got into this corner of the field.

CI:      But it hooked you anyway, right from the beginning?

GC:    It hooked me completely. The professor who hooked me was John Lewis, who is now at Arizona. He is a fabulous character. I didn’t know it at the time, but the man is barking mad—in the best possible sense. He’s just so enthusiastic! In many ways he’s been a role model for me of what it means to jump feet first into anything you do. He’s also a good scientist in that even though he had his pet theories, he was willing to discard them given the right data. The ability to be objective was something we learned early on watching him. Which, I’m afraid, a lot of scientists never learn.

CI:      In other words, you had the perfect role model for how to do and think science?

GC:    Right. I believe so. I’ve always admired his approach to things.  

CI:      How did you pick your research specialty?

GC:    The original research that I did with John Lewis was planetary chemistry. That was because at the time I was doing better in my chemistry courses than in my physics courses. A year later I had mastered physics, so I eventually wound up going into a sort of geophysics. Since I started out doing geochemistry and wound up dabbling in physics, my career has been on the join between the two.

           I got my master’s degree by modeling the icy moons of Jupiter. In those days, the only things we knew about those moons were roughly their size and mass, out of which we could get a very crude density measurement. We also had also observed water ice on their surface.

           The model we built first tried to predict the rock/ice ratio from density. Then it tried to answer the question of heat: if a certain amount of heat comes out of radioactive elements in the rock, will it be enough to melt the ice? If so, how much? The models turned out to be incredibly crude, and they had a lot of bad assumptions in them, but most of the bad assumptions canceled each other out. In the end, what we predicted is pretty close to what we actually see.

           When I wrote my thesis on the icy moons, I was a science fiction fan, so I threw in an off-hand comment in the Appendix pointing out that water in the oceans under the crust of Europa—which I predicted for all the wrong reasons—should have chemical reactions leading to salts or even organic complexes. I made a throwaway statement, “I stop short of predicting life in the oceans of these moons and I’ll leave that for others to do.” That was sort of a snide way to claim it. As far as I know that’s the first place any science has ever talked about any life in the oceans of a place like Europa. So it could be that my little teenage dreams were precious, but for all the wrong reasons.

CI:      For most people, the notion that the moons of giant planets are worlds with atmospheres, geologies, water and oceans is a novelty. It resets our notion of what a habitable zone means.

GC:    Exactly. If we look at the giant Jupiters that are orbiting close to other stars, we see they’re much too hot. But they could have moons with thick ice crusts which harbor life underneath them. My gut feeling is that life is ubiquitous; it’s hard to stop it. But I’d still like to have some data.

CI:      This topic brings up an interesting point about life on Earth. Most people think that the rocky bodies of our Solar System are just that—rocky bodies. But Earth had to get its water from somewhere. What is the current thinking of where the oceans came from?

GC:    There are two competing theories. One is that a late veneer of comet-like material added water at the last minute. The other is that the water was incorporated early on—maybe in the form of hydrous minerals—in the stuff that made the Earth. Each theory has its strengths and weaknesses.

           The real trouble with the late veneer idea is that the isotopic ratios that you see in the water in comets are distinctly different than what you seen in the water on Earth. Maybe it was different in the original Solar System, but to explain it, you have to invoke something strange like that.   

CI:      When you talk about late veneer, how late is late?

GC:    Still close to 4.5 billion years ago.

CI:      So it doesn’t affect the timing of the emergence of life in any direct way.

GC:    No, it’ll be indistinguishable in terms of when the water gets there. But of course that water would probably have organics with it because there are organics in common with certain asteroids.

CI:      With what we know about the architecture of rocky and icy bodies in our Solar System, can we make any speculations about what the environments of other solar systems might be like? What about their ability to create a watery terrestrial planet?

GC:    Well, we thought we did, until we actually saw what other solar systems looked like! Our Solar System has rocky planets close to the Sun and icy planets farther out. The Jupiter moon system has rocky moons close to Jupiter and icier moons further out. Having seen two examples of this, we used to think that this was the rule of thumb. But the first solar systems we discovered beyond our own star have giant planets very close in. That means that this nice quiet picture that we had of warmer inside, cooler outside, may not be a general rule. All bets are off at this point.

CI:      Assuming there’s some issue with our ability to detect terrestrial-type architectures, there are certainly mechanisms within solar systems to transport icy material to the inner regions.

GC:    Absolutely. That’s one of the strong points of the late-veneer model—that you would expect it to happen. There’s an idea that solar nebula convection could dry out material on the inside. Then, as the water-rich nebula got convected to colder regions, it would freeze and build up the ice in the outer solar system. Then a late veneer would bring the ice back in and add the water at the end.

           I have to point out another problem with the late veneer model—the fact that the Moon is bone dry. If the Earth got blasted with water, why didn’t the Moon? It’s conceivable that the veneer happened before the impact that caused the formation of the Moon. That’s one way of getting around it. But all of this is pretty much wild speculation.

CI:      What about the other critical ingredient for life—carbon? Where did the organic compounds come from?

GC:    Presumably with late veneer, you’d get the organics and the water together. But if the water was built into the rocks that formed the planet, then the carbon would have to be the late-veneer. That would be the separation.

           Then there’s a third element most people don’t think about, which is where all the nitrogen came from.

CI:      Right.

GC:    We have a substantial nitrogen atmosphere in Venus and Earth. You don’t notice it in Venus because the carbon dioxide overwhelms it, but if you took away the carbon dioxide, the amount of nitrogen on Venus is comparable to that on Earth. And nitrogen does not exist in rocks. It’s just not something that’s normally formed in minerals—you have to find a way to bring it in. It could be either a late-veneer, or dissolved in the iron that makes the iron cores of the planets. I don’t know anybody who’s really working on that much, but it’s something that John Millis talked about thirty years ago.

CI:      I’ve heard relatively recently that phosphorous is another important thing that gets deposited. It’s obviously essential in terms of the molecules that form the backbone of life.

GC:    Right. Again, we see phosphates in iron meteorites, so it may be ironically enough—no pun intended—that some of the hotter stuff that you normally think of as being the center of the planet could be carrying two of the essential ingredients to make life on the surface.

CI:      When you look at what we think of as ingredients necessary for early life and the particular architecture of our Solar System, is it still a leap to say that these ingredients should have been deposited on many terrestrial planets in other solar systems? Or should we be convinced of the “Rare Earth” idea: that what happened here was really unusual?

GC:    Well, we have absolutely no data. That’s the embarrassing answer to that one. Either one is possible. That’s one of the reasons we’re so desperate to find planets around other stars. It would help put a lot of constraints on how these things work. For example, in the last ten years we’ve finally been able to observe protoplanetary discs around other stars. Because of this, we’re suddenly able to put a lot of constraints on what our own nebula must have been like.

CI:      Since you work on asteroids and meteorites, can you talk about what these small objects tell us about the history of our Solar System in general?

GC:    What you find out from the meteorites first of all is what chemical elements were around and what their general abundance was. The astonishing thing is that all meteorites are homogeneous to a tenth of a percent level, including isotopes with most extreme chemical abundances. Whatever differences there are are easily explained in terms of how much heat they were subjected to. In general, the chemical clues are pretty uniform.

           But when you go to below a tenth of a percent level, you see all sorts of hard-to-explain differences, and that’s really exciting. Those differences are mostly in the isotopes present. For example, the amount of oxygen-16 compared to oxygen-17 and 18, and the amounts of certain isotopes that we now recognize as being the daughters of radioactive elements with very short half-lives. When you see an excess of magnesium-26, it tells you that there was live aluminum-26 when the rock was formed, and that the atoms were put together in the rock crystals. It tells you that it must have been formed in our Solar System, yet aluminum-26 is generally thought to be made in supernovas elsewhere.  

CI:      Is it also saying that the formation process was very rapid?

GC:    It says that either it was very rapid or that it happened in a neighborhood with lots of other stars. That’s consistent with what you see in places like the Orion nebula. It’s not a stretch. On the other hand, there’s also evidence of materials with a half-life of days. That’s only possible if the sun itself is very energetic, and we know young stars are very energetic by looking at young stars in X-rays.

           We’ve basically got two different ways of making the isotopes. There are some isotopes that can only be made by supernovas, some isotopes that can be made by an energetic sun, and a whole bunch that can be made both ways.

CI:      To ask a very simple but important question: does the age dating of the most primitive meteorites really set the timescale of our Solar System? Is that our most accurate and reliable estimate?

GC:    Yes, and it’s extremely accurate. There are white inclusions in a particular variety of meteorite—the CD3’s—the most famous of which is the Allan Hills meteorite. You can date these white inclusions with potassium sodium and lead, which gives agreement to within a million years 4.56 billion years ago. This is consistent between the meteorites. Because we have more than one of these tracers and they give a consistent answer, that number becomes something we’re very confident in.

CI:      Let’s talk a little about another intriguing aspect of meteorites: the presence of organic materials. Has there been any kind of reliable evidence for anything more complex than amino acids in any meteorites that have been recovered recently?

GC:    I really don’t know what the latest in that is. The one meteorite that you’d look at is called Tagus Lake. In terms of molecules that have left-handedness or right-handedness, life on Earth always gives you left-handedness, while the meteoritic ones show more of an even ratio. This implies they are not made by life, but by random processes in the nebula. Most of the organics you find in the carbon-rich meteorites have been very difficult to characterize because they’re so complicated, and the chemistry is not really consistent from place to place. Most people just look at it and throw up their hands and call it organic goo.  

CI:      Since the “life-in-a-bottle” Miller-Urey experiment was updated to the proper early atmospheric composition and didn’t have that much trouble producing amino acids, does that mean that the deposition of those kinds of molecules doesn’t necessarily accelerate the formation of life?

GC:    That’s correct. There’s some debate about whether those molecules would survive passage through Earth’s atmosphere to get to the surface. If they became particle-sized dust, they could. Because dust hitting the top of the atmosphere gets decelerated pretty quickly and gently floats down. So it could be a source of organics, but it’s certainly not the only source of it.

CI:      I want to move to the fact that you are the guardian and curator of a truly impressive set of meteorites at the Vatican Observatory. Can you talk about how long you’ve been curating that collection and how it came about?

GC:    I’d been a scientist doing geology and geophysics for fifteen years when I decided to enter the Jesuit Order, mostly as a way to teach. But instead they ordered me to Rome. You know you take this vow of obedience that goes with all the other vows, so I had to go to Rome and live in this palace and eat this terrible Italian food.

CI:      All the other vows?Ivows? I thought there were only two other ones.

GC:    Oh, it feels like a lot.

CI:      Maybe they’ve been adding to the list. So when was this?

GC:    That was 1993. I’d only been a Jesuit for four years at that time, but I’d been a scientist about twenty years. When I arrived there, I discovered why they sent me. I knew about the meteorite collection, but I didn’t really know what state it was in. I knew that in the 1930’s, the widow of a French gentleman scientist had donated his rock and mineral collection to the Vatican. The Vatican didn’t know what to do with it so they dumped it on the on the Observatory. The Observatory gave away the minerals but kept the meteorites. The minerals are in Vienna now.   

CI:      I’m glad somebody knew how to tell the difference.

GC:    Yes, well that is questionable at times. The meteorites were in a complete jumble when I got there. It took a couple of months just to sort through them, organize them, and do an inventory.

CI:      But that must have been like being a child at Christmas.

GC:    It was exactly like that! Only it was more exciting because I had done research on meteorites for ten years without ever really seeing one.

           In my case it really changed my perspective because I suddenly understood a lot just by handling the rocks and looking at their textures and colors. I was able to start a research project just by measuring the densities of the meteorites. Part of that came because we had twelve hundred samples.

CI:      Wow!

GC:    About five hundred different meteorites in different pieces. And no equipment. When I got there, the only microscope I had was one that was designed to help solder wires to electric circuits. The only scale I had was one that was donated to the Pope from a scale maker in Germany in 1929. It was a beautiful antique but very, very difficult to use. A lot of what I did in the first two years was simply to assemble the equipment. It turned out that one of my colleagues in Arizona was also interested in this project and was great at scrounging equipment.

           Between the two of us, we put together a very good lab for measuring meteorite density at just the time that people were beginning to measure asteroid density. There’s been a long-established connection between asteroid surface colors and meteorite spectra; we were able to compare densities and show that asteroids are grossly underdense compared to the meteorites that we thought came from them.

CI:      Does that mean we don’t know where the meteorites come from?

GC:    No, it just means that we didn’t understand the things that the asteroids have been through. Apparently the asteroids have been broken up and reassembled, and in some cases never really completely compacted. That means that there are places within the asteroids, perhaps in the center, with cores of ice and organic stuff that no one’s recognized before. There are implications for astrobiology there in terms of a possible way of transporting organics and water in material that, at least on the surface, looks very dry. 

CI:      What about the implications for the impact environment of Earth?

GC:    It makes it a little trickier because the things that are hitting us probably aren’t as massive as we thought, by a factor of two. But they’re so big that a factor of two doesn’t particularly matter. It’s the seed that they’re coming in. It does mean, for instance, that if you’re going to try to stop a full ice asteroid it’s going to be a lot harder than you thought. Blowing them up like Bruce Willis does in the movies isn’t going to work. If something is that porous, it just absorbs explosions without cracking or shattering or doing anything. 

CI:      I have often wondered how people looking at crater sizes try to extrapolate to the size distribution that you see in the asteroid belt today. Can they connect the dots and make a sensible story?                 

GC:    They can make a sensible story, but it’s not necessarily a unique story. The big obstacle is to understand the material and how a rock of a certain size makes a crater of a certain size.

CI:      In round numbers, what’s the ratio of the crater size to the impactor size?

GC:    Well, let’s look at it this way: the object that made Meteor Crater, which is a couple of kilometers across, was maybe a few tens of meters across.

CI:      You’ve got this incredible meteorite collection and you’ve wrestled it into shape—what are the most exotic or fascinating pieces of it? I know there’s at least one Martian meteorite in it, maybe more?

GC:    There are more, actually. The three main Martian meteorites are called the SNCs. We’ve got a bit of each of them which is unusual—especially the C class, since it’s considered to be very rare. The N that we have was actually donated by John Ball, who was the acting head of the Egyptian Geological Survey back in 1912. It’s now one of the most valuable meteorites around because it’s a beautiful piece of Mars. In addition to that, we’ve got some fascinating and unusual iron meteorites. The iron meteorites are typically very poorly understood. There are also a whole variety of one-of-a-kinds that we just don’t know about. They have odd chemistry, like molten metal surrounding pieces of rock that look like they’ve never been melted or even hot. Physically, that’s hard to explain.  

           Then we have a few meteorites that are interesting for historical reasons. Like the Leglite—the one that was found in 1803 by the French scientist Biot. He was one of the first scientists to convince people that rocks really do fall out of the sky and are not just pieces of a volcano or something.

CI:      Was that the one that led to Thomas Jefferson to say that he thought it more likely that Yankee professors would lie than rocks could fall from space?

GC:    No, that was the Wintersfield meteorite in Connecticut. That fell near Yale at about the same time. His retort for Biot’s was: “What do you expect from a lying Frenchman?” He was very skeptical about lots of things.

CI:      You’re mentioning a classic episode in the history of science, because the mythological idea of things falling from the sky had been dismissed by scientists. Biot really nailed it with the scientific method.

GC:    Absolutely. One of the other meteorites that had led to this being thought a myth was one that fell in 1492. The townspeople stored it in their church. By the time of the Enlightenment it was, “Oh, these superstitious people—what do they know?” Well, it’s a real meteorite. We have it in the collection.

CI:      What’s the nature of the meteorite at the Kabbah in Mecca?

GC:    No one has ever gotten a piece of it, so no one knows for sure. The best theory that I’ve heard is that it may not be a meteorite but a piece of glass formed by the impact of a meteorite. And it’s black simply because there have been a thousand years of people rubbing it with their hands.

CI:      Have you ever thought of doing a little inter-religion initiative to figure it out?

GC:    I wouldn’t be the first one.

CI:      Right. Let me ask also about work in the field. You’ve done a little meteorite hunting yourself, right? In Antarctica? That must have been a fascinating experience.

GC:    Well, every year for the past thirty years, the Americans have sent teams to the blue ice regions of Antarctica. Blue ice regions are places where the ice has been flowing down from the South Pole towards the ocean and runs into an obstruction—a mountain range or something that makes it stop. The ice has little specks of dust or gas bubbles mixed into it, which causes it to look blue because those points scatter the blue light, just like the sky. Meteorites that might have fallen during the thousands of years that it took to flow to this position are also trapped in this ice. The meteorites are kept frozen so they don’t rust, which is what happens to meteorites anywhere else. A typical meteorite that falls in North America, unless it falls in the desert, is going to turn into dust within twenty years. That’s why you don’t notice them. But in Antarctica, they can last for thousands of years. It’s very easy to find them once they’re on the surface: the meteorites are black, the ice is blue.

CI:      What’s the deposition rate? If you could recognize all the meteorites that fell in a particular area, what amount of material would you be looking at?

GC:    Generally, the people who talk about this say that something like ten thousand meteorites hit Earth a year. Now of that, three-quarters land in the ocean. After that you just work out the statistics. Given how long they last, and how fast they come down, you might expect to see a meteorite roughly every two square kilometers. But in fact, you don’t. They’re just completely lost.

CI:      Do you expect to see these literally lying on the surface, or imbedded in the top few inches of ice?

GC:    Imbedded in the top few inches. Stony meteorites, when they hit Earth’s atmosphere, slow down and break apart into small pieces. The pieces that survive to land don’t make much depth. If they hit houses—which they do every now and then—they’ll poke a hole through the roof, and maybe go as far as crashing all the way through to the basement of the house. But they don’t destroy the house. They’ve already slowed down enough and are essentially traveling at terminal velocity.                                    

           Iron meteorites, when they hit, don’t do that. They’re much stronger and stay together. So they carry quite a wallop. Iron meteorites make impact craters like Meteor Crater’s.

CI:      Were you ever part of a crew in Antarctica?          

GC:    I was part of a crew in 1996. We lived in a tent out on the Antarctic Plateau, hundreds of kilometers from anybody.

CI:      It wasn’t even a nice base with a little movie theatre and cozy canteen?

GC:    No. There are six people in three tents. You do your toilet business outdoors, you know, in the snow bank.

CI:      And it’s pretty cold, right? Even in the summer?

GC:    Even in the summer it’s very cold. 

CI:      Then there’s some hazard associated with doing your toilet business.

GC:    There is indeed.

CI:      That’s really roughing it.

GC:    It really is. Except in a lot of ways, the things that always bugged me about camping were mosquitoes or being really damp. That doesn’t happen in Antarctica. You don’t have to worry about either of those things.

CI:      How long are you out there in a stretch?

GC:    The American group is out there for six to eight weeks at a time every year. The Japanese build a camp and stay there for eighteen months. A winter, a summer, and then another winter.

CI:      That’s brutal.

GC:    Yeah. And they go down by boat. We go down by airplane which is ten hours of misery. They’ve got two weeks of misery. But both groups essentially do the same thing. You simply go out in mechanized skidoos and traverse the blue ice regions, just sweeping back and forth and picking up anything that’s not the ice.

CI:      Do you use sticky rollers for the little stuff?

GC:    No, we haven’t been doing that. There are some groups looking for dust that will dig quarries of ice and melt the ice to try to collect it that way. But with meteorites you actually have to be very careful about handling. You don’t touch them with your hands. You put them into sterilized Teflon bags using forceps. Actually, what we used a lot was sterilized scissors. For some reason, scissors get a nice, tight grip on them. But the whole point is to try to keep them as free from contamination as possible.

CI:      Were you working close to the place where the famous Allan Hills meteorite was found?

GC:    Yes. We were about twenty or thirty miles away, I think, from where Allan Hills was. It just happened to be where we were that year. The difference is that there are some regions—and I believe the Allan Hills is one of them—where the meteorites are found among terrestrial rocks in a glacial moraine. You have to be able to recognize the one rock that looks different among the thousand rocks that are identical. It was something of an accomplishment that they saw the Allan Hills rock because the odd thing about Martian meteorites or lunar meteorites is that they don’t look like other meteorites. They look a little more like terrestrial rocks. I heard that even in the field there was some argument as to whether it was a terrestrial rock or not; I guess they decided it was better to take it than not.  

CI:      How did you do? Did you find any?

GC:    We found four hundred meteorites, which is a pretty good haul. There have been places that yielded over a thousand, but eight hundred of those thousand are often tiny pieces of the same fall, so it’s kind of boring. We got four hundred meteorites, most of them unique, and one of them was a piece of a lunar meteorite. So we brought back a piece of the Moon.

CI:      Was it recognizable in the field?

GC:    Yes it was. Several of our people had worked with Moon rocks before. One of our guys worked at the Johnson Space Center. It was obvious to us almost immediately because it had all the classic characteristics of a lunar meteorite. That was very exciting.

CI:      When were you there? Are you planning on going back?

GC:    I was there in 1996. I probably won’t be going back. I’m past fifty now, and even then, the fact that I needed bifocals meant that it was hard for me to make certain kinds of identifications. It’s frankly a young guy’s game unless you’re in really great shape. So, I’m leaving it to the younger people.

CI:      But it sounds like quite an adventure.

GC:    I’m reminded of my sister’s description of childbirth. In retrospect, it’s wonderful. But at the time you’re in it you’re thinking—why the heck am I doing this? It was very rough. Although I loved it there and thought it was beautiful, I was also really happy to get back to civilization. You know, hot showers are a wonderful idea.  

CI:      Definitely. I wanted to get an idea of how you think astrobiology might play out given the limits and amount we’ve learned about our own Solar System and the history of Earth. You mentioned that you’re optimistic that other solar systems are likely to be built for life. But how do you see the field going in the next decade or so?

GC:    I think the real push—the fastest way we could find life elsewhere—would be if we found any evidence that it had been on Mars. That’s simply because Mars is the easiest place to get to and explore where life might be or might have been. The more we look, the more we realize how hard it is to know if you’ve found life. All of the chemical tracers that you would think of as signs for life can be mimicked in many places by exotic, inorganic chemistry. And because it’s Mars, you don’t know what’s exotic and what’s not.

CI:      That’s what was behind the whole controversy over the Allan Hills meteorite itself.

GC:    That’s right. It’s also behind the controversy of the methane they found on Mars last year. People initially thought that it could only have been made by life. However, they went back and saw odd, but very plausible, inorganic ways that it could be made. On the other had, maybe it is made by life. 

CI:      That actually leads to a cultural point about science for the public. They see the first sexy headline and immediately react. You rarely ever see the same emphasis placed on the more nuanced discussions that the scientists have on these issues. Do you encounter that, too?

GC:    All the time. It’s a problem in journalism that there’s never been a distinction made between the cutting edge stuff, which has a fifty percent chance of being right, and the textbook stuff—the stuff that we’re pretty convinced that we know is right.

           That’s why I think you’re not going to hear about life on Mars reliably in the newspapers. It’s going to be one of those issues that will be around long enough to finally become convincing. You’ll have to read in a textbook the actual story of how it was discovered and scientifically proven.

CI:      We’re anticipating and planning sample return missions, but they’re very expensive and they’re still going to take awhile. Do you think that we really need them? Are Martian meteorites of slightly unknown providence and history never going to really convince us?

GC:    That’s for sure. Especially because the kinds of rocks that we’re convinced come from Mars are not typical of what we see over most of the surface of Mars. What we see over most of the surface of Mars, and the kinds of rocks we think might have life are apparently too small or too fragile to survive being launched off that way. We will probably have to bring back samples. I do worry about sending human being to Mars until we know what’s going on. Simply because human beings are leaky. And the worst possible result would be to find life on Mars and say what we found is identical to life on Earth. Because then we’ll never know if we brought it there ourselves.

CI:      Are you anticipating that we’ll have the answer within a decade or so?

GC:    No. Fifty years I’d say, for Mars, and a hundred years for Europa. I’m pessimistic about how fast we can advance our technology to explore these places. I think we know where to go, but we sure don’t know how to get there yet. Just as an example, there is a fascinating place in Antarctica—Lake Vostok—which we know from seismic measurements is a liquid water region. It’s like a lens of liquid water underneath the Antarctic ice that’s been isolated from everything for thousands of years. We’ve drilled close to it, but no one has been able to figure out a way to drill down and sample the water without contaminating it.

CI:      So that’s our Europa analog.

GC:    Exactly. And if we can’t do it here on Earth, what gives us the confidence to know how to deal with it when we get to Europa? Someday we’ll be able to, but that someday isn’t yet.

CI:      When we’re talking more about remote sensing and biomarkers, might we find there’s still too much ambiguity in how we’d interpret spectroscopic evidence?

GC:    I’m afraid there will always be that ambiguity—and rightly so. Because it’s such an exciting and important discovery, you really want to be sure you’ve got it nailed.  

CI:      That’s the Sagan quote about extraordinary claims requiring extraordinary evidence.

GC:    I’m afraid that’s right.

CI:      I wanted to finish by asking you a little bit about how the pieces of your life are integrated. You’re a priest, you work on science, and you’re in the heart of the Vatican with meteorites. For some people, that would seem like an unusual life.

GC:    It isn’t unusual at all. Most of science is collecting data, sorting data, and filing data. It’s clerical work. The reason that work is called clerical work is that until the 19th Century, it was clerics that did it. Only clerics had the free time and the education to do that kind of science.

CI:      Also to preserve knowledge during all those dark times in history.

GC:    During the Dark Ages, sure. Which would be not just the Middle Ages but the French Revolution. It’s a great luxury to be able to dedicate your life to the stuff that won’t make you rich and won’t put food on the table, but does make life all the more interesting to live. I think there’s a great religious motivation for doing the science. The joy that I feel when I make a scientific discovery is an awful lot like the joy I feel in a really wonderful moment of prayer. I feel it’s that same connection to what is out there. Some scientists would call it a connection to the universe; I’d go further and say that it’s not just a connection to the universe, but a connection to the Creator of the universe.

           The important thing is that science and religion, when they’re done right, are dedicated to truth. And truth trumps any of one’s preconceptions. But along with that is the humility to know that what you think is true now, or what you think you knew, like the new discoveries in the newspapers—there’s a fifty-fifty chance that it may not be what you think it is. So you don’t want to throw away the old stuff too quickly just because of the new discovery. Rather, you’d want to see how all of these different pieces give you a grander idea of how the universe works.

CI:      In this country, there are tensions between certain religious traditions. You’re lucky in a sense that you’re in a religious tradition that really encourages intellectual thinking and questioning.      

GC:    One of the great things about being a Jesuit and a scientist is that a lot of other scientists have been able to tell me about their religions. There are scientists of every religious tradition you could imagine—including Evangelicals—doing good, solid science. A number of people working on the Allan Hills 84001 meteorite in fact belonged to the same Presbyterian Church. Which is actually the same church that one of the astronauts belonged to—the one who took a chalice of communion wine to the moon.

           There is, I think, a great religious motivation for what we do. The conflict comes when people are afraid of what science is going to teach them. I think a person who’s afraid of science is really a person that’s afraid for their faith because their faith isn’t very strong. Likewise, I think a scientist who feels threatened by religious people tends to be afraid of not being taken seriously as a scientist if they were religious. It’s a myth that you have to choose between one and the other. It means lots of good religious people miss out on all the fun that science can be. And vice versa.

CI:      That’s a nice perspective. My last question is about the big picture of astrobiology. What if we’re faced with the reality that our biology is not unique? That life in the universe is not unique? There must be some interplay with that as a religious person, because many religious traditions have emphasized the specialness of man or the specialness of life. How do you view the prospect of not only life, but intelligent life?

GC:    It reminds me of the medieval theologians who worked out the phrase that we are made in the image and likeness of God. I believe it’s Thomas Aquinas who really formulated it. What we’re really talking about is the soul, intellect, and free will—that you have knowledge of yourself and knowledge of the other person. You’ve got self-awareness and you’re free to do something about that. You’re free to love that other person. You’re free to make decisions for good or for evil.

           If we’re going to have any interaction with any intelligent being that we discover, it must have those two attributes. If we’re going to call them intelligent we should be able to interact with them and they should be free to choose or not choose what they’re going to tell us. That’s more than just talking to a computer. In that case, they are also in possession of what we would call the essential of the soul. And so they are no different from us and no different for the moral challenges. Just as I would expect their bodies to obey the same laws of chemistry and physics, I think they’d be faced with the same moral laws. It would be really interesting if we could communicate. I’m not sure in our lifetime or in the next millennium that we’ll be able to.

           I read a wonderful comment by a theologian, Ernie McMullen: “You know, Christians faced with another race and all of these issues will make us start to reexamine our theology of original sin and our theology of the meaning of salvation.” But then he says, “On the other hand, we’ve been arguing about these things for two thousand years now without any consensus so it won’t be that much of a difference.” 

CI:      So you’re excited by the prospect. Because it will force us to look deeper at ourselves as well as force us to understand our place in the universe better.

GC:    Yes. And in some ways it will force us to look at all the other assumptions that we’ve made. To bring it to an analogous conclusion, there was an announcement a few months ago of the discovery of an object bigger than Pluto. I’m on the committee that’s supposed to be looking at whether it’s a planet or not. It’s a fascinating question and a fascinating discovery, but now that I know that there are more things than Pluto out there, it’s changed what I think about Pluto.  It’s put the entire classification of objects in the Solar System into totally new categories. I think finding life elsewhere will do that for our understanding of what life is. Probably in ways that we can’t even guess at yet.